[Federal Register: May 15, 2008 (Volume 73, Number 95)]
[Rules and Regulations]
[Page 28211-28303]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15my08-18]
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Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Determination of
Threatened Status for the Polar Bear (Ursus maritimus) Throughout Its
Range; Final Rule
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R7-ES-2008-0038; 1111 FY07 MO-B2]
RIN 1018-AV19
Endangered and Threatened Wildlife and Plants; Determination of
Threatened Status for the Polar Bear (Ursus maritimus) Throughout Its
Range
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
threatened status for the polar bear (Ursus maritimus) under the
Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et
seq.). Polar bears evolved to utilize the Arctic sea ice niche and are
distributed throughout most ice-covered seas of the Northern
Hemisphere. We find, based upon the best available scientific and
commercial information, that polar bear habitat--principally sea ice--
is declining throughout the species' range, that this decline is
expected to continue for the foreseeable future, and that this loss
threatens the species throughout all of its range. Therefore, we find
that the polar bear is likely to become an endangered species within
the foreseeable future throughout all of its range. This final rule
activates the consultation provisions of section 7 of the Act for the
polar bear. The special rule for the polar bear, also published in
today's edition of the Federal Register, sets out the prohibitions and
exceptions that apply to this threatened species.
DATES: This rule is effective May 15, 2008. The U.S. District Court
order in Center for Biological Diversity v. Kempthorne, No. C 08-1339
CW (N.D. Cal., April 28, 2008) ordered that the 30-day notice period
otherwise required by the Administrative Procedure Act be waived,
pursuant to 5 U.S.C. 553(d)(3).
ADDRESSES: Comments and materials received, as well as supporting
scientific documentation used in the preparation of this rule, will be
available for public inspection, by appointment, during normal business
hours at: U.S. Fish and Wildlife Service, Marine Mammals Management
Office, 1011 East Tudor Road, Anchorage, AK 99503. Copies of this final
rule are also available on the Service's Marine Mammal website: http://
alaska.fws.gov/fisheries/mmm/polarbear/issues.htm.
FOR FURTHER INFORMATION CONTACT: Scott Schliebe, Marine Mammals
Management Office (see ADDRESSES section) (telephone 907-786-3800).
Persons who use a telecommunications device for the deaf (TDD) may call
the Federal Information Relay Service (FIRS) at 1-800-877-8339, 24
hours a day, 7 days a week.
SUPPLEMENTARY INFORMATION:
Background
Information in this section is summarized from the following
sources: (1) The Polar Bear Status Review (Schliebe et al. 2006a); (2)
information received from public comments in response to our proposal
to list the polar bear as a threatened species published in the Federal
Register on January 9, 2007 (72 FR 1064); (3) new information published
since the proposed rule (72 FR 1064), including additional sea ice and
climatological studies contained in the Intergovernmental Panel on
Climate Change (IPCC) Fourth Assessment Report (AR4) and other
published papers; and (4) scientific analyses conducted by the U.S.
Geological Survey (USGS) and co-investigators at the request of the
Secretary of the Department of the Interior specifically for this
determination. For more detailed information on the biology of the
polar bear, please consult the Status Review and additional references
cited throughout this document.
Species Biology
Taxonomy and Evolution
Throughout the Arctic, polar bears are known by a variety of common
names, including nanook, nanuq, ice bear, sea bear, isbj[oslash]rn,
white bears, and eisb[auml]r. Phipps (1774, p. 174) first proposed and
described the polar bear as a species distinct from other bears and
provided the scientific name Ursus maritimus. A number of alternative
names followed, but Harington (1966, pp. 3-7), Manning (1971, p. 9),
and Wilson (1976, p. 453) (all three references cited in Amstrup 2003,
p. 587) subsequently promoted the name Ursus maritimus that has been
used since.
The polar bear is usually considered a marine mammal since its
primary habitat is the sea ice (Amstrup 2003, p. 587), and it is
evolutionarily adapted to life on sea ice (see further discussion under
General Description section). The polar bear is included on the list of
species covered under the U.S. Marine Mammal Protection Act of 1972, as
amended (16 U.S.C. 1361 et seq.) (MMPA).
Polar bears diverged from grizzly bears (Ursus arctos) somewhere
between 200,000 and 400,000 years ago (Talbot and Shields 1996a, p.
490; Talbot and Shields 1996b, p. 574). However, fossil evidence of
polar bears does not appear until after the Last Interglacial Period
(115,000 to 140,000 years ago) (Kurten 1964, p. 25; Ingolfsson and Wiig
2007). Only in portions of northern Canada, Chukotka, Russia, and
northern Alaska do the ranges of polar bears and grizzly bears overlap.
Cross-breeding of grizzly bears and polar bears in captivity has
produced reproductively viable offspring (Gray 1972, p. 56; Stirling
1988, p. 23). The first documented case of cross-breeding in the wild
was reported in the spring of 2006, and Wildlife Genetics International
confirmed the cross-breeding of a female polar bear and male grizzly
bear (Paetkau, pers. comm. May 2006).
General Description
Polar bears are the largest of the living bear species (DeMaster
and Stirling 1981, p. 1; Stirling and Derocher 1990, p. 190). They are
characterized by large body size, a stocky form, and fur color that
varies from white to yellow. They are sexually dimorphic; females weigh
181 to 317 kilograms (kg) (400 to 700 pounds (lbs)), and males up to
654 kg (1,440 lbs). Polar bears have a longer neck and a proportionally
smaller head than other members of the bear family (Ursidae) and are
missing the distinct shoulder hump common to grizzly bears. The nose,
lips, and skin of polar bears are black (Demaster and Stirling 1981, p.
1; Amstrup 2003, p. 588).
Polar bears evolved in sea ice habitats and as a result are
evolutionarily adapted to this habitat. Adaptations unique to polar
bears in comparison to other Ursidae include: (1) White pelage with
water-repellent guard hairs and dense underfur; (2) a short, furred
snout; (3) small ears with reduced surface area; (4) teeth specialized
for a carnivorous rather than an omnivorous diet; and (5) feet with
tiny papillae on the underside, which increase traction on ice
(Stirling 1988, p. 24). Additional adaptations include large, paddle-
like feet (Stirling 1988, p. 24), and claws that are shorter and more
strongly curved than those of grizzly bears, and larger and heavier
than those of black bears (Ursus americanus) (Amstrup 2003, p. 589).
Distribution and Movements
Polar bears evolved to utilize the Arctic sea ice niche and are
distributed throughout most ice-covered seas of the Northern
Hemisphere. They occur throughout the East Siberian, Laptev, Kara, and
Barents Seas of Russia; Fram Strait (the narrow strait between northern
Greenland and Svalbard),
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Greenland Sea and Barents Sea of northern Europe (Norway and Greenland
(Denmark)); Baffin Bay, which separates Canada and Greenland, through
most of the Canadian Arctic archipelago and the Canadian Beaufort Sea;
and in the Chukchi and Beaufort Seas located west and north of Alaska.
Over most of their range, polar bears remain on the sea ice year-
round or spend only short periods on land. However, some polar bear
populations occur in seasonally ice-free environs and use land habitats
for varying portions of the year. In the Chukchi Sea and Beaufort Sea
areas of Alaska and northwestern Canada, for example, less than 10
percent of the polar bear locations obtained via radio telemetry were
on land (Amstrup 2000, p. 137; Amstrup, USGS, unpublished data); the
majority of land locations were bears occupying maternal dens during
the winter. A similar pattern was found in East Greenland (Wiig et al.
2003, p. 511). In the absence of ice during the summer season, some
populations of polar bears in eastern Canada and Hudson Bay remain on
land for extended periods of time until ice again forms and provides a
platform for them to move to sea. Similarly, in the Barents Sea, a
portion of the population is spending greater amounts of time on land.
Although polar bears are generally limited to areas where the sea
is ice-covered for much of the year, they are not evenly distributed
throughout their range on sea ice. They show a preference for certain
sea ice characteristics, concentrations, and specific sea ice features
(Stirling et al. 1993, pp. 18-22; Arthur et al. 1996, p. 223; Ferguson
et al. 2000a, p. 1,125; Ferguson et al. 2000b, pp. 770-771; Mauritzen
et al. 2001, p. 1,711; Durner et al. 2004, pp. 18-19; Durner et al.
2006, p. pp. 34-35; Durner et al. 2007, pp. 17 and 19). Sea-ice habitat
quality varies temporally as well as geographically (Ferguson et al.
1997, p. 1,592; Ferguson et al. 1998, pp. 1,088-1,089; Ferguson et
al.2000a, p. 1,124; Ferguson et al.2000b, pp. 770-771; Amstrup et al.
2000b, p. 962). Polar bears show a preference for sea ice located over
and near the continental shelf (Derocher et al. 2004, p. 164; Durner et
al. 2004, p. 18-19; Durner et al. 2007, p. 19), likely due to higher
biological productivity in these areas (Dunton et al. 2005, pp. 3,467-
3,468) and greater accessibility to prey in near-shore shear zones and
polynyas (areas of open sea surrounded by ice) compared to deep-water
regions in the central polar basin (Stirling 1997, pp. 12-14). Bears
are most abundant near the shore in shallow-water areas, and also in
other areas where currents and ocean upwelling increase marine
productivity and serve to keep the ice cover from becoming too
consolidated in winter (Stirling and Smith 1975, p. 132; Stirling et
al. 1981, p. 49; Amstrup and DeMaster 1988, p. 44; Stirling 1990, pp.
226-227; Stirling and [Oslash]ritsland 1995, p. 2,607; Amstrup et al.
2000b, p. 960).
Polar bear distribution in most areas varies seasonally with the
seasonal extent of sea ice cover and availability of prey. The seasonal
movement patterns of polar bears emphasize the role of sea ice in their
life cycle. In Alaska in the winter, sea ice may extend 400 kilometers
(km) (248 miles (mi)) south of the Bering Strait, and polar bears will
extend their range to the southernmost proximity of the ice (Ray 1971,
p. 13). Sea ice disappears from the Bering Sea and is greatly reduced
in the Chukchi Sea in the summer, and polar bears occupying these areas
move as much as 1,000 km (621 mi) to stay with the pack ice (Garner et
al. 1990, p. 222; Garner et al. 1994, pp. 407-408). Throughout the
polar basin during the summer, polar bears generally concentrate along
the edge of or into the adjacent persistent pack ice. Significant
northerly and southerly movements of polar bears appear to depend on
seasonal melting and refreezing of ice (Amstrup 2000, p. 142). In other
areas, for example, when the sea ice melts in Hudson Bay, James Bay,
Davis Strait, Baffin Bay, and some portions of the Barents Sea, polar
bears remain on land for up to 4 or 5 months while they wait for winter
and new ice to form (Jonkel et al. 1976, pp. 13-22; Schweinsburg 1979,
pp. 165, 167; Prevett and Kolenosky 1982, pp. 934-935; Schweinsburg and
Lee 1982, p. 510; Ferguson et al. 1997, p. 1,592; Lunn et al. 1997, p.
235; Mauritzen et al. 2001, p. 1,710).
In areas where sea ice cover and character are seasonally dynamic,
a large multi-year home range, of which only a portion may be used in
any one season or year, is an important part of the polar bear life
history strategy. In other regions, where ice is less dynamic, home
ranges are smaller and less variable (Ferguson et al. 2001, pp.51-52).
Data from telemetry studies of adult female polar bears show that they
do not wander aimlessly on the ice, nor are they carried passively with
the ocean currents as previously thought (Pedersen 1945 cited in
Amstrup 2003, p. 587). Results show strong fidelity to activity areas
that are used over multiple years (Ferguson et al. 1997, p. 1,589). All
areas within an activity area are not used each year.
The distribution patterns of some polar bear populations during the
open water and early fall seasons have changed in recent years. In the
Beaufort Sea, for example, greater numbers of polar bears are being
found on shore than recorded at any previous time (Schliebe et al.
2006b, p. 559). In Baffin Bay, Davis Strait, western Hudson Bay and
other areas of Canada, Inuit hunters are reporting an increase in the
numbers of bears present on land during summer and fall (Dowsley and
Taylor 2005, p. 2; Dowsley 2005, p. 2). The exact reasons for these
changes may involve a number of factors, including changes in sea ice
(Stirling and Parkinson 2006, p. 272).
Food Habits
Polar bears are carnivorous, and a top predator of the Arctic
marine ecosystem. Polar bears prey heavily throughout their range on
ice-dependent seals (frequently referred to as ``ice seals''),
principally ringed seals (Phoca hispida), and, to a lesser extent,
bearded seals (Erignathus barbatus). In some locales, other seal
species are taken. On average, an adult polar bear needs approximately
2 kg (4.4 lbs) of seal fat per day to survive (Best 1985, p. 1035).
Sufficient nutrition is critical and may be obtained and stored as fat
when prey is abundant.
Although seals are their primary prey, polar bears occasionally
take much larger animals such as walruses (Odobenus rosmarus), narwhal
(Monodon monoceros), and belugas (Delphinapterus leucas) (Kiliaan and
Stirling 1978, p. 199; Smith 1980, p. 2,206; Smith 1985, pp. 72-73;
Lowry et al. 1987, p. 141; Calvert and Stirling 1990, p. 352; Smith and
Sjare 1990, p. 99). In some areas and under some conditions, prey other
than seals or carrion may be quite important to polar bear sustenance
as short-term supplemental forms of nutrition. Stirling and
[Oslash]ritsland (1995, p. 2,609) suggested that in areas where ringed
seal populations were reduced, other prey species were being
substituted. Like other ursids, polar bears will eat human garbage
(Lunn and Stirling 1985, p. 2,295), and when confined to land for long
periods, they will consume coastal marine and terrestrial plants and
other terrestrial foods (Russell 1975, p. 122; Derocher et al. 1993, p.
252); however the significance of such other terrestrial foods to the
long-term welfare of polar bears may be limited (Lunn and Stirling
1985, p. 2,296; Ramsay and Hobson 1991, p. 600; Derocher et al. 2004,
p. 169) as further expanded under the section entitled ``Adaptation''
below.
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Reproduction
Polar bears are characterized by late sexual maturity, small litter
sizes, and extended parental investment in raising young, all factors
that contribute to a low reproductive rate (Amstrup 2003, pp. 599-600).
Reproduction in the female polar bear is similar to that in other
ursids. Females generally mature and breed for the first time at 4 or 5
years and give birth at 5 or 6 years of age. Litters of two cubs are
most common, but litters of three cubs are seen sporadically across the
Arctic (Amstrup 2003, p. 599). When foraging conditions are difficult,
polar bears may ``defer'' reproduction in favor of survival (Derocher
et al. 1992, p. 564).
Polar bears enter a prolonged estrus between March and June, when
breeding occurs. Ovulation is induced by mating (Wimsatt 1963, p. 72),
and implantation is delayed until autumn. The total gestation period is
195 to 265 days (Uspenski 1977, cited in Amstrup 2003, p. 599),
although active development of the fetus is suspended during most of
this period. The timing of implantation, and therefore the timing of
birth, is likely dependent on body condition of the female, which
depends on a variety of environmental factors. Pregnant females that
spend the late summer on land prior to denning may not feed for 8
months (Watts and Hansen 1987, p. 627). This may be the longest period
of food deprivation of any mammal, and it occurs at a time when the
female gives birth to and then nourishes new cubs.
Newborn polar bears are helpless and have hair, but are blind and
weigh only 0.6 kg (1.3 lb) (Blix and Lentfer 1979, p. 68). Cubs grow
rapidly, and may weigh 10 to 12 kg (22 to 26 lbs) by the time they
emerge from the den in the spring. Young bears will stay with their
mothers until weaning, which occurs most commonly in early spring when
the cubs are 2.3 years of age. Female polar bears are available to
breed again after their cubs are weaned; thus the reproductive interval
for polar bears is 3 years.
Polar bears are long-lived mammals not generally susceptible to
disease, parasites, or injury. The oldest known female in the wild was
32 years of age and the oldest known male was 28, though few polar
bears in the wild live to be older than 20 years (Stirling 1988, p.
139; Stirling 1990, p. 225). Due to extremely low reproductive rates,
polar bears require a high survival rate to maintain population levels
(Eberhardt 1985, p. 1,010; Amstrup and Durner 1995, pp. 1,313, 1,319).
Survival rates increase up to a certain age, with cubs-of-the-year
having the lowest rates and prime age adults (between 5 and 20 years of
age) having survival rates that can exceed 90 percent. Amstrup and
Durner (1995, p. 1,319) report that high survival rates (exceeding 90
percent for adult females) are essential to sustain populations.
Polar Bear--Sea Ice Habitat Relationships
Polar bears are distributed throughout the ice-covered waters of
the circumpolar Arctic (Stirling 1988, p. 61), and rely on sea ice as
their primary habitat (Amstrup 2003, p. 587). Polar bears depend on sea
ice for a number of purposes, including as a platform from which to
hunt and feed upon seals; as habitat on which to seek mates and breed;
as a platform to move to terrestrial maternity denning areas, and
sometimes for maternity denning; and as a substrate on which to make
long-distance movements (Stirling and Derocher 1993, p. 241). Mauritzen
et al. (2003b, p. 123) indicated that habitat use by polar bears during
certain seasons may involve a trade-off between selecting habitats with
abundant prey availability versus the use of safer retreat habitats
(i.e., habitats where polar bears have lower probability of becoming
separated from the main body of the pack ice) of higher ice
concentrations with less prey. Their findings indicate that polar bear
distribution may not be solely a reflection of prey availability, but
other factors such as energetic costs or risk may be involved.
Stirling et al. (1993, p. 15) defined seven types of sea ice
habitat and classified polar bear use of these ice types based on the
presence of bears or bear tracks in order to determine habitat
preferences. The seven types of sea ice are: (1) stable fast ice with
drifts; (2) stable fast ice without drifts; (3) floe edge ice; (4)
moving ice; (5) continuous stable pressure ridges; (6) coastal low
level pressure ridges; and (7) fiords and bays. Polar bears were not
evenly distributed over these sea ice habitats, but concentrated on the
floe ice edge, on stable fast ice with drifts, and on areas of moving
ice (Stirling 1990 p. 226; Stirling et al. 1993, p. 18). In another
assessment, categories of ice types included pack ice, shore-fast ice,
transition zone ice, polynyas, and leads (linear openings or cracks in
the ice) (USFWS 1995, p. 9). Pack ice, which consists of annual and
multi-year older ice in constant motion due to winds and currents, is
the primary summer habitat for polar bears in Alaska. Shore-fast ice
(also known as ``fast ice'', it is defined by the Arctic Climate Impact
Assessment (2005, p. 190) as ice that grows seaward from a coast and
remains in place throughout the winter; typically it is stabilized by
grounded pressure ridges at its outer edge) is used for feeding on seal
pups, for movement, and occasionally for maternity denning. Open water
at leads and polynyas attracts seals and other marine mammals and
provides preferred hunting habitats during winter and spring. Durner et
al. (2004, pp. 18-19; Durner et al. 2007, pp. 17-18) found that polar
bears in the Arctic basin prefer sea ice concentrations greater than 50
percent located over the continental shelf with water depths less than
300 m (984 feet (ft)).
Polar bears must move throughout the year to adjust to the changing
distribution of sea ice and seals (Stirling 1988, p. 63; USFWS 1995, p.
4). In some areas, such as Hudson Bay and James Bay, polar bears remain
on land when the sea ice retreats in the spring and they fast for
several months (up to 8 months for pregnant females) before fall
freeze-up (Stirling 1988, p. 63; Derocher et al. 2004, p. 163; Amstrup
et al. 2007, p. 4). Some populations unconstrained by land masses, such
as those in the Barents, Chukchi, and Beaufort Seas, spend each summer
on the multi-year ice of the polar basin (Derocher et al. 2004, p. 163;
Amstrup et al. 2007, p. 4). In intermediate areas such as the Canadian
Arctic, Svalbard, and Franz Josef Land archipelagos, bears stay on the
sea ice most of the time, but in some years they may spend up to a few
months on land (Mauritizen et al. 2001, p. 1,710). Most populations use
terrestrial habitat partially or exclusively for maternity denning;
therefore, females must adjust their movements in order to access land
at the appropriate time (Stirling 1988, p. 64; Derocher et al. 2004, p.
166).
Sea ice changes between years in response to environmental factors
may have consequences for the distribution and productivity of polar
bears as well as their prey. In the southern Beaufort Sea, anomalous
heavy sea ice conditions in the mid-1970s and mid-1980s (thought to be
roughly in phase with a similar variation in runoff from the Mackenzie
River) caused significant declines in productivity of ringed seals
(Stirling 2002, p. 68). Each event lasted approximately 3 years and
caused similar declines in the birth rate of polar bears and survival
of subadults, after which reproductive success and survival of both
species increased again.
Maternal Denning Habitat
Throughout the species' range, most pregnant female polar bears
excavate
[[Page 28215]]
dens in snow located on land in the fall-early winter period (Harington
1968, p. 6; Lentfer and Hensel 1980, p. 102; Ramsay and Stirling 1990,
p. 233; Amstrup and Gardner 1994, p. 5). The only known exceptions are
in western and southern Hudson Bay, where polar bears first excavate
earthen dens and later reposition into adjacent snow drifts (Jonkel et
al. 1972, p. 146; Ramsay and Stirling 1990, p. 233), and in the
southern Beaufort Sea, where a portion of the population dens in snow
caves located on pack and shore-fast ice. Successful denning by polar
bears requires accumulation of sufficient snow for den construction and
maintenance. Adequate and timely snowfall combined with winds that
cause snow accumulation leeward of topographic features create denning
habitat (Harington 1968, p. 12).
A great amount of polar bear denning occurs in core areas
(Harington 1968, pp. 7-8), which show high use over time (see Figure
8). In some portions of the species' range, polar bears den in a more
diffuse pattern, with dens scattered over larger areas at lower density
(Lentfer and Hensel 1980, p. 102; Stirling and Andriashek 1992, p. 363;
Amstrup 1993, p. 247; Amstrup and Gardner 1994, p. 5; Messier et al.
1994, p. 425; Born 1995, p. 81; Ferguson et al. 2000a, p. 1125; Durner
et al. 2001, p. 117; Durner et al. 2003, p. 57).
Habitat characteristics of denning areas vary substantially from
the rugged mountains and fjordlands of the Svalbard archipelago and the
large islands north of the Russian coast (L[oslash]n[oslash] 1970, p.
77; Uspenski and Kistchinski 1972, p. 182; Larsen 1985, pp. 321-322),
to the relatively flat topography of areas such as the west coast of
Hudson Bay (Ramsay and Andriashek 1986, p. 9; Ramsay and Stirling 1990,
p. 233) and north slope of Alaska (Amstrup 1993, p. 247; Amstrup and
Gardner 1994, p. 7; Durner et al. 2001, p. 119; Durner et al. 2003, p.
61), to offshore pack ice-pressure ridge habitat (Amstrup and Gardner
1994, p. 4; Fischbach et al. 2007, p. 1,400). The key characteristic of
all denning habitat is topographic features that catch snow in the
autumn and early winter (Durner et al. 2003, p. 61). Across the range,
most polar bear dens occur relatively near the coast. The main
exception to coastal denning occurs in the western Hudson Bay area,
where bears den farther inland in traditional denning areas (Kolenosky
and Prevett 1983, pp. 243-244; Stirling and Ramsay 1986, p. 349).
Current Population Status and Trend
The total number of polar bears worldwide is estimated to be
20,000-25,000 (Aars et al. 2006, p. 33). Polar bears are not evenly
distributed throughout the Arctic, nor do they comprise a single
nomadic cosmopolitan population, but rather occur in 19 relatively
discrete populations (Aars et al. 2006, p. 33). The use of the term
``relatively discrete population'' in this context is not intended to
equate to the Act's term ``distinct population segments'' (Figure 1).
Boundaries of the 19 polar bear populations have evolved over time and
are based on intensive study of movement patterns, tag returns from
harvested animals, and, to a lesser degree, genetic analysis (Aars et
al. 2006, pp. 33-47). The scientific studies regarding population
bounds began in the early 1970s and continue today. Within this final
rule we have adopted the use of the term ``population'' to describe
polar bear management units consistent with their designation by the
World Conservation Union-International Union for Conservation of Nature
and Natural Resources (IUCN), Species Survival Commission (SSC) Polar
Bear Specialist Group (PBSG) with information available as of October
2006 (Aars et al. 2006, p. 33), and to describe a combination of two or
more of these populations into ``ecoregions,'' as discussed in
following sections. Although movements of individual polar bears
overlap extensively, telemetry studies demonstrate spatial segregation
among groups or stocks of polar bears in different regions of their
circumpolar range (Schweinsburg and Lee 1982, p. 509; Amstrup et al.
1986, p. 252; Amstrup et al., 2000b, pp. 957-958.; Garner et al. 1990,
p. 224; Garner et al. 1994, pp.112-115; Amstrup and Gardner 1994, p. 7;
Ferguson et al. 1999, pp. 313-314; Lunn et al. 2002, p. 41). These
patterns, along with information obtained from survey and
reconnaissance, marking and tagging studies, and traditional knowledge,
have resulted in recognition of 19 relatively discrete polar bear
populations (Aars et al. 2006, p. 33). Genetic analysis reinforces the
boundaries between some designated populations (Paetkau et al. 1999, p.
1,571; Amstrup 2003, p. 590) while confirming the existence of overlap
and mixing among others (Paetkau et al. 1999, p. 1,571; Cronin et al.
2006, p. 655). There is considerable overlap in areas occupied by
members of these groups (Amstrup et al. 2004, p. 676; Amstrup et al.
2005, p. 252), and boundaries separating the groups are adjusted as new
data are collected. These boundaries, however, are thought to be
ecologically meaningful, and the 19 units they describe are managed as
populations, with the exception of the Arctic Basin population where
few bears are believed to be year-round residents.
[[Page 28216]]
[GRAPHIC] [TIFF OMITTED] TR15MY08.002
Population size estimates and qualitative categories of current
trend and status for each of the 19 polar bear populations are
discussed below. This discussion was derived from information presented
at the IUCN/SSC PBSG meeting held in Seattle, Washington, in June 2005,
and updated with results that became available in October 2006 (Aars et
al. 2006, p. 33). The following narrative incorporates results from two
recent publications (Stirling et al. 2007; Obbard et al. 2007). The
remainder of the information on each population is based on the
available status reports and revisions given by each nation, as
reported in Aars et al. (2006).
Status categories include an assessment of whether a population is
believed to be not reduced, reduced, or severely reduced from historic
levels of abundance, or if insufficient data are available to estimate
status. Trend categories include an assessment of whether the
population is currently increasing, stable, or declining, or if
insufficient data are available to estimate trend. In general, an
assessment of trend requires a monitoring program or data to allow
population size to be estimated at more than one point in time.
Information on the date of the current population estimate and
information on previous population estimates and the basis for
[[Page 28217]]
those estimates is detailed in Aars et al. (2006, pp. 34-35). In some
instances a subjective assessment of trend has been provided in the
absence of either a monitoring program or estimates of population size
developed for more than one point in time. This status and trend
analysis only reflects information about the past and present polar
bear populations. Later in this final rule a discussion will be
presented about the scientific information on threats that will affect
the species within the foreseeable future. The Act establishes a five-
factor analysis for using this information in making listing decisions.
Populations are discussed in a counterclockwise order from Figure
1, beginning with East Greenland. There is no population size estimate
for the East Greenland polar bear population because no population
surveys have been conducted there. Thus, the status and trend of this
population have not been determined. The Barents Sea population was
estimated to comprise 3,000 animals based on the only population survey
conducted in 2004. Because only one abundance estimate is available,
the status and trend of this population cannot yet be determined. There
is no population size estimate for the Kara Sea population because
population surveys have not been conducted; thus status and trend of
this population cannot yet be determined. The Laptev Sea population was
estimated to comprise 800 to 1,200 animals, on the basis of an
extrapolation of historical aerial den survey data (1993). Status and
trend cannot yet be determined for this population.
The Chukchi Sea population is estimated to comprise 2,000 animals,
based on extrapolation of aerial den surveys (2002). Status and trend
cannot yet be determined for this population. The Southern Beaufort Sea
population is comprised of 1,500 animals, based on a recent population
inventory (2006). The predicted trend is declining (Aars et al. 2006,
p.33), and the status is designated as reduced. The Northern Beaufort
Sea population was estimated to number 1,200 animals (1986). The trend
is designated as stable, and status is believed to be not reduced.
Stirling et al. (2007, pp. 12-14) estimated long-term trends in
population size for the Northern Beaufort Sea population. The model-
averaged estimate of population size from 2004 to 2006 was 980 bears,
and did not differ in a statistically significantly way from estimates
for the periods of 1972 to 1975 (745 bears) and 1985 to 1987 (867
bears), and thus the trend is stable. Stirling et al. (2007, p. 13)
indicated that, based on a number of indications and separate annual
abundance estimates for the study period, the population estimate may
be slightly biased low (i.e., might be an underestimate) due to
sampling issues.
The Viscount Melville Sound population was estimated to number 215
animals (1992). The observed or predicted trend based on management
action is listed as increasing (Aars et al. 2006, p. 33), although the
status is designated as severely reduced from prior excessive harvest.
The Norwegian Bay population estimate was 190 animals (1998); the
trend, based on computer simulations, is noted as declining, while the
status is listed as not reduced. The Lancaster Sound population
estimate was 2,541 animals (1998); the trend is thought to be stable,
and status is not reduced. The M'Clintock Channel population is
estimated at 284 animals (2000); the observed or predicted trend based
on management actions is listed as increasing although the status is
severely reduced from excessive harvest. The Gulf of Boothia population
estimate is 1,523 animals (2000); the trend is thought to be stable,
and status is designated as not reduced. The Foxe Basin population was
estimated to number 2,197 animals in 1994; the population trend is
thought to be stable, and the status is not reduced. The Western Hudson
Bay population estimate is 935 animals (2004); the trend is declining,
and the status is reduced. The Southern Hudson Bay population was
estimated to be 1,000 animals in 1988 (Aars et al. 2006, p. 35); the
trend is thought to be stable, and status is not reduced. In a more
recent analysis, Obbard et al. (2007) applied open population capture-
recapture models to data collected from 1984-86 and 1999-2005 to
estimate population size, trend, and survival for the Southern Hudson
Bay population. Their results indicate that the size of the Southern
Hudson Bay population appears to be unchanged from the mid-1980s. From
1984-1986, the population was estimated at 641 bears; from 2003-2005,
the population was estimated at 681 bears. Thus, the trend for this
population is stable. The Kane Basin population was estimated to be
comprised of 164 animals (1998); its trend is declining, and status is
reduced. The Baffin Bay population was estimated to be 2,074 animals
(1998); the trend is declining, and status is reduced. The Davis Strait
population was estimated to number 1,650 animals based on traditional
ecological knowledge (TEK) (2004); data were unavailable to assess
trends or status. Preliminary information from the second of a 3-year
population assessment estimates the population number to be 2,375 bears
(Peacock et al. 2007, p. 7). The Arctic Basin population estimate,
trend, and status are unknown (Aars et al. 2006, p. 35).
On the basis of information presented above, two polar bear
populations are designated as increasing (Viscount Melville Sound and
M'Clintock Channel-both were severely reduced in the past and are
recovering under conservative harvest limits); six populations are
stable (Northern Beaufort Sea, Southern Hudson Bay, Davis Strait,
Lancaster Sound, Gulf of Bothia, Foxe Basin); five populations are
declining (Southern Beaufort Sea, Norwegian Bay, Western Hudson Bay,
Kane Basin, Baffin Bay); and six populations are designated as data
deficient (Barents Sea, Kara Sea, Laptev Sea, Chukchi Sea, Arctic
Basin, East Greenland) with no estimate of trend. The two populations
with the most extensive time series of data, Western Hudson Bay and
Southern Beaufort Sea, are both considered to be declining.
As previously noted, scientific information assessing this species
in the foreseeable future is provided later in this final rule.
Polar Bear Ecoregions
Amstrup et al. (2007, pp. 6-8) grouped the 19 IUCN-recognized polar
bear populations (Aars et al. 2006, p. 33) into four physiographically
different functional groups or ``ecoregions'' (Figure 2) in order to
forecast future polar bear population status on the basis of current
knowledge of polar bear populations, their relationships to sea ice
habitat, and predicted changes in sea ice and other environmental
variables. Amstrup et al. (2007, p. 7) defined the ecoregions ``on the
basis of observed temporal and spatial patterns of ice formation and
ablation (melting or evaporation), observations of how polar bears
respond to those patterns, and how general circulation models (GCMs)
forecast future ice patterns.''
The Seasonal Ice Ecoregion includes the Western and Southern Hudson
Bay populations, as well as the Foxe Basin, Baffin Bay, and Davis
Strait populations. These 5 IUCN-recognized populations are thought to
include a total of about 7,200 polar bears (Aars et al. 2006, p. 34-
35). The 5 populations experience sea ice that melts entirely in
summer, and bears spend extended periods of time on shore.
[[Page 28218]]
[GRAPHIC] [TIFF OMITTED] TR15MY08.003
The Archipelago Ecoregion, islands and channels of the Canadian
Arctic, has approximately 5,000 polar bears representing 6 populations
recognized by the IUCN (Aars et al. 2006, p. 34-35). These populations
are Kane Basin, Norwegian Bay, Viscount Melville Sound, Lancaster
Sound, M'Clintock Channel, and the Gulf of Boothia. Much of this region
is characterized by heavy annual and multi-year ice that fills the
inter-island channels year round and polar bears remain on the sea ice
throughout the year.
The polar basin was split into a Convergent Ecoregion and a
Divergent Ecoregion, based upon the different patterns of sea ice
formation, loss (via melt and transport) (Rigor et al. 2002, p. 2,658;
Rigor and Wallace 2004, p. 4; Maslanik et al. 2007, pp. 1-3; Meier et
al. 2007, pp. 428-434; Ogi and Wallace 2007, pp. 2-3).
The Divergent Ecoregion is characterized by extensive formation of
annual sea ice that is transported toward the Canadian Arctic islands
and Greenland, or out of the polar basin through Fram Strait. The
Divergent ecoregion includes the Southern Beaufort, Chukchi, Laptev,
Kara, and Barents Seas populations, and is thought to contain up to
9,500 polar bears. In the Divergent Ecoregion, as in the Archipelago
Ecoregion, polar bears mainly stay on the sea ice year-round.
The Convergent Ecoregion, composed of the Northern Beaufort Sea,
Queen Elizabeth Islands (see below), and East Greenland populations, is
thought to contain approximately 2,200 polar bears. Amstrup et al.
(2007, p. 7) modified the IUCN-recognized population boundaries (Aars
et al. 2006, pp. 33,36) of this ecoregion by redefining a Queen
Elizabeth Islands population and extending the original boundary of
that population to include northwestern Greenland (see Figure 2). The
area contained within this boundary is characterized by heavy multi-
year ice, except for a recurring lead system that runs along the Queen
Elizabeth Islands from the northeastern Beaufort Sea to northern
Greenland (Stirling 1980, pp. 307-308). The area may contain over 200
polar bears and some bears from other regions have been recorded moving
through the area (Durner and Amstrup 1995, p. 339; Lunn et al. 1995,
pp. 12-13). The Northern Beaufort Sea and Queen Elizabeth Islands
populations occur in a region of the polar basin that accumulates ice
(hence, the Convergent Ecoregion) as it is moved from the polar basin
Divergent Ecoregion, while the East Greenland population occurs in area
where ice is transported out of the polar basin through the Fram Strait
(Comiso 2002, pp. 17-18; Rigor and Wallace 2004, p. 3; Belchansky et
al. 2005, pp. 1-2; Holland et al. 2006, pp. 1-5; Durner et al. 2007, p.
3; Ogi and Wallace 2007, p. 2; Serreze et al. 2007, pp. 1,533-1536).
Amstrup et al. (2007) do not incorporate the central Arctic Basin
population into an ecoregion. This population was defined by the IUCN
in 2001 (Lunn et al. 2002, p.29) to recognize polar bears that may
reside outside the territorial jurisdictions of the polar nations. The
Arctic Basin region is characterized by very deep water, which is known
to be unproductive (Pomeroy 1997, pp. 6-7). Available data indicate
that polar bears prefer sea ice over shallow water (less then 300 m
(984 ft) deep) (Amstrup et
[[Page 28219]]
al. 2000b, p. 962; Amstrup et al. 2004, p. 675; Durner et al. 2007, pp.
18-19), and it is thought that this preference reflects increased
hunting opportunities over more productive waters. Also, tracking
studies indicate that few if any bears are year-round residents of the
central Arctic Basin, and therefore this relatively unpopulated portion
of the Arctic was not designated as an ecoregion.
Sea Ice Environment
As described in detail in the ``Species Biology'' section of this
rule, above, polar bears are evolutionarily adapted to life on sea ice
(Stirling 1988, p. 24; Amstrup 2003, p. 587). They need sea ice as a
platform for hunting, for seasonal movements, for travel to terrestrial
denning areas, for resting, and for mating (Stirling and Derocher 1993,
p. 241). Moore and Huntington (in press) classify the polar bear as an
``ice-obligate'' species because of its reliance on sea ice as a
platform for resting, breeding, and hunting, while Laidre et al. (in
press) similarly describe the polar bear as a species that principally
relies on annual sea ice over the continental shelf and areas toward
the southern edge of sea ice for foraging. Some polar bears use
terrestrial habitats seasonally (e.g., for denning or for resting
during open water periods). Open water is not considered to be an
essential habitat type for polar bears, because life functions such as
feeding, reproduction, or resting do not occur in open water. However,
open water is a fundamental part of the marine system that supports
seal species, the principal prey of polar bears, and seasonally
refreezes to form the ice needed by the bears (see ``Open Water
Habitat'' section for more information). Further, the open water
interface with sea ice is an important habitat used to a great extent
by polar bears. In addition, the extent of open water is important
because vast areas of open water may limit a bear's ability to access
sea ice or land (see ``Open Water Swimming'' section for more detail).
Snow cover, both on land and on sea ice, is an important component of
polar bear habitat in that it provides insulation and cover for young
polar bears and ringed seals in snow dens or lairs (see ``Maternal
Denning Habitat'' section for more detail).
Sea Ice Habitat
Overview of Arctic Sea Ice
According to the Arctic Climate Impact Assessment (ACIA 2005),
approximately two-thirds of the Arctic is ocean, including the Arctic
Ocean and its shelf seas plus the Nordic, Labrador, and Bering Seas
(ACIA 2005, p. 454). Sea ice is the defining characteristic of the
marine Arctic (ACIA 2005, p. 30). The Arctic sea ice environment is
highly dynamic and follows annual patterns of expansion and
contraction. Sea ice is typically at its maximum extent (the term
``extent'' is formally defined in the ``Observed Changes in Arctic Sea
Ice'' section) in March and at its minimum extent in September
(Parkinson et al. 1999, p. 20,840). The two primary forms of sea ice
are seasonal (or first year) ice and perennial (or multi-year) ice
(ACIA 2005, p. 30). Seasonal ice is in its first autumn/winter of
growth or first spring/summer of melt (ACIA 2005, p. 30). It has been
documented to vary in thickness from a few tenths of a meter near the
southern margin of the sea ice to 2.5 m (8.2 ft) in the high Arctic at
the end of winter (ACIA 2005, p. 30), with some ice also that is
thinner and some limited amount of ice that can be much thicker,
especially in areas with ridging (C. Parkinson, NASA, in litt. to the
Service, November 2007). If first-year ice survives the summer melt, it
becomes multi-year ice. This ice tends to develop a distinctive
hummocky appearance through thermal weathering, becoming harder and
almost salt-free over several years (ACIA 2005, p. 30). Sea ice near
the shore thickens in shallow waters during the winter, and portions
become grounded. Such ice is known as shore-fast ice, land-fast ice, or
simply fast ice (ACIA 2005, p. 30). Fast ice is found along much of the
Siberian coast, the White Sea (an inlet of the Barents Sea), north of
Greenland, the Canadian Archipelago, Hudson Bay, and north of Alaska
(ACIA 2005, p. 457).
Pack ice consists of seasonal (or first-year) and multi-year ice
that is in constant motion caused by winds and currents (USFWS 1995,
pp. 7-9). Pack ice is used by polar bears for traveling, feeding, and
denning, and it is the primary summer habitat for polar bears,
including the Southern Beaufort Sea and Chukchi Sea populations, as
first year ice retreats and melts with the onset of spring (see ``Polar
Bear-Sea Ice Habitat Relationships'' section for more detail on ice
types used by polar bears). Movements of sea ice are related to winds,
currents, and seasonal temperature fluctuations that in turn promote
its formation and degradation. Ice flow in the Arctic often includes a
clockwise circulation of sea ice within the Canada Basin and a
transpolar drift stream that carries sea ice from the Siberian shelves
to the Barents Sea and Fram Strait.
Sea ice is an important component of the Arctic climate system
(ACIA 2005, p. 456). It is an effective insulator between the oceans
and the atmosphere. It also strongly reduces the ocean-atmosphere heat
exchange and reduces wind stirring of the ocean. In contrast to the
dark ocean, pond-free sea ice (i.e., sea ice that has no meltwater
ponds on the surface) reflects most of the solar radiation back into
space. Together with snow cover, sea ice greatly restricts the
penetration of light into the sea, and it also provides a surface for
particle and snow deposition (ACIA 2005, p. 456). Its effects can
extend far south of the Arctic, perhaps globally, e.g., through
impacting deepwater formation that influences global ocean circulation
(ACIA 2005, p. 32).
Sea ice is also an important environmental factor in Arctic marine
ecosystems. ``Several physical factors combine to make arctic marine
systems unique including: a very high proportion of continental shelves
and shallow water; a dramatic seasonality and overall low level of
sunlight; extremely low water temperatures; presence of extensive areas
of multi-year and seasonal sea-ice cover; and a strong influence from
freshwater, coming from rivers and ice melt'' (ACIA 2005, p. 454). Ice
cover is an important physical characteristic, affecting heat exchange
between water and atmosphere, and light penetration to organisms in the
water below. It also helps determine the depth of the mixed layer, and
provides a biological habitat above, within, and beneath the ice. The
marginal ice zone, at the edge of the pack ice, is important for
plankton production and plankton-feeding fish (ACIA 2005, p. 456)
Observed Changes in Arctic Sea Ice
Sea ice is the defining physical characteristic of the marine
Arctic environment and has a strong seasonal cycle (ACIA 2005, p. 30).
There is considerable inter-annual variability both in the maximum and
minimum extent of sea ice, but it is typically at its maximum extent in
March and minimum extent in September (Parkinson et al. 1999, p. 20,
840). In addition, there are decadal and inter-decadal fluctuations to
sea ice extent due to changes in atmospheric pressure patterns and
their associated winds, river runoff, and influx of Atlantic and
Pacific waters (Gloersen 1995, p. 505; Mysak and Manak 1989, p. 402;
Kwok 2000, p. 776; Parkinson 2000b, p. 10; Polyakov et al. 2003, p.
2,080; Rigor et al. 2002, p. 2,660; Zakharov 1994, p. 42). Sea ice
``extent'' is normally defined as the area of the ocean with at least
15 percent ice coverage, and sea ice ``area'' is normally defined as
the integral sum of areas actually covered by sea ice
[[Page 28220]]
(Parkinson et al. 1999). ``Area'' is a more precise measure of the
areal extent of the ice itself, since it takes into account the
fraction of leads (linear openings or cracks in the ice) within the
ice, but ``extent'' is more reliably observed (Zhang and Walsh 2006).
The following sections discuss specific aspects of observed sea ice
changes of relevance to polar bears.
Summer Sea Ice
Summer sea ice area and sea ice extent are important factors for
polar bear survival (see ``Polar Bear-Sea Ice Habitat Relationships''
section). Seasonal or first-year ice that remains at the end of the
summer melt becomes multi-year (or perennial) ice. The amount and
thickness of perennial ice is an important determinant of future sea
ice conditions (i.e., gain or loss of ice) (Holland and Bitz 2003; Bitz
and Roe 2004). Much of the following discussion focuses on summer sea
ice extent (rather than area).
Prior to the early 1970s, ice extent was measured with visible-band
satellite imagery and aircraft and ship reports. With the advent of
passive microwave (PM) satellite observations, beginning in December
1972 with a single channel instrument and then more reliably in October
1978 with a multi-channel instrument, we have a more accurate, 3-decade
record of changes in summer sea ice extent and area. Over the period
since October 1978, successive papers have documented an overall
downward trend in Arctic sea ice extent and area. For example,
Parkinson et al. (1999) calculated Arctic sea ice extents, areas, and
trends for late 1978 through the end of 1996, and documented a decrease
in summer sea ice extent of 4.5 percent per decade. Comiso (2002)
documented a decline of September minimum sea ice extent of 6.7 percent
plus or minus 2.4 percent per decade from 1981 through 2000. Stroeve et
al. (2005) analyzed data from 1978 through 2004, and calculated a
decline in minimum sea ice extent of 7.7 percent plus or minus 3
percent per decade. Comiso (2006, p. 72) included observations for
2005, and calculated a per-decade decline in minimum sea ice extent of
up to 9.8 percent plus or minus 1.5 percent. Most recently, Stroeve et
al. (2007, pp. 1-5) estimated a 9.1 percent per-decade decline in
September sea ice extent for 1979-2006, while Serreze et al. (2007, pp.
1,533-1,536) calculated a per-decade decline of 8.6 percent plus or
minus 2.9 percent for the same parameter over the same time period.
These estimates differ only because Serreze et al. (2007, pp. 1,533-
1,536) normalized the trend by the 1979-2000 mean, in order to be
consistent with how the National Snow and Ice Data Center \1\
calculates its estimates (J. Stroeve, in litt. to the Service, November
2007). This decline translates to a decrease of 60,421 sq km (23,328 sq
mi) per year (NSIDC Press Release, October 3, 2006).
---------------------------------------------------------------------------
\1\ The NSIDC is part of the University of Colorado Cooperative
Institute for Research in Environmental Sciences (CIRES), is funded
largely by the National Aeronautics and Space Administration (NASA),
and is affiliated with the National Oceanic and Atmospheric
Administration (NOAA) National Geophysical Data Center through a
cooperative agreement. A large part of NSIDC is the Polar
Distributed Active Archive Center, which is funded by NASA.
---------------------------------------------------------------------------
The rate of decrease in September sea ice extent appears to have
accelerated in recent years, although the acceleration to date has not
been shown to be statistically significant (C. Bitz, in litt. to the
Service, November 2007). The years 2002 through 2007 all exceeded
previous record lows (Stroeve et al. 2005; Comiso 2006; Stroeve et al.
2007, pp. 1-5; Serreze et al. 2007, pp. 1,533-1,536; NSIDC Press
Release, October 1, 2007), and 2002, 2005, and 2007 had successively
lower record-breaking minimum extent values (http://www.nsidc.org). The
2005 absolute minimum sea ice extent of 5.32 million sq km (2.05
million sq mi) for the entire Arctic Ocean was a 21 percent reduction
compared to the mean for 1979 to 2000 (Serreze et al. 2007, pp. 1,533-
1,536). Nghiem et al. (2006) documented an almost 50 percent reduction
in perennial (multi-year) sea ice extent in the East Arctic Ocean (0 to
180 degrees east longitude) between 2004 and 2005, while the West
Arctic Ocean (0 and 180 degrees west longitude) had a slight gain
during the same period, followed by an almost 70 percent decline from
October 2005 to April 2006. Nghiem et al. (2007) found that the extent
of perennial sea ice was significantly reduced by 23 percent between
March 2005 and March 2007 as observed by the QuikSCAT/SeaWinds
satellite scatterometer. Nghiem et al. (2006) presaged the extensive
decline in September sea ice extent in 2007 when they stated: ``With
the East Arctic Ocean dominated by seasonal ice, a strong summer melt
may open a vast ice-free region with a possible record minimum ice
extent largely confined to the West Arctic Ocean.''
Arctic sea ice declined rapidly to unprecedented low extents in
summer 2007 (Stroeve et al. 2008). On August 16-17, 2007, Arctic sea
ice surpassed the previous single-day (absolute minimum) record for the
lowest extent ever measured by satellite (set in 2005), and the sea ice
was still melting (NSIDC Arctic Sea Ice News, August 17, 2007). On
September 16, 2007 (the end of the melt season), the 5-day running mean
sea ice extent reported by NSIDC was 4.13 million sq km (1.59 million
sq mi), an all-time record low. This was 23 percent lower than the
previous record minimum reported in 2005 (see Figure 3) (Stroeve et al.
2008) and 39 percent below the long-term average from 1979 to 2000 (see
Figure 4) (NSIDC Press Release, October 1, 2007). Arctic sea ice
receded so much in 2007 that the so-called ``Northwest Passage''
through the straits of the Canadian Arctic Archipelago completely
opened for the first time in recorded history (NSIDC Press Release,
October 1, 2007). Based on a time-series of data from the Hadley
Centre, extending back before the advent of the PM satellite era, sea
ice extent in mid-September 2007 may have fallen by as much as 50
percent from the 1950s to 1970s (Stroeve et al. 2008). The minimum
September Arctic sea ice extent since 1979 is now declining at a rate
of approximately 10.7 percent per decade (Stroeve et al. 2008), or
approximately 72,000 sq km (28,000 sq mi) per year (see Figure 3 below)
(NSIDC Press Release, October 1, 2007).
[[Page 28221]]
[GRAPHIC] [TIFF OMITTED] TR15MY08.004
[GRAPHIC] [TIFF OMITTED] TR15MY08.005
[[Page 28222]]
In August 2007, Arctic sea ice area (recall that ``area'' is a
different metric than ``extent'' used in the preceding paragraphs) also
broke the record for the minimum Arctic sea ice area in the period
since the satellite PM record began in the 1970s (University of
Illinois Polar Research Group 2007 web site; http://
arctic.atmos.uiuc.edu/cryosphere/). The new record was set a full month
before the historic summer minimum typically occurs, and the record
minimum continued to decrease over the next several weeks (University
of Illinois Polar Research Group 2007 web site). The Arctic sea ice
area reached an historic minimum of 2.92 million sq km (1.13 million sq
mi) on September 16, 2007, which was 27 percent lower than the previous
(2005) record Arctic ice minimum area (University of Illinois Polar
Research Group 2007 web site). In previous record sea ice minimum
years, ice area anomalies were confined to certain sectors (North
Atlantic, Beaufort/Bering Sea, etc.), but the character of the 2007
summer sea ice melt was unique in that it was both dramatic and covered
the entire Arctic Basin. Atlantic, Pacific, and the central Arctic
sectors all showed large negative sea ice area anomalies (University of
Illinois Polar Research Group 2007 web site).
Two key factors contributed to the September 2007 extreme sea ice
minimum: thinning of the pack ice in recent decades and an unusual
pattern of atmospheric circulation (Stroeve et al. 2008). Spring 2007
started out with less ice and thinner ice than normal. Ice thickness
estimates from the ICESat satellite laser altimeter instrument
indicated ice thicknesses over the Arctic Basin in March 2007 of only 1
to 2 m (3.3 to 6.6 ft) (J. Stroeve, in litt. to the Service, November
2007). Thinner ice takes less energy to melt than thicker ice, so the
stage was set for low levels of sea ice in summer 2007 (J. Stroeve,
quoted in NSIDC Press Release, October 1, 2007). In general, older sea
ice is thicker than younger ice. Maslanik et al. (2007) used an ice-
tracking computer algorithm to estimate changes in the distribution of
multi-year sea ice of various ages. They estimated: that the area of
sea ice at least 5 years old decreased by 56 percent between 1985 and
2007; that ice at least 7 years old decreased from 21 percent of the
ice cover in 1988 to 5 percent in 2007; and that sea ice at least 9
years old essentially disappeared from the central Arctic Basin.
Maslanik et al. (2007) attributed thinning in recent decades to both
ocean-atmospheric circulation patterns and warmer temperatures. Loss of
older ice in the late 1980s to mid-1990s was accentuated by the
positive phase of the Arctic Oscillation during that period, leading to
increased ice export through the Fram Strait (Stroeve et al. 2008).
Another significant change since the late 1990s has been the role of
the Beaufort Gyre, ``the dominant wind and ice drift regime in the
central Arctic'' (Maslanik et al. 2007). ``Since the late 1990s * * *
ice typically has not survived the transit through the southern portion
of the Beaufort Gyre,'' thus not allowing the ice to circulate in its
formerly typical clockwise pattern for years while it aged and
thickened (Maslanik et al. 2007). Temperature changes in the Arctic are
discussed in detail in the section entitled ``Air and Sea
Temperatures.''
Another factor that contributed to the sea ice loss in the summer
of 2007 was an unusual atmospheric pattern, with persistent high
atmospheric pressures over the central Arctic Ocean and lower pressures
over Siberia (Stroeve et al. 2008). The skies were fairly clear under
the high-pressure cell, promoting strong melt. At the same time, the
pattern of winds pumped warm air into the region. While the warm winds
fostered further melt, they also helped push ice away from the Siberian
shore.
Winter Sea Ice
The maximum extent of Arctic winter sea ice cover, as documented
with PM satellite data, has been declining at a lower rate than summer
sea ice (Parkinson et al. 1999, p. 20,840; Richter-Menge et al. 2006,
p. 16), but that rate appears to have accelerated in recent years.
Parkinson and Cavalieri (2002, p. 441) reported that winter sea ice
cover declined at a rate of 1.8 percent plus or minus 0.6 percent per
decade for the period 1979 through 1999. More recently, Richter-Menge
et al. (2006, p. 16) reported that March sea ice extent was declining
at a rate of 2 percent per decade based on data from 1979-2005, Comiso
(2006) calculated a decline of 1.9 plus or minus 0.5 percent per decade
for 1979-2006, and J. Stroeve (in litt. to the Service, November 2007)
calculated a decline of 2.5 percent per decade, also for 1979-2005.
In 2005 and 2006, winter maximum sea ice extent set record lows for
the era of PM satellite monitoring (October 1978 to present). The 2005
record low winter maximum preceded the then-record low summer minimum
during the same year, while winter sea ice extent in 2006 was even
lower than that of 2005 (Comiso 2006). The winter 2007 Arctic sea ice
maximum was the second-lowest in the satellite record, narrowly missing
the March 2006 record (NSIDC Press Release, April 4, 2007). J. Stroeve
(in litt. to the Service, November 2007) calculated a rate of decline
of 3.0 plus or minus 0.8 percent per decade for 1979-2007.
Cumulative Annual Sea Ice
Parkinson et al. (1999) documented that Arctic sea ice extent for
all seasons (i.e., annual sea ice extent) declined at a rate of 2.8
percent per decade for the period November 1978 through December 1996,
with considerable regional variation (the greatest absolute declines
were documented for the Kara and Barents Sea, followed by the Seas of
Okhotsk and Japan, the Arctic Ocean, Greenland Sea, Hudson Bay, and
Canadian Archipelago; percentage declines were greatest in the Seas of
Okhotsk and Japan, at 20.1 percent per decade, and the Kara and Barents
Seas, at 10.5 percent per decade). More recently, Comiso and Nishio
(2008) utilized satellite data gathered from late 1978 into 2006, and
estimated an annual rate decline of 3.4 percent plus or minus 0.2
percent per decade. They also found regions where higher negative
trends were apparent, including the Greenland Sea (8.0 percent per
decade), the Kara/Barents Seas (7.2 percent per decade), the Okhotsk
Sea (8.7 percent per decade), and Baffin Bay/Labrador Sea (8.6 percent
per decade). Comiso et al. (2008) included satellite data from 1979
through early September 2007 in their analyses. They found that the
trend of the entire sea ice cover (seasonal and perennial sea ice) has
accelerated from a decline of about 3 percent per decade in 1979-1996
to a decline of about 10 percent per decade in the last 10 years.
Statistically significant negative trends in Arctic sea ice extent now
occur n all calendar months (Serreze et al. 2007, pp. 1,533-1,536).
Sea Ice Thickness
Sea ice thickness is an important element of the Arctic climate
system. The sea ice thickness distribution influences the sea ice mass
budget and ice/ocean/atmosphere exchange (Holland et al. 2006a). Sea
ice thickness has primarily been measured with upward-looking sonar on
submarines and on moored buoys; this sonar provides information on ice
draft, the component of the total ice thickness (about 90 percent) that
projects below the water surface (Serreze et al. 2007, pp. 1,533-
1,536). Rothrock et al. (1999, p. 3,469) compared sea-ice draft data
acquired on submarine cruises between 1993 and 1997 with similar data
acquired between 1958 and 1976, and concluded that the mean sea-ice
draft at
[[Page 28223]]
the end of the melt season (i.e., perennial or multi-year ice) had
decreased by about 1.3 m (4.3 ft) in most of the deep water portion of
the Arctic Ocean. One limitation of submarine sonar data is sparse
sampling, which complicates interpretation of the results (Serreze et
al. 2007, pp. 1,533-1,536). Holloway and Sou (2002) noted concerns
regarding the temporal and spatial sampling of ice thickness data used
in Rothrock et al. (1999), and concluded from their modeling exercise
that ``a robust characterization over the half-century time series
consists of increasing volume to the mid-1960s, decadal variability
without significant trend from the mid-1960s to the mid-1980s, then a
loss of volume from the mid-1980s to the mid-1990s.'' Rothrock et al.
(2003, p. 28) conducted further analysis of the submarine-acquired data
in conjunction with model simulations and review of other modeling
studies, and concluded that all models agree that sea ice thickness
decreased between 0.6 and 0.9 m (2 and 3 ft) from 1987 to 1996. Their
model showed a modest recovery in thickness from 1996 to 1999. Yu et
al. (2004, p. 11) further analyzed submarine sonar data and concluded
that total ice volume decreased by 32 percent from the 1960s and 1970s
to the 1990s in the central Arctic Basin.
Fowler et al. (2004) utilized a new technique for combining
remotely-sensed sea ice motion and sea ice extent to ``track'' the
evolution of sea ice in the Arctic region from October 1978 through
March 2003. Their analysis revealed that the area of the oldest sea ice
(i.e., sea ice older than 4 years) was decreasing in the Arctic Basin
and being replaced by younger (first-year) ice. The extent of the older
ice was retreating to a relatively small area north of the Canadian
Archipelago, with narrow bands spreading out across the central Arctic
(Fowler et al. 2004, pp. 71-74). More recently, Maslanik et al. (2007)
documented a substantial decline in the percent coverage of old ice
within the central Arctic Basin. In 1987, 57 percent of the ice pack in
this area was 5 or more years old, with 25 percent of this ice at least
9 years old. By 2007, only 7 percent of the ice pack in this area was 5
or more years old, and ice at least 9 years old had completely
disappeared. This is significant because older ice is thicker than
younger ice, and therefore requires more energy to melt. The reduction
in the older ice types in the Arctic Basin translates into a reduction
in mean ice thickness from 2.6 m in March 1987 to 2.0 m in March 2007
(Stroeve et al. 2008).
Kwok (2007, p. 1) studied six annual cycles of perennial (multi-
year) Arctic sea ice coverage, from 2000 to 2006, and found that after
the 2005 summer melt, only about four percent of the thin, first-year
ice that formed the previous winter survived to replenish the multi-
year sea ice area (NASA/JPL News Release, April 3, 2007). That was the
smallest amount of multi-year ice replenishment documented in the
study, and resulted in perennial ice coverage in January 2006 that was
14 percent smaller than in January 2005. Kwok (2007, p. 1) attributed
the decline to unusually high amounts of ice exported from the Arctic
in the summer of 2005, and also to an unusually warm winter and summer
prior to September 2005.
Length of the Melt Period
The length of the melt period (or season) affects sea ice cover
(extent and area) and sea ice thickness (Hakkinen and Mellor 1990;
Laxon et al. 2003). In general terms, earlier onset of melt and
lengthening of the melt season result in decreased total sea ice cover
at the end of summer (i.e., the end of the melt season) (Stroeve et al.
2005, p. 3). Belchansky et al. (2004, p. 1) found that changes in
multi-year ice area measured in January were significantly correlated
with duration of the intervening melt season. Kwok found a correlation
between the number of freezing and melting temperature days and area of
multi-year sea ice replenished in a year (NASA/JPL News Release, April
3, 2007).
Comiso (2003, p. 3,506), using data for the period 1981-2001,
calculated that the Arctic sea ice melt season was increasing at a rate
of 10 to 17 days per decade during that period. Including additional
years in his analyses, Comiso (2005, p. 50) subsequently found that the
length of the melt season was increasing at a rate of approximately
13.1 days per decade. Stroeve et al. (2006 pp. 367-374) analyzed melt
season duration and melt onset and freeze-up dates from satellite
passive microwave data for the period 1979 through 2005, and found that
the Arctic is experiencing an overall lengthening of the melt season at
a rate of about 2 weeks per decade.
The NSIDC documented a trend of earlier onset of the melt season
for the years 2002 through 2005; the melt season arrived earliest in
2005, occurring approximately 17 days before the mean date of onset of
the melt season (NSIDC 2005, p. 6). In 2007, in addition to the record-
breaking September minimum sea ice extent, NSIDC scientists noted that
the date of the lowest sea ice extent shifted to later in the year
(NSIDC Press Release, October 1, 2007). The minimum sea ice extent
occurred on September 16, 2007; from 1979 to 2000, the minimum usually
occurred on September 12. This is consistent with a lengthening of the
melt season.
Parkinson (2000) documented a clear decrease in the length of the
sea ice season throughout the Greenland Sea, Kara and Barents Seas, Sea
of Okhotsk, and most of the central Arctic Basin. On the basis of
observational data, Stirling et al. (cited in Derocher et al. 2004)
calculated that break-up of the annual ice in Western Hudson Bay is
occurring approximately 2.5 weeks earlier than it did 30 years ago.
Consistent with these results, Stirling and Parkinson (2006) analyzed
satellite data for Western Hudson Bay for November 1978 through 2004
and found that, on average, ice break-up has been occurring about 7 to
8 days earlier per decade. Stirling and Parkinson (2006) also
investigated ice break-up in Foxe Basin, Baffin Bay, Davis Strait, and
Eastern Hudson Bay in Canada. They found that ice break-up in Foxe
Basin has been occurring about 6 days earlier each decade and ice
break-up in Baffin Bay has been occurring 6 to 7 days earlier per
decade. Long-term results from Davis Strait were not conclusive,
particularly because the maximum percentage of ice cover in Davis
Strait varies considerably more between years than in western Hudson
Bay, Foxe Basin, or Baffin Bay. Conversely, Stirling and Parkinson
(2006) documented a negative short-term trend from 1991 to 2004 in
Davis Strait. In eastern Hudson Bay, there was not a statistically
significant trend toward earlier break-up.
Understanding Observed Declines in Arctic Sea Ice
The observed declines in the extent of Arctic sea ice are well
documented, and more pronounced in the summer than in the winter. There
is also evidence that the rate of sea ice decline is increasing. This
decline in sea ice is of great importance to our determination
regarding the status of the polar bear. Understanding the causes of the
decline is also of great importance in assessing what the future might
hold for Arctic sea ice, and, thus, considerable effort has been
devoted to enhancing our understanding. This understanding will inform
our determination regarding the status of the polar bear within the
foreseeable future as determined in this rule.
In general terms, sea ice declines can be attributed to three
conflated factors: warming, atmospheric changes (including circulation
and clouds), and changes in oceanic circulation (Stroeve and Maslowski
2007). Serreze et al.
[[Page 28224]]
(2007, pp. 1,533-1,536) characterize the decline of sea ice as a
conflation of thermodynamic and dynamic processes: ``Thermodynamic
processes involve changes in surface air temperature (SAT), radiative
fluxes, and ocean conditions. Dynamic processes involve changes in ice
circulation in response to winds and ocean currents.'' In the following
paragraphs we discuss warming, changes in the atmosphere, and changes
in oceanic circulation, followed by a synthesis. It is critically
important that we understand the dynamic forces that govern all aspects
of sea ice given the polar bear's almost exclusive reliance on this
habitat.
Air and Sea Temperatures
Estimated rates of change in surface air temperature (SAT) over the
Arctic Ocean over the past 100 or more years vary depending on the time
period, season, and data source used (Serreze et al. 2007, pp. 1,533-
1,536). Serreze et al. (2007, pp. 1,533-1,536) note that, although
natural variability plays a large role in SAT variations, the overall
pattern has been one of recent warming.
Polyakov et al. (2003) compiled SAT trends for the maritime Arctic
for the period 1875 through 2000 (as measured by coastal land stations,
drifting ice stations, and Russian North Pole stations) and found that,
since 1875, the Arctic has warmed by 1.2 degrees Celsius (C), an
average warming of 0.095 degree C per decade over the entire period,
and an average warming of 0.05 0.04 degree C per decade
during the 20th century. The increases were greatest in winter and
spring, and there were two relative maxima during the century (the late
1930s and the 1990s). The ACIA analyzed land-surface air temperature
trends as recorded in the Global Historical Climatology Network (GHCN)
database, and documented a statistically significant warming trend of
0.09 degree C per decade during the period 1900-2003 (ACIA 2005, p.
35). For periods since 1950, the rate of temperature increase in the
marine Arctic documented in the GHCN (ACIA 2005, p. 35) is similar to
the increase noted by Polyakov et al. (2003).
Rigor et al. (2000) documented positive trends in SAT for 1979 to
1997; the trends were greatest and most widespread in spring. Comiso
(2006) analyzed data from the Advanced Very High Resolution Radiometer
(AVHRR) for 1981 to 2005, and documented an overall warming trend of
0.54 0.11 degrees C per decade over sea ice. Comiso noted
that ``it is apparent that significant warming has been occurring in
the Arctic but not uniformly from one region to another.'' The Serreze
et al. (2007, pp. 1,533-1,536) assessment of data sets from the
National Centers for Environmental Prediction and the National Center
for Atmospheric Research indicated strong surface and low-level warming
for the period 2000 to 2006 relative to 1979 to 1999, consistent with
the observed sea ice losses.
Stroeve and Maslowski (2007) noted that anomalously high
temperatures have been consistent throughout the Arctic since 2002.
Further support for warming comes from studies indicating earlier onset
of spring melt and lengthening of the melt season (e.g., Stroeve et al.
2006, pp. 367-374), and data that point to increased downward radiation
toward the surface, which is linked to increased cloud cover and water
vapor (Francis and Hunter 2006, cited in Serreze et al. 2007, pp.
1,533-1,536).
According to the IPCC AR4 (IPCC 2007, p. 36), 11 of 12 years from
1995 to 2006 (the exception being 1996) were among the 12 warmest years
on record since 1850; 2005 and 1998 were the warmest two years in the
instrumental global surface air temperature record since 1850. Surface
temperatures in 1998 were enhanced by the major 1997-1998 El
Ni[ntilde]o but no such large-scale atmospheric anomaly was present in
2005. The IPCC AR4 concludes that the ``warming in the last 30 years is
widespread over the globe, and is greatest at higher northern latitudes
(IPCC 2007, p. 37).'' Further, the IPCC AR4 states that greatest
warming has occurred in the northern hemisphere winter (December,
January, February) and spring (March, April, May). Average Arctic
temperatures have been increasing at almost twice the rate of the rest
of the world in the past 100 years. However, Arctic temperatures are
highly variable. A slightly longer Arctic warm period, almost as warm
as the present, was observed from 1925 to 1945, but its geographical
distribution appears to have been different from the recent warming
since its extent was not global.
Finally, Comiso (2005, p. 43) determined that for each 1 degree C
increase in surface temperature (global average) there is a
corresponding decrease in perennial sea ice cover of about 1.48 million
sq km (0.57 million sq mi).
Changes in Atmospheric Circulation
Links have also been established between sea ice loss and changes
in sea ice circulation associated with the behavior of key atmospheric
patterns, including the Arctic Oscillation (AO; also called the
Northern Annular Mode (NAM)) (e.g., Thompson and Wallace 2000;
Limpasuvan and Hartmann 2000) and the more regional, but closely
related North Atlantic Oscillation (NAO; e.g., Hurrell 1995). First
described in 1998 by atmospheric scientists David Thompson and John
Wallace, the Arctic Oscillation is a measure of air-pressure and wind
patterns in the Arctic. In the so-called ``positive phase'' (or high
phase), air pressure over the Arctic is lower than normal and strong
westerly winds occur in the upper atmosphere at high latitudes. In the
so-called ``negative phase'' (or low phase), air pressure over the
Arctic is higher than normal, and the westerly winds are weaker.
Rigor et al. (2002, cited in Stroeve and Maslowski 2007) showed
that when the AO is positive in winter, altered wind patterns result in
more offshore ice motion and ice divergence along the Siberian and
Alaskan coastlines; this leads to the production of more extensive
areas of thinner, first-year ice that requires less energy to melt.
Rigor and Wallace (2004, cited in Deweaver 2007) suggested that the
recent reduction in September ice extent is a delayed reaction to the
export of multi-year ice during the high-AO winters of 1989 through
1995. They estimated that the recovery of sea ice to its normal extent
should take between 10 and 15 years. However, Rigor and Wallace (2004)
estimated that the combined winter and summer AO-indices can explain
less than 20 percent of the variance in summer sea ice extent in the
western Arctic Ocean where most of the recent reductions in sea ice
cover have occurred. The notion that AO-related export of multi-year
ice from the Arctic is the principal cause of observed declines in
Arctic sea ice extent has been questioned by several authors, including
Overland and Wang (2005), Comiso (2006), Stroeve and Maslowski (2007),
Serreze et al. (2007, pp. 1,533-1,536), and Stroeve et al. (2008) who
note that sea ice extent has not recovered despite the return of the AO
to a more neutral state since the late 1990s. Overland and Wang (2005)
noted that the return of the AO to a more neutral state was accompanied
by southerly wind anomalies from 2000-2005 which contributed to
reducing the ice cover over time and ``conditioning'' the Arctic for
the extensive summer sea ice reduction in 2007 (J. Overland NOAA, pers.
comm. to FWS, 2007). Maslanik et al. (2007) reached a similar
conclusion that despite the return of the AO to a more neutral state,
wind and ice transport patterns that favor reduced ice cover in the
western and central Arctic continued to play a role in the loss of sea
ice in those regions. Maslanik et al.
[[Page 28225]]
(2007) believe that circulation patterns such as the Beaufort Gyre,
which in the past helped to maintain old ice in the Arctic Basin, are
now acting to export ice, as the multi-year ice is no longer surviving
the transport through the Chukchi and East Siberian Seas.
According to DeWeaver (2007): ``Recognizing the need to incorporate
AO variability into considerations of recent sea ice decline, Lindsay
and Zhang (2005) used an ocean-sea ice model to reconstruct the sea ice
behavior of the satellite era and identify separate contributions from
ice motion and thermodynamics. Similar experiments with similar results
were also reported by Rothrock and Zhang (2005) and Koberle and Gerdes
(2003).'' Rothrock and Zhang (2005, cited in Serreze et al. 2007, pp.
1,533-1,536), using a coupled ice-ocean model, argued that although
wind forcing was the dominant driver of declining ice thickness and
volume from the late 1980s through the mid-1990s, the ice response to
generally rising air temperatures was more steadily downward over the
study period (1948 to 1999). ``In other words, without wind forcing,
there would still have been a downward trend in ice extent, albeit
smaller than that observed'' (Serreze et al. 2007, pp. 1,533-1,536).
Lindsay and Zhang (2005, cited in Serreze et al. 2007, pp. 1,533-1,536)
came to similar conclusions in their modeling study: ``Rising air
temperature reduced ice thickness, but changes in circulation also
flushed some of the thicker ice out of the Arctic, leading to more open
water in summer and stronger absorption of solar radiation in the upper
(shallower depths of the) ocean. With more heat in the ocean, thinner
ice grows in autumn and winter.''
Changes in Oceanic Circulation
According to Serreze et al. (2007, pp. 1,533-1,536), it appears
that changes in ocean heat transport have played a role in declining
Arctic sea ice extent in recent years. Warm Atlantic waters enter the
Arctic Ocean through the Fram Strait and Barents Sea (Serreze et al.
2007, pp. 1,533-1,536). This water is denser than colder, fresher (less
dense) Arctic surface waters, and sinks (subducts) to form an
intermediate layer between depths of 100 and 800 m (328 and 2,624 ft)
(Quadfasel et al. 1991) with a core temperature significantly above
freezing (DeWeaver 2007; Serreze et al. 2007, pp. 1,533-1,536).
Hydrographic data show increased import of Atlantic-derived waters in
the early to mid-1990s and warming of this inflow (Dickson et al. 2000;
Visbeck et al. 2002). This trend has continued, characterized by
pronounced pulses of warm inflow (Serreze et al. 2007, pp. 1,533-
1,536). For example, strong ocean warming in the Eurasian Basin of the
Arctic Ocean in 2004 can be traced to a pulse entering the Norwegian
Sea in 1997-1998 and passing through Fram Strait in 1999 (Polyakov et
al. 2007). The anomaly found in 2004 was tracked through the Arctic
system and took about 1.5 years to travel from the Norwegian Sea to the
Fram Strait region, and an additional 4.5-5 years to reach the Laptev
Sea slope (Polyakov et al. 2007).
Polyakov et al. (2007) reported that mooring-based records and
oceanographic surveys suggest that a new pulse of anomalously warm
water entered the Arctic Ocean in 2004. Further Polyakov et al. (2007)
stated that: ``combined with data from the previous warm anomaly * * *
this information provides evidence that the Nansen Basin of the Arctic
Ocean entered a new warm state. These two warm anomalies are
progressing towards the Arctic Ocean interior * * * but still have not
reached the North Pole observational site. Thus, observations suggest
that the new anomalies will soon enter the central Arctic Ocean,
leading to further warming of the polar basin. More recent data, from
summer 2005, showed another warm anomaly set to enter the Arctic Ocean
through the Fram Strait (Walczowski and Piechura 2006). These inflows
may promote ice melt and discourage ice growth along the Atlantic ice
margin (Serreze et al. 2007, pp. 1,533-1,536).
Once Atlantic water enters the Arctic Ocean, the cold halocline
layer (CHL) separating the Atlantic and surface waters largely
insulates the ice from the heat of the Atlantic layer. Observations
suggest a retreat of the CHL in the Eurasian basin in the 1990s (Steele
and Boyd 1998, cited in Serreze et al. 2007, pp. 1,533-1,536). This
likely increased Atlantic layer heat loss and ice-ocean heat exchange
(Serreze et al. 2007, pp. 1,533-1,536), which would serve to erode the
edge of the sea ice on a year-round basis (C. Bitz, in litt. to the
Service, November 2007). Partial recovery of the CHL has been observed
since 1998 (Boyd et al. 2002, cited in Serreze et al. 2007, pp. 1,533-
1,536), and future behavior of the CHL is an uncertainty in projections
of future sea ice loss (Serreze et al. 2007, pp. 1,533-1,536).
Synthesis
From the previous discussion, surface air temperature warming,
changes in atmospheric circulation, and changes in oceanic circulation
have all played a role in observed declines of Arctic sea ice extent in
recent years.
According to DeWeaver (2007): ``Lindsay and Zhang (2005) propose a
three-part explanation of sea ice decline,'' which incorporates both
natural AO variability and warming climate. In their explanation, a
warming climate preconditions the ice for decline as warmer winters
thin the ice, but the loss of ice extent is triggered by natural
variability such as flushing by the AO. Sea ice loss continues after
the flushing because of the sea-ice albedo feedback mechanism which
warms the sea even further. In recent years, flushing of sea ice has
continued through other mechanisms despite a relaxation of the AO since
the late 1990s. The sea-ice albedo feedback effect is the result of a
reduction in the extent of brighter, more reflective sea ice or snow,
which reflects solar energy back into the atmosphere, and a
corresponding increase in the extent of darker, more absorbing water or
land that absorbs more of the sun's energy. This greater absorption of
energy causes faster melting, which in turn causes more warming, and
thus creates a self-reinforcing cycle or feedback loop that becomes
amplified and accelerates with time. Lindsay and Zhang (2005, p. 4,892)
suggest that the sea-ice albedo feedback mechanism caused a tipping
point in Arctic sea ice thinning in the late 1980s, sustaining a
continual decline in sea ice cover that cannot easily be reversed.
DeWeaver (2007) believes that the work of Lindsay and Zhang (2005)
suggests that the observed record of sea ice decline is best
interpreted as a combination of internal variability and external
forcing (via GHGs), and raises the possibility that the two factors may
act in concert rather than as independent agents.
Evidence that warming resulting from GHG forcing has contributed to
sea ice declines comes largely from model simulations of the late 20th
century climate. Serreze et al. (2007, pp. 1,533-1,536) summarized
results from Holland et al. (2006, pp. 1-5) and Stroeve et al. (2007,
pp. 1-5), and concluded that the qualitative agreement between model
results and actual observations of sea ice declines over the PM
satellite era is strong evidence that there is a forced component to
the decline. This is because each of these models would be in its own
phase of natural variability and thus could show an increase or
decrease in sea ice, but the fact that they all show a decrease
indicates that more than natural variability is involved, i.e., that
external forcing by GHGs is a factor. In addition, the model results do
not show a decline if they are not forced with the observed GHGs.
Serreze et al.
[[Page 28226]]
(2007, pp. 1,533-1,536) concluded: ``These results provide strong
evidence that, despite prominent contributions of natural variability
in the observed record, GHG loading has played a role.''
Hegerl et al. (2007) used a new approach to reconstruct and
attribute a 1,500-year temperature record for the Northern Hemisphere.
Based on their analysis to detect and attribute temperature change over
that period, they estimated that about a third of the warming in the
first half of the 20th century can be attributed to anthropogenic GHG
emissions. In addition, they estimated that the magnitude of the
anthropogenic signal is consistent with most of the warming in the
second half of the 20th century being anthropogenic.
Observed Changes in Other Key Parameters
Snow Cover on Ice
Northern Hemisphere snow cover, as documented by satellite over the
1966 to 2005 period, decreased in every month except November and
December, with a step like drop of 5 percent in the annual mean in the
late 1980s (IPCC 2007, p. 43). April snow cover extent in the Northern
Hemisphere is strongly correlated with temperature in the region
between 40 and 60 degrees N Latitude; this reflects the feedback
between snow and temperature (IPCC 2007, p. 43).
The presence of snow on sea ice plays an important role in the
Arctic climate system (Powell et al. 2006). Arctic sea ice is covered
by snow most of the year, except when the ice first forms and during
the summer after the snow has melted (Sturm et al. 2006). Warren et al.
(1999, cited in IPCC 2007 Chapter 4) analyzed 37 years (1954-1991) of
snow depth and density measurements made at Soviet drifting stations on
multi-year Arctic sea ice. They found a weak negative trend for all
months, with the largest being a decrease of 8 cm (3.2 in) (23 percent)
in May.
Precipitation
The Arctic Climate Impact Assessment (2005) concluded that
``overall, it is probable that there was an increase in arctic
precipitation over the past century.'' An analysis of data in the
Global Historical Climatology Network (GHCN) database indicated a
significant positive trend of 1.4 percent per decade (ACIA 2005) for
the period 1900 through 2003. New et al. (2001, cited in ACIA 2005))
used uncorrected records and found that terrestrial precipitation
averaged over the 60 degree to 80 degree N latitude band exhibited an
increase of 0.8 percent per decade over the period from 1900 to 1998.
In general, the greatest increases were observed in autumn and winter
(Serreze et al. 2000). According to the ACIA (2005) calculations: (1)
during the Arctic warming in the first half of the 20th century (1900-
1945), precipitation increased by about 2 percent per decade, with
significant positive trends in Alaska and the Nordic region; (2) during
the two decades of Arctic cooling (1946-1965), the high-latitude
precipitation increase was roughly 1 percent per decade, but there were
large regional contrasts with strongly decreasing values in western
Alaska, the North Atlantic region, and parts of Russia; and (3) since
1966, annual precipitation has increased at about the same rate as
during the first half of the 20th century. The ACIA report (2005) notes
that these trends are in general agreement with results from a number
of regional studies (e.g., Karl et al. 1993; Mekis and Hogg 1999;
Groisman and Rankova 2001; Hanssen-Bauer et al. 1997; F[oslash]rland et
al. 1997; Hanssen-Bauer and F[oslash]rland 1998). In addition to the
increase, changes in the characteristics of precipitation have also
been observed (ACIA 2005). Much of the precipitation increase appears
to be coming as rain, mostly in winter and to a lesser extent in autumn
and spring. The increasing winter rains, which fall on top of existing
snow, cause faster snowmelt. Increased rain in late winter and early
spring could affect the thermal properties of polar bear dens (Derocher
et al. 2004), thereby negatively impacting cub survival. Increased rain
in late winter and early spring may even cause den collapse (Stirling
and Smith 2004).
According to the IPCC AR4 (2007, pp. 256-258), distinct upward
trends in precipitation are evident in many regions at higher
latitudes, especially from 30 to 85 degrees N latitude. Winter
precipitation has increased at high latitudes, although uncertainties
exist because of changes in undercatch, especially as snow changes to
rain (IPCC 2007, p. 258). Annual precipitation for the circumpolar
region north of 50 degrees N has increased during the past 50 years by
approximately 4 percent but this increase has not been homogeneous in
time and space (Groisman et al. 2003, 2005, both cited in IPCC 2007, p.
258). According to the IPCC AR4: ``Statistically significant increases
were documented over Fennoscandia, coastal regions of northern North
America (Groisman et al. 2005), most of Canada (particularly northern
regions) up until at least 1995 when the analysis ended (Stone et al.
2000), the permafrost-free zone of Russia (Groisman and Rankova 2001)
and the entire Great Russian Plain (Groisman et al. 2005, 2007).'' That
these trends are real, extending from North America to Europe across
the North Atlantic, is also supported by evidence of ocean freshening
caused by increased freshwater run-off (IPCC 2007, p. 258).
Rain-on-snow events have increased across much of the Arctic. For
example, over the past 50 years in western Russia, rain-on-snow events
have increased by 50 percent (ACIA 2005). Groisman et al. (2003)
considered rain-on-snow trends over a 50-year period (1950-2000) in
high latitudes in the northern hemisphere and found an increasing trend
in western Russia and decreases in western Canada (the decreasing
Canadian trend was attributed to decreasing snow pack). Putkonen and
Roe (2003), working on Spitsbergen Island, where the occurrence of
winter rain-on-snow events is controlled by the North Atlantic
Oscillation, demonstrated that these events are capable of influencing
mean winter soil temperatures and affecting ungulate survival. These
authors include the results of a climate modeling effort (using the
earlier-generation Geophysical Fluid Dynamics Laboratory climate model
and a 1 percent per year increase in CO2 forcing scenario)
that predicted a 40 percent increase in the worldwide area of land
affected by rain-on-snow events from 1980-1989 to 2080-2089. Rennert et
al. (2008) discussed the significance of rain-on-snow events to
ungulate survival in the Arctic, and used the dataset European Center
for Medium-range Weather Forecasting (ECMWF) European 40 Year (ERA40)
Reanalysis (Uppala et al. 2005) to create a climatology of rain-on-snow
events for thresholds that impact ungulate populations and permafrost.
In addition to contributing to increased incidence of polar bear den
collapse, increased rain-on-snow events during the late winter or early
spring could also damage or eliminate snow-covered pupping lairs of
ringed seals (the polar bear's principal prey), thereby increasing pup
exposure and the risk of hypothermia, and facilitating predation by
polar bears and Arctic foxes. This could negatively impact ringed seal
recruitment.
Projected Changes in Arctic Sea Ice
Background
To make projections about future ecosystem effects that could
result from climate change, one must first make projections of changes
in physical
[[Page 28227]]
climate parameters based on changes in external factors that can affect
the physical climate (ACIA 2005). Climate models use the laws of
physics to simulate the main components of the climate system (the
atmosphere, ocean, land surface, and sea ice) (DeWeaver 2007), and make
projections of future climate scenarios-plausible representations of
future climate-that are consistent with assumptions about future
emissions of GHGs and other pollutants (these assumptions are called
``emissions scenarios'') and with present understanding of the effects
of increased atmospheric concentrations of these components on the
climate (ACIA 2005).
Virtually all climate models use emissions scenarios developed as
part of the IPCC effort; specifically the IPCC's Special Report on
Emissions Scenarios (SRES) (IPCC 2000) details a number of plausible
future emissions scenarios based on assumptions on how societies,
economies, and energy technologies are likely to evolve. The SRES
emissions scenarios were built around four narrative storylines that
describe the possible evolution of the world in the 21st century (ACIA
2005, p.119). Around these four narrative storylines the SRES
constructed six scenario groups and 40 different emissions scenarios.
Six scenarios (A1B, A1T, A1FI, A2, B1, and B2) were then chosen as
illustrative ``marker'' scenarios. These scenarios have been used to
estimate a range of future GHG emissions that affect the climate. The
scenarios are described on page 18 of the AR4 Working Group I: Summary
for Policymakers (IPCC 2007), and in greater detail in the SRES Report
(IPCC 2000).
The most commonly-used scenarios for current-generation climate
modeling are the B1, A1B, and A2 scenarios. In the B1 scenario,
CO2 concentration is around 549 parts per million (ppm) by
2100; this is often termed a `low' scenario. In the A1B scenario,
CO2 concentration is around 717 ppm by the end of the
century; this is a 'medium' or `middle-of-the-road' scenario. In the A2
scenario, CO2 concentration is around 856 ppm at the end of
the 21st century; this is considered a `high' scenario with respect to
GHG concentrations. It is important to note that the SRES scenarios
include no additional mitigation initiatives, which means that no
scenarios are included that explicitly assume the implementation of the
United Nations Framework Convention on Climate Change (UNFCC) or the
emission targets of the Kyoto Protocol.
Of the various types of climate models, the Atmosphere-Ocean
General Circulation Models (AOGCMs, also known as General Circulation
Models (GCMs)) are acknowledged as the principal and most rapidly-
developing tools for simulating the response of the global climate
system to various GHG and aerosol emission scenarios. The climates
simulated by these models have been verified against observations in
several model intercomparison programs (e.g., Achuta Rao et al. 2004;
Randall et al. 2007) and have been found to be generally realistic
(DeWeaver 2007). Additional confidence in model simulations comes from
experiments with a hierarchy of simpler models, in which the dominant
processes represented by climate models (e.g., heat and momentum
transport by mid-latitude weather systems) can be isolated and studied
(DeWeaver 2007).
For projected changes in climate and Arctic sea ice conditions, our
proposed rule (72 FR 1064) relied primarily on results in the IPCC's
Third Assessment Report (TAR) (IPCC 2001b), the Arctic Climate Impact
Assessment (ACIA 2005, p. 99), and selected peer-reviewed papers (e.g.,
Johannessen et al. 2004; Holland et al. 2006, pp. 1-5). The IPCC TAR
used results derived from 9-AOGCM ensemble (i.e, averaged results from
9 AOGCMs) and three SRES emissions scenarios (A2, B2, and IS92a). The
ACIA (2005, p. 99) used a 5-AOGCM ensemble under two SRES emissions
scenarios (A2 and B2); however, the B2 emissions scenario was chosen as
the primary scenario for use in ACIA analyses (ACIA 2005). These
reports relied on ensembles rather than single models, because ``no one
model can be chosen as 'best' and it is important to use results from a
range of models'' (IPCC 2001, Chapter 8). The other peer-reviewed
papers used in the proposed rule (72 FR 1064) tend to report more-
detailed results from a one or two model simulations using one SRES
scenario.
After the proposed rule was published (72 FR 1064), the IPCC
released its Fourth Assessment Report (AR4) (IPCC 2007), a detailed
assessment of current and predicted future climates around the globe.
Projected changes in climate and Arctic sea ice conditions presented in
the IPCC AR4 have been used extensively in this final rule. The IPCC
AR4 used results from state-of-the-art climate models that have been
substantially improved over the models used in the IPCC TAR and ACIA
reports (M. Holland, NCAR, in litt. to the Service, 2007; DeWeaver
2007). In addition, the IPCC AR4 used results from a greater number of
models (23) than either the IPCC TAR or ACIA reports. ``This larger
number of models running the same experiments allows better
quantification of the multi-model signal as well as uncertainty
regarding spread across the models, and also points the way to
probabilistic estimates of future climate change'' (IPCC 2007, p. 761).
Finally, the IPCC AR4 used a greater number of emissions scenarios (4)
than either the IPCC TAR or ACIA reports. The emission scenarios
considered in the AR4 include A2, A1B, and B1, as well as a ``year 2000
constant concentration'' scenario; this choice was made solely due to
the limited computational resources for multi-model simulations using
comprehensive AOGCMs, and ``does not imply any preference or
qualification of these three scenarios over the others'' (IPCC 2007,
p.761). For all of these reasons, there is considerable confidence that
the AOGCMs used in the IPCC AR4 provide credible quantitative estimates
of future climate change, particularly at continental scales and above
(IPCC 2007, p. 591), and we have determined that these results are
rightly included in the category of best available scientific
information upon which to base a listing decision for the polar bear.
In addition to the IPCC AR4 results, this final rule utilizes
results from a large number of peer-reviewed papers (e.g., Parkinson et
al. 2006; Zhang and Walsh 2006; Arzel et al. 2006; Stroeve et al. 2007,
pp. 1-5; Holland et al. 2006, pp. 1-5; Wang et al. 2007, pp. 1,093-
1,107; Overland and Wang 2007a, pp. 1-7; Chapman and Walsh 2007) that
provide more detailed information on climate change projections for the
Arctic.
Uncertainty in Climate Models
The fundamental physical laws reflected in climate models are well
established, and the models are broadly successful in simulating
present-day climate and recent climate change (IPCC 2007, cited in
DeWeaver 2007). For Arctic sea ice, model simulations unanimously
project declines in areal coverage and thickness due to increased GHG
concentrations (DeWeaver 2007). They also agree that GHG-induced
warming will be largest in the high northern latitudes and that the
loss of sea ice will be much larger in summer than in winter (Meehl et
al. 2007, cited in DeWeaver 2007). However, despite the qualitative
agreement among climate model projections, individual model results for
Arctic sea ice decline span a considerable range (DeWeaver 2007). Thus,
projections from models are often expressed in terms of the typical
[[Page 28228]]
behavior of a group (ensemble) of simulations (e.g., Arzel et al. 2006;
Flato et al. 2004; Holland et al. 2006, pp. 1-5).
DeWeaver (2007) presents a detailed analysis of uncertainty
associated with climate models and their projections for Arctic sea ice
conditions. He concludes that two main sources of uncertainty should be
considered in assessing Arctic sea ice simulations: uncertainties in
the construction of climate models and unpredictable natural
variability of the climate system. DeWeaver (2007) states that while
most aspects of climate simulations have some degree of uncertainty,
projections of Arctic climate change have relatively higher
uncertainty. This higher level of uncertainty is, to some extent, a
consequence of the smaller spatial scale of the Arctic, since climate
simulations are believed to be more reliable at continental and larger
scales (Meehl et al. 2007, IPCC 2007, both cited in DeWeaver 2007). The
uncertainty is also a consequence of the complex processes that control
the sea ice, and the difficulty of representing these processes in
climate models. The same processes which make Arctic sea ice highly
sensitive to climate change, the ice-albedo feedback in particular,
also make sea ice simulations sensitive to any uncertainties in model
physics (e.g., the representation of Arctic clouds) (DeWeaver 2007).
DeWeaver (2007) also discusses natural variability of the climate
system. He states that the atmosphere, ocean, and sea ice comprise a
``nonlinear chaotic system'' with a high level of natural variability
unrelated to external climate forcing. Thus, even if climate models
perfectly represented all climate system physics and dynamics, inherent
climate unpredictability would limit our ability to issue highly,
detailed forecasts of climate change, particularly at regional and
local spatial scales, into the middle and distant future (DeWeaver
2007).
DeWeaver (2007) states that the uncertainty in model simulations
should be assessed through detailed model-to-model and model-to-
observation comparisons of sea ice properties like thickness and
coverage. In principle, inter-model sea ice variations are attributable
to differences in model construction, but attempts to relate simulation
differences to specific model differences generally have not been
successful (e.g., Flato et al. 2004, cited in DeWeaver 2007). A
practical consequence of uncertainty in climate model simulations of
sea ice is that a mean and spread of an ensemble of simulations should
be considered in deciding the likely fate of Arctic sea ice. Some
model-to-model variation (or spread) in future sea ice behaviors is
expected even among high-quality simulations due to natural
variability, but spread that is a consequence of poor simulation
quality should be avoided. Thus, it is desirable to define a selection
criterion for membership in the ensemble, so that only those models
that demonstrate sufficient credibility in present-day sea ice
simulation are included. Fidelity in sea ice hindcasts (i.e., the
ability of models to accurately simulate past to present-day sea ice
conditions) is an important consideration. This same perspective is
shared by other researchers, including Overland and Wang (2007a, p. 1),
who state: ``Our experience (Overland and Wang 2007b) as well as others
(Knutti et al. 2006) suggest that one method to increase confidence in
climate projections is to constrain the number of models by removal of
major outliers through validating historical simulations against
observations. This requirement is especially important for the
Arctic.''
Projection Results in the IPCC TAR and ACIA
This section briefly summarizes the climate model projections of
the IPCC TAR and the ACIA, the principal reports used in the proposed
rule (72 FR 1064), while the following section presents detailed
results published subsequent to those reports, including in the IPCC
AR4.
All models in the IPCC TAR predicted continued Arctic warming and
continued decreases in the Arctic sea ice cover in the 21st century due
to increasing global temperatures, although the level of increase
varied between models. The TAR projected a global mean temperature
increase of 1.4 degree C by the mid-21st century compared to the
present climate for both the A2 and B2 scenarios (IPCC 2001b). Toward
the end of the 21st century (2071 to 2100), the mean change in global
average surface air temperature, relative to the period 1961-1990, was
projected to be 3.0 degrees C (with a range of 1.3 to 4.5 degrees C)
for the A2 scenario, and 2.2 degrees C (with a range of 0.9 to 3.4
degrees C) for the B2 scenario. Relative to glacier and sea ice change,
the TAR reported that ``The representation of sea-ice processes
continues to improve, with several climate models now incorporating
physically based treatments of ice dynamics * * *. Glaciers and ice
caps will continue their widespread retreat during the 21st century and
Northern Hemisphere snow cover and sea ice are projected to decrease
further.''
The ACIA concluded that, for both the A2 and B2 emissions
scenarios, models projected mean temperature increases of 2.5 degrees C
for the region north of 60 degrees N latitude by the mid-21st century
(ACIA 2005, p. 100). By the end of the 21st century, Arctic temperature
increases were projected to be 7 degrees C and 5 degrees C for the A2
and B2 scenarios, respectively, compared to the present climate (ACIA
2005, p. 100). Greater warming was projected for the autumn and winter
than for the summer (ACIA 2005, p. 100).
The ACIA utilized projections from the five ACIA-designated AOGCMs
to evaluate changes in sea ice conditions for three points in time
(2020, 2050, and 2080) relative to the climatological baseline (2000)
(ACIA 2005, p. 192). In 2020, the duration of the sea ice freezing
period was projected to be shorter by 10 days; winter sea ice extent
was expected to decline by 6 to 10 percent from baseline conditions;
summer sea ice extent was expected to decline such that continental
shelves were likely to be ice free; and there would be some reduction
in multi-year ice, especially on shelves (ACIA 2005, Table 9.4). In
2050, the duration of the sea ice freezing period was projected to be
shorter by 15 to 20 days; winter sea ice extent was expected to decline
by 15 to 20 percent; summer sea ice extent was expected to decline 30
to 50 percent from baseline conditions; and there would be significant
loss of multi-year ice, with no multi-year ice on shelves. In 2080, the
duration of the sea ice freezing period was projected to be shorter by
20 to 30 days; winter sea ice extent was expected to decline such that
there probably would be open areas in the high Arctic (Barents Sea and
possibly Nansen Basin); summer sea ice extent was expected to decline
50 to 100 percent from baseline conditions; and there would be little
or no multi-year ice.
According to ACIA (2005, p. 193), one model indicated an ice-free
Arctic during September by the mid-21st century, but this model
simulated less than half of the observed September sea-ice extent at
the start of the 21st century. None of the other models projected ice-
free summers in the Arctic by 2100, although the sea-ice extent
projected by two models decreased to about one-third of initial (2000)
and observed September values by 2100.
Projection Results in the IPCC AR4 and Additional Projections
The IPCC AR4, released a few months after publication of our
proposed listing
[[Page 28229]]
rule for the polar bear (72 FR 1064), presents results from state-of-
the-art climate models that are substantially improved over models used
in the IPCC TAR and ACIA reports (M. Holland, NCAR, in litt. to the
Service FWS, 2007; DeWeaver 2007). Results of the AR4 are presented in
this section, followed by discussion of several key, peer-reviewed
articles that discuss results presented in the AR4 in greater detail or
use AR4 simulations to conduct additional, in-depth analyses.
In regard to surface air temperature changes, the IPCC AR4 states
that the range of expected globally averaged surface air temperature
warming shows limited sensitivity to the choice of SRES emissions
scenarios for the early 21st century (between 0.64 and 0.69 degrees C
for 2011 to 2030 compared to 1980 to 1999, a range of only 0.05
[deg]C), largely due to climate change that is already committed (IPCC
2007, p. 749). By the mid-21st century (2046-2065), the choice of SRES
scenario becomes more important for globally averaged surface air
temperature warming (with increases of 1.3 degree C for the B1
scenario, 1.8 degree C for A1B, and 1.7 degree C for A2). During this
time period, about a third of that warming is projected to be due to
climate change that is already committed (IPCC 2007, p. 749).
The ``limited sensitivity'' of the results is because the state-of-
the-art climate models used in the AR4 have known physics in connecting
increases in GHGs to temperature increases through radiation processes
(Overland and Wang 2007a, pp. 1-7, cited in J. Overland, NOAA, in litt.
to the Service, 2007), and the GHG levels used in the SRES emissions
scenarios are relatively similar until around 2040-2050 (see Figure 5).
Because increases in GHGs have lag effects on climate and projections
of GHG emissions can be extrapolated with greater confidence over the
next few decades, model results projecting out for the next 40 to 50
years (near-term climate change estimates) have greater credibility
than results projected much further into the future (long-term climate
change) (J. Overland, NOAA, in litt. to the Service, 2007). Thus, the
uncertainty associated with emissions is relatively smaller for the 45-
year ``foreseeable future'' for the polar bear listing. After 2050,
uncertainty associated with various climate mechanisms and policy/
societal changes begins to increase, as reflected in the larger
confidence intervals around the trend lines in Figure 5 beyond 2050.
[GRAPHIC] [TIFF OMITTED] TR15MY08.006
[[Page 28230]]
However, even if GHG emissions had stabilized at 2000 levels, the
global climate system would already be committed to a warming trend of
about 0.1 degree C per decade over the next two decades, in the absence
of large changes in volcanic or solar forcing. Meehl et al. (2006)
conducted climate change scenario simulations using the Community
Climate System Model, version 3 (CCSM3, National Center for Atmospheric
Research), with all GHG emissions stabilized at 2000 levels, and found
that the global climate system would already be committed to 0.40
degree C more warming by the end of the 21st century.
With respect to warming in the Arctic itself, the AR4 concludes:
``At the end of the 21st century, the projected annual warming in the
Arctic is 5 degrees C, estimated by the multi-model A1B ensemble mean
projection'' (see IPCC 2007, p. 908, Fig. 11.21). The across-model
range for the A1B scenario varied from 2.8 to 7.8 degrees C. Larger
mean warming was found for the A2 scenario (5.9 degrees C), and smaller
mean warming was found for the B1 scenario (3.4 degrees C); both with
proportional across-model ranges. Chapman and Walsh (2007, cited IPCC
2007, p. 904) concluded that the across-model and across-scenario
variability in the projected temperatures are both considerable and of
comparable amplitude.
In regard to changes in sea ice, the IPCC AR4 concludes that, under
the A1B, A2, and B1 SRES emissions scenarios, large parts of the Arctic
Ocean are expected to be seasonally ice free by the end of the 21st
century (IPCC 2007, p. 73). Some projections using the A2 and A1B
scenarios achieve a seasonally ice-free Arctic by as early as 2080-2090
(IPCC 2007, p.771, Figure 10.13a, b). Sea ice reductions are greater in
summer than winter, thus it is summer sea ice cover that is projected
to be lost in some models by 2080-2090, not winter sea ice cover. The
reduction in sea ice cover is accelerated by positive feedbacks in the
climate system, including the ice-albedo feedback (which allows open
water to receive more heat from the sun during summer, the insulating
effect of sea ice is reduced and the increase in ocean heat transport
to the Arctic further reduces ice cover) (IPCC 2007, p. 73).
While the conclusions of the IPCC TAR and AR4 are similar with
respect to the Arctic, the confidence level associated with independent
reviews of AR4 is greater, owing to improvements in the models used and
the greater number of models and emissions scenarios considered (J.
Overland, NOAA, in litt. to the Service, 2007). Climate models still
have challenges modeling some of the regional differences caused by
changing decadal climate patterns (e.g., Arctic Oscillation). To help
improve the models further, the evaluation of AR4 models has been on-
going both for how well they represent conditions in the 20th century
and how their predicted results for the 21st century compare (Parkinson
et al. 2006; Zhang and Walsh 2006; Arzel et al. 2006; Stroeve et al.
2007, pp. 1-5; Holland et al. 2006, pp. 1-5; Wang et al. 2007, pp.
1,093-1,107; Chapman and Walsh 2007).
Arzel et al. (2006) and Zhang and Walsh (2006) evaluate the sea ice
results from the IPCC AR4 models in more detail. Arzel et al. (2006)
investigated projected changes in sea ice extent and volume simulated
by 13 AOGCMs (also known as GCMs) driven by the SRES A1B emissions
scenario. They found that the models projected an average relative
decrease in sea ice extent of 15.4 percent in March, 61.7 percent in
September, and 27.7 percent on an annual basis when comparing the
periods 1981-2000 and 2081-2100; the average relative decrease in sea
ice volume was 47.8 percent in March, 78.9 percent in September, and
58.8 percent on an annual basis when comparing the periods 1981-2000
and 2081-2100. More than half the models (7 of 13) reach ice-free
September conditions by 2100, as reported in some previous studies
(Gregory et al. 2002, Johannessen et al. 2004, both cited in Arzel et
al. 2006).
Zhang and Walsh (2006) investigated changes in sea ice area
simulated by 14 AOGCMs driven by the SRES A1B, A2, and B1 emissions
scenarios. They found that the annual mean sea ice area during the
period 2080-2100 would be decreased by 31.1 percent in the A1B
scenario, 33.4 percent in the A2 scenario, and 21.6 percent in the B1
scenario relative to the observed sea ice area during the period 1979-
1999. They further determined that the area of multi-year sea ice
during the period 2080-2100 would be decreased by 59.7 percent in the
A1B scenario, 65.0 percent in the A2 scenario, and 45.8 percent in the
B1 scenario relative to the ensemble mean multi-year sea ice area
during the period 1979-1999.
Dumas et al. (2006) generated projections of future landfast ice
thickness and duration for nine sites in the Canadian Arctic and one
site on the Labrador coast using the Canadian Centre for Climate
Modelling and Analysis global climate model (CGCM2). For the Canadian
Arctic sites the mean maximum ice thickness is projected to decrease by
roughly 30 cm (11.8 in) from 1970-1989 to 2041-2060 and by roughly 50-
55 cm (19.7-21.7 in) from 1970-1989 to 2081-2100. Further, they
projected a reduction in the duration of sea ice cover of 1 and 2
months by 2041-2060 and 2081-2100, respectively, from the baseline
period of 1970-1989. In addition simulated changes in freeze-up and
break-up revealed a 52-day later freeze-up and 30-day earlier break-up
by 2081-2100.
Holland et al. (2006, pp. 1-5) analyzed an ensemble of seven
projections of Arctic summer sea ice from the Community Climate System
Model, version 3 (CCSM3; National Center for Atmospheric Research, USA)
utilizing the SRES A1B emissions scenario. CCSM3 is the model that
performed best in simulating the actual observations for Arctic ice
extent over the PM satellite era (Stroeve et al. 2007, pp. 1-5).
Holland et al. (2006, pp. 1-5) found that the CCSM3 simulations
compared well to actual observations for Arctic ice extent over the PM
satellite era, including the rate of its recent retreat. They also
found that the simulations did not project that sea ice retreat would
continue at a constant rate into the future. Instead, the CCSM3
simulations indicate abrupt shifts in the ice cover, with one CCSM3
simulation showing an abrupt transition starting around 2024 with
continued rapid retreat for around 5 years. Every CCSM3 run had at
least one abrupt event (an abrupt event being defined as a time when a
5-year running mean exceeded three times the 2001-2005 observed
retreat) in the 21st century, indicating that near ice-free Septembers
could be reached within 30-50 years from now.
Holland et al. (2006, pp. 1-5) also discussed results from 15
additional models used in the IPCC AR4, and concluded that 6 of 15
other models ``exhibit abrupt September ice retreat in the A1B scenario
runs.'' The length of the transition varied from 3 to 8 years among the
models. Thus, in these model simulations, it was found that once the
Arctic ice pack thins to a vulnerable state, natural variability can
trigger an abrupt loss of the ice cover so that seasonally ice-free
conditions can happen within a decade's time (J. Stroeve, in litt. to
the Service, November 2007).
Finally, Holland et al. (2006, pp. 1-5) noted that the emissions
scenario used in the model affected the likelihood of future abrupt
transitions. In models using the SRES B1 scenario (i.e., with GHG
levels increasing at a slower rate), only 3 of 15 models show abrupt
declines lasting from 3 to 5 years. In models using the A2 scenario
(i.e., with
[[Page 28231]]
GHG levels increasing at a faster rate), 7 of 11 models with available
data obtain an abrupt retreat in the ice cover; the abrupt events last
from 3 to 10 years (Holland et al. 2006, pp. 1-5).
In order to increase confidence in climate model projections,
several studies have sought to constrain the number of models used by
validating climate change in the models simulations against actual
observations (Knutti et al. 2006; Hall and Ou 2006). The concept is to
create a shorter list of ``higher confidence'' models by removing
outlier model projections that do not perform well when compared to
20th century observational data (Overland and Wang 2007a, pp. 1-7).
This has been done for temperatures (Wang et al. 2007, pp. 1,093-
1,107), sea ice (Overland and Wang 2007a, pp. 1-7; Stroeve et al. 2007,
pp. 1-5), and sea level pressure (SLP; defined as atmospheric pressure
at sea level) and precipitation (Walsh and Chapman, pers. comm. with J.
Overland, NOAA, cited in litt. to the Service, 2007).
Overland and Wang (2007a, pp. 1-7) investigated future regional
reductions in September sea ice area utilizing a subset of AR4 models
that closely simulate observed regional ice concentrations for 1979-
1999 and were driven by the A1B emissions scenario. They used a
selection criterion, similar to Stroeve et al. (2007, pp. 1-5), to
constrain the number of models used by removing outliers so as to
increase confidence in the projections used. Out of an initial set of
20 potential models, 11 models were retained for the Arctic-wide area,
4 were retained for the Kara/Laptev Sea area, 8 were retained for the
East Siberian/Chukchi Sea, and 11 were retained for the Beaufort Sea
(Overland and Wang 2007a, pp. 1-7). Using these constrained subsets,
Overland and Wang (2007a, pp. 1-7) found that there is: ``considerable
evidence for loss of sea ice area of greater than 40 percent by 2050 in
summer for the marginal seas of the Arctic basin. This conclusion is
supported by consistency in the selection of the same models across
different regions, and the importance of thinning ice and increased
open water at mid-century to the rate of ice loss.'' More specifically,
Overland and Wang (2007a, pp. 1-7) found that ``By 2050, 7 of 11 models
estimate a loss of 40 percent or greater of summer Arctic ice area. Six
of 8 models show a greater than 40 percent ice loss in the East
Siberian/Chukchi Seas and 7 of 11 models show this loss for the
Beaufort Sea. The percentage of models with major ice loss could be
considered higher, as two of the models that retain sea ice are from
the same Canadian source and thus cannot be considered to be completely
independent. These results present a consistent picture: there is a
substantial loss of sea ice for most models and regions by 2050'' (see
Figure 6). With less confidence, they found that the Bering, Okhotsk,
and Barents seas have a similar 40 percent loss of sea ice area by 2050
in winter; Baffin Bay/Labrador shows little change compared to current
conditions (Overland and Wang 2007a, pp. 1-7). Overland and Wang
(2007a, pp. 1-7) also note that the CCSM3 model (Holland et al. 2006,
pp. 1-5) is one of the models with the most rapid ice loss in the 21st
century; this model is also one of the best at simulating historical
20th century observations (also see Figure 12 in DeWeaver (2007)).
[[Page 28232]]
[GRAPHIC] [TIFF OMITTED] TR15MY08.007
DeWeaver (2007), applying a similar conceptual approach as Overland
and Wang (2007a, pp. 1-7) and Stroeve et al. (2007, pp. 1-5), used a
selection criterion to construct an ensemble of 10 climate models that
most accurately depicted sea-ice extent, from the 20 models that
contributed sea ice data to the AR4. This 10-model ensemble was used by
the USGS for assessing potential polar bear habitat loss (Durner et al.
2007). DeWeaver's selection criterion was to include only those models
for which the mean 1953-1995 simulated September sea ice extent is
within 20 percent of its actual observed value (as taken from the
Hadley Center Sea Ice and Sea Surface Temperature (HadISST) data set
(Raynor et al. 2003)). DeWeaver (2007) then investigated the future
performance of his 10-model
[[Page 28233]]
ensemble driven by the SRES A1B emissions scenario. He found that: all
10 models projected declines of September sea ice extent of over 30
percent by the middle of the 21st century (i.e., 2045-2055); 4 of 10
models projected declines September sea ice in excess of 80 percent by
mid-21st century; and 7 of 10 models lose over 97 percent of their
September sea ice by the end of the 21st century (i.e., 2090-2099)
(DeWeaver 2007).
Stroeve et al. (2007, pp. 1-5) compared observed Arctic sea ice
extent from 1953-2006 with 20th and 21st century simulation results
from an ensemble of 18 AR4 models forced with the SRES A1B emission
scenario. Like Overland and Wang (2007a) and DeWeaver (2007), Stroeve
et al. (2007, pp. 1-5) applied a selection criterion to limit the
number of models used for comparison. Of the original 18 models in the
ensemble, 13 were selected because their performance simulating 20th
century September sea ice extent satisfied the selection criterion
established by the authors (i.e., model simulations for the the period
1953-1995 had to be within 20 percent of observations). The
observational record for the Arctic by Stroeve et al. (2007, pp. 1-5)
made use of a blended record of PM satellite-era (post November 1978)
and pre-PM satellite era data (early satellite observation, aircraft
and ship reports) described by Meier et al. (2007, pp. 428-434) and
spanning the years 1953-2006 (Stroeve et al. 2007, pp. 1-5).
Stroeve et al.'s (2007, pp. 1-5) results revealed that the observed
trend of September sea ice from 1953-2006 (a decline of 7.8 0.6 percent per decade) is three times larger than the 13-model
mean trend (a decline of 2.5 0.2 percent per decade). In
addition, none of the 13 models or their individual ensemble members
has trends in September sea ice as large as the observed trend for the
entire observation period (1953-2006) or the 11-year period 1995-2006
(Stroeve et al. 2007, pp. 1-5) (see Figure 7). March sea ice trends are
not as dramatic, but the modeled decreases are still smaller than
observed (Stroeve et al. 2007, pp. 1-5). Stroeve et al. (2007, pp. 1-5)
offer two alternative interpretations to explain the discrepancies
between the modeled results and the observational record. The first is
that the ``observed September trend is a statistically rare event and
imprints of natural variability strongly dominate over any effect of
GHG loading'' (Stroeve et al. 2007, pp. 1-5). The second is that, if
one accepts that the suite of simulations is a representative sample,
``the models are deficient in their response to anthropogenic forcing''
(Stroeve et al. 2007, pp. 1-5). Although there is some evidence that
natural variability is influencing the sea ice decrease, Stroeve et al.
(2007, pp. 1-5) believe that ``while IPCC AR4 models incorporate many
improvements compared to their predecessors, shortcomings remain''
(Stroeve et al. 2007, pp. 1-5) when they are applied to the Arctic
climate system, particularly in modeling Arctic Oscillation variability
and accurately parameterizing sea ice thickness.
[GRAPHIC] [TIFF OMITTED] TR15MY08.008
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The observational record indicates that current summer sea ice
losses appear to be about 30 years ahead of the ensemble of modeled
values, which suggests that a transition towards a seasonally ice-free
Arctic might occur sooner than the models indicate (J. Stroeve, in
litt. to the Service, November 2007). However, Stroeve et al. (2007,
pp. 1-5) note that the two models that best match observations over the
PM satellite era-CCSM3 and UKMO--HADGEM1 (Hadley Center for Climate
Prediction and Research, UK)-incorporate relatively sophisticated sea
ice models (McLaren et al. 2006 and Meehl et al. 2006, both cited in
Stroeve et al. 2007, pp. 1-5). The same two models were mentioned by
Gerdes and Koberle (2007) as having the most realistic sea ice
thickness simulations. If only the results of CCSM3 are considered, as
in Holland et al. (2006, pp. 1-5), model simulations compare well to
actual observations for Arctic ice extent over the PM satellite era,
including the rate of its recent retreat, and simulations of future
conditions indicate that near ice-free Septembers could be reached
within 30-50 years from now. If the record ice losses from the summer
of 2007 are considered, it appears more likely the transition towards a
seasonal ice cover will occur during the first half of this century
(Stroeve et al. 2007, pp. 1-5) (see Figure 7). DeWeaver (2007) cautions
that reliance on a multi-model ensemble is preferred to a single model,
because the ensemble represents a balance between the desire to focus
on the most credible models and the competing desire to retain a large
enough sample to assess the spread of possible outcomes.
Projected Changes in Other Parameters
Air Temperature
As previously noted, IPCC AR4 simulations using a multi-model
ensemble and the A1B emissions scenario project that, at the end of the
21st century (i.e., the period 2080-2099), the Arctic will be
approximately 5 degrees C warmer, on an annual basis, than in the
earlier part of 20th century (i.e., the period 1980-1999) (IPCC 2007,
p. 904). Larger mean warming of 5.9 degrees C is projected for the A2
scenario, while smaller mean warming of 3.4 degrees C is projected for
the B1 scenario. J. Overland (NOAA, in litt. to the Service, 2007) and
associates recently estimated Arctic land temperatures north of 60
degrees N latitude out to 2050 for the 12 models selected in Wang et
al. (2007, pp. 1,093-1,107). The average warming from this reduced set
of models is an increase of 3 degrees C in surface temperatures; the
range of model projections is 2-4 degrees C, which is an estimate of
the range of uncertainly in scientists' ability to model Arctic
climate. An increase in surface temperatures of 3 degrees C by 2050
will have a major impact on the timing of snowmelt timing (i.e., will
lead to earlier snowmelt) (J. Overland, NOAA, in litt. to the Service,
2007).
Precipitation
The IPCC AR4 simulations show a general increase in precipitation
over the Arctic at the end of the 21st century (i.e., the period 2080-
2099) in comparison to the 20th century (i.e., the period 1980-1999)
(IPCC 2007, p. 906). According to the AR4 report (IPCC 2007, p. 906),
``the precipitation increase is robust among the models and
qualitatively well understood, attributed to the projected warming and
related increased moisture convergence.'' Differences between the
projections for different emissions scenarios are small in the first
half of the 21st century but increase later. ``The spatial pattern of
the projected change shows the greatest percentage increase over the
Arctic Ocean (30 to 40 percent) and smallest (and even slight decrease)
over the northern North Atlantic (less then 5 percent). By the end of
the 21st century, the projected change in the annual mean arctic
precipitation varies from 10 to 28 percent, with an ensemble median of
18 percent in the A1B scenario'' (IPCC 2007, p. 906). Larger mean
precipitation increases are found for the A2 scenario with 22 percent;
smaller mean precipitation increases are found for the B1 scenario with
13 percent. The percentage precipitation increase is largest in winter
and smallest in summer, consistent with the projected warming. The
across-model scatter of the precipitation projections is substantial.
Putkonen and Roe (2003) presented the results of a global climate
modeling effort using an older simulation model (from the TAR era) that
predicted a 40 percent increase in the worldwide area of land affected
by rain-on-snow events from 1980-1989 to 2080-2089. Rennert et al.
(2008) refined the estimate in Putkonen and Roe (2003) using daily data
from a 5-member ensemble of the CCSM3 for the periods 1980-1999 and
2040-2059. The future scenario indicated increased frequency of rain-
on-snow events in much of Alaska and far eastern Siberia. Decreases in
rain-on-snow were shown broadly to be due to projected decreases in
snow pack in the model, not a decrease in rain events.
Previous Federal Actions
Information about previous Federal actions for the polar bear can
be found in our proposed rule and 12-month finding published in the
Federal Register on January 9, 2007 (72 FR 1064), and the ``Summary of
Comments and Recommendations'' section below.
On April 28, 2008, the United States District Court for the
Northern District of California ordered us to publish the final
determination on whether the polar bear should be listed as an
endangered or threatened species by May 15, 2008. AS part of its order,
the Court ordered us to waive the standard 30-day effective date for
the final determination.
Summary of Comments and Recommendations
In the January 9, 2007, proposed rule to list the polar bear as a
threatened species under the Act (72 FR 1064), we opened a 90-day
public comment period and requested that all interested parties submit
factual reports, information, and comments that might contribute to
development of a final determination for polar bear. The public comment
period closed on April 9, 2007. We contacted appropriate Federal and
State agencies, Alaska Native Tribes and tribal organizations,
governments of polar bear range countries (Canada, Russian Federation,
Denmark (Greenland) and Norway), city governments, scientific
organizations, peer reviewers (see additional discussion below
regarding peer review of proposed rule), and other interested parties
to request comments. The Secretary of the Interior also announced the
proposed rule and public comment period in a press release issued on
December 27, 2006. Newspaper articles appeared in the Anchorage Daily
News, Washington Post, New York Times, Los Angeles Times, Wall Street
Journal, and many local or regional papers across the country, as well
as local, national, and international television and radio news
programs that also notified the public about the proposed listing and
comment period.
In response to requests from the public, public hearings were held
in Washington, DC (March 5, 2007), Anchorage, Alaska (March 1, 2007),
and Barrow, Alaska (March 7, 2007). These hearings were announced in
the Federal Register of February 15, 2007 (72 FR 7381), and in the
Legal Section of the Anchorage Daily News (February 2, 2007). For the
Barrow, Alaska, public hearing we established teleconferencing
capabilities to provide an opportunity to receive testimony from
outlying
[[Page 28235]]
communities. The communities of Kaktovik, Gambell, Kotzebue,
Shishmaref, and Point Lay, Alaska, participated in this public hearing
via teleconference. The public hearings were attended by a total of
approximately 305 people.
In addition, the Secretary of the Interior, at the time the
proposal to list the polar bear as a threatened species was announced,
asked the U.S. Geological Survey (USGS) to assist the Service by
collecting and analyzing scientific data and developing models and
interpretations that would enhance the base of scientific data for the
Service's use in developing the final decision. On September 7, 2007,
the USGS provided the Service with its analyses in the form of nine
scientific reports that analyze and integrate a series of studies on
polar bear population dynamics, range-wide habitat use, and changing
sea ice conditions in the Arctic. The Service, in turn, reopened the
public comment period on September 20, 2007 (72 FR 53749), for 15 days
to notify the public of the availability of these nine reports, to
announce our intent to consider the reports in making our final listing
determination, and to ask the public for comments on the reports. On
the basis of numerous requests from the public, including the State of
Alaska, the public comment period on the nine reports was extended
until October 22, 2007 (72 FR 56979).
While some commenters provided extensive technical comments on the
reports, a thorough evaluation of comments received found no
significant scientific disagreement regarding the adequacy or accuracy
of the scientific information used in the reports. In general, comments
on the nine reports raised the following themes: assertions that loss
of sea ice reflects natural variability and not a trend; current
population status or demographics do not warrant listing; new
information justifies listing as endangered; and additional information
is needed because of uncertainty associated with future climate
scenarios. Commenters also re-iterated concerns and issues raised
during the public comment period on the proposed rule. New,
supplementary information became available following publication of the
proposed rule that supports the climate models used in the nine USGS
reports, and helps clarify the relative contribution of natural
variability in future climate scenarios provided by the climate models.
Comments on the significance of the status and demographic information
helped clarify our analyses. We find that the USGS reports, in concert
with additional new information in the literature, clarify our
understanding of polar bears and their environment and support our
initial conclusions regarding the status of the species. We believe the
information presented by USGS and other sources provides a broad and
solid scientific basis for the analyses and findings in this rule.
Technical comments received from the public on the USGS reports and our
responses to those comments are available on our website at: http://
alaska.fws.gov/fisheries/mmm/polarbear/issues.htm.
During the public comment periods, we received approximately
670,000 comments including letters and post cards (43,513), e-mail
(626,947), and public hearing testimony (75). We received comments from
Federal agencies, foreign governments, State agencies, Alaska Native
Tribes and tribal organizations, Federal commissions, local
governments, commercial and trade organizations, conservation
organizations, non-governmental organizations, and private citizens.
Comments received provided a range of opinions on the proposed
listing, as follows: (1) unequivocal support for the listing with no
additional information included; (2) unequivocal support for the
listing with additional information provided; (3) equivocal support for
the listing with or without additional information included; (4)
unequivocal opposition to the listing with no additional information
included; and (5) unequivocal opposition to the listing with additional
information included. Outside the public comment periods, we received
an additional approximately 58,000 cards, petitions, and letters
pertaining to the proposed listing of the polar bear as a threatened
species. We reviewed those submissions in detail for content and found
that they did not provide information that was substantively diiferent
from what we had already received. Therefore, we determined that
reopening the comment period was not necessary.
To accurately review and incorporate the publicly-provided
information in our final determination, we worked with the eRulemaking
Research Group, an academic research team at the University of
Pittsburgh that has developed the Rule-Writer's Workbench (RWW)
analytical software. The RWW enhanced our ability to review and
consider the large numbers of comments, including large numbers of
similar comments, on our proposed listing, allowing us to identify
similar comments as well as individual ideas, data, recommendations, or
suggestions on the proposed listing.
Peer Review of the Proposed Rule
In accordance with our policy published on July 1, 1994 (59 FR
34270), we solicited expert opinion on information contained in the
proposed rule from 14 knowledgeable individuals with scientific
expertise that includes familiarity with the polar bear, the geographic
region in which the polar bear occurs, Arctic ecology, climatology, and
Traditional Ecological Knowledge (TEK). The selected polar bear
specialists included scientists from all polar bear range countries,
and who work in both academia and in government. The selected climate
scientists are all active in research and published in Arctic climate
systems and sea ice dynamics. We sought expertise in TEK from
internationally recognized native organizations.
We received responses from all 14 peer reviewers. Thirteen peer
reviewers found that, in general, the proposed rule represented a
thorough, clear, and balanced review of the best scientific information
available from both published and unpublished sources of the current
status of polar bears. The one exception expressed concern that the
proposed rule was flawed, biased, and incomplete, that it would do
nothing to address the underlying issues associated with global
warming, and that a listing would be detrimental to the Inuit of the
Arctic. In addition, peer reviewers stated that the background material
on the ecology of polar bears represents a solid overview of the
species' ecology relevant to the issue of population status. They also
stated that information about the five natural or manmade factors that
may already have affected polar bear populations, or may affect them in
the future, is presented and evaluated in a fair and balanced way and
is based on scientifically sound data. They further stated that the
information as presented justified the conclusion that polar bears face
threats throughout their range. Several peer reviewers provided
additional insights to clarify points in the proposed rule, or
references to recently-published studies that update material in the
proposal.
Several peer reviewers referenced the Fourth Assessment Report of
the Intergovernmental Panel on Climate Change (IPCC AR4). Reports from
Working Groups I, II, and III of the IPCC AR4 were published earlier in
2007, and the AR4 Synthesis Report was released in November 2007. The
Working Group I report updates information in the proposed rule with
considerable new observational information on global
[[Page 28236]]
climate change, as well results from independent scientific review of
the results from over 20 current-generation climate models. The
significance of the Working Group I report, as noted by the peer
reviewers with climatological expertise, is that the spatial resolution
and physics of climate models have improved such that uncertainties
associated with various model components, including prescribed ocean
conditions, mobile sea ice, clouds/radiation, and land/atmosphere
exchanges, have been reduced significantly from previous-generation
models (i.e., those used in the IPCC Third Assessment Report).
One peer reviewer recommended that appropriate effort should be
made to integrate the existing sources of Alaska native and other
indigenous traditional and contemporary ecological knowledge (TEK) into
our final rule. In addition, the peer reviewer recommended that we
actively conduct community outreach to obtain this information from
Alaska villages located within the range of the polar bear.
One peer reviewer opposed the listing and asserted that existing
regulatory mechanisms are adequate because the Inuit people will
account for climate change in setting harvest quotas for polar bears.
Peer Review Comments
We reviewed all comments received from peer reviewers for
substantive issues and new information regarding the proposed
designation of the polar bear as a threatened species. Comments and
responses have been consolidated into key issues in this section.
Comment PR1: The importance of sea ice to polar bears is not well
articulated in the proposed rule, and the consequences of polar bears
using land as an alternative ``platform'' are understated.
Our response: We recognize the vital importance of sea ice as
habitat for polar bears. New information and analyses of specific sea
ice characteristics important to polar bears has been prepared by USGS
(Durner et al. 2007), and incorporated into this final rule.
Projections of changes to sea ice and subsequent effects on resource
values to polar bears during the foreseeable future have also been
included in the analyses in this final rule (see ``Polar Bear--Sea Ice
Habitat Relationships'' section). The consequences of prolonged use of
terrestrial habitats by polar bears are also discussed in detail in the
``Effects of Sea Ice Habitat Change on Polar Bears'' section of this
final rule. We believe that we have objectively assessed these
consequences, and have not under- or overstated them.
Comment PR2: The importance of snow cover to successful
reproduction by polar bears and their primary prey, ringed seals,
should receive greater emphasis.
Our response: We recognize the importance of snow cover for denning
polar bears and pupping ringed seals. Additional new information has
been included in the sections on climate and the section ``Effects of
Sea Ice Habitat Changes on Polar Bear Prey,'' ``Maternal Denning
Habitat,'' and ``Access to and Alteration of Denning Areas'' sections.
Comment PR3: Harvest programs in Canada provide conservation
benefits for polar bears and are therefore important to maintain. In
addition, economic benefits from subsistence hunting and sport hunting
occur.
Our response: We recognize the important contribution to
conservation that scientifically based sustainable use programs can
have. We further recognize the past significant benefits to polar bear
management in Canada that have accrued as a result of the 1994
amendments to the MMPA that allow U.S. citizens who legally sport-
harvest a polar bear from an MMPA-approved population in Canada to
bring their trophies back into the United States. In addition, income
from fees collected for trophies imported into the United States are
directed by statute to support polar bear research and conservation
programs that have resulted in conservation benefits to polar bears in
the Chukchi Sea region.
We recognize that hunting provides direct economic benefits to
local native communities that derive income from supporting and guiding
hunters, and also to people who conduct sport hunting programs for U.S.
citizens. However these benefits cannot be and have not been factored
into our listing decision for the polar bear.
We note that, under the MMPA, the polar bear will be considered a
``depleted'' species on the effective date of this listing. As a
depleted species, imports could only be authorized under the MMPA if
the import enhanced the survival of the species or was for scientific
research. Therefore, authorization for the import of sport-hunted
trophies will no longer be available under section 104(c)(5) of the
MMPA. Neither the Act nor the MMPA restricts take beyond the United
States and the high seas, so otherwise legal take in Canada is not
affected by the threatened listing.
Comment PR4: The ability of polar bears to adapt to a changing
environment needs to be addressed directly, with a focus on the
importance of rates of environmental change relative to polar bear
generation time.
Our response: We have addressed this issue by adding a section to
the final rule entitled ``Adaptation'' under ``Summary of Factors
Affecting the Polar Bear.'' Information regarding how polar bears
survived previous warming events is scant, but some evidence indicates
that polar bears survived by altering their geographic range, rather
than evolving through natural selection. The pace at which ice
conditions are changing and the long generation time of polar bears
appear to preclude adaptation of new physiological mechanisms and
physical characteristics through natural selection. In addition, the
known current physiological, physical, and behavioral characteristics
of polar bears suggest that behavioral adaptation will be insufficient
to prevent a pronounced reduction in polar bear distribution, and
therefore abundance, as a result of declining sea ice. Current evidence
suggests there is little likelihood that extended periods of torpor,
consumption of terrestrial foods, or capture of seals in open water
will be sufficient mechanisms to counter the loss of sea ice as a
platform for hunting seals. Projections of population trends based upon
habitat availability, as discussed in the USGS reports by Durner et al.
(2007) and Amstrup et al. (2007) serve to further clarify the changes
currently occurring, or expected to occur, as sea ice declines.
Comment PR5: Harvest levels for some polar bear populations in
Nunavut (Canada) are not sustainable and should be discussed; however,
these concerns do not materially alter the primary finding of the
proposed rule.
Our response: Although we have some concerns about the current
harvest levels for some polar populations in Nunavut, we agree that
these concerns do not materially alter the primary finding of the
proposed rule. As discussed in Factors B and D, impacts from sport
hunting or harvest are not threats to the species throughout its range.
We recognize that, as discussed in detail in this final rule, the
management of polar bears in Canada and other countries is evolving. We
believe that our evaluation of the management of the polar bear
populations in Canada, which includes participation in the annual
Canadian Polar Bear Technical Committee (PBTC) meeting, provides us
with the best available information upon which to base future
management decisions.
Comment PR6: The most important aspect relative to climate change
is that
[[Page 28237]]
the most recent assessment of the IPCC (AR4) includes projections that
climate warming and sea ice decline are likely to continue. This new
information as well as other new sea ice information needs to be
incorporated into the final analysis.
Our response: We agree that new information on climate warming and
sea ice decline, as discussed in the IPCC AR4 as well as numerous other
recent scientific papers, is of great significance relative to
assessing polar bear habitat and population status and trends. Our
final analysis has been updated to incorporate this new information
(see ``Sea Ice Habitat'' and ``Polar Bear--Sea Ice Habitat
Relationships'' sections).
Comment PR7: Polar bear population status information needs to
highlight areas of both population decline and population increase, and
the relationship of the two to overall status of the species.
Our response: Our final analysis has been updated with new
population information (see ``Current Population Status and Trend''
section).
Comment PR8: The Service did not consider the impacts of listing
the polar bear on Inuit economies.
Our response: Under section 4(b)(1)(A) of the Act, we must base a
listing decision solely on the best scientific and commercial data
available as it relates to the listing five factors in section 4(a)(1)
of the Act. The legislative history of this provision clearly states
the intent of Congress to ensure that listing decisions are ``* * *
based solely on biological criteria and to prevent non-biological
criteria from affecting such decisions * * *'' (House of
Representatives Report Number 97-835, 97th Congress, Second Session 19
(1982)). As further stated in the legislative history, ``* * * economic
considerations have no relevance to determinations regarding the status
of species * * *'' (Id. at 20).
Comment PR9: Concerning sport hunting, listing will not help reduce
take of polar bears.
Our response: As discussed under Factors B and D below, we
recognize that sport hunting or other forms of harvest (both legal and
illegal) may be affecting several polar bear populations, but we have
determined that overutilization is not a threat to the species
throughout all or a significant portion of its range. Amstrup et al.
(2007) found that the impact of harvest on the status of polar bear
populations is far outweighed by the effects of sea ice losses
projected into the future. In addition, we have concluded that, in
general, national and local management regimes established for the
sustainable harvest of polar bears are adequate. We have determined
that polar bear harvest by itself, in the absence of declines due to
changes in sea ice habitat, would not be a sufficient threat to justify
listing the species in all or a significant portion of its range.
However, we have also concluded that harvest may become a more
important factor in the future for populations experiencing nutritional
stress.
Comment PR10: Inuit will account for climate change in setting
subsistence harvest quotas, thus the existing regulatory mechanism is
adequate.
Our response: As discussed in this final rule (see ``Polar Bear--
Sea Ice Habitat Relationships'' section), the loss of sea ice habitat
is considered to threaten the polar bear throughout its range.
Adjusting harvest levels based on the consequences of habitat loss and
corresponding reduction in physical condition, recruitment, and
survival rates is prudent and precautionary, and such adjustments may
be addressed through existing and future harvest management regimes.
However, we find that these steps will not be sufficient to offset
population declines resulting from loss of sea ice habitat.
Comment PR11: The proposed rule does not adequately reflect the
state of traditional and contemporary indigenous knowledge regarding
polar bears and climate change.
Our response: We have further expanded this rule to include
information obtained from Kavry's work in Chukotka, Russia (Kochnev et
al. 2003) and Dowsley and Taylor's work in Nunavut, Canada (Dowsley and
Taylor 2005), as well as information received during our public
hearings. Additionally, we have reviewed information available on polar
bears and climate change from the Alaska Native Science Commission
(http://www.nativescience.org/issues/climatechange.htm). Discussion
documents available on their web page generally support the conclusions
reached in this document; for example, they observe that: ``Saami are
seeing their reindeer grazing pastures change, Inuit are watching polar
bears waste away because of a lack of sea ice, and peoples across the
Arctic are reporting new species, particularly insects'' (http://
www.arcticpeoples.org/KeyIssues/ClimateChange/Start.html). Thus,
traditional and contemporary indigenous knowledge recognizes that
climate-related changes are occurring in the Arctic and that these
changes are negatively impacting polar bears.
Comment PR12: The proposed rule does not sufficiently question the
reliability of scientific models used. Science is not capable of
responding to vague terms such as ``it is likely'' ``foreseeable
future.''
Our response: Literature used in the proposed rule was the best
available peer-reviewed scientific information at the time. The
proposed rule was based largely on results presented in the Arctic
Climate Impact Assessment (ACIA 2005) and the IPCC Third Assessment
Report (TAR) (IPCC 2001), plus several individual peer-reviewed journal
articles. The ACIA and IPCC TAR are synthesis documents that present
detailed information on climate observations and projections, and
represent the consensus view of a large number of climate change
scientists. Thus, they constituted the best scientific information
available at the time the proposed rule was drafted. The proposed rule
contained a determination of ``foreseeable future'' (i.e., 45 years) as
it pertains to a possible listing of polar bears under the Act, and an
explanation of how that 45-year timeframe was determined. This final
rule contains the same determination of ``foreseeable future'' (i.e.,
45 years), as well as an explanation of how that 45-year timeframe was
determined (through a consideration of reliable data on changes
currently being observed and projected for the polar bear's sea ice
habitat, and supported by information on the life history (generation
time) and population dynamics of polar bears). Thus, we disagree with
the commenter that this is a vague term.
The final rule has been revised to reflect the most current
scientific information, including the results of the IPCC AR4 plus a
large number of peer-reviewed journal articles. The IPCC AR4 assigns
specific probability values to terms such as ``unlikely,'' ``likely,''
and ``very likely.'' We have attempted to use those terms in a manner
consistent with how they are used in the IPCC AR4.
We have taken our best effort to identify the limitations and
uncertainties of the climate models and their projections used in the
proposed rule. In this final rule, we have provided a more detailed
discussion to ensure a balanced analysis regarding the causes and
potential impacts of climate change, and have discussed the limitations
and uncertainties in the information that provided the basis for our
analysis and decision.
Public Comments
We reviewed all comments received from the public for substantive
issues and new information regarding the proposed designation of the
polar bear as a threatened species. Comments and
[[Page 28238]]
responses have been consolidated into key issues in this section.
Issue 1: Polar Bear Population Decline
Comment 1: Current polar bear populations are stable or increasing
and the polar bear occupies its entire historical range. As such, the
polar bear is not in imminent danger of extinction and, therefore,
should not be listed under the Act.
Our response: We agree that polar bears presently occupy their
available range and that some polar bear populations are stable or
increasing. As discussed in the ``Current Population Status and Trend''
section of the rule, two polar bear populations are designated by the
PBSG as increasing (Viscount Melville Sound and M'Clintock Channel);
six populations are stable (Northern Beaufort Sea, Southern Hudson Bay,
Davis Strait, Lancaster Sound, Gulf of Bothia, Foxe Basin); five
populations are declining (Southern Beaufort Sea, Norwegian Bay,
Western Hudson Bay, Kane Basin, Baffin Bay), and six populations are
designated as data deficient (Barents Sea, Kara Sea, Laptev Sea,
Chukchi Sea, Arctic Basin, East Greenland) with no estimate of trend
(Aars et al. 2006). The two populations with the most extensive time
series of data, Western Hudson Bay and Southern Beaufort Sea, are
considered to be declining. The two increasing populations (Viscount
Melville Sound and M'Clintock Channel) were severely reduced in the
past as a result of overharvest and are now recovering as a result of
coordinated international efforts and harvest management.
The current status must be placed in perspective, however, as many
populations were declining prior to 1973 due to severe overharvest. In
the past, polar bears were harvested extensively throughout their range
for the economic or trophy value of their pelts. In response to the
population declines, five Arctic nations (Canada, Denmark on behalf of
Greenland, Norway, Union of Soviet Socialist Republics, and the United
States), recognized the polar bear as a significant resource and
adopted an inter-governmental approach for the protection and
conservation of the species and its habitat, the 1973 Agreement on the
Conservation of Polar Bears (1973 Agreement). This agreement limited
the use of polar bears for specific purposes, instructed the Parties to
manage populations in accordance with sound conservation practices
based on the best available scientific data, and called the range
States to take appropriate action to protect the ecosystems upon which
polar bears depend. In addition, Russia banned harvest in 1956, harvest
quotas were established in Canada in 1968, and Norway banned hunting in
1973. With the passage of the MMPA in 1972, the United States banned
sport hunting of polar bears and limited the hunt to Native people for
subsistence purposes. As a result of these coordinated international
efforts and harvest management leading to a reduction in harvest, polar
bear numbers in some previously-depressed populations have grown during
the past 30 years.
We have determined that listing the polar bear as a threatened
species under the Act is appropriate, based on our evaluation of the
actual and projected effects of the five listing factors on the species
and its habitat. While polar bears are currently distributed throughout
their range, the best available scientific information, including new
USGS studies relating status and trends to loss of sea ice habitat
(Durner et al. 2007; Amstrup et al. 2007), indicates that the polar
bear is not currently in danger of extinction throughout all or a
significant portion of their range, but are likely to become so within
the 45-year ``foreseeable future'' that has been established for this
rule. This satisfies the definition of a threatened species under the
Act; consequently listing the species as threatened is appropriate. For
additional information on factors affecting, or projected to affect,
polar bears, please see the ``Summary of Factors Affecting the Polar
Bear'' section of this final rule.
Comment 2: The perceived status of the Western Hudson Bay
population is disputed because data are unreliable, earlier population
estimates cannot be compared to current estimates, and factors other
than climate change could contribute to declines in the Western Hudson
Bay population.
Our response: The Western Hudson Bay population is the most
extensively studied polar bear population in the world. Long-term
demographic and vital rate (e.g., survival and recruitment) data on
this population exceed those available for any other polar bear
population. Regehr et al. (2007a) used the most advanced analysis
methods available to conduct population analyses of the Western Hudson
Bay population. Trend data demonstrate a statistically-significant
population decline over time with a substantial level of precision. The
authors attributed the population decline to increased natural
mortality associated with earlier sea ice breakup and to the continued
harvest of approximately 40 polar bears per year. Other factors such as
the effects of research, tourism harassment, density dependence, or
shifts in distribution were not demonstrated to impact this population.
Regehr et al. (2007a) indicated that overharvest did not cause the
population decline; however, as the population declined, harvest rates
could have contributed to further depressing the population. Additional
information has been included in the ``Western Hudson Bay'' section of
this final rule that provides additional details on these points.
Comment 3: The apparent decline in the Southern Beaufort Sea
population is not significantly different from the previous population
estimate.
Our response: The Southern Beaufort Sea and Western Hudson Bay
populations are the two most studied polar bear populations. Regehr et
al. (2006) found no statistically significant difference between the
most recent and earlier population estimates for the Southern Beaufort
Sea population due to the large confidence interval for the earlier
population estimate, which caused the confidence intervals for both
estimates to overlap. However, we note that the Southern Beaufort Sea
population has already experienced decreases in cub survival,
significant decreases in body weights for adult males, and reduced
skull measurements (Regehr et al. 2006; Rode et al. 2007). Similar
changes were documented in the Western Hudson Bay population before a
statistically significant decline in that population was documented
(Regehr et al. 2007a). The status of the Southern Beaufort Sea
population was determined to be declining on the basis of declines in
vital rates, reductions in polar bear habitat in this area, and
declines in polar bear condition, factors noted by both the Canadian
Polar Bear Technical Committee (PBTC 2007) and the IUCN Polar Bear
Specialist Group (Aars et al. 2006).
Comment 4: Population information from den surveys of the Chukchi
Sea polar bear population is not sufficiently reliable to provide
population estimates.
Our response: We recognize that the population estimates from
previous den and aerial surveys of the Chukchi Sea population
(Chelintsev 1977; Derocher et al. 1998; Stishov 1991a, b; Stishov et
al. 1991) are quite dated and have such wide confidence intervals that
they are of limited value in determining population levels or trends
for management purposes. What the best available information indicates
is that, while the status of the Chukchi Sea population is thought to
have increased following a reduction of hunting pressure in the United
States, this
[[Page 28239]]
population is now thought to be declining due primarily to overharvest.
Harvest levels for the past 10-15 years (150-200 bears per year), which
includes the legal harvest in Alaska and an illegal harvest in
Chukoktka, Russia, are probably unsustainable. This harvest level is
close to or greater than the unsustainable harvest levels experienced
prior to 1972 (when approximately 178 bears were taken per year).
Furthermore, this population has also been subject to unprecedented
summer/autumn sea ice recessions in recent years, resulting in a
redistribution of more polar bears to terrestrial areas in some years.
Please see additional discussion of this population in the ``Current
Population Status and Trend'' section of this document.
Comment 5: Interpretation of population declines is questionable
due, in some cases, to the age of the data and in other cases the need
for caution due to perceived biases in data collection.
Our response: We used the best available scientific information in
assessing population status, recognizing the limitations of some of the
information. This final rule benefits from new information on several
populations (Obbard et al. 2007; Stirling et al. 2007; Regehr et al.
2007a, b) and additional analyses of the relationship between polar
bear populations and sea ice habitat (Durner et al. 2007). New
information on population status and trends is included in the
``Current Population Status and Trend'' section of this rule.
Comment 6: Polar bear health and fitness parameters do not provide
reliable insights into population trends.
Our response: We recognize there are limits associated with direct
correlations between body condition and population dynamics; however
changes in body condition have been shown to affect reproduction and
survival, which in turn can have population level effects. For example,
the survival of polar bear cubs-of-the-year has been directly linked to
their weight and the weight of their mothers, with lower weights
resulting in reduced survival (Derocher and Stirling 1996; Stirling et
al. 1999). Changes in body condition indices were documented in the
Western Hudson Bay population before a statistically significant
decline in that population was documented (Regehr et al. 2007a). Thus,
changes in these indices serve as an ``early warning'' that may signal
imminent population declines. New information from Rode et al. (2007)
on the relationship between polar bear body condition indices and sea
ice cover is also included in the ``Effects of Sea Ice Habitat Change
on Polar Bears'' section of this final rule.
Comment 7: Polar bears have survived previous warming events and
therefore can adapt to current climate changes.
Our response: We have addressed this issue by adding two sections
to the final rule entitled ``Adaptation'' and ``Previous Warming
Periods and Polar Bears'' under ``Summary of Factors Affecting the
Polar Bear.'' To summarize these sections, we find that the long
generation time of polar bears and the known physiological and physical
characteristics of polar bears significantly constrain their ability to
adapt through behavioral modification or natural selection to the
unprecedentedly rapid loss of sea ice habitat that is occurring and is
projected to continue throughout the species' range. Derocher et al.
(2004, p. 163, 172) suggest that this rate of change will limit the
ability of polar bears to respond and survive in large numbers. In
addition, polar bears today experience multiple stressors (e.g.,
harvest, contaminants, oil and gas development, and additional
interactions with humans) that were not present during historical
warming periods. Thus, both the cumulative effects of multiple
stressors and the rapid rate of climate change today create a unique
and unprecedented challenge for present-day polar bears in comparison
to historical warming events. See also above response to Comment PR4.
Comment 8: Polar bears will adapt and alternative food sources will
provide nutrition in the future. There are many food resources that
polar bears could exploit as alternate food sources.
Our response: New prey species could become available to polar
bears in some parts of their range as climate change affects prey
species distributions. However, polar bears are uniquely adapted to
hunting on ice and need relatively large, stable seal populations to
survive (Stirling and [Oslash]ritsland 1995). The best available
evidence indicates that ice-dependent seals (also called ``ice seals'')
are the only species that would be accessible in sufficient abundance
to meet the high energetic requirements of polar bears. Polar bears are
not adapted to hunt in open water, therefore, predation on pelagic
(open-ocean) seals, walruses, and whales, is not likely due to the
energetic effort needed to catch them in an open-water environment.
Other ice-associated seals, such as harp or hooded seals, may expand
their ranges and provide a near-term source of supplemental nutrition
in some areas. Over the long term, however, extensive periods of open
water may ultimately stress seals as sea ice (summer feeding habitat)
retreats further north from southern rookeries. We found no new
evidence suggesting that seal species with expanding ranges will be
able to compensate for the nutritional loss of ringed seals throughout
the polar bear's current range. Terrestrial food sources (e.g., animal
carcasses, birds, musk oxen, vegetation) are not likely to be reliably
available in sufficient amounts to provide the caloric value necessary
to sustain polar bears. For additional information on this subject,
please see the expanded discussion of ``Adaptation'' under ``Summary of
Factors Affecting the Polar Bear.''
Comment 9: Commenters expressed a variety of opinions on the
determination of ``foreseeable future'' for the polar bear, suggesting
factors such as the number and length of generations as well as the
timeframe over which the threat can be analyzed be used to identify an
appropriate timeframe.
Our response: ``Foreseeable future'' for purposes of listing under
the Act is determined on the basis of the best available scientific
data. In this rule, it is based on the timeframe over which the best
available scientific data allow us to reliably assess the effect of
threats--principally sea ice loss--on the polar bear, and is supported
by species-specific factors, including the species' life history
characteristics (generation time) and population dynamics. The
timeframe over which the best available scientific data allow us to
reliably assess the effect of threats on the species is the critical
component for determining the foreseeable future. In the case of the
polar bear, the key threat is loss of sea ice, the species' primary
habitat. Available information, including results of the IPCC AR4,
indicates that climate change projections over the next 40-50 years are
more reliable than projections over the next 80-90 years. On the basis
of our analysis, as reinforced by conclusions of the IPCC AR4, we have
determined that climate changes projected within the next 40-50 years
are more reliable than projections for the second half of the
21stcentury, for a number of reasons (see section on ``Projected
Changes in Arctic Sea Ice'' for a detailed explanation). For this final
rule, we have also identified three polar bear generations (adapted
from the IUCN Red List criteria) or 45 years as an appropriate
timeframe over which to assess the effects of threats on polar bear
populations. This timeframe is long enough to take into account multi-
generational population dynamics, natural variation inherent with
populations, environmental and habitat
[[Page 28240]]
changes, and the capacity for ecological adaptation (Schliebe et al.
2006a). The 45-year timeframe coincides with the timeframe within which
climate model projections are most reliable. This final rule provides a
detailed explanation of the rationale for selecting 45 years as the
foreseeable future, including its relationship to observed and
projected changes in sea ice habitat (as well as the precision and
certainty of the projected changes) and polar bear life history and
population dynamics. Therefore, this period of time is supported by
species-specific aspects of polar bears and the time frame of projected
habitat loss with the greatest reliability.
One commenter erroneously identified Congressional intent to limit
foreseeable future to 10 years. We reviewed the particular document
provided by the commenter-a Congressional Question & Answer response,
dated September 26, 1972, which was provided by the U.S. Department of
Commerce's National Oceanic and Atmospheric Administration's Deputy
Administrator Pollock. Rather than expressing Congressional intent,
this correspondence reflects the Commerce Department's perspective at
that time about foreseeable future and not Congressional intent.
Furthermore, Mr. Pollock's generic observations in 1972 are not
relevant to the best scientific data available regarding the status of
the polar bear, which has been recognized by leading polar bear
biologists as having a high degree of reliability out to 2050.
Issue 2: Changes in Environmental Conditions
Comment 10: An increase in landfast ice will result in increased
seal productivity and, therefore, increased feeding opportunities for
polar bears.
Our response: We agree that future feeding opportunities for polar
bears will in part relate to how climate change affects landfast ice
because of its importance as a platform for ringed seal lairs. As long
as landfast ice is available, ringed seals probably will be available
to polar bears. Research by Rosing-Asvid (2006) documented a strong
increase in the number of polar bears harvested in Greenland during
milder climatic periods when ringed seal habitat was reduced (less ice
cover) and lair densities were higher because seals were concentrated;
these two factors provide better spring hunting for polar bears. In
contrast to periodic warming, however, climate models project continued
loss of sea ice and changes in precipitation patterns in the Arctic.
Seal lairs require sufficient snow cover for lair construction and
maintenance, and snow cover of adequate quality that persists long
enough to allow pups to wean prior to onset of the melt period. Several
studies described in this final rule have linked declines in ringed
seal survival and recruitment with climate change that has resulted in
increased rain events (which has lead to increased predation on seals)
and decreased snowfall. Therefore, while polar bears may initially
respond favorably to a warming climate due to an increased ability to
capture seals, future reductions in seal populations will ultimately
lead to declines in polar bear populations. Additional information was
added to the section ``Effects of Sea Ice Habitat Changes on Polar Bear
Prey'' to clarify this point.
Comment 11: Polar bears will have increased hunting opportunities
as the amount of marginal, unconsolidated sea ice increases.
Our response: Marginal ice occurs at the edge of the polar basin
pack ice; ice is considered unconsolidated when concentrations decline
to less than 50 percent. The ability of polar bears to catch a
sufficient number of seals in marginal sea ice will depend upon both
the characteristics of the sea ice and the abundance of and access to
prey. Loss of sea ice cover will reduce seal numbers and accessibility
to polar bears, as discussed in ``Reduced prey availability'' section
of this final rule. Even if ringed seals maintained their current
population levels, which is unlikely, Harwood and Stirling (2000)
suggest that ringed seals would remain near-shore in open water during
summer ice recession, thereby limiting polar bear access to them.
Benthic (ocean bottom) feeders, such as bearded seals and walruses, may
also decrease in abundance and/or accessibility as ice recedes farther
away from shallow continental shelf waters. Increased open water and
reduced sea ice concentrations will provide seals with additional
escape routes, diminish the need to maintain breathing holes, and serve
to make their location less predictable and less accessible to polar
bears, resulting in lowered hunting success. Polar bears would also
incur higher energetic costs from additional movements required for
hunting in or swimming through marginal, unconsolidated sea ice.
Additional information from Derocher et al. (2004) was added to the
section ``Effects of Sea Ice Habitat Changes on Polar Bear Prey'' to
clarify this point.
Comment 12: Polar bears will benefit from increased marine
productivity as ocean waters warm farther north.
Our response: If marine productivity in the Arctic increases, polar
bears may benefit from increased seal productivity initially, provided
that sea ice habitat remains available. As previously mentioned, polar
bears need sea ice as a platform for hunting. Evidence from Western
Hudson Bay, Southern Hudson Bay, and Southern Beaufort Sea populations
indicates that reductions in polar bear body condition in these
populations are the result of reductions in sea ice. Additional new
information on the relationship between body condition, population
parameters, and sea ice habitat for the Southern Beaufort Sea
population (Rode et al. 2007) has been incorporated into the section on
effects of sea ice change on polar bears.
The extent to which marine productivity increases may benefit polar
bears will be influenced, in part, by ringed seals' access to prey.
Arctic cod (Boreogadus saida), which are the dominant prey item in many
areas, depend on sea ice cover for protection from predators (Gaston et
al. 2003). In western Hudson Bay, Gaston et al. (2003) detected Arctic
cod declines during periods of reduced sea ice habitat. Should Arctic
cod abundance decline in other areas, we do not know whether ringed
seals will be able to switch to other pelagic prey or whether alternate
food sources will be adequate to replace the reductions in cod.
Comment 13: Sufficient habitat will remain in the Canadian Arctic
and polar region to support polar bears for the next 40-50 years;
therefore, listing is not necessary.
Our response: Both the percentage of sea ice habitat and the
quality of that habitat will be significantly reduced from historic
levels over the next 40-50 years (Meehl et al. 2007; Durner et al.
2007; IPCC 2007). New information on the extent and magnitude of sea
ice loss is included previously in the section entitled ``Observed
Changes in Arctic Sea Ice'' of this rule. Reductions in the area,
timing, extent, and types of sea ice,among other effects, are expected
to increase the energetic costs of movement and hunting to polar bears,
reduce access to prey, and reduce access to denning areas. The ultimate
effect of these impacts are likely to result in reductions in
reproduction and survival, and corresponding decreases in population
numbers. We agree that receding sea ice may affect archipelagic polar
bear populations later than populations inhabiting the polar basin,
because seasonal ice is projected to remain present longer in the
archipelago than in other areas of the polar bear's range. The high
Arctic archipelago is limited however, in its ability to sustain
[[Page 28241]]
a large number of polar bears because: (1) changes in the extent of ice
and precipitation patterns are already occurring in the region; (2) the
area is characterized by lower prey productivity (e.g., lower seal
densities); and (3) polar bears moving into this area would increase
competition among bears and ultimately affect polar bear survival. In
addition, a small, higher-density population of polar bears in the
Canadian Arctic would be subject to increased vulnerability to
perturbations such as disease or accidental oil discharge from vessels.
Because of the habitat changes anticipated in the next 40-50 years, and
the corresponding reductions in reproduction and survival, and,
ultimately, population numbers, we have determined that the polar bear
is likely to be in danger of extinction throughout all or a significant
portion of its range by 2050.
Issue 3: Anthropogenic Effects
Comment 14: Disturbance from and cumulative effects of oil and gas
activities in the Arctic are underestimated or incompletely addressed.
Our response: Oil and gas activities will likely continue in the
future in the Arctic. Additional, updated information has been included
in the section ``Oil and Gas Exploration, Development, and Production''
in Factor A. We acknowledge that disturbance from oil and gas
activities can be direct or indirect and may, if not subject to
appropriate mitigation measures, displace bears or their primary prey
(ringed and bearded seals). Such disturbance may be critical for
denning polar bears, who may abandon established dens before cubs are
ready to leave due to direct disturbance. We note that incidental take
of polar bears due to oil and gas activities in Alaska are evaluated
and regulated under the MMPA (Sec. 101a(5)A) and incidental take
regulations are in place based on an overall negligible effect finding.
Standard and site specific mitigation measures are prescribed by the
Service and implemented by the industry (see detailed discussion in the
section ``Marine Mammal Protection Act of 1972, as amended'' under
Factor D).
Indirect and cumulative effects of the myriad of activities
associated with major oil and gas developments can be a concern
regionally. However, the effects of oil and gas activities, such as oil
spills, are generally associated with low probabilities of occurrence,
and are generally localized in nature, We acknowledge that the sum
total of documented impacts from these activities in the past have been
minimal (see discussion in the ``Oil and Gas Exploration, Development,
and Production'' section). Therefore, we do not believe that we have
underestimated or incompletely addressed disturbance from or cumulative
effects of oil and gas activities on polar bears, and have accurately
portrayed the effect of oil and gas activities on the status of the
species within the foreseeable future.
Comment 15: The potential effects of oil spills on polar bears are
underestimated, particularly given the technical limitations of
cleaning up an oil spill in broken ice.
Our response: We do not wish to minimize our concern for oil spills
in the Arctic marine environment. We agree that the effects of a large
volume oil spill to polar bears could be significant within the
specific area of occurrence, but we believe that the probability of
such a spill in Alaska is generally very low. At a regional level we
have concerns over the high oil spill probabilities in the Chukchi Sea
under hypothetical future development scenarios (Minerals Management
Service (MMS) 2007). An oil spill in this area could have significant
consequences to the Chukchi Sea polar bear population (MMS 2007).
However, under the MMPA, since 1991 the oil and gas industry in Alaska
has sought and obtained incidental take authorization for take of small
numbers of polar bears. Incidental take cannot be authorized under the
MMPA unless the Service finds that any take that is likely to occur
will have no more than a negligible impact on the species. Through this
authorization process, the Service has consistently found that a large
oil spill is unlikely to occur. The oil and gas industry has
incorporated technological and response measures that minimize the risk
of an oil spill. A discussion of potential additive effects of
mortalities associated with an oil spill in polar bear populations
where harvest levels are close to the maximum sustained yield has been
included in this final rule (see discussion in the ``Oil and Gas
Exploration, Development, and Production'' section).
Comment 16: The effects to polar bears from contaminants other than
hydrocarbons are underestimated.
Our response: We added information on the status of regulatory
mechanisms pertaining to contaminants, which summarizes what is
currently known about the potential threat of each class of
contaminants with respect to current production and future trends in
production and use. Based on a thorough review of the scientific
information on their sources, pathways, geographical distribution, and
biological effects, and as discussed in the analysis section of this
final rule, we do not believe that contaminants currently threaten the
polar bear.
Comment 17: Cumulative effects of threat factors on polar bear
populations are important, and need a more indepth analysis than
presented in the proposed rule.
Our response: The best available information on the potential
cumulative effects from oil and gas activities in Alaska to polar bears
and their habitat was incorporated into the final rule (National
Research Council (NRC) 2003). We also considered the cumulative effects
of hunting, contaminants, increased shipping, increases in epizootic
events, and inadequacy of existing regulatory mechanisms in our
analyses. We have determined that there are no known regulatory
mechanisms in place at the national or international level that
directly and effectively address the primary threat to polar bears-the
rangewide loss of sea ice habitat within the foreseeable future. We
also acknowledge that there are some existing regulatory mechanisms to
address anthropogenic causes of climate change, and these mechanisms
are not expected to be effective in counteracting the worldwide growth
of GHG emissions within the foreseeable future. In addition, we have
determined that overutilization does not currently threaten the species
throughout all or a significant portion of its range. However, harvest
is likely exacerbating the effects of habitat loss in several
populations. In addition, continued harvest and increased mortality
from bear-human encounters or other forms of mortality may become a
more significant threat factor in the future, particularly for
populations experiencing nutritional stress or declining population
numbers as a consequence of habitat change. We have found that the
other factors, while not currently rising to a level that threatens the
species, may become more significant in the future as populations face
stresses from habitat loss. Modeling of potential effects on polar
bears of various factors (Amstrup et al. 2007) identified loss of sea
ice habitat as the dominant threat. Therefore, our analysis in this
final rule has focused primarily on the ongoing and projected effects
of sea ice habitat loss on polar bears within the foreseeable future.
Issue 4: Harvest
Comment 18: Illegal taking of bears is a significant issue that
needs additional management action.
[[Page 28242]]
Our response: We recognize that illegal take has an impact on some
polar bear populations, especially for the Chukchi Sea population and
possibly for other populations in Russia. We also believe that a better
assessment of the magnitude of illegal take in Russia is needed, and
that illegal harvest must be considered when developing sustainable
harvest limits. We also conclude that increased use of coastal habitat
by polar bears could increase the impact of illegal hunting in Russia,
by bringing bears into more frequent contact with humans. However,
available scientific information indicates that poaching and illegal
international trade in bear parts do not threaten the species
throughout all or a significant portion of its range.
Comment 19: The Service should not rely solely on the Bilateral
Agreement to remedy illegal take in Russia. Listing under the Act is
necessary to allow for continued legal subsistence hunting.
Our response: As discussed in the ``Summary of Factors Affecting
the Polar Bear'' section of this rule, we have found that harvest and
poaching affect some polar bear populations, but those effects are not
significant enough to threaten the species throughout all or a
significant portion of its range. To the extent that poaching is
affecting local populations in Russia, the Service believes that the
best tool to address these threats is the Agreement between the United
States of America and the Russian Federation on the Conservation and
Management of the Alaska-Chukotka Polar Bear Population (Bilateral
Agreement), which was developed and is supported by both government and
Native entities and includes measures to reduce poaching. The
Convention on International Trade in Endangered Species of Wild Fauna
and Flora (CITES) would address attempted international trade of
unlawfully taken polar bears (or parts), and the MMPA would address
attempted import into the United States of unlawfully taken animals or
their parts. Subsistence hunting by natives in the United States is
exempt from prohibitions under both the MMPA and the Act. Subsistence
harvest does not require action under the Act to ensure its
continuation into the future.
Comment 20: The Service should prohibit the importation into the
United States of polar bear trophies taken in Canada, and should amend
the MMPA to prohibit sport hunting of polar bears.
Our response: The polar bear is currently listed in Appendix II of
CITES. Section 9(c)(2) of the Act provides that the non-commercial
import of threatened and Appendix-II species, including their parts,
that were taken in compliance with CITES is not presumed to be in
violation of the Act. Thus, an import permit would not ordinarily be
required under the Act. We note that the MMPA does not allow sport
hunting of polar bears within the United States. In addition, we note
that, under the MMPA, the polar bear will be considered a ``depleted''
species on the effective date of this listing. As a depleted species,
imports could only be authorized under the MMPA if the import enhanced
the survival of the species or was for scientific research. Therefore,
authorization for the import of sport-hunted trophies would no longer
be available under section 104(c)(5) of the MMPA.
Comment 21: The Service failed to consider the negative impacts of
listing on the long-term management of polar bears developed in Canada
that integrates subsistence harvest allocations with a token sport
harvest.
Our response: We acknowledge the important contribution to
conservation from scientifically-based sustainable use programs.
Significant benefits to polar bear management in Canada have accrued as
a result of the 1994 amendments to the MMPA that allow U.S. citizens
who legally sport-harvest a polar bear from an MMPA-approved population
in Canada to bring their trophies back into the United States. These
benefits include economic revenues to native hunters and communities;
enhanced funding a support for research; a United States conservation
fund derived from permit fees that is used primarily on the Chukchi Sea
population; and increased local support of scientifically-based
conservation programs. Without this program, there would be a loss of
funds derived from import fees; loss of economic incentives that
promote habitat protection and maintain sustainable harvest levels in
Canada; and loss of research opportunities in Canada and Russia, which
are funded through sport-hunting revenue. While we recognize these
benefits, the Service must list a species when the best scientific and
commercial information available shows that the species meets the
definition of endangered or threatened. The effect of the listing, in
this case an end to the import provision under Section 104(c)(5) of the
MMPA, is not one of the listing factors. Furthermore, the benefits
accrued to the species through the import program do not offset or
reduce the overall threat to polar bears from loss of sea ice habitat.
Comment 22: The Service should promulgate an exemption under
section 4(d) of the Act that would allow importation of polar bear
trophies.
Our response: We recognize the role that polar bear sport harvest
has played in the support of subsistence, economic, and cultural values
in northern communities, and we have supported the program where
scientific data have been available to ensure sustainable harvest. We
again note that, under the MMPA, the polar bear will be considered a
``depleted'' species on the effective date of this listing. The MMPA
contains provisions that prevent the import of sport-hunted polar bear
trophies from Canada once the species is designated as depleted. A 4(d)
rule under the Act cannot affect existing requirements under the MMPA.
Comment 23: The rights of Alaska Natives to take polar bears should
be protected.
Our response: We recognize the social and cultural importance of
polar bears to coastal Alaska Native communities, and we anticipate
continuing to work with the Alaska Native community in a co-management
fashion to address subsistence-related issues. Section 101(b) of the
MMPA already exempts take of polar bears by Native people for
subsistence purposes as long as the take is not accomplished in a
wasteful manner. Section 10(e) of the Act also provides an exemption
for Alaska Natives that allows for taking as long as such taking is
primarily for subsistence purposes and the taking is not accomplished
in a wasteful manner. In addition, non-edible byproducts of species
taken in accordance with the exemption, when made into authentic native
articles of handicraft and clothing, may be transported, exchanged, or
sold in interstate commerce. Since 1987, we have monitored the Alaska
Native harvest of polar bears through our Marking, Tagging and
Reporting program [50 CFR 18.23(f)]. The reported harvest of polar
bears by Alaska Natives is 1,614 animals during this nearly 20-year
period, of which 965 were taken from the Chukchi Sea population and 649
were taken from the Southern Beaufort Sea population.
Alaska Natives' harvest of polar bears from the Southern Beaufort
and Chukchi Seas is not exclusive, since both of these populations are
shared across international boundaries with Canada and Russia
respectively, where indigenous populations in both countries also
harvest animals. Since 1988, the Inuvialuit Game Council (IGC) (Canada)
and the North Slope Borough (NSB) (Alaska) have implemented an
Inuvialuit-Inupiat Polar Bear Management Agreement for harvest of polar
bears in the Southern Beaufort
[[Page 28243]]
Sea. The focus of this agreement is to ensure that harvest of animals
from this shared population is conducted in a sustainable manner. The
Service works with the parties of this agreement, providing technical
assistance and advice regarding, among other aspects, information on
abundance estimates and sustainable harvest levels. We expect that
future harvest levels may be adjusted as a result of discussions at the
meeting between the IGC and NSB, held in February 2008.
We do have concerns regarding the harvest levels of polar bears
from the Chukchi Sea, where a combination of Alaska Native harvest and
harvest occurring in Russia may be negatively affecting this
population. However, implementation of the recently ratified
``Agreement between the United States of America and the Russian
Federation on the Conservation and Management of the Alaska-Chukotka
Polar Bear Population'' (Bilateral Agreement), with its provisions for
establishment of a shared and enforced quota system between the United
States and Russia, should ensure that harvest from the Chukchi Sea
population is sustainable.
Comment 24: If the polar bear is listed, subsistence hunting should
be given precedence over other forms of take.
Our response: As noted above, Alaska Native harvest of polar bears
for subsistence is currently exempt under both the MMPA and the Act.
Sport hunting of polar bears is not allowed in the United States under
the MMPA, and take for other purposes is tightly restricted. For polar
bears, the other primary type of take is incidental harassment during
otherwise lawful activities. The Service has issued incidental take
regulations under the MMPA since 1991, and these regulations include a
finding that such takings will not have an adverse impact on the
availability of polar bears for subsistence uses. Thus, the needs of
the Alaska Native community, who rely in part on the subsistence
harvest of polar bears, are addressed by existing provisions under both
the MMPA and the Act.
Issue 5: Climate Change
Comment 25: The accuracy and completeness of future climate
projections drawn from climate models are questionable due to the
uncertainty or incompleteness of information used in the models.
Our response: Important new climate change information is included
in this final rule. The Working Group I Report of the IPCC AR4,
published in early 2007, is a key part of the new information, and
represents a collaborative effort among climate scientists from around
the world with broad scientific consensus on the findings. In addition,
a number of recent publications are used in the final rule to
supplement and expand upon results presented in the AR4; these include
Parkinson et al. (2006), Zhang and Walsh (2006), Arzel et al. (2006),
Stroeve et al. (2007, pp. 1-5), Wang et al. (2007, pp. 1,093-1,107),
Chapman and Walsh (2007), Overland and Wang (2007a, pp. 1-7), DeWeaver
(2007), and others. Information from these publications has been
incorporated into appropriate sections of this final rule.
Atmosphere-ocean general circulation models (AOGCMs, also known as
General Circulation Models (GCMs)) are used to provide a range of
projections of future climate. GCMs have been consistently improved
over the years, and the models used in the IPCC AR4 are significantly
improved over those used in the IPCC TAR and the ACIA report. There is
``considerable confidence that the GCMs used in the AR4 provide
credible quantitative estimates of future climate change, particularly
at continental scales and above'' (IPCC 2007, p. 591). This confidence
comes from the foundation of the models in accepted physical principles
and from their ability to reproduce observed features of current
climate and past climate changes. Additional confidence comes from
considering the results of suites of models (called ensembles) rather
than the output of a single model. Confidence in model outcomes is
higher for some climate variables (e.g., temperature) than for others
(e.g., precipitation).
Despite improvements in GCMs in the last several years, these
models still have difficulties with certain predictive capabilities.
These difficulties are more pronounced at smaller spatial scales and
longer time scales. Model accuracy is limited by important small-scale
processes that cannot be represented explicitly in models and so must
be included in approximate form as they interact with larger-scale
features. This is partly due to limitations in computing power, but
also results from limitations in scientific understanding or in the
availability of detailed observations of some physical processes.
Consequently, models continue to display a range of outcomes in
response to specified initial conditions and forcing scenarios. Despite
such uncertainties, all models predict substantial climate warming
under GHG increases, and the magnitude of warming is consistent with
independent estimates derived from observed climate changes and past
climate reconstructions (IPCC 2007, p. 761; Overland and Wang 2007a,
pp. 1-7; Stroeve et al. 2007, pp. 1-5).
We also note the caveat, expressed by many climate modelers and
summarized by DeWeaver (2007), that, even if global climate models
perfectly represent all climate system physics and dynamics, inherent
climate variability would still limit the ability to issue accurate
forecasts (predictions) of climate change, particularly at regional and
local geographical scales and longer time scales. A forecast is a more-
precise prediction of what will happen and when, while a projection is
less precise, especially in terms of the timing of events. For example,
it is difficult to accurately forecast the exact year that seasonal sea
ice will disappear, but it is possible to project that sea ice will
disappear within a 10-20 year window, especially if that projection is
based on an ensemble of modeling results (i.e., results from several
models averaged together). It is simply not possible to engineer all
uncertainty out of climate models, such that accurate forecasts are
possible. Climate scientists expend considerable energy in trying to
understand and interpret that uncertainty. The section in this rule
entitled ``Uncertainty in Climate Models'' discusses uncertainty in
climate models in greater depth than is presented here.
In summary, confidence in GCMs comes from their physical basis and
their ability to represent observed climate and past climate changes.
Models have proven to be extremely important tools for simulating and
understanding climate and climate change, and we find that they provide
credible quantitative estimates of future climate change, particularly
at larger geographical scales.
Comment 26: Commenters provided a number of regional examples to
contradict the major conclusions regarding climate change.
Our response: As noted in our response to Comment 25, GCMs are less
accurate in projecting climate change over finer geographic scales,
such as the variability noted for some regions in the Arctic, than they
are for addressing global or continental-level climate change. Climate
change projections for the Barents Sea are difficult, for example,
because regional physics includes both local winds and local currents.
Cyclic processes, such as the North Atlantic Oscillation (NAO), can
also drive regional variability. We agree with one commenter that the
NAO is particularly strong for Greenland (Chylek et al. 2006). However,
the natural variability associated with this
[[Page 28244]]
phenomenon simply suggests that the future will also have large
variability, but does not negate overall climate trends, because the
basic physics of climate processes, including sea ice albedo feedback,
are modeled in all major sectors of the Arctic Basin. The increased
understanding of the basic physics related to climate processes and the
inclusion of these parameters in current climate models, such as those
used in the IPCC AR4, present a more complete, comprehensive, and
accurate view of range-wide climate change than earlier models.
Comment 27: Other models should be used in the analysis of
forecasted environmental and population changes including population
viability assessment and precipitation models.
Our response: The Service has not relied upon the published results
or use of a single climate model or single scenario in its analyses.
Instead we have considered a variety of information derived from
numerous climate model outputs. These include modeled changes in
temperature, sea ice, snow cover, precipitation, freeze-up and breakup
dates, and other environmental variables. The recent report of the IPCC
AR4 provides a discussion of the climate models used, and why and how
they resulted in improved analyses of climatic variable and future
projections. Not only have the models themselves been improved, but
many advances have been made in terms of how the model results were
used. The AR4 utilized multiple results from single models (called
multi-member ensembles) to, for example, test the sensitivity of
response to initial conditions, as well as averaged results from
multiple models (called multi-model ensembles). These two different
types of ensembles allow more robust evaluation of the range of model
results and more quantitative comparisons of model results against
observed trends in a variety of parameters (e.g., sea ice extent,
surface air temperature), and provide new information on simulated
statistical variability. This final rule benefits from specific
analyses of uncertainty associated with model prediction of Arctic sea
ice decline (DeWeaver 2007; Overland and Wang 2007a, pp. 1-7), and
identification of those models that best simulated observed changes in
Arctic sea ice.
We also updated this final rule with information on recently
completed population models (e.g., Hunter et al. 2007), habitat values
and use models (Durner et al. 2007), and population projection models
(Amstrup et al. 2007), which can be found in the ``Current Population
Status and Trend'' section.
Comment 28: Future emission scenarios are unreliable or incomplete
and use speculative carbon emission scenarios that inaccurately portray
future levels.
Our response: Emissions scenarios used in climate modeling were
developed by the IPCC and published in its Special Report on Emissions
Scenarios in 2000. These emissions scenarios are representations of
future levels of GHGs based on assumptions about plausible demographic,
socioeconomic, and technological changes. The most recent,
comprehensive climate projections in the IPCC AR4 used scenarios that
represent a range of future emissions: low, medium, and high. The
majority of models used a ``medium'' or ``middle-of-the-road'' scenario
due to the limited computational resources for multi-model simulations
using GCMs (IPCC 2007, p. 761). In addition, Zhang and Walsh (2006) use
three emission scenarios representative of the suite of possibilities
and DeWeaver (2007 p. 28), in subsequent analyses, used the A1B
``business as usual'' scenario as a representative of the medium-range
forcing scenario, and other scenarios were not considered due to time
constraints. Similarly, our final analysis considered a range of
potential outcomes, based in part on the range of emission scenarios.
For additional details see the previous section, ``Projected Changes in
Arctic Sea Ice.''
We agree that emissions scenarios out to 2100 are less certain with
regard to technology and economic growth than projections out to 2050.
This is reflected in the larger confidence interval around the mean at
2100 than at 2050 in graphs of these emissions scenarios (see Figure
SPM-5 in IPCC 2007). However, GHG loading in the atmosphere has
considerable lags in its response, so that what has already been
emitted and what can be extrapolated to be emitted in the next 15-20
years will have impacts out to 2050 and beyond (IPCC 2007, p. 749; J.
Overland, NOAA, in litt. to the Service, 2007). This is reflected in
the similarity of low, medium, and high SRES emissions scenarios out to
about 2050 (see discussion of climate change under ``Factor A. Present
or Threatened Destruction, Modification, or Curtailment of the Species'
Habitat or Range''). Thus, the uncertainty associated with emissions is
lower for the foreseeable future timeframe (45 years) for the polar
bear listing than longer timeframes.
Comment 29: Atmospheric CO2 is an indicator of global
warming and not a major contributor.
Our response: Carbon dioxide (CO2) is one of four
principal anthropogenically-generated GHGs, the others being nitrous
oxide (N2O), methane (CH4), and halocarbons (IPCC
2007, p. 135). The IPCC AR4 considers CO2 to be the most
important anthropogenic GHG (IPCC 2007, p. 136). The GHGs affect
climate by altering incoming solar radiation and out-going thermal
radiation, and thus altering the energy balance of the Earth-atmosphere
system. Since the start of the industrial era, the effect of increased
GHG concentrations in the atmosphere has been widespread warming of the
climate, with disproportionate warming in large areas of the Arctic
(IPCC 2007, p. 37). A net result of this warming is a loss of sea ice,
with notable reductions in Arctic sea ice.
Comment 30: Atmospheric CO2 levels are not greater today
than during pre-industrial time.
Our response: The best available scientific evidence unequivocally
contradicts this comment. Atmospheric concentration of carbon dioxide
(CO2) has increased significantly during the post-industrial
period based on information from polar ice core records dating back at
least 650,000 years. The recent rate of change is also dramatic and
unprecedented, with the increase documented in the last 20 years
exceeding any increase documented over a thousand-year period in the
historic record (IPCC AR4, p. 115). Specifically, the concentration of
atmospheric CO2 has increased from a pre-industrial value of
about 280 ppm to 379 ppm in 2005, with an annual growth rate larger
during the last 10 years than it has been since continuous direct
atmospheric measurements began in 1960. These increases are largely due
to global increases in GHG emissions and land use changes such as
deforestation and burning (IPCC 2007, pp. 25-26).
Comment 31: Consider the impacts of black carbon (soot) due to
increased shipping as a factor affecting the increase in the melting of
the sea ice.
Our response: We recognize that there are large uncertainties about
the contribution of soot to snow melt patterns. A general understanding
is that soot (from black carbon aerosols) deposited on snow reduces the
surface albedo with a resulting increase in snow melt process (IPCC
2007, p. 30). Estimates of the amount of effect from all sources of
soot have wide variance, and the exact contribution from increased
shipping cannot be determined at this time.
Comment 32: Climate models do not adequately address naturally
occurring phenomena.
[[Page 28245]]
Our response: In IPCC AR4 simulations, models were run with natural
and anthropogenic (i.e., GHG) forcing for the period of the
observational record (i.e., the 20th century). Results from different
models and different runs of the same model can be used to simulate the
observed range of natural variability in the 20th century (such as warm
in 1930s and cool in the 1960s). Only when GHG forcing is added to
natural variability, however, do the models simulate the warming
observed in the later portion of the 20th century (Wang et al. 2007).
This is shown for the Arctic by Wang et al. (2007, pp. 1,093-1,107).
This separation is shown graphically in Figure SPM-4 of the IPCC AR4
(shown below, reproduced from IPCC 2007 with permission); note the
separation of the model results with and without greenhouse gases at
the end of the 20th century for different regions. Thus comparison of
forced CO2 trends and natural variability were central to
the IPCC AR4 analyses, and are discussed in this final rule.
[GRAPHIC] [TIFF OMITTED] TR15MY08.009
Analyses of paleoclimate data increase confidence in the role of
external influences on climate. The GCMs used to predict future climate
provide insight into past climatic conditions of the Last Glacial
Maximum and the mid-Holocene. While many aspects of these past climates
are still uncertain, climate models reproduce key features by using
boundary conditions and natural forcing factors for those periods. The
IPCC AR4 concluded that a substantial fraction of the reconstructed
Northern Hemisphere inter-decadal temperature variability of the seven
centuries prior to 1950 is very likely attributable to natural external
forcing, and it is likely that anthropogenic forcing contributed to the
early 20th-century warming evident in these records (IPCC 2007).
Comment 33: Current climate patterns are part of the natural cycle
and reflect natural variability.
Our response: Considered on a global scale, climate is subject to
an inherent degree of natural variability. However, evidence of human
influence on the recent evolution of climate has accumulated steadily
during the past two decades. The IPCC AR4 has concluded that (1) most
of the observed increase in globally-averaged temperatures since the
mid-20th century is very likely due to the observed increase in
anthropogenic GHG concentrations; and (2) it is likely there has been
significant anthropogenic warming over the past 50 years averaged over
each continent (except Antarctica) (IPCC 2007, p. 60).
[[Page 28246]]
Comment 34: There was a selective use of climate change information
in the proposed rule, and the analysis ignored climate information
about areas that are cooling.
Our response: We acknowledge that climate change and its effects on
various physical processes (such as ice formation and advection,
snowfall, precipitation) vary spatially and temporally, and that this
has been considered in our analysis. While GCMs are more effective in
characterizing climate change on larger scales, we have considered that
the changes and effects are not uniform in their timing, location, or
magnitude such as identified by Laidre et al. (2005) and Zhang and
Walsh (2006). Indeed, the region southwest of Greenland does not show
substantial warming by 2050 according to some climate projections.
However, most polar bear habitat regions do show the substantial loss
of sea ice by 2040-2050. While regional differences in climate change
exist, this will not change the effect of climatic warming anticipated
to occur within the foreseeable future within the range of polar bears.
Updated information on regional climate variability has been added to
the section ``Overview of Arctic Sea Ice Change.''
Comment 35: The world will be cooler by 2030 based on sunspot cycle
phenomena, which is the most important determinant of global warming
(e.g., Soon et al. 2005; Jiang et al. 2005).
Our response: The issue of solar influences, including sunspots, in
climate change has been considered by many climate scientists, and
there is considerable disagreement about any large magnitude of solar
influences and their importance (Bertrand et al. 2002; IPCC 2007). The
most current synthesis of the IPCC (AR4, p. 30) describes a well
established, 11-year cycle with no significant long term trend based on
new data obtained through significantly improved measurements over a
28-year period. Solar influence is considered in the IPCC models and is
a small effect relative to volcanoes and CO2 forcing in the
later half of the 20th century. While more complex solar influences due
to cosmic ray/ionosphere/cloud connections have been hypothesized,
there is no clear demonstration of their having a large effect.
Comment 36: The IPCC report fails to give proper weight to the
geological context and relationship to climate change.
Our response: Paleoclimatic events were analyzed in the IPCC AR4,
which concluded that ``Confidence in the understanding of past climate
change and changes in orbital forcing is strengthened by the improved
ability of current models to simulate past climate conditions.'' Model
results indicate that the Last Glacial Maximum (about 21,000 years ago)
and the mid-Holocene (6,000 years ago) were different from the current
climate not because of random variability, but because of altered
seasonal and global forcing linked to known differences in the Earth's
orbit. This additional information has been incorporated in this final
rule.
Comment 37: Movement of sea ice from the Arctic depends on the
Aleutian Low, Arctic Oscillation (AO), North Atlantic Oscillation
(NAO), and Pacific Decadal Oscillation (PDO) rather than GHG emissions.
Our response: Sea ice is lost from the Arctic by a combination of
dynamic and thermodynamic mechanisms. Not only is it lost by advection,
but lost as a result of changes in surface air and water temperatures.
Changes in surface air temperature are strongly influenced by warming
linked to GHG emissions, while increases in water temperature are
influenced by warming, the sea ice-albedo feedback mechanism, and the
influx of warmer subpolar waters (largely in the North Atlantic)
(Serreze et al. 2007). Recent studies (IPCC 2007, p. 355; Stroeve et al
2007; Overland and Wang 2007a, pp. 1-7) recognize considerable natural
variability in the pattern of sea ice motion relative to the AO, NAO,
and PDO, which will continue into the 21st century. However, the
distribution of sea ice thickness is a factor in the amount of sea ice
that is advected from the Arctic, and this distribution is
significantly affected by surface air and water temperature.
Comment 38: Changes in the sea ice extent vary throughout the
Arctic but overall extent has not changed in past 50 years.
Our response: All observational data collected since the 1950s
points to a decline in both Arctic sea ice extent and area, as well as
an increasing rate of decline over the past decade. While sea ice cover
does have a component of natural variability, such variability does not
account for the influence that increased air and water temperatures
will have on sea ice in the future. The pattern of natural variability
will continue, but will be in conjunction with the overall declining
trend due to warming, and the combination could result in abrupt
declines in sea ice cover faster than would be expected from GHG
warming alone.
Comment 39: Evidence that does not support climate change was not
included in the analyses.
Our response: We recognize that there are scientific differences of
opinion on many aspects of climate change, including the role of
natural variability in climate and also the uncertainties involved with
both the observational record and climate change projections based on
GCMs. We have reviewed a wide range of documents on climate change,
including some that espouse the view that the Earth is experiencing
natural cycles rather than directional climate change (e.g., Damon and
Laut 2004; Foukal et al. 2006). We have consistently relied on
synthesis documents (e.g., IPCC AR4; ACIA) that present the consensus
view of a very large number of experts on climate change from around
the world. We have found that these synthesis reports, as well as the
scientific papers used in those reports or resulting from those
reports, represent the best available scientific information we can use
to inform our decision and have relied upon them and provided citation
within our analysis.
Comment 40: Current conditions, based on past variation in Arctic
sea ice and air temperatures, are by no means unprecedented and
consequently the survival of polar bears and other marine mammals is
not of concern.
Our response: We acknowledge that previous warming events (e.g.,
the Last Interglacial period (LIG), Holocene Thermal Maximum (HTM))
likely affected polar bears to some unknown degree. The fact that polar
bears survived these events does not mean that they are not being
affected by current sea ice and temperature changes. Indeed, the best
available scientific information indicates that several populations are
currently being negatively affected, and projections indicate that all
populations will be negatively affected within the foreseeable future,
such that the species will be in danger of extinction throughout all or
a significant portion of its range within that timeframe. We have
included additional information regarding previous warming events and
an explanation of potential for polar bears to adapt in the section
``Effects of Sea Ice Habitat Changes on Polar Bear Prey.''
We agree that there is considerable natural variability and region-
to-region differences in sea ice cover as documented by numerous
journal articles and other references (Comiso 2001; Omstedt and Chen
2001; Jevrejeva 2001; Polyakov et al. 2003; Laidre and Heide-Jorgensen
2005). However, current conditions are unprecedented (IPCC 2007, p.
24). Climate scientists agree that atmospheric concentrations of
[[Page 28247]]
CO2 and CH4 far exceed the natural range over the
last 650,000 years. The rate of growth in atmospheric concentration of
GHGs is considered unprecedented (IPCC 2007, p. 24). The recent
publication by Canadell et al. (2007) indicates that the growth rate of
atmospheric CO2 is increasing rapidly. An increasing
CO2 concentration is consistent with results of climate-
carbon cycle models, but the magnitude of the observed atmospheric
CO2 concentration appears larger than that estimated by
models. The authors suggest that these changes characterize a carbon
cycle that is generating stronger-than-expected and sooner-than-
expected climate forcing. What also is unprecedented is the potential
for continued sea ice loss into the 21st century based on the physics
of continued warming due to external forcing, and the accelerated
impact of the ice albedo feedback as more open water areas open.
Consideration of future loss of sea ice does not depend only on the sea
ice observational record by itself. However, current sea ice loss,
which now averages about 10 percent per decade over the last 25 years,
plus the extreme loss of summer sea ice in 2007, is a warning sign that
significant changes are underway, and data indicate that these extremes
will continue into the foreseeable future.
Issue 6: Regulatory Mechanisms
Comment 41: Treaties, agreements, and regulatory mechanisms for
population management of polar bears exist and are effective; thus
there is no need to list the species under the Act.
Our response: The Service recognizes that existing polar bear
management regulatory mechanisms currently in place have been effective
tools in the conservation of the species; the ability of the species as
a whole to increase in numbers from low populations, as discussed in
our response to Comment 1, associated with over-hunting pressures of
the mid 20th century attest to such effectiveness. As discussed under
Factor D, there is a lack of regulatory mechanisms to address the loss
of habitat due to reductions in sea ice. We acknowledge that progress
is being made, and may continue to be made, to address climate change
resulting from human activity; however, the current and expected impact
to polar bear habitat indicates that in the foreseeable future, as
defined in this rule, such efforts will not ameliorate loss of polar
bear habitat or numbers of polar bears.
Comment 42: The Service did not consider existing local, State,
National, and International efforts to address climate change (e.g.,
the Kyoto Protocol or United Nations Framework Convention on Climate
Change) and is incorrect in concluding that there are no known
regulatory mechanisms effectively addressing reductions in sea ice
habitat. Furthermore, the Service failed to consider the probability of
a global response to growing demands to deal with global climate
change.
Our response: We have included discussion of domestic and
international efforts to address climate change in the ``Inadequacy of
Existing Regulatory Mechanisms'' (Factor D) section. While we note
various efforts are ongoing, we conclude that such efforts have not yet
proven to be effective at preventing loss of sea ice. The Service's
``Policy for Evaluation of Conservation Efforts When Making Listing
Decisions'' (68 FR 15100) provides guidance for analyzing future
conservation efforts and requires that the Service only rely on efforts
that we have found will be both implemented and effective. While we
note that efforts are being made to address climate change, we are
unaware of any programs currently being shown to effectively reduce
loss of polar bear ice habitat at a local, regional, or Arctic-wide
scale.
Comment 43: The Service should evaluate the recent Supreme Court
ruling that the U.S. Environmental Protection Agency (EPA) has the
authority under the Clean Air Act to regulate GHGs.
Our response: The Service recognizes the leading role the EPA plays
in implementing the Clean Air Act. However, specific considerations
regarding the recent Supreme Court decision are beyond the scope of
this decision.
Comment 44: The effort to list the polar bear is an inappropriate
attempt to regulate GHG emissions. Any decision to limit GHG emissions
should be debated in the open and not regulated through the ``back
door'' by the Act.
Our response: The Service was petitioned to evaluate the status of
polar bears under the Act. In doing so, we evaluated the best
scientific and commercial information available on present and
foreseeable future status of polar bears and their habitat as required
by the Act. The role of the Service is to determine the appropriate
biological status of the polar bear and that is the scope of this rule.
Some commenters to the proposed rule suggested that the Service should
require other agencies (e.g., the EPA) to regulate emissions from all
sources, including automobiles and power plants. The science, law, and
mission of the Service do not lead to such action. Climate change is a
worldwide issue. A direct causal link between the effects of a specific
action and ``take'' of a listed species is well beyond the current
level of scientific understanding (see additional discussion of this
topic under the ``Available Conservation Measures'' section).
Comment 45: Listing of the polar bear is more about the politics of
global climate change than biology of polar bears.
Our response: The Service was petitioned to list polar bears under
the Act and we evaluated the best available scientific and commercial
information available on threats to polar bears and their habitat as
required by the Act. The role of the Service is to determine the
appropriate status of the polar bear under the Act, and that is the
scope of this rule.
Issue 7: Listing Justification
Comment 46: Justification for listing is insufficient or limited to
few populations, and thus range-wide listing is not warranted.
Our response: This document contains a detailed evaluation of the
changing sea ice environment and research findings that describe the
effect of environmental change on the declining physical condition of
polar bears, corresponding declines in vital rates, and declines in
population abundance. We acknowledge that the timing, rate and
magnitude of impacts will not be the same for all polar bear
populations. However, the best available scientific information
indicates that several populations are currently being negatively
affected, and projections indicate that all populations will be
negatively affected within the foreseeable future, such that the
species will be in danger of extinction throughout all or a significant
portion of its range within that timeframe.
Since the proposed rule was published (72 FR 1064), the USGS
completed additional analyses of population trajectories for the
Southern Beaufort Sea population (Hunter et al. 2007), and updated
population estimates for the Northern Beaufort Sea (Stirling et al.
2007) and Southern Hudson Bay (Obbard et al. 2007) populations
(summarized in the ``Background'' section of this final rule). The USGS
also has conducted additional modeling of habitat resource selection in
a declining sea ice environment (Durner et al. 2007), and an evaluation
of the levels of uncertainty or likelihood of outcomes for a variety of
climate models (DeWeaver 2007). Information from these recent USGS
analyses is included
[[Page 28248]]
and cited within this rule and balanced with other published
information evaluating current and projected polar bear status. In
addition, since the publication of the proposed rule (72 FR 1064), the
IPCC AR4 and numerous other publications related to climate change and
modeled climate projections have become available in published form and
are now included and cited within this rule.
We considered whether listing particular Distinct Population
Segments (DPSs) is warranted, but we could not identify any geographic
areas or populations that would qualify as a DPS under our 1996 DPS
Policy (61 FR 4722), because there are no population segments that
satisfy the criteria of the DPS Policy.
Finally, we analyzed the status of polar bears in portions of its
range to determine if differential threat levels in those areas warrant
a determination that the species is endangered rather than threatened
in those areas. The overall direction and magnitude of threats to polar
bears lead us to conclude that the species is threatened throughout its
range, and that there are no significant portions of the range where
the polar bear would be considered currently in danger of extinction.
On the basis of all these analyses, we have concluded that the best
available scientific information supports a determination that the
species is threatened throughout all of its range.
Comment 47: Traditional ecological knowledge (TEK) does not support
the conclusion that polar bear populations are declining and negatively
impacted by climate change.
Our response: We acknowledge that TEK may provide a relevant source
of information on the ecology of polar bears obtained through direct
individual observations. We have expanded and incorporated additional
discussion of TEK into our determination. Additionally, we have
received and reviewed comments from individuals with TEK on both
climate change and polar bears. While there may be disagreement among
individuals on the impacts of climate change on polar bears, we believe
there is general scientific consensus that sea ice environment is
diminishing.
Comment 48: Cannibalism, starvation, and drowning are naturally
occurring events and should not be inferred as reasons for listing.
Our response: We agree that cannibalism, starvation, and drowning
occur in nature; however, we have not found that these are mortality
factors that threaten the species throughout all or a significant
portion of its range. Rather, we find that recent research findings
have identified the unusual nature of some reported mortalities, and
that these events serve as indicators of stressed populations. The
occurrence and anecdotal observation of these events and potential
relationship to sea ice changes is a current cause for concern. In the
future, these events may take on greater significance, especially for
populations that may be experiencing nutritional stress or related
changes in their environment.
Comment 49: The Service did not adequately consider polar bear use
of marginal ice zones in the listing proposal.
Our response: Due to the dynamic and cyclic nature of sea ice
formation and retreat, marginal ice zones occur on an annual basis
within the circumpolar area and indeed are important habitat for polar
bears. The timing of occurrence, location, and persistence of these
zones over time are important considerations because they serve as
platforms for polar bears to access prey. Marginal ice zones that are
associated with shallow and productive nearshore waters are of greatest
importance, while marginal ice zones that occur over the deeper, less
productive central Arctic basin are not believed to provide values
equivalent to the areas nearshore. New information on polar bear
habitat selection and use (Durner et al. 2007) is included in this
rule's sections ``Polar Bear-Sea Ice Habitat Relationships'' and
``Effects of Sea Ice Habitat Change on Polar Bears.''
Comment 50: The effects of climate change on polar bears will vary
among populations.
Our response: We recognize that the effects of climate change will
vary among polar bear populations, and have discussed those differences
in detail in this final rule. We have determined that several
populations are currently being negatively affected, and projections
indicate that all populations will be negatively affected within the
foreseeable future. Preliminary modeling analyses of future scenarios
using a new approach (the Bayesian Network Model) describe four
``ecoregions'' based on current and projected sea ice conditions
(Amstrup et al. 2007); a discussion of these analyses is included in
Factor A of the ``Summary of Factors Affecting the Species.''
Consistent with other projections, the preliminary model projects that
southern populations with seasonal ice-free conditions and open Arctic
Basin populations in areas of ``divergent'' sea ice will be affected
earliest and to the greatest extent,while populations in the Canadian
archipelago populations and populations in areas of ``convergent ``sea
ice'' will be affected later and to a lesser extent. These model
projections indicate that impacts will happen at different times and
rates in different regions. On the basis of the best available
scientific information derived from this preliminary model and other
extensive background information, we conclude that the species is not
currently in danger of extinction throughout all or a significant
portion of its range, but is very likely to become so within the
foreseeable future. We have not identified any areas or populations
that would qualify as Distinct Population Segments under our 1996 DPS
Policy, or any significant portions of the polar bear's range that
would qualify for listing as endangered (see response to Comment 47).
Comment 51: The 19 populations the Service has identified cannot be
thought of as discrete or stationary geographic units, and polar bears
should be considered as one Arctic population.
Our response: We agree that the boundaries of the 19 populations
are not static or stationary. Intensive scientific study of movement
patterns and genetic analysis reinforces boundaries of some populations
while confirming that overlap and mixing occur among others. Neither
movement nor genetic information is intended to mean that the
boundaries are absolute or stationary geographic units; instead, they
most accurately represent discrete functional management units based on
generalized patterns of use.
Comment 52: The Service should evaluate the status of the polar
bear in significant portions of the range or distinct population
segments, due to regional differences in climate parameters, and
therefore the response of polar bears.
Our response: We analyzed the status of polar bears by population
and region in the section ``Demographic Effects of Sea Ice Changes on
Polar Bear'' and considered how threats may differ between areas. We
recognize that the level, rate, and timing of threats will be uneven
across the Arctic and, thus, that polar bear populations will be
affected at different rates and magnitudes depending on where they
occur. We find that, although habitat (i.e., sea ice) changes may occur
at different rates, the direction of change is the same. Accepted
climate models (IPCC AR4 2007; DeWeaver 2007), based on their ability
to simulate present day ice patterns, all project a unidirectional loss
of sea ice. Similarly, new analyses of polar bear habitat distribution
in the polar basin projected over time (Durner et al. 2007) found that
while the rate of
[[Page 28249]]
change in habitat varied between GCMs, all models projected habitat
loss in the polar basin within the 45-year foreseeable future
timeframe. Therefore, despite the regional variation in changes and
response, we find that the primary threat (loss of habitat) is
occurring and is projected to continue to occur throughout the Arctic.
In addition, the USGS also examined how the effects of climate change
will vary across time and space; their model projections also indicate
that impacts will happen at different times and rates in different
regions (Amstrup et al. 2007).
Recognizing the differences in the timing, rate, and magnitude of
threats, we evaluated whether there were any specific areas or
populations that may be disproportionately threatened such that they
currently meet the definition of an endangered species versus a
threatened species. We first considered whether listing one or more
Distinct Population Segments (DPS) as endangered may be warranted. We
then considered whether there are any significant portions of the polar
bear's range (SPR) where listing the species as endangered may be
warranted. In evaluating current status of all populations and
projected sea ice changes and polar bear population projections, we
were unable to identify any distinct population segments or significant
portions of the range of the polar bear where the species is currently
in danger of extinction. Rather, we have concluded that the polar bear
is likely to become an endangered species throughout its range within
the foreseeable future. Thus, we find that threatened status throughout
the range is currently the most appropriate listing under the Act.
Comment 53: One commenter asserted that the best available
scientific information indicates that polar bear populations in two
ecoregions defined by Amstrup et al. (2007)--the Seasonal Ice ecoregion
and the polar basin Divergent ecoregion--should be listed as
endangered.
Our response: We separately evaluated whether polar bear
populations in these two ecoregions qualify for a different status than
polar bears in the remainder of the species' range. We determined that
while these polar bears are likely to become in danger of extinction
within the foreseeable future, they are not currently in danger of
extinction. See our analysis in the section ``Distinct Population
Segment (DPS) and Significant Portion of the Range (SPR) Evaluation.''
Comment 54: There is insufficient evidence to conclude that the
polar bear will be threatened or extinct within three generations as no
quantitative analysis or models of population numbers (or prey
abundance) are offered.
Our response: New information on population status and trends for
the Southern Beaufort Sea (Hunter et al. 2007; Regehr et al. 2007b) and
updated population estimates for the Northern Beaufort Sea (Stirling et
al. 2007) and Southern Hudson Bay (Obbard et al. 2007) populations is
included in this rule along with range-wide population projections
based on polar bear ecological relationship to sea ice and to changes
in sea ice over time (Amstrup et al. 2007). These studies, plus the
IPCC AR4, and additional analyses of climate change published within
the last year, have added substantially to the final rule. Taken
together, the new information builds on previous analyses to provide
sufficient evidence to demonstrate that: (1) polar bears are sea ice-
dependent species; (2) reductions in sea ice are occurring now and are
very likely to continue to occur within the foreseeable future; (3) the
linkage between reduced sea ice and population reductions has been
established; (4) impacts on polar bear populations will vary in their
timing and magnitude, but all populations will be affected within the
foreseeable future; and (5) the rate and magnitude of the predicted
changes in sea ice will make adaptation by polar bears unrealistic. On
these bases, we have determined that the polar bear is not currently in
danger of extinction throughout all or a significant portion of its
range, but is likely to become so within the foreseeable future.
Comment 55: Perceptions differ as to whether polar bear populations
will decline with loss of sea ice habitat.
Our response: Long-term data sets necessary to establish the
linkage between population declines and climate change do not exist for
all polar bear populations within the circumpolar Arctic. However, the
best available scientific information indicates a link between polar
bear vital rates or population declines and climate change. For two
populations with extensive time series of data, Western Hudson Bay and
Southern Beaufort Sea, either the population numbers or survival rates
are declining and can be related to reductions in sea ice. In addition,
scientific literature indicates that the Davis Strait, Baffin Bay, Foxe
Basin, and the Eastern and Western Hudson Bay populations are expected
to decline significantly in the foreseeable future based on reductions
of sea ice projected in Holland et al. (2006, pp. 1-5). Additional
population analyses (Regehr et al. 2007a, b; Hunter et al. 2007; Obbard
et al. 2007) that further detail this relationship have been recently
completed and are included in this final rule.
Comment 56: Factors supporting listing are cumulative and thus are
unlikely to be quickly reversed. Polar bears are likely to become
endangered within one to two decades.
Our response: We have concluded that habitat loss (Factor A) is the
primary factor that threatens the polar bear throughout its range. We
have also determined that there are no known regulatory mechanisms in
place, and none that we are aware of that could be put in place, at the
national or international level, that directly and effectively address
the rangewide loss of sea ice habitat within the foreseeable future
(Factor D). However, we have also concluded that other factors (e.g.,
overutilization) may interact with and exacerbate these primary threats
(particularly habitat loss) within the 45-year foreseeable future.
Polar bear populations are being affected by habitat loss now, and
will continue to be affected within the foreseeable future. We do not
believe that the species is currently endangered, but we believe it is
likely that the species will become endangered during the foreseeable
future given current and projected trends; see detailed discussion
under Factor A in the section ``Demographic Effects of Sea Ice Changes
on Polar Bear''. We intend to continue to evaluate the status of polar
bears and will review and amend the status determination if conditions
warrant. Through 5-year reviews and international circumpolar
monitoring, we will closely track the status of the polar bear over
time.
Comment 57: Polar bears face unprecedented threats from climate
change, environmental degradation, and hunting for subsistence and
sport.
Our response: We agree in large part as noted in detail within this
final rule, but clarify that hunting for subsistence or sport does not
currently threaten the species in all or a significant portion of its
range, and where we have concerns regarding the harvest we are hopeful
that existing or newly established regulatory processes, e.g., the
recently adopted Bilateral Agreement, will be adequate to ensure that
harvest levels are sustainable and can be adjusted as our knowledge of
population status changes over time. Please see the ``Summary of
Factors Affecting the Polar Bear'' for additional discussion of these
issues.
[[Page 28250]]
Issue 8: Listing Process
Comment 58: Listing the polar bear under the Act should be delayed
until reassessment of the status of the species under Canada's Species
at Risk Act (SARA) is completed.
Our response: When making listing decisions, section 4 of the Act
establishes firm deadlines that must be followed, and does not allow
for an extension unless there is substantial scientific disagreement
regarding the sufficiency or accuracy of relevant data. Section 4(b)
directs the Secretary to take into account any efforts being made by
any State or foreign nation to protect the species under consideration;
however, the Act does not allow the Secretary to defer a listing
decision pending the outcome of any such efforts. The status of the
polar bear under Canada's SARA is discussed under Factor D.
Comment 59: The Act was not designed to list species based on
future status.
Our response: We agree. We have determined that the polar bear's
current status is that it is ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' This is the definition of a threatened species under
the Act, and we are accordingly designating the species as threatened.
Comment 60: Use of the IUCN Red Listing criteria for a listing
determination under the Act is questionable, and should not be used.
Our response: While we may consider the opinions and
recommendations of other experts (e.g., IUCN), the determination as to
whether a species meets the definition of threatened or endangered must
be made by the Service, and must be based upon the criteria and
standards in the Act. After reviewing the best available scientific and
commercial information, we have determined that the polar bear is
threatened throughout its range, based upon an assessment of threats
according to section 4 of the Act. While some aspects of our
determination may be in line with the IUCN Red List criteria (e.g., we
used some Red List criteria for determination of generation time), we
have not used the Red List criteria as a standard for our
determination. Rather, in accordance with the Act, we conducted our own
analyses and made our own determination based on the beast available
information. Please see the ``Summary of Factors Affecting the
Species'' section for in-depth discussion.
Comment 61: The peer review process is flawed due to biases of the
individual peer reviewers.
Our response: We conducted our peer review in accordance with our
policy published on July 1, 1994 (59 FR 34270), and based on our
implementation of the OMB Final Information Quality Bulletin for Peer
Review, dated December 16, 2004. Peer reviewers were chosen based upon
their ability to provide independent review, their standing as experts
in their respective disciplines as demonstrated through publication of
articles in peer reviewed or referred journals, and their stature
promoting an international cross-section of views. Please see ``Peer
Review'' section above for additional discussion.
Peer review comments are available to the public and have been
posted on the Service's web site at: http://alaska.fws.gov/fisheries/
mmm/polarbear/issues.htm. In addition to peer review comments, the
Service also provides an open public comment process to ensure in part
that any potential issues of bias are specifically identified to allow
for the issue to be evaluated for merit. In our analysis of peer review
and public comments we find that peer review comments were objective,
balanced and without bias.
Comment 62: Requests were received for additional public hearings
and extension of the public comment period.
Our response: Procedures for public participation and review in
regard to proposed rules are provided at section 4(b)(5) of the Act, 50
CFR 424, and the Administrative Procedure Act (5 U.S.C. 551 et
seq.)(APA). We are obligated to hold at least one public hearing on a
listing proposal, if requested to do so within 45 days after the
publication of the proposal (16 U.S.C. 1533(b)(5)(E)). As described
above, in response to requests from the public, we held three public
hearings. We were not able to hold a public hearing that could be
easily accessed by each and every requester, as we received comments
from throughout the United States and many other countries. We accepted
and considered oral comments given at the public hearings, and we
incorporated those comments into the administrative record for this
action. In making our decision on the proposed rule, we gave written
comments the same weight as oral comments presented at hearings.
Furthermore, our regulations require a 60-day comment period on
proposed rules (50 CFR 424.16(c)(2)), but the initial public comment
period on the proposed rule to list the polar bear was open from
January 9 to April 9, 2007, encompassing approximately 90 days. The
comment period was reopened for comments on new scientific information
from September 20 through October 22, 2007, an extra 32 days. We
believe the original 90-day comment period, three public hearings, and
second public comment period provided ample opportunity for public
comment, as intended under the Act, our regulations, and the APA.
Comment 63: The Service's conclusion that this regulatory action
does not constitute a significant energy action and that preparation of
a ``Statement of Energy Effects'' is not required is flawed.
Our response: In 1982, the Act was amended by the United States
Congress to clarify that listing and delisting determinations are to be
based on the best scientific and commercial data available (Pub. L. 97-
304, 96 Stat. 1411) to clarify that the determination was intended to
be a biological decision and made without reference to economic or
other non-biological factors. The specific language from the
accompanying House Report (No. 97-567) stated, ``The principal purpose
of the amendments to Section 4 is to ensure that decisions pertaining
to the listing and delisting of species are based solely upon
biological criteria and to prevent non-biological considerations from
affecting such decisions.'' Further as noted in another U.S. House of
Representatives Report, economic considerations have no relevance to
determinations regarding the status of the species and the economic
analysis requirements of Executive Order 12291, and such statutes as
the Regulatory Flexibility Act and Paperwork Reduction Act, will not
apply to any phase of the listing process.'' (H.R. Rep. No 835, 97th
Cong., Sess. 19 (1982)). On the basis of the amendments to the Act put
forth by Congress in 1982 and Congressional intent as evidenced in the
quotation above, we have determined that the provisions of Executive
Order 13211 ``Actions Concerning Regulations That Significantly Affect
Energy Supply, Distribution, or Use'' (66 FR 28355), do not apply to
listing and delisting determinations under section 4 of the Act because
of their economic basis. Therefore, Executive Order 13211 does not
apply to this determination to list the polar bear as threatened
throughout its range.
Comment 64: There is insufficient information to proceed with a
listing, and thus our proposal was arbitrary and capricious.
Our response: Under the APA, a court may set aside an agency
rulemaking if found to be, among other things, ``arbitrary, capricious,
an abuse of discretion, or otherwise not in accordance with law'' (5
U.S.C. 706(2)(A)). The Endangered Species Act
[[Page 28251]]
requires that listing decisions be based solely on the best scientific
and commercial information available. We have used the best available
scientific information throughout our analysis, and have taken a number
of steps-as required by the Act and its implementing regulations, the
APA, and our peer review policy--to ensure that our analysis of the
available information was balanced and objective. The evaluation of
information contained within the final rule and all other related
documents (e.g., the Status Review (Schliebe et al. 2006a) is a result
of multiple levels of review and validation of information. We sought
peer review and public comment, and incorporated all additional
information received through these processes, where applicable. These
steps were transparent and made available to the public for inspection,
review, and comment. We have determined that the best available
scientific and commercial information is sufficient to find that the
polar bear meets the definition of a threatened species under the Act.
Comment 65: The Service did not comply with the Information Quality
Act and with the Service's Information Quality Guidelines.
Our response: The Information Quality Act requires Federal agencies
to ensure the quality, objectivity, utility, and integrity of the
information they disseminate. ``Utility'' refers to the usefulness of
the information to its intended users, and ``integrity'' pertains to
the protection of the information from unauthorized access or revision.
According to OMB guidelines (67 FR 8452), technical information that
has been subjected to formal, independent, external peer review, as is
performed by scientific journals, is presumed to be of acceptable
objectivity. Literature used in the proposed rule was considered the
best available peer-reviewed literature at the time. In addition, our
proposed rule was peer-reviewed by 14 experts in the field of polar
bear biology and climatology. In instances where information used in
the proposed rule has become outdated, this final rule has been revised
to reflect the most current scientific information. Despite being peer-
reviewed, most scientific information has some limitations and
statements of absolute certainty are not possible. In this rule, and in
accordance with our responsibilities under the Act, we sought to
provide a balanced analysis by considering all available information
relevant to the status of polar bears and potential impacts of climate
change and by acknowledging and considering the limitations of the
information that provided the basis for our analysis and decision-
making (see ``Summary of Factors Affecting the Polar Bear'' and ``Issue
5: Climate Change'' for more information).
Comment 66: National Environmental Policy Act (NEPA) compliance is
lacking, and an Environmental Impact Statement is needed as this is a
significant Federal action.
Our response: The rule is exempt from NEPA procedures. In 1983,
upon recommendation of the Council on Environmental Quality, the
Service determined that NEPA documents are not required for regulations
adopted pursuant to section 4(a) of the Act. A notice outlining the
Service's reasons for this determination was published in the Federal
Register on October 25, 1983 (48 FR 49244). A listing rule provides the
appropriate and necessary prohibitions and authorizations for a species
that has been determined to be threatened under section 4(a) of the
Act. The opportunity for public comments-one of the goals of NEPA-is
also already provided through section 4 rulemaking procedures. This
determination was upheld in Pacific Legal Foundation v. Andrus, 657
F.2d 829 (6th Cir. 1981).
Comment 67: The Service should fulfill its requirement to have
regular and meaningful consultation and collaboration with Alaska
Native organizations in the development of this Federal action.
Our response: As detailed in the preamble to this section of the
final rule, we actively engaged in government-to-government
consultation with Alaska Native Tribes in accordance with E.O. 13175
and Secretarial Order 3225. Since 1997, the Service has worked closely
with the Alaska Nanuuq Commission (Commission) on polar bear management
and conservation for subsistence purposes. Not only was the Commission
kept fully informed throughout the development of the proposed rule,
but that organization was asked to serve as a peer reviewer of the
Status Review (Schliebe et al. 2006a) and the proposed rule (72 FR
1064). Following publication of the proposed rule, the Service actively
solicited comments from Alaska Natives living within the range of the
polar bear. We received comments on the proposed rule from seven tribal
associations. We held a public hearing in Barrow, Alaska, to enable
Alaska Natives to provide oral comment. We invited the 15 villages in
the Commission to participate in the hearing, and we offered the
opportunity to provide oral comment via teleconference. Thus, we
believe we have fulfilled our requirement to have regular and
meaningful consultation and collaboration with Alaska Native
organizations in the development of this final rule.
Comment 68: An Initial Regulatory Flexibility Analysis (IRFA)
should be completed prior to the publication of a final rule.
Our response: Under the Regulatory Flexibility Act (5 U.S.C. 601 et
seq., as amended by the Small Business Regulatory Enforcement Fairness
Act (SBREFA) of 1996), an IRFA is prepared in order to describe the
effects of a rule on small entities (small businesses, small
organizations, and small government jurisdictions). An IRFA is not
prepared in a listing decision because we consider only the best
available scientific information and do not consider economic impacts
(please see response to Comment 70 for additional discussion).
Comment 69: Some commenters stated that the Service should
designate critical habitat concurrent with this rulemaking; however,
several other commenters disagreed.
Our response: Section 4(a)(3) of the Act requires that, to the
maximum extent prudent and determinable, the Secretary designate
critical habitat at the time the species is listed. Accordingly, we are
not able to forego the process of designating critical habitat when
doing so is prudent and critical habitat is determinable. Service
regulations (50 CFR 424.12(a)) state that critical habitat is not
determinable if information sufficient to perform required analyses of
the impacts of designation is lacking or if the biological needs of the
species are not sufficiently well known to permit identification of an
area as critical habitat. Given the complexity and degree of
uncertainty at this time as to which specific areas in Alaska might be
essential to the conservation of the polar bear in the long-term under
rapidly changing environmental conditions, we have determined that we
will need additional time to conduct a thorough evaluation and peer
review of a potential critical habitat designation. Thus, we are not
publishing a proposed designation of critical habitat concurrently with
this final listing rule, but we intend to publish a proposed
designation in the very near future. Please see the ``Critical
Habitat'' section below for further discussion.
Issue 9: Impacts of Listing
Comment 70: Several comments highlighted potential impacts of
listing, such as economic consequences, additional regulatory burden,
and conservation benefits. Other commenters noted that economic factors
cannot be taken into consideration at this stage of the listing.
[[Page 28252]]
Our response: Under section 4(b)(1)(A) of the Act, we must base a
listing decision solely on the best scientific and commercial data
available. The legislative history of this provision clearly states the
intent of Congress to ensure that listing decisions are ``* * * based
solely on biological criteria and to prevent non-biological criteria
from affecting such decisions * * *'' (see reponse to Comment PR8 for
more details). Therefore, we did not consider the economic impacts of
listing the polar bear. In our Notice of Interagency Cooperative Policy
of Endangered Species Act Section 9 Prohibitions (59 FR 34272), we
stated our policy to identify, to the extent known at the time a
species is listed, specific activities that will not be considered
likely to result in violation of section 9 of the Act. In accordance
with that policy, we have published in this final rule a list of
activities we believe will not result in violation of section 9 of the
Act (see ``Available Conservation Measures'' section of this rule for
further discussion). However, because the polar bear is listed as a
threatened species and the provisions of section 4(d) of the Act
authorize the Service to implement, by regulation, those measures
included in section 9 of the Act that are deemed necessary and
advisable to provide for the conservation of the species, please
consult the special rule for the polar bear that is published in
today's edition of the Federal Register for all of the prohibitions and
exceptions that apply to this threatened species.
Comment 71: Several comments were received pertaining to the
effectiveness of listing the polar bear under the Act, specifically
whether listing would or would not contribute to the conservation of
the species.
Our response: The potential efficacy of a listing action to
conserve a species cannot be considered in making the listing decision.
The Service must make its determination based on a consideration of the
factors affecting the species, utilizing only the best scientific and
commercial information available and is not able to consider other
factors or impacts (see response to Comment 70 for additional
discussion). Listing recognizes the status of the species and invokes
the protection and considerations under the Act, including regulatory
provisions, consideration of Federal activities that may affect the
polar bear, potential critical habitat designation. The Service will
also develop a recovery plan and a rangewide conservation strategy.
Please see the responses to comments under ``Issue 10: Recovery'' as
well as the ``Available Conservation Measures'' section of this rule
for further discussion.
Comment 72: Listing under the Act may result in additional
regulation of industry and development activities in the Arctic. A
discussion of incidental take authorization should be included in the
listing rule. Some comments reflected concern regarding the perceived
economic implications of regulatory and administrative requirements
stemming from listing.
Our response: Section 7(a)(2) of the Act, as amended, requires
Federal agencies to consult with the Service to ensure that the actions
they authorize, fund, or carry out are not likely to jeopardize the
continued existence of listed species. Informal consultation provides
an opportunity for the action agency and the Service to explore ways to
modify the action to reduce or avoid adverse effects to the listed
species or designated critical habitat. In the event that adverse
effects are unavoidable, formal consultation is required. Formal
consultation is a process in which the Service determines if the action
will result in incidental take of individuals, assesses the action's
potential to jeopardize the continued existence of the species, and
develops an incidental take statement. Formal consultation concludes
when the Service issues a biological opinion, including any mandatory
measures prescribed to reduce the amount or extent of incidental take
of the action. In the case of marine mammals, the Service must also
ensure compliance with regulations promulgated under section 101(a)(5)
of the MMPA. Authorization of incidental take under the MMPA is
discussed under Factor D. Actions that are already subject to section 7
consultation requirements in the Arctic, some of which may involve the
polar bear, include, but are not limited to: Refuge operations and
research permits; U.S. Army Corps of Engineers and Environmental
Protection Agency permitting actions under the Clean Water Act and
Clean Air Act; Bureau of Land Management land-use planning and
management activities including onshore oil and gas leasing activities;
Minerals Management Service administration of offshore oil and gas
leasing activities; and Denali Commission funding of fueling and power
generation projects.
Issue 10: Recovery
Comment 73: Several comments identified additional research needs
related to polar bears, their prey, indigenous people, climate, and
anthropogenic and cumulative effects on polar bears. Some specific
recommendations include increased research and continued monitoring of
polar bear populations and their prey, monitoring of polar bear
harvest, and development of more comprehensive climate change models.
Our response: We agree that additional research would benefit the
conservation of the polar bear. The Service will continue to work with
the USGS, the State of Alaska, the IUCN/PBSG, independent scientists,
indigenous people, and other interested parties to conduct research and
monitoring on Alaska's shared polar bear populations. While the Service
does not have appropriate resources or management responsibility for
conducting climate research, we have and will continue to work with
climatologists and experts from USGS, NASA, and NOAA to address polar
bear-climate related issues. Furthermore, we will consider appropriate
research and monitoring recommendations received from the public in the
development of a rangewide conservation strategy.
Comment 74: Several commenters provided recommendations for
recovery actions, to be considered both in addition to and in lieu of
listing. Other commenters cited the need for immediate recovery
planning and implementation upon completion of a final listing rule.
Our response: As discussed throughout this final rule, the Service
has been working with Range countries on conservation actions for the
polar bears for a number of years. Due to the significant threats to
the polar bear's habitat, however, it is our determination that the
polar bear meets the definition of a threatened species under the Act
and requires listing. With completion of this final listing rule, the
Service will continue and expand coordination with the Range countries
regarding other appropriate international initiatives that would assist
in the development of a rangewide conservation strategy. However, it
must be recognized that the threats to the polar bear's habitat may
only be addressed on a global level. Recovery planning under section
4(f) of the Act will be limited to areas under U.S. jurisdiction, since
the preparation of a formal recovery plan would not promote the
conservation of polar bears in foreign countries that are not subject
to the implementation schedules and recovery goals established in such
a plan. However, the Service will use its section 8 authorities to
carry out conservation measures for polar bears in cooperation with
foreign countries.
[[Page 28253]]
Summary of Factors Affecting the Polar Bear
Section 4 of the Act (16 U.S.C. 1533), and implementing regulations
at 50 CFR part 424, set forth procedures for adding species to the
Federal Lists of Endangered and Threatened Wildlife and Plants. Under
section 4(a) of the Act, we may list a species on the basis of any of
five factors, as follows: (A) The present or threatened destruction,
modification, or curtailment of its habitat or range; (B)
overutilization for commercial, recreational, scientific, or
educational purposes; (C) disease or predation; (D) the inadequacy of
existing regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence. In making this finding, the best
scientific and commercial information available regarding the status
and trends of the polar bear is considered in relation to the five
factors provided in section 4(a)(1) of the Act.
In the context of the Act, the term ``endangered species'' means
any species or subspecies or, for vertebrates, Distinct Population
Segment (DPS), that is in danger of extinction throughout all or a
significant portion of its range, and a ``threatened species'' is any
species that is likely to become an endangered species within the
foreseeable future. The Act does not define the term ``foreseeable
future.'' For this final rule, we have identified 45 years as the
foreseeable future for polar bears; our rationale for selecting this
timeframe is presented in the following section.
Foreseeable Future
For this final rule, we have determined the ``foreseeable future''
in terms of the timeframe over which the best available scientific data
allow us to reliably assess the effects of threats on the polar bear.
The principal threat to polar bears is the loss of their primary
habitat-sea ice. The linkage between habitat loss and corresponding
effects on polar bear populations was hypothesized in the past (Budyko
1966, p. 20; Lentfer 1972, p. 169; Tynan and DeMaster 1997, p. 315;
Stirling and Derocher 1993, pp. 241-244; Derocher et al. 2004, p. 163),
but is now becoming well established through long-term field studies
that span multiple generations (Stirling et al. 1999, pp. 300-302;
Stirling and Parkinson 2006, pp. 266-274; Regehr et al. 2006; Regehr et
al. 2007a, 2007b; Rode et al. 2007, pp. 5-8; Hunter et al. 2007, pp. 8-
14; Amstrup et al. 2007).
The timeframe over which the best available scientific data allows
us to reliably assess the effect of threats on the species is the
critical component for determining the foreseeable future. In the case
of the polar bear, the key threat is loss of sea ice, the species'
primary habitat. Sea ice is rapidly diminishing throughout the Arctic,
and the best available evidence is that Arctic sea ice will continue to
be affected by climate change. Recent comprehensive syntheses of
climate change information (e.g., IPCC AR4) and additional modeling
studies (e.g., Overland and Wang 2007a, pp. 1-7; Stroeve et al. 2007,
pp. 1-5) show that, in general, the climate models that best simulate
Arctic conditions all project significant losses of sea ice over the
21st century. A key issue in determining what timeframe to use for the
foreseeable future has to do with the uncertainty associated with
climate model projections at various points in the future. Virtually
all of the climate model projections in the AR4 and other studies
extend to the end of the 21st century, so we considered whether a
longer timeframe for the foreseeable future was appropriate. The AR4
and other studies help clarify the scientific uncertainty associated
with climate change projections, and allow us to make a more objective
decision related to the timeframe over which we can reliably assess
threats.
Available information indicates that climate change projections
over the next 40-50 years are more reliable than projections over the
next 80-90 years. This is illustrated in Figure 5 above. Examination of
the trend lines for temperature using the three emissions scenarios, as
shown in Figure 5, illustrates that temperature increases over the next
40-50 years are relatively insensitive to the SRES emissions scenario
used to model the projected change (i.e., the lines in Figure 5 are
very close to one another for the first 40-50 years). The ``limited
sensitivity'' of the results is because the state-of-the-art climate
models used in the AR4 have known physics connecting increases in GHGs
to temperature increases through radiation processes (Overland and Wang
2007a, pp. 1-7, cited in J. Overland, NOAA, in litt. to the Service,
2007), and the GHG levels used in the SRES emissions scenarios follow
similar trends until around 2040-2050. Because increases in GHGs have
lag effects on climate and projections of GHG emissions can be
extrapolated with greater confidence over the next few decades, model
results projecting out for the next 40-50 years (near-term climate
change estimates) have greater credibility than results projected much
further into the future (long-term climate change) (J. Overland, NOAA,
in litt. to the Service, 2007). Thus, the uncertainty associated with
emissions is relatively smaller for the 45-year ``foreseeable future''
for the polar bear listing. After 2050, greater uncertainty associated
with various climate mechanisms, including the carbon cycle, is
reflected in the increasingly larger confidence intervals around
temperature trend lines for each of the SRES emissions scenarios (see
Figure 5). In addition, beyond 40-50 years, the trend lines diverge
from one another due to differences among the SRES emissions scenarios.
These SRES scenarios diverge because each makes different assumptions
about the effects that population growth, potential technological
improvements, societal and regulatory changes, and economic growth have
on GHG emissions, and those differences are more pronounced after 2050.
The divergence in the lines beyond 2050 is another source of
uncertainty in that there is less confidence in what changes might take
place to affect GHG emissions beyond 40-50 years from now.
The IPCC AR4 reaches a similar conclusion about the reliability of
projection results over the short term (40-50 years) versus results
over the long term (80-90 years) (IPCC 2007, p. 749) in discussing
projected changes in surface air temperatures (SATs):
``There is close agreement of globally averaged SAT multi-model
mean warming for the early 21st century for concentrations derived
from the three non-mitigated IPCC Special Report on Emission
Scenarios (SRES: B1, A1B and A2) scenarios (including only
anthropogenic forcing) run by the AOGCMs * * * this warming rate is
affected little by different scenario assumptions or different model
sensitivities, and is consistent with that observed for the past few
decades * * *. Possible future variations in natural forcings (e.g.,
a large volcanic eruption) could change those values somewhat, but
about half of the early 21st-century warming is committed in the
sense that it would occur even if atmospheric concentrations were
held fixed at year 2000 values. By mid-century (2046-2065), the
choice of scenario becomes more important for the magnitude of
multi-model globally averaged SAT warming * * *. About a third of
that warming is projected to be due to climate change that is
already committed. By late century (2090-2099), differences between
scenarios are large, and only about 20% of that warming arises from
climate change that is already committed.''
On the basis of our analysis, reinforced by conclusions of the IPCC
AR4, we have determined that climate changes projected within the next
40-50 years are more reliable than projections for the second half of
the 21st century.
The 40-50 year timeframe for a reliable projection of threats to
habitat corresponds closely to the timeframe of
[[Page 28254]]
three polar bear generations (45 years), as determined by the method
described in the following paragraph. Long-term studies have
demonstrated, and world experts (e.g., PBSG) are in agreement, that
three generations is an appropriate timespan to use to reliably assess
the status of the polar bear and the effects of threats on population-
level parameters (e.g., body condition indices, vital rates, and
population numbers). This is based on the life history of the polar
bear, the large natural variability associated with polar bear
population processes, and the capacity of the species for ecological
and behavioral adaptation (Schliebe et al. 2006a, pp. 59-60). Although
not relied on as the basis for determining ``foreseeable future'' in
this rule, the correspondence of this timeframe with important
biological considerations provides greater confidence for this listing
determination.
Polar bears are long-lived mammals, and adults typically have high
survival rates. Both sexes can live 20 to 25 years (Stirling and
Derocher 2007), but few polar bears in the wild live to be older than
20 years (Stirling 1988, p. 139; Stirling 1990, p. 225). Due to
extremely low reproductive rates, polar bears require a high survival
rate to maintain population levels. Survival rates increase up to a
certain age, with cubs-of-the-year having the lowest rates and prime
age adults (between 5 and 20 years of age) having survival rates that
can exceed 90 percent. Generation length is the average age of parents
of the current cohort; generation length therefore reflects the
turnover rate of breeding individuals in a population. We adapted the
criteria of the IUCN Red List process (IUCN 2004) for determining polar
bear generation time in both the proposed rule (72 FR 1064) and this
final rule. A generation span, as defined by IUCN, is calculated as the
age of sexual maturity (5 years for polar bears) plus 50 percent of the
length of the lifetime reproductive period (20 years for polar bears).
The IUCN Red List process also uses a three-generation timeframe ``to
scale the decline threshold for the species'' life history'' (IUCN
2004), recognizing that a maximum time cap is needed for assessments
based on projections into the future because ``the distant future
cannot be predicted with enough certainty to justify its use'' in
determining whether a species is threatened or endangered. Based on
these criteria, the length of one generation for the polar bear is 15
years, and, thus, three generations are 45 years.
The appropriate timeframe for assessing the effects of threats on
polar bear population status must be determined on the basis of an
assessment of the reliability of available biological and threat
information at each step. For polar bear, the reliability of biological
information and, therefore, population status projections, increases if
a multigenerational analysis is used. In general, the reliability of
information and projections increases with time, until a point when
reliability begins to decline again due to uncertainty in projecting
threats and corresponding responses by polar bear populations (S.
Schliebe, pers. comm., 2008). This decline in reliability depends on
the level of uncertainty associated with projected threats and their
relationship to the population dynamics of the species. With polar
bears, we expect the reliability of population status projections to
diminish around 4-5 generations. Thus, 3 generations is the
optimal timeframe to reliably assess the status of the polar bear
response to population-level threats. This progression can be
illustrated by results from studies of the Western Hudson Bay polar
bear population.
In western Hudson Bay, break-up of the annual sea ice now occurs
approximately 2.5 weeks earlier than it did 30 years ago (see
discussion of ``Western Hudson Bay'' population under Factor A and
Stirling and Parkinson 2006, p. 265). Stirling and colleagues measured
mean estimated mass of lone adult female polar bears from 1980 through
2004, and determined that their average weight declined by about 65 kg
(143 lbs) over that period. Stirling and Parkinson (2006, p. 266)
project that cub production could cease in 20 to 30 years if climate
trends continue as projected by the IPCC. The overall timeframe covered
by this scenario is 45-55 years, which is within the 3
generation timeframe. In addition, Regehr et al. (2007a, p. 2,673)
analyzed population trend data for 1987 through 2004 and documented a
long-term, gradual decline in population size that is anticipated to
continue into the future. These two lines of evidence indicate that the
species will likely be in danger of extinction within the next 45
years. Beyond that timeframe, the population trend and threats
information are too uncertain to reliably project the status of the
species.
In summary, we considered the timeframe over which the best
available scientific data allow us to reliably assess the effect of
threats on the polar bear, and determined that there is substantial
scientific reliability associated with climate model projections of sea
ice change over the next 40-50 years. Confidence limits are much closer
(i.e., more certain) for projections of the next 40-50 years and all
projections agree that sea ice will continue to decrease. In
comparison, periods beyond 50 years exhibit wider confidence limits,
although all trends continue to express warming and loss of sea ice
(IPCC 2007, p. 749; Overland and Wang 2007a, pp. 1-7; Stroeve et al.
2007, pp. 1-5). This timespan compares well with the 3-generation (45-
year) timeframe over which we can reliably evaluate the effects of
environmental change on polar bear life history and population
parameters. Therefore, we believe that a 45-year foreseeable future is
a reasonable and objective timeframe for analysis of whether polar
bears are likely to become endangered.
This 45-year timeframe for assessing the status of the species is
consistent with the work of the PBSG in reassessing the status of polar
bears globally in June 2005 (Aars et al. 2006, p. 31) for purposes of
IUCN Red List classification. More than 40 technical experts were
involved in the PBSG review (including polar bear experts from the
range countries and other invited polar bear specialists), and these
PBSG technical experts supported the definition of a polar bear
generation as 15 years, and the application of three generations as the
appropriate timeframe over which to evaluate polar bear population
trends for the purposes of IUCN Red List categorization. Although the
Red List process is not the same as our evaluation for listing a
species under the Act, the basic rationale for determining generation
length and timeframe for analysis of threats is similar in both. None
of the experts raised an issue with the 45-year timeframe for analysis
of population trends.
In addition, when seeking peer review of both the Status Review
(Schliebe et al. 2006a) and the proposed rule to list the polar bear as
threatened (72 FR 1064), we specifically asked peer reviewers to
comment on the 45-year foreseeable future and the method we used to
derive that timeframe. All reviewers that commented on this subject
indicated that a 45-year timeframe for the foreseeable future was
appropriate, with the exception of one reviewer who thought the
foreseeable future should be 100 years. Thus, both the independent
reviews by PBSG and the input from peer reviewers corroborate our final
decision and our rationale for using 45 years as the foreseeable future
for the polar bear.
[[Page 28255]]
Our evaluation of the five factors with respect to polar bear
populations is presented below. We considered all relevant available
scientific and commercial information under each of the listing factors
in the context of the present-day distribution of the polar bear.
Factor A. Present or Threatened Destruction, Modification, or
Curtailment of the Polar Bear's Habitat or Range
Introduction
As described in detail in the ``Species Biology'' section of this
rule, polar bears are evolutionarily adapted to life on sea ice
(Stirling 1988, p. 24; Amstrup 2003, p. 587). They need sea ice as a
platform for hunting, for seasonal movements, for travel to terrestrial
denning areas, for resting, and for mating (Stirling and Derocher 1993,
p. 241). Moore and Huntington (in press) classify polar bears as an
``ice-obligate'' species because of their reliance on sea ice as a
platform for resting, breeding, and hunting. Laidre et al. (in press)
similarly describe the polar bear as a species that principally relies
on annual sea ice over the continental shelf and areas toward the
southern extent of the edge of sea ice for foraging. Some polar bears
use terrestrial habitats seasonally (e.g., for denning or for resting
during open water periods). Open water by itself is not considered to
be a habitat type frequently used by polar bears, because life
functions such as feeding, reproduction, or resting do not occur in
open water. However, open water is a fundamental part of the marine
system that supports seal species, the principal prey of polar bears,
and seasonally refreezes to form the ice needed by the bears (see
``Open Water Habitat'' section for more information). In addition, the
extent of open water is important because vast areas of open water may
limit a bear's ability to access sea ice or land (see ``Open Water
Swimming'' section for more detail). Snow cover, both on land and on
sea ice, is an important component of polar bear habitat in that it
provides insulation and cover for young polar bears and ringed seals in
snow dens or lairs on sea ice (see ``Maternal Denning Habitat'' section
for more detail).
Previous Warming Periods and Polar Bears
Genetic evidence indicates that polar bears diverged from grizzly
bears between 200,000-400,000 years ago (Talbot and Shields 1996a, p.
490; Talbot and Shields 1996b, p. 574); however, polar bears do not
appear in the fossil record until the Last Interglacial Period (LIG)
(115,000-140,000 years ago) (Kurten 1964, p. 25; Ingolfsson and Wiig
2007). Depending on the exact timing of their divergence, polar bears
may have experienced several periods of climatic warming, including a
period 115,000-140,000 years ago, a period of warming 4,000-12,000
years ago (Holocene Thermal Maximum), and most recently during medieval
times (800 to 1200 A.D.). During these periods there is evidence
suggesting that regional air temperatures were higher than present day
and that sea ice and glacial ice were significantly reduced
(Circumpolar Arctic PaleoEnvironments (CAPE) 2006, p. 1394; Jansen et
al. 2007, p. 435, 468). This section considers historical information
available on polar bears and the environmental conditions during these
warming periods.
During the LIG (115,000-140,000 years ago), some regions of the
world including parts of the Arctic experienced warmer than present day
temperatures as well as greatly reduced sea ice in some areas,
including what is now coastal Alaska and Greenland (Jansen et al. 2007,
p. 453). CAPE (2006, p.1393) concludes that all sectors of the Arctic
were warmer than present during the LIG, but that the magnitude of
warming was not uniform across all regions of the Arctic. Summer
temperature anomalies at lower Northern Hemisphere latitudes below the
Arctic were not as pronounced as those at higher latitudes but still
are estimated to have ranged from 0-2 degrees C above present (CAPE
2006, p. 1394). Furthermore, according to the IPCC, while the average
temperature when considered globally during the LIG was not notably
higher than present day, the rate of warming averaged 10 times slower
than the rate of warming during the 20th century (Jansen et al. 2007,
p. 453). However, the rate at which change occurred may have been more
rapid regionally, particularly in the Arctic (CAPE 2006, p. 1394).
While the specific responses of polar bears to regional changes in
climate during the LIG are not known, they may have survived regional
warming events by altering their distribution and/or retracting their
range. Similar range retraction is projected for polar bears in the
21st century (Durner et al. 2007). However, the slower rate of climate
change and more regional scale of change during the LIG suggest that
polar bears had more opportunity to adapt during this time in
comparison to the current observed and projected relatively rapid,
global climate change (Jansen et al. 2007, p. 776; Lemke et al. 2007,
p. 351).
The HTM 4,000-12,000 years ago also appears to have affected
climate Arctic-wide, though summer temperature anomalies were lower
than those that occurred during the LIG (CAPE 2006, p. 1394). Kaufman
et al. (2003, p. 545) report that mean surface temperatures during the
HTM were 1.6 0.8 degrees C (range: 0.5-3 degrees C) higher
in terrestrial habitats and 3.8 1.9 degrees C at marine
sites than present-day temperatures at 120 sites throughout the western
Arctic (Northeast Russia to Iceland, including all of North America).
Furthermore, Birks and Amman (2000, pp. 1,392-1,393) provide evidence
that change in some areas may have been rapid, including an increase of
0.2-0.3 degrees C per 25 years in Norway and Switzerland. However, the
timing of warming across the Arctic was not uniform, with Alaska and
northwest Canada experiencing peak warming 4,000 years prior to
northeast Canada (Kaufman et al. 2004, p. 529). Thus while regional
changes in temperature are believed to have occurred, the IPCC
concluded that annual global mean temperatures were not warmer than
present day any time during the Holocene (Jansen et al. 2007, p. 465).
While polar bears did experience warmer temperatures in their range
during this time, the regional nature of warming that occurred may have
aided their survival through this period in certain areas. However, the
degree to which polar bears may have been impacted either regionally or
Arctic-wide is unknown.
The most recent period of warming occurred during the Medieval
period (generally considered to be the period from 950 to 1300 AD).
This episode again appears to have been regional rather than global
(Broecker 2001, p. 1,497; Jansen et al. 2007, p. 469); additionally,
temperatures during this period are estimated to be 0.1-0.2 degrees C
below the 1961 to 1990 mean and significantly below the instrumental
data after 1980 (Jansen et al. 2007, p. 469). Thus, temperatures and
rate of change estimated for this time period do not appear comparable
to present day conditions.
Unfortunately, the limited scientific evidence currently available
to us for these time periods does limit our ability to assess how polar
bears responded to previous warming events. For example, while genetic
analyses can be useful for identifying significant reductions in
population size throughout a species' history (Hedrick 1996, p. 897;
Driscoll et al. 2002, p. 414), most genetic studies of polar bears have
focused on analyzing
[[Page 28256]]
variation in micro-satellite DNA for the purposes of differentiating
populations (i.e., identifying genetic structure; Paetkau et al. 1995,
p. 347; Paetkau et al. 1999, p. 1,571; Cronin et al. 2006, p. 655).
Additionally, genetic analyses for the purpose of identifying
population bottlenecks require accurate quantification of mutation
rates to determine how far back in time an event can be detected and a
combination of mitochondrial and nuclear DNA analyses to eliminate
potential alternative factors, other than a population bottleneck, that
might result in or counteract low genetic variation (Driscoll et al.
2002, pp. 420-421; Hedrick 1996, p. 898; Nystrom et al. 2006, p. 84).
The results of micro-satellite studies for polar bears have documented
that within-population genetic variation is similar to black and
grizzly bears (Amstrup 2003, p. 590), but that among populations,
genetic structuring or diversity is low (Paetkau et al. 1995, p. 347;
Cronin et al. 2006, pp. 658-659). The latter has been attributed with
extensive population mixing associated with large home ranges and
movement patterns, as well as the more recent divergence of polar bears
in comparison to grizzly and black bears (Talbot and Shields 1996a, p.
490; Talbot and Shields 1996b, p. 574; Paetkau et al. 1999, p. 1,580).
Inferring whether the degree of genetic variation from these studies is
indicative of a population bottleneck, however, requires additional
analyses that have yet to be conducted. Furthermore, the very limited
fossil record of polar bears sheds little light on possible population-
level responses of polar bears to previous warming events (Derocher et
al. 2004, p. 163).
Thus, while polar bears as a species have survived at least one
period of regional warming greater than present day, it is important to
recognize that the degree that they were impacted is not known and
there are differences between the circumstances surrounding historical
periods of climate change and present day. First, the IPCC concludes
that the current rate of global climate change is much more rapid and
very unusual in the context of past changes (Jansen et al. 2007, p.
465). Although large variation in regional climate has been documented
in the past 200,000 years, there is no evidence that mean global
temperature increased at a faster rate than present warming (Jansen et
al. 2007, p. 465), nor is there evidence that these changes occurred at
the same time across regions. Furthermore, projected rates of future
global change are much greater than rates of global temperature
increase during the past 50 million years (Jansen et al. 2007, p. 465).
Derocher et al. (2004, p. 163, 172) suggest that this rate of change
will limit the ability of polar bears to respond and survive in large
numbers. Secondly, polar bears today experience multiple stressors that
were not present during historical warming periods. As explained
further under Factors B, C, and E, polar bears today contend with
harvest, contaminants, oil and gas development, and additional
interactions with humans (Derocher et al. 2004, p. 172) that they did
not experience in previous warming periods, whereas during the HTM,
humans had just begun to colonize North America. Thus, both the
cumulative effects of multiple stressors and the rapid rate of climate
change today create a unique and unprecedented challenge for present-
day polar bears in comparison to historical warming events.
Effects of Sea Ice Habitat Change on Polar Bears
Observed and predicted changes in sea ice cover, characteristics,
and timing have profound effects on polar bears (Derocher and Stirling
1996, p. 1,250; Stirling et al. 1999, p. 294; Stirling and Parkinson
2006, p. 261; Regehr et al. 2007b, p. 18). As noted above, sea ice is a
highly dynamic habitat with different types, forms, stages, and
distributions that all operate as a complex matrix in determining
biological productivity and use by marine organisms, including polar
bears and their primary prey base, ice seal species. Polar bear use of
sea ice is not uniform. Their preferred habitat is the annual ice
located over the continental shelf and inter-island archipelagos that
circle the Arctic basin. Ice seal species demonstrate a similar
preference for these ice habitats.
In the Arctic, Hudson Bay, Canada has experienced some of the
earliest ice changes due to its southerly location on a divide between
a warming and a cooling region (Arctic Monitoring Assessment Program
(AMAP) 2003, p. 22), making it an ideal area to study the impacts of
climate change. In addition, Hudson Bay has the most extensive long-
term data on the ecology of polar bears and is the location where the
first evidence of major and ongoing impacts to polar bears from sea ice
changes has been documented. Many researchers over the past 40 years
have predicted an array of impacts to polar bears from climatic change
that include adverse effects on denning, food chain disruption, and
prey availability (Budyko 1966, p. 20; Lentfer 1972, p. 169; Tynan and
DeMaster 1997, p. 315; Stirling and Derocher 1993, pp. 241-244).
Stirling and Derocher (1993, p. 240) first noted changes, such as
declining body condition, lowered reproductive rates, and reduced cub
survival, in polar bears in western Hudson Bay; they attributed these
changes to a changing ice environment. Subsequently, Stirling et al.
(1999, p. 303) established a statistically significant link between
climate change in western Hudson Bay, reduced ice presence, and
observed declines in polar bear physical and reproductive parameters,
including body condition (weight) and natality. More recently Stirling
and Parkinson (2006, p. 266) established a statistically significant
decline in weights of lone and suspected pregnant adult female polar
bears in western Hudson Bay between 1988 and 2004. Reduced body weights
of adult females during fall have been correlated with subsequent
declines in cub survival (Atkinson and Ramsay 1995, p. 559; Derocher
and Stirling 1996, p. 1,250; Derocher and Wiig 2002, p. 347).
Increased Polar Bear Movements
The best scientific data available suggest that polar bears are
inefficient moving on land and expend approximately twice the average
energy than other mammals when walking (Best 1982, p. 63; Hurst 1982,
p. 273). However, further research is needed to better understand the
energy dynamics of this highly mobile species. Studies have shown that,
although sea ice circulation in the Arctic is clockwise, polar bears
tend to walk against this movement to maintain a position near
preferred habitat within large geographical home ranges (Mauritzen et
al. 2003a, p. 111). Currently, ice thickness is diminishing (Rothrock
et al. 2003, p. 3649; Yu et al. 2004) and movement of sea ice out of
the polar region has occurred (Lindsay and Zhang 2005). As the climate
warms, and less multi-year ice is present, we expect to see a decrease
in the export of multi-year ice (e.g., Holland et al. 2006, pp. 1-5).
Increased rate and extent of ice movements will, in turn, require
additional efforts and energy expenditure by polar bears to maintain
their position near preferred habitats (Derocher et al. 2004, p. 167).
This may be an especially important consideration for females
encumbered with small cubs. Ferguson et al. (2001, p. 51) found that
polar bears inhabiting areas of highly dynamic ice had much larger
activity areas and movement rates compared to those bears inhabiting
more stable, persistent ice habitat.
[[Page 28257]]
Although polar bears are capable of living in areas of highly dynamic
ice movement, they show inter-annual fidelity to the general location
of preferred habitat (Mauritzen et al. 2003b, p. 122; Amstrup et al.
2000b, p. 963).
As sea ice becomes more fragmented, polar bears would likely use
more energy to maintain contact with consolidated, higher concentration
ice, because moving through highly fragmented sea ice is more energy-
intensive than walking over consolidated sea ice (Derocher et al. 2004,
p. 167). During summer periods, the remaining ice in much of the
central polar basin is now positioned away from more productive
continental shelf waters and occurs over much deeper, less productive
waters, such as in the Beaufort and Chukchi Seas of Alaska. If the
width of leads or extent of open water increases, the transit time for
bears and the need to swim or to travel will increase (Derocher et al.
2004, p. 167). Derocher et al. (2004, p. 167) suggest that as habitat
patch sizes decrease, available food resources are likely to decline,
resulting in reduced residency time and increased movement rates. The
consequences of increased energetic costs to polar bears from increased
movements are likely to be reduced body weight and condition, and a
corresponding reduction in survival and recruitment rates (Derocher et
al. 2004, p. 167).
Additionally, as movement of sea ice increases and areas of
unconsolidated ice also increase, some bears are likely to lose contact
with the main body of ice and drift into unsuitable habitat from which
it may be difficult to return (Derocher et al. 2004, p. 167). This has
occurred historically in some areas such as Southwest Greenland as a
result of the general drift pattern of sea ice in the area (Vibe 1967)
and also occurs offshore of Newfoundland, Canada (Derocher et al. 2004,
p. 167). Increased frequency of such events could negatively impact
survival rates and contribute to population declines (Derocher et al.
2004, p. 167).
Polar Bear Seasonal Distribution Patterns Within Annual Activity Areas
Increasing temperatures and reductions in sea ice thickness and
extent, coupled with seasonal retraction of sea ice poleward, will
cause redistribution of polar bears seasonally into areas previously
used either irregularly or infrequently. While polar bears have
demonstrated a wide range of space-use patterns within and between
populations, the continued retraction and fragmentation of sea ice
habitats that is projected to occur will alter previous patterns of use
seasonally and regionally. These changes have been documented at an
early onset stage for a number of polar bear populations with the
potential for large-scale shifts in distribution by the end of the 21st
century (Durner et al. 2007, pp. 18-19).
This section provides examples of distribution changes and
interrelated consequences. Recent studies indicate that polar bear
movements and seasonal fidelity to certain habitat areas are changing
and that these changes are strongly correlated to similar changes in
sea ice and the ocean-ice system. Changes in movements and seasonal
distributions can have effects on polar bear nutrition, body condition,
and more significant longer term redistribution. Specifically, in
western Hudson Bay, break-up of the annual sea ice now occurs
approximately 2.5 weeks earlier than it did 30 years ago (Stirling et
al. 1999, p. 299). The earlier spring break-up was highly correlated
with dates that female polar bears came ashore (Stirling et al. 1999,
p. 299). Declining reproductive rates, subadult survival, and body mass
(weights) have occurred because of longer periods of fasting on land as
a result of the progressively earlier break-up of the sea ice and the
increase in spring temperatures (Stirling et al. 1999, p. 304; Derocher
et al. 2004, p. 165).
Stirling et al. (1999, p. 304) cautioned that, although downward
trends in the size of the Western Hudson Bay population had not been
detected, if trends in life history parameters continued downward,
``they will eventually have a detrimental effect on the ability of the
population to sustain itself.'' Subsequently, Parks et al. (2006, p.
1282) evaluated movement patterns of adult female polar bears
satellite-collared from 1991 to 2004 with respect to their body
condition. Reproductive status and variation in ice patterns were
included in the analysis. Parks et al. (2006, p. 1281) found that
movement patterns were not dependent on reproductive status of females
but did change significantly with season. They found that annual
distances moved had decreased in Hudson Bay since 1991. This suggested
that declines in body condition were due to reduced prey consumption as
opposed to increased energy output from movements (Parks et al. 2006,
p. 281). More recently, Regehr et al. (2007a, p. 2,673) substantiated
Stirling et al.'s (1999, p. 304) predictions, noting population
declines in western Hudson Bay during analysis of data from an ongoing
mark-recapture population study. Between 1987 and 2004, the number of
polar bears in the Western Hudson Bay population declined from 1,194 to
935, a reduction of about 22 percent (Regehr et al. 2007a, p. 2,673).
Progressive declines in the condition and survival of cubs, subadults,
and bears 20 years of age and older appear to have been caused by
progressively earlier sea ice break-up, and likely initiated the
decline in population. Once the population began to decline, existing
harvest rates contributed to the reduction in the size of the
population (Regehr et al. 2007a, p. 2,680).
Since 2000, Schliebe et al. (2008) observed increased use of
coastal areas by polar bears during the fall open-water period in the
southern Beaufort Sea. High numbers of bears (a minimum of 120) were
found to be using coastal areas during some years, where prior to the
1990s, according to native hunters, industrial workers, and researchers
operating on the coast at this time of year, such observations of polar
bears were rare. This study period (2000-2005) also included record
minimal sea ice conditions for the month of September in 4 of the 6
survey years. Polar bear density along the mainland coast and on
barrier islands during the fall open water period in the southern
Beaufort Sea was related to distance from pack ice edge and the density
of ringed seals over the continental shelf. The distance between pack
ice edge and the mainland coast, as well as the length of time that
these distances prevailed, was directly related to polar bear density
onshore. As the sea ice retreated and the distance to the edge of the
ice increased, the number of bears near shore increased. Conversely, as
near-shore areas became frozen or sea ice advanced toward shore, the
number of bears near shore decreased (Schliebe et al. 2008). The
presence of subsistence-harvested bowhead whale carcasses and their
relationship to polar bear distribution were also analyzed. These
results suggest that, while seal densities near shore and availability
of bowhead whale carcasses may play a role in polar bear distribution
changes, that sea ice conditions (possibly similar to conditions
observed in western Hudson Bay) are influencing the distribution of
polar bears in the southern Beaufort Sea. They also suggest that
increased polar bear use of coastal areas may continue if the summer
retreat of the sea ice continues into the future as predicted (Serreze
et al. 2000, p. 159; Serreze and Barry 2005).
Others have observed increased numbers of polar bears in novel
habitats. During bowhead whale surveys conducted in the southern
Beaufort Sea during September, Gleason et al. (2006)
[[Page 28258]]
observed a greater number of bears in open water and on land during
surveys in 1997-2005, years when sea ice was often absent from their
study area, compared to surveys conducted between 1979-1996, years when
sea ice was a predominant habitat within their study area. Bears in
open water likely did not select water as a choice habitat, but rather
were swimming in an attempt to reach offshore pack ice or land. Their
observation of a greater number of bears on land during the later
period was concordant with the observations of Schliebe et al. (2008).
Further, the findings of Gleason et al. (2006) coincide with the lack
of pack ice (concentrations of greater than 50 percent) caused by a
retraction of ice in the study area during the latter period (Stroeve
et al. 2005, p. 2; Comiso 2003, p. 3,509; Comiso 2005, p. 52). The
findings of Gleason et al. (2006) confirm an increasing use of coastal
areas by polar bears in the southern Beaufort Sea in recent years and a
decline in ice habitat near shore. The immediate causes for changes in
polar bear distribution are thought to be (1) retraction of pack ice
far to the north for greater periods of time in the fall and (2) later
freeze-up of coastal waters.
Other polar bear populations exhibiting seasonal distribution
changes with larger numbers of bears on shore have been reported.
Stirling and Parkinson (2006, pp. 261-275) provide an analysis of pack
ice and polar bear distribution changes for the Baffin Bay, Davis
Strait, Foxe Basin, and Hudson Bay populations. They indicate that
earlier sea ice break-up will likely result in longer periods of
fasting for polar bears during the extended open-water season. This may
explain why more polar bears have been observed near communities and
hunting camps in recent years. Seasonal distribution changes of polar
bears have been noted during a similar period of time for the northern
coast of Chukotka (Kochnev 2006, p. 162) and on Wrangel Island, Russia
(Kochnev 2006, p. 162; N. Ovsyanikov, Russian Federation Nature
Reserves, pers. comm.). The relationship between the maximum number of
polar bears, the number of dead walruses, and the distance to the ice
edge from Wrangel Island was evaluated. The subsequent results revealed
that the most significant correlation was between bear numbers and
distance to the ice-edge (Kochnev 2006, p. 162), which again supports
the observation that when sea ice retreats far off shore, the numbers
of bears present or stranded on land appears to increase.
In Baffin Bay, traditional Inuit knowledge studies and anecdotal
reports indicate that in many areas greater numbers of bears are being
encountered on land during the summer and fall open-water seasons
(Dowsley 2005, p. 2). Interviews with elders and senior hunters
(Dowsley and Taylor 2005, p. 2) in three communities in Nunavut,
Canada, revealed that most respondents (83 percent) believed that the
population of polar bears had increased. The increase was attributed to
more bears seen near communities, cabins, and camps; hunters also
encountered bear sign (e.g., tracks, scat) in areas not previously used
by bears. Some people interviewed noted that these observations could
reflect a change in bear behavior rather than an increase in
population. Many (62 percent) respondents believed that bears were less
fearful of humans now than 15 years ago. Most (57 percent) respondents
reported bears to be skinnier now, and five people in one community
reported an increase in fighting among bears. Respondents also
discussed climate change, and they indicated that there was more
variability in the sea ice environment in recent years than in the
past. Some respondents indicated a general trend for ice floe edge to
be closer to the shore than in the past, the sea ice to be thinner,
fewer icebergs to be present, and glaciers to be receding. Fewer
grounded icebergs, from which shorefast ice forms and extends, were
thought to be partially responsible for the shift of the ice edge
nearer to shore. Respondents were uncertain if climate change was
affecting polar bears or what form the effects may be taking (Dowsley
2005, p. 1). Also, results from an interview survey of 72 experienced
polar bear hunters in Northwest Greenland in February 2006 indicate
that during the last 10-20 years, polar bears have occurred closer to
the coast. Several of those interviewed believed the change in
distribution represented an increase in the population size (e.g., Kane
Basin and Baffin Bay), although others suggested that it may be an
effect of a decrease in the sea ice (Born et al., in prep).
Recently Vladilen Kavry, former Chair of the Union of Marine Mammal
Hunters of Chukotka, Russia, Polar Bear Commission, conducted a series
of traditional ecological knowledge interviews with indigenous Chukotka
coastal residents regarding their impression of environmental changes
based on their lifetime of observations (Russian Conservation News No.
41 Spring/Summer 2006). The interviewees included 17 men and women
representing different age and ethnic groups (Chukchi, Siberian Yupik,
and Russian) in Chukotka, Russia. Respondents noted that across the
region there was a changing seasonal weather pattern with increased
unpredictability and instability of weather. Respondents noted shorter
winters, observing that the fall-winter transition was occurring later,
and spring weather was arriving earlier. Many described these
differences as resulting in a one-month-later change in the advent of
fall and one-month-earlier advent of spring. One 71-year-old Chukchi
hunter believed that winter was delayed two months and indicated that
the winter frosts that had previously occurred in September were now
taking place in November. He also noted that thunderstorms were more
frequent. Another 64-year-old hunter noted uncharacteristic snow storms
and blizzards as well as wintertime rains. He also noted that access to
sea ice by hunters was now delayed from the normal access date of
November to approximately one month later into December. This
individual also noted that blizzards and weather patterns had changed
and that snow is more abundant and wind patterns caused snow drifts to
occur in locations not previously observed. With increased spring
temperatures, lagoons and rivers are melting earlier. The sea ice
extent has declined and the quality of ice changed. The timing of fall
sea ice freezing is delayed two months into November. The absence of
sea ice in the summer is thought to have caused walrus to use land
haulouts for resting in greater frequency and numbers than in the past.
Stirling and Parkinson (2006, p. 263) evaluated sea ice conditions
and distribution of polar bears in five populations in Canada: Western
Hudson Bay, Eastern Hudson Bay, Baffin Bay, Foxe Basin, and Davis
Strait. Their analysis of satellite imagery beginning in the 1970s
indicates that the sea ice is breaking up at progressively earlier
dates, so bears must fast for longer periods of time during the open-
water season. Stirling and Parkinson (2006, pp. 271-272) point out that
long-term data on population size and body condition of bears from the
Western Hudson Bay population, and population and harvest data from the
Baffin Bay population, indicate that these populations are declining or
likely to be declining. The authors indicate that as bears in these
populations become more nutritionally stressed, the numbers of animals
will decline, and the declines will probably be significant. Based on
the recent findings of Holland et al.
[[Page 28259]]
(2006, pp. 1-5) regarding sea ice changes, these events are predicted
to occur within the foreseeable future as defined in this rule
(Stirling, pers. comm. 2006).
Seasonal polar bear distribution changes noted above, the negative
effect of reduced access to primary prey, and prolonged use of
terrestrial habitat are a concern for polar bears. Although polar bears
have been observed using terrestrial food items such as blueberries
(Vaccinium sp.), snow geese (Anser caerulescens), and reindeer
(Rangifer tarandus), these alternate foods are not believed to
represent significant sources of energy (Ramsay and Hobson 1991, p.
600; Derocher et al. 2004, p. 169) because they do not provide the high
fat, high caloric food source that seals do. Also, the potential
inefficiency of polar bear locomotion on land noted above may explain
why polar bears are not known to regularly hunt musk oxen (Ovibos
moschatus) or snow geese, despite their occurrence as potential prey in
many areas (Lunn and Stirling 1985, p. 2,295). The energy needed to
catch such species would almost certainly exceed the amount of energy a
kill would provide (Lunn and Stirling 1985, p. 2,295). Consequently,
greater use of terrestrial habitats as a result of reduced presence of
sea ice seasonally will not offset energy losses resulting from
decreased seal consumption. Nutritional stress appears to be the only
possible result.
Effects of Sea Ice Habitat Changes on Polar Bear Prey
Reduced Seal Productivity
Polar bear populations are known to fluctuate with prey abundance
(Stirling and Lunn 1997, p. 177). Declines in ringed and bearded seal
numbers and productivity have resulted in marked declines in polar bear
populations (Stirling 1980, p. 309; Stirling and [Oslash]ritsland 1995,
p. 2,609; Stirling 2002, p. 68). Thus, changes in ringed seal
productivity have the potential to affect polar bears directly as a
result of reduced predation on seal pups and indirectly through reduced
recruitment of this important prey species. Ringed seal productivity is
dependent on the availability of secure habitat for birth lairs and
rearing young and, as a result, is susceptible to changes in sea ice
and snow dynamics. Ringed seal pups are the smallest of the seals and
survive because they are born in snow lairs (subnivian dens) that
afford protection from the elements and from predation (Hall 1866;
Chapskii 1940; McLaren 1958; Smith and Stirling 1975, all cited in
Kelly 2001, p. 47). Pups are born between mid-March and mid-April,
nursed for about 6 weeks, and weaned prior to spring break-up in June
(Smith 1980, p. 2,201; Stirling 2002, p. 67). During this time period,
both ringed seal pups and adults are hunted by polar bears (Smith 1980,
p. 2,201). Stirling and Lunn (1997, p. 177) found that ringed seal
young-of-the-year represented the majority of the polar bear diet,
although the availability of ringed seal pups from about mid-April to
ice break up sometime in July (Stirling and Lunn 1997, p. 176) is also
important to polar bears.
In many areas, ringed seals prefer to create birth lairs in areas
of accumulated snow on stable, shore-fast ice over continental shelves
along Arctic coasts, bays, and inter-island channels (Smith and Hammill
1981, p. 966). While some authors suggest that landfast ice is the
preferred pupping habitat of ringed seals due to its stability
throughout the pupping and nursing period (McLaren 1958, p. 26; Burns
1970, p. 445), others have documented ringed seal pupping on drifting
pack ice both nearshore and offshore (Burns 1970; Smith 1987; Finley et
al. 1983, p. 162; Wiig et al. 1999, p. 595; Lydersen et al. 2004).
Either of these habitats can be affected by earlier warming and break-
up in the spring, which shortens the length of time pups have to grow
and mature (Kelly 2001, p. 48; Smith and Harwood 2001). Harwood et al.
(2000, pp. 11-12) reported that an early spring break-up negatively
impacted the growth, condition, and apparent survival of unweaned
ringed seal pups. Early break-up was believed to have interrupted
lactation in adult females, which in turn, negatively affected the
condition and growth of pups. Earlier ice break-ups similar to those
documented by Harwood et al. (2000, p. 11) and Ferguson et al. (2005,
p. 131) are predicted to occur more frequently with warming
temperatures, and result in a predicted decrease in productivity and
abundance of ringed seals (Ferguson et al. 2005, p. 131; Kelly 2001).
Additionally, high fidelity to birthing sites exhibited by ringed seals
makes them more susceptible to localized impacts from birth lair snow
degradation, harvest, or human activities (Kelly 2006, p. 15).
Unusually heavy ice has also been documented to result in markedly
lower productivity of ringed seals and reduced polar bear productivity
(Stirling 2002, p. 59). While reduced ice thickness associated with
warming in some areas could be expected to improve seal productivity,
the transitory and localized benefits of reduced ice thickness on
ringed seals are expected to be outweighed by the negative effects of
increased vulnerability of seal pups to predation and thermoregulatory
costs (Derocher et al. 2004, p. 168). The number of studies that have
documented negative effects associated with earlier warming and break-
up and reduced snow cover (Hammill and Smith 1989, p. 131; Harwood et
al. 2000, p. 11; Smith et al. 1991; Stirling and Smith 2004, p. 63;
Ferguson et al. 2005, p. 131), in comparison to any apparent benefits
of reduced ice thickness further support this conclusion.
Snow depth on the sea ice, in addition to the timing of ice break-
up, appears to be important in affecting the survival of ringed seal
pups. Ferguson et al. (2005, pp. 130-131) attributed decreased snow
depth in April and May with low ringed seal recruitment in western
Hudson Bay. Reduced snowfall results in less snow drift accumulation on
the leeward side of pressure ridges; pups in lairs with thin snow roofs
are more vulnerable to predation than pups in lairs with thick roofs
(Hammill and Smith 1989, p.131; Ferguson et al. 2005, p. 131). Access
to birth lairs for thermoregulation is also considered to be crucial to
the survival of nursing pups when air temperatures fall below 0 degrees
C (Stirling and Smith 2004, p. 65). Warming temperatures that melt
snow-covered birth lairs can result in pups being exposed to ambient
conditions and suffering from hypothermia (Stirling and Smith 2004, p.
63). Others have noted that when lack of snow cover has forced birthing
to occur in the open, nearly 100 percent of pups died from predation
(Kumlien 1879; Lydersen et al. 1987; Lydersen and Smith 1989, p. 489;
Smith and Lydersen 1991; Smith et al. 1991, all cited in Kelly 2001, p.
49). More recently, Kelly et al. (2006, p. 11) found that ringed seal
emergence from lairs was related to structural failure of the snow
pack, and PM satellite measurements indicating liquid moisture in snow.
These studies suggest that warmer temperatures have and will continue
to have negative effects on ringed seal pup survival, particularly in
areas such as western Hudson Bay (Ferguson et al. 2005, p. 121).
Similar to earlier spring break-up or reduced snow cover, increased
rain-on-snow events during the late winter also negatively impact
ringed seal recruitment by damaging or eliminating snow-covered pupping
lairs, increasing exposure and the risk of hypothermia, and
facilitating predation by polar bears and Arctic foxes (Alopex lagopus)
(Stirling and Smith 2004, p. 65). Stirling and Smith (2004, p. 64)
document the
[[Page 28260]]
collapse of snow roofs of ringed seal birth lairs associated with rain
events near southeastern Baffin Island and the resultant exposure of
adult seals and pups to hypothermia. Predation of pups by polar bears
was observed, and the researchers suspect that most of the pups in
these areas were eventually killed by polar bears (Stirling and
Archibald 1977, p. 1,127), Arctic foxes (Smith 1976, p. 1,610) or
possibly gulls (Lydersen and Smith 1989). Stirling and Smith (2004, p.
66) postulated that should early season rain become regular and
widespread in the future, mortality of ringed seal pups will increase,
especially in more southerly parts of their range. Any significant
decline in ringed seal numbers, especially in the production of young,
could negatively affect reproduction and survival of polar bears
(Stirling and Smith 2004, p. 66).
Changes in snow and ice conditions can also have impacts on polar
bear prey other than ringed seals (Born 2005a, p. 152). These species
include harbor seals (Phoca vitulina), spotted seals (Phoca largha),
and ribbon seals (Phoca fasciata), and in the north Atlantic, harp
seals (Phoca greenlandica) and hooded seals (Crystophora cristata). The
absence of ice in southerly pupping areas or the relocation of pupping
areas for other ice-dependent seal species to more northerly areas has
been demonstrated to negatively affect seal production. For example,
repeated years of little or no ice in the Gulf of St. Lawrence resulted
in almost zero production of harp seal pups, compared to hundreds of
thousands in good ice years (ACIA 2005, p. 510). Marginal ice
conditions and early ice break-up during harp seal whelping (pupping)
are believed to have resulted in increased juvenile mortality from
starvation and cold stress and an overall reduction in this age class
(Johnston et al. 2005, pp. 215-216). Northerly shifts of whelping areas
for hooded seals were reported to occur during periods of warmer
climate and diminished ice (Burns 2002, p. 42). In recent years, the
location of a hooded seal whelping patch near Jan Mayen, in East
Greenland, changed position apparently in response to decreased sea ice
in this area. This change in distribution has corresponded with a
decrease in seal numbers (T. Haug, pers. comm. 2005). Laidre et al. (in
press) concluded that harp and hooded seals will be susceptible to
negative effects associated with reduced sea ice because they whelp in
large numbers at high density with a high degree of fidelity to
traditional and critical whelping locations. Because polar bears prey
primarily on seal species whose reproductive success is closely linked
to the availability of stable, spring ice, the productivity of these
species, and, therefore, prey availability for polar bears, is expected
to decline in response to continued declines in the extent and duration
of sea ice.
Reduced Prey Availability
Current evidence suggests that prey availability to polar bears
will be altered due to reduced prey abundance, changes in prey
distribution, and changes in sea ice availability as a platform for
hunting seals (Derocher et al. 2004, pp. 167-169). Young, immature
bears may be particularly vulnerable to changes in prey availability.
Polar bears feed preferentially on blubber, and adult bears often leave
much of a kill behind (Stirling and McEwan 1975, p. 1,021). Younger
bears, which are not as efficient at taking seals, are known to utilize
these kills to supplement their diet (Derocher et al. 2004, p. 168).
Younger bears may be disproportionately impacted if there are fewer
kills or greater consumption of kills by adults, resulting in less prey
to scavenge (Derocher et al. 2004, pp. 167-168). Altered prey
distribution would also likely lead to increased competition for prey
between dominant and subordinate bears, resulting in subordinate or
subadult bears having reduced access to prey (Derocher et al. 2004, p.
167). Thus, a decrease in prey abundance and availability would likely
result in a concomitant effect to polar bears.
Reduction in food resources available to seals, in addition to the
previously discussed effects on reproduction, could affect seal
abundance and availability as a prey resource to polar bears. Ringed
seals are generalist feeders but depend on Arctic cod (Boreogadus
saida) as a major component of their diet (Lowry et al. 1980, p. 2,254;
Bradstreet and Cross 1982, p. 3; Welch et al. 1997, p. 1,106; Weslawski
et al. 1994, p. 109). Klumov (1937) regarded Arctic cod as the
'biological pivot' for many northern marine vertebrates, and as an
important intermediary link in the food chain. Arctic cod are strongly
associated with sea ice throughout their range and use the underside of
the ice to escape from predators (Bradstreet and Cross 1982, p. 39;
Craig et al. 1982, p. 395; Sekerak 1982, p. 75). While interrelated
changes in the Arctic food web and effects to upper level consumers are
difficult to predict, a decrease in seasonal ice cover could negatively
affect Arctic cod (Tynan and DeMaster 1997, p. 314; Gaston et al. 2003,
p. 231). Though decreased ice could improve the ability of ringed seals
to access and prey upon Arctic cod in open water, this change would
come at increased costs for pups that are forced into the water at an
earlier age and at risk of predation and thermal challenges (Smith and
Harwood 2001). For example, studies have shown that even in the
presence of abundant prey, growth and condition of ringed seals
continued to be negatively affected by earlier ice break-up (Harwood et
al. 2000, p. 422). Ice seals, including the ringed seal, are vulnerable
to habitat loss from changes in the extent or concentration of Arctic
ice because they depend on pack-ice habitat for pupping, foraging,
molting, and resting (Tynan and DeMaster 1997, p. 312; Derocher et al.
2004, p. 168).
Sea ice is an essential platform that allows polar bears to access
their prey. The importance of sea ice to polar bear foraging is
supported by documented relationships between the duration and extent
of sea ice and polar bear condition, reproduction, and survival that
are apparent across decades, despite likely fluctuations in ringed seal
abundance (Stirling et al. 1999, p. 294; Regehr et al. 2007a; p. 2,673;
Regehr et al. 2007b, p. 18; Rode et al. 2007, p. 6-8). Ferguson et al.
(2000b, p. 770) reported that higher seal density in Baffin Bay in
comparison to the Arctic Archipelago did not correspond with a higher
density of polar bears as a result of the more variable ice conditions
that occur there. These results emphasize the dependence of polar bears
on sea ice as a means of accessing prey. Not only does ice have to be
present over areas of abundant prey, but the physical characteristics
of sea ice appear to also be important. Stirling et al. (2008, in
press) noted that unusually rough and rafted sea ice in the
southeastern Beaufort Sea from about Atkinson Point to the Alaska
border during the springs of 2004-2006 resulted in reduced hunting
success of polar bears seeking seals despite extensive searching for
prey. Thus, transitory or localized increases in prey abundance will
have no benefit for polar bears if these changes are accompanied by a
reduction in ice habitat or changes in physical characteristics of ice
habitat that negate its value for hunting or accessing seals.
Observations-to-date and projections of future ice conditions support
the conclusion that accessibility of prey to polar bears is likely to
decline.
Adaptation
Animals can adapt to changing environmental conditions principally
through behavioral plasticity or as a result of natural selection.
Behavioral
[[Page 28261]]
changes allow adaptation over shorter timeframes and can complement and
be a precursor to the forces of natural selection that allow animals to
evolve to better fit new or changed environmental patterns. Unlike
behavioral plasticity, natural selection is a multi-generational
response to changing conditions, and its speed is dependent upon the
organism's degree of genetic variation and generation time and the rate
of environmental change (Burger and Lynch 1995, p. 161). While some
short-lived species have exhibited micro-evolutionary responses to
climate change (e.g., red squirrels (Reale et al. 2003, p. 594)), the
relatively long generation time (Amstrup 2003, pp. 599-600) and low
genetic variation of polar bears (Amstrup 2003, p. 590) combined with
the relatively rapid rate of predicted sea ice changes that are
expected (Comiso 2006, p. 72; Serreze et al. 2007, p. 1,533-1,536;
Stroeve et al. 2007, pp. 1-5; Hegerl et al. 2007, p. 716), suggest that
adaptation through natural selection will be limited for polar bears
(Stirling and Derocher 1990, p. 201). Furthermore, several recent
reviews of species adaptation to changing climate suggest that rather
than evolving, species appear to first alter their geographic
distribution (Walther et al. 2002, p. 390; Parmesan 2006, p. 655). For
example, evidence suggests that altered species distribution was the
mechanism allowing many species to survive during the Pleistocene
warming period (Parmesan 2006, p. 655). Because polar bears already
occur in cold extreme climates, they are constrained from responding to
climate change by significantly altering their distribution (Parmesan
2006, p. 653). Furthermore, a number of physiological and physical
characteristics of polar bears constrain their ability to adapt
behaviorally to rapid and extensive alteration of their sea-ice
habitat.
Bears as a genus display a high degree of behavioral plasticity
(Stirling and Derocher 1990, p. 189), opportunistic feeding strategies
(Lunn and Stirling 1985, p. 2295; Schwartz et al. 2003, p. 568), and
physiological mechanisms for energy conservation (Derocher et al. 1990,
p. 196; McNab 2002, p. 385). However, polar bears evolved to be the
largest of the bear species (Amstrup 2003, p. 588) by specializing on a
calorically dense, carnivorous diet that differs from all other bear
species. Their large size has the advantage of both increased fat
storage capability (McNab 2002, p. 383) and reduced surface-area to
volume ratios that minimize heat loss in the Arctic environment (McNab
2002, pp. 102-103). Because reproduction in polar bears and other bears
is dependent upon achieving sufficient body mass (Atkinson and Ramsay
1995, p. 559; Derocher and Stirling 1996, p. 1,246; Derocher and
Stirling 1998, p. 253), population density is directly linked to the
availability of high-quality food and primary productivity (Hilderbrand
et al. 1999, p. 135; Ferguson and McLoughlin 2000, p. 196). Thus,
maintenance of a high caloric intake is facilitated by the high fat
content of seals, which is required to maintain polar bears at the body
size and in the numbers in which they exist today.
The most recent population estimates of ringed seals, the preferred
prey of most polar bear populations, range to about 4 million or more,
making them one of the most abundant seal species in the world
(Kingsley 1990, p. 140). Rather than switching to alternative prey
items when ringed seal populations decline as a result of environmental
conditions, several studies demonstrated corresponding declines in
polar bear abundance (Stirling and [Oslash]ritsland 1995, p. 2,594;
Stirling 2002, p. 68). For those polar bear populations that have been
shown to utilize alternative prey species in response to changing
availability, such shifts have been among other ice-dependent pinnipeds
(Derocher et al. 2002, p. 448; Stirling 2002, p. 67; Iverson et al.
2006, pp. 110-112). For example, Stirling and Parkinson (2006, p. 270)
and Iverson et al. (2006, p. 112) have shown that polar bears in the
Davis Strait region have taken advantage of increases in availability
of harp and hooded seals. See also the section ``Effects of Sea Ice
Habitat Changes on Polar Bear Prey.'' However, harp and hooded seals
have historically occurred in areas not frequented by polar bears, and
are extremely vulnerable to polar bear predation and in Davis Strait
survival of juveniles is believed to have declined in recent years due
to significant and rapid reduction in sea ice in the spring (Stirling
and Parkinson 2006, p. 270).
Changes in ringed seal distribution and abundance in response to
changing ice conditions and the ability of polar bears to respond to
those changes will likely be the most important factor determining
effects on polar bear populations. Currently, access to ringed seals is
seasonal for most polar bear populations, resulting in cycles of weight
gain and weight loss. The most important foraging periods occur during
the spring, early summer, and following the open-water period in the
fall (Stirling et al. 1999, p. 303; Derocher et al. 2002, p. 449;
Durner et al. 2004, pp. 18-19). Because observed and predicted changes
in sea ice are most dramatic during the summer/fall period (Lemke et
al. 2007, p. 351; Serreze et al. 2007, p. 1,533-1,536), this is the
timeframe with the greatest potential for reduced access to ringed
seals as prey. Most POLAR BEAR POPULATIONs forage minimally during the
fall open-water period, but a reduction in sea ice can extend the time
period in which bears have minimal or no access to prey (Stirling et
al. 1999, p. 299). The effects of a lengthened ice-free season during
this time period have been associated with declines in polar bear
condition (Stirling et al. 1999, p. 304; Rode et al. 2007, p. 8),
reproduction (Regehr et al. 2006; Rode et al. 2007, p. 8-9), survival
(Regehr et al. 2007a, p. 2,677-2,678; Regehr et al 2007b, p. 13) and
population size (Regehr et al. 2007a, p. 2,678-2,679;).
Marine mammal carcasses do not currently constitute a large portion
of polar bear diets and are unlikely to contribute substantially to
future diets of polar bears. Although marine mammal carcass
availability occasionally is predictable where whales are harvested for
subsistence by Native people (Miller et al. 2006, p. 1) or where
walruses haul out on land and are killed in stampeding events (Kochnev
2006, p. 159), in most cases scavenging opportunities are unpredictable
and not a substitute for normal foraging by polar bears. Even where
their distribution is predictable, marine mammal carcasses are
presently used by only a small proportion of most populations or
contribute minimally to total diet (Bentzen 2006, p. 23; Iverson et al.
2006, p. 111), and do not appear to be a preferred substitute for the
normal diet. For example, on the Alaskan Southern Beaufort Sea coast,
from 2002-2004, on average less than 5 percent of the estimated
population size of 1,500 polar bears visited subsistence-harvested
whale carcasses (Miller et al. 2006, p. 9). A small fraction of
collared pregnant adult females visited whale harvest sites (Fischbach
et al. 2007, pp. 1,401-1,402). Quotas on subsistence whale harvest
preclude the possibility that carcasses will be increasingly available
in the future. Similarly, while walrus contributed up to 24 percent of
diets of a few individual bears in Davis Strait, population wide,
walruses composed a small fraction of the total diet (Iverson et al.
2006, p. 112). Less predictable sea-ice conditions could increase the
frequency of future marine mammal strandings (Derocher et al. 2004, p.
89), and some polar bears may benefit from such increases in marine
[[Page 28262]]
mammal mortality. However, if stranding events become frequent, they
are likely to result in declines of source populations. Thus, the
likelihood of polar bears relying heavily on stranded or harvested
marine mammals as a food source is low.
The potential for polar bears to substitute terrestrial food
resources in place of their current diet of marine mammals is limited
by the low quality and availability of foods in most northern
terrestrial environments. Although smaller bears can maintain their
body weight consuming diets consisting largely of berries and
vegetation, low digestibility (Pritchard and Robbins 1990, p. 1,645),
physical constraints on intake rate, and in the case of berries, low
protein content, prevent larger bears from similarly subsisting on
vegetative resources (Stirling and Derocher 1990, p. 191; Rode and
Robbins 2000, p. 1,640; Rode et al. 2001, p. 70; Welch et al. 1997, p.
1,105). While some meat sources are available in terrestrial Arctic
habitats, such as caribou, muskox, and Arctic char, the relative
scarcity of these resources results in these areas supporting some of
the smallest grizzly bears in the world at some of the lowest densities
of any bear populations (Hilderbrand et al. 1999, p. 135; Miller et al.
1997, p. 37). Lunn and Stirling (1985, p. 2,295) suggest that predation
on terrestrially-based prey by polar bears may be rare due to the high
energetic cost of locomotion in polar bears in comparison to grizzly
bears (Best 1982, p. 63). Energy expended to pursue terrestrial prey
could exceed the amount of energy obtained. Furthermore, terrestrial
meat resources are primarily composed of protein and carbohydrates that
provide approximately half as many calories per gram as fats (Robbins
1993, p. 10). Because the wet weight of ringed seals is composed of up
to 50 percent fat (Stirling 2002, p. 67), they provide a substantially
higher caloric value in comparison to terrestrial foods. Physiological
and environmental limitations, therefore, preclude the possibility that
terrestrial food sources alone or as a large portion of the diet would
be an equivalent substitute for the high fat diet supporting the
population densities and body size of present-day polar bear
populations.
An alternative to maintaining caloric intake would be for polar
bears to adopt behavioral strategies that reduce energy expenditure and
requirements. Across populations, polar bears do appear to alter home
range size and daily travel distances in response to varying levels of
prey density (Ferguson et al. 2001, p. 51). Additionally, polar bears
exhibit a variety of patterns of fasting and feeding throughout their
range, including 3-to 8-month-long fasts, denning by pregnant females,
and moving between a fasting and a feeding metabolism based on
continuously changing food availability throughout the year (Derocher
et al. 1990, p. 202). These physiological and behavioral strategies
have occurred in response to regional variation in environmental
conditions but have limitations relative to their application across
all regions and habitats. Both the long fasts that occur in Western
Hudson Bay and denning of females throughout polar bear ranges are
dependent on prey availability that allows sufficient accumulation of
body fat to survive fasting periods (Derocher and Stirling 1995, p.
535). The 3-to 8-month-long periods of food deprivation exhibited by
bears in the southern reaches of their range are supported by a rich
marine environment that allows spring weight gains sufficient to
sustain extended summer fasts. In the southern Beaufort Sea, for
example, the heaviest polar bears were observed during autumn (Durner
and Amstrup 1996, p. 483). In the Beaufort Sea and other regions of the
polar basin, the probability that polar bears could survive extended
summer fasting periods appears to be low. The documented reduction in
polar bear condition in Western Hudson Bay associated with the recent
lengthening of the ice-free season (Stirling et al. 1999, p. 294)
suggests that even in the productive Hudson Bay environment there are
limits to the ability of polar bears to fast.
Any period of fasting, whether while denning or resting onshore,
would require an increase in food availability during alternative, non-
fasting periods for fat accumulation. Adequate food may not be
available to support sex and age classes other than pregnant females to
adopt a strategy of denning over extended periods of time during food
shortage. Furthermore, the ability to take advantage of seasonally
fluctuating food availability and avoid extended torpor and associated
physiological costs (Humphries et al. 2003, p. 165) has allowed polar
bears to maximize access to food resources and is an important factor
contributing to their large size.
The known current physiological and physical characteristics of
polar bears suggest that behavioral adaptation will be sufficiently
constrained to cause a pronounced reduction in polar bear distribution,
and abundance, as a result of declining sea ice. The pace at which ice
conditions are changing and the long generation time of polar bears
precludes adaptation of new physiological mechanisms and physical
characteristics through natural selection. Current evidence opposes the
likelihood that extended periods of torpor, consumption of terrestrial
foods, or capture of seals in open water will be sufficient mechanisms
to counter the loss of ice as a platform for hunting seals. Polar bear
survival and maintenance at sustainable population sizes depends on
large and accessible seal populations and vast areas of ice from which
to hunt.
Open Water Habitat
While sea ice is considered essential habitat for polar bear life
functions because of the importance for feeding, reproduction, or
resting, open water is not. Vast areas of open water can present a
barrier or hazard under certain circumstances for polar bears to access
sea ice or land. Diminished sea ice cover will increase the energetic
cost to polar bears for travel, and will increase the risk of drowning
that may occur during long distance swimming or swimming under
unfavorable weather conditions. In addition, diminished sea ice cover
may result in hypothermia for young cubs that are forced to swim for
longer periods than at present. Under diminishing sea ice projections
(IPCC 2001, p. 489; ACIA 2005, p. 192; Serreze 2006), ice-dependent
seals, the principal prey of polar bears, will also be affected through
distribution changes and reductions in productivity that will
ultimately translate into reductions in seal population size.
Reduced Hunting Success
Polar bears are capable of swimming great distances, but exhibit a
strong preference for sea ice (Mauritzen et al. 2003b, pp. 119-120).
However, polar bears will also quickly abandon sea ice for land once
the sea ice concentration drops below 50 percent. This is likely due to
reduced hunting success in broken ice with significant open water
(Derocher et al. 2004, p. 167; Stirling et al. 1999, pp. 302-303).
Bears have only rarely been reported to capture ringed seals in open
water (Furnell and Oolooyuk 1980, p. 88), therefore, hunting in ice-
free water would not compensate for the corresponding loss of sea ice
and the access sea ice affords polar bears to hunt ringed seals
(Stirling and Derocher 1993, p. 241; Derocher et al. 2004, p. 167).
Reduction in sea ice and corresponding increase in open water would
likely result in a net reduction in ringed and bearded seals, and
Pacific walrus abundance (ACIA 2005, p. 510), as well as a reduction in
ribbon and spotted seals (Born 2005a). While harp
[[Page 28263]]
and hooded seals may change their distribution and temporarily serve as
alternative prey for polar bears, it appears that these species cannot
successfully redistribute in a rapidly changing environment and
reproduce and survive at former levels. Furthermore, a recent study
suggests that these two species will be the most vulnerable to effects
of changing ice conditions (Laidre et al. in press). Loss of southern
pupping areas due to inadequate or highly variable ice conditions will,
in the long run, also serve to reduce these species as a potential
polar bear prey (Derocher et al. 2004, p. 168). That increased take of
other species such as bearded seals, walrus, harbor seals, or harp and
hooded seals, if they were available, would not likely compensate for
reduced availability of ringed seals (Derocher et al. 2004, p. 168).
Open Water Swimming
Open water is considered to present a potential hazard to polar
bears because it can result in long distances that must be crossed to
access sea ice or land habitat. In September 2004, four polar bears
drowned in open water while attempting to swim in an area between shore
and distant ice (Monnett and Gleason 2006, p. 5). Seas during this
period were rough, and extensive areas of open water persisted between
pack ice and land. Because the survey area covered 11 percent of the
study area, an extrapolation of the survey data to the entire study
area suggests that a larger number of bears may have drowned during
this event. Mortalities due to offshore swimming during years when sea
ice formation nearshore is delayed (or mild) may also be an important
and unaccounted source of natural mortality given energetic demands
placed on individual bears engaged in long-distance swimming (Monnett
and Gleason 2006, p. 6). This suggests that drowning related deaths of
polar bears may increase in the future if the observed trend of
recession of pack ice with longer open-water periods continues.
However, this phenomenon may be shortlived if natural selection
operates against the behavioral inclination to swim between ice and
land and favors bears that remain on land or on ice.
Wave height (sea state) increases as a function of the amount of
open water surface area. Thus ice reduction not only increases areas of
open water across which polar bears must swim, but may have an
influence on the size of wave action. Considered together, these may
result in increases in bear mortality associated with swimming when
there is little sea ice to buffer wave action (Monnett and Gleason
2006, p. 5). Evidence of such mortality was also reported east of
Svalbard in 2006, where one exhausted and one apparently dead polar
bear were stranded ( J. Dowdeswell, Head of the Scott Polar Research
Institute of England, pers. obs.).
Terrestrial Habitat
Although sea ice is the polar bear's principal habitat, terrestrial
habitat serves a vital function seasonally for maternal denning. In
addition, use of terrestrial habitat is seasonally important for
resting and feeding in the absence of suitable sea ice. Due to
retreating sea ice, polar bears may be forced to make increased use of
land in future years. The following sections describe the effects or
potential effects of climate change and other factors on polar bear use
of terrestrial habitat. One section focuses on access to or changes in
the quality of denning habitat, and one focuses on distribution changes
and corresponding increases in polar bear-human interactions in coastal
areas. Also discussed are the potential consequences of and potential
concerns for development, primarily oil and gas exploration and
production which occur in polar bear habitat (both marine and
terrestrial).
Access to and Alteration of Denning Areas
Many female polar bears repeatedly return to specific denning areas
on land (Harrington 1968, p. 11; Schweinsburg et al. 1984, p. 169;
Garner et al. 1994, p. 401; Ramsay and Stirling 1990, p. 233; Amstrup
and Gardner 1995, p. 8). For bears to access preferred denning areas,
pack ice must drift close enough or must freeze sufficiently early in
the fall to allow pregnant females to walk or swim to the area by late
October or early November (Derocher et al. 2004, p. 166), although
polar bears may den into early December (Amstrup 2003, p. 597).
Stirling and Andriashek (1992, p. 364) found that the distribution of
polar bear maternal dens on land was related to the proximity of
persistent summer sea ice, or areas that develop sea ice early in the
autumn.
Derocher et al. (2004, p. 166) predicted that under future climate
change scenarios, pregnant female polar bears will likely be unable to
reach many of the most important denning areas in the Svalbard
Archipelago, Franz Josef Land, Novaya Zemlya, Wrangel Island, Hudson
Bay, and the Arctic National Wildlife Refuge and north coast of the
Beaufort Sea (see Figure 8). Under likely climate change scenarios, the
distance between the edge of the pack ice and land will increase (ACIA
2005, pp. 456-459). As distance increases between the southern edge of
the pack ice and coastal denning areas, it will become increasingly
difficult for females to access preferred denning locations. In
addition to suitable access and availability of den sites, body
condition is an important prerequisite for cub survival, and
recruitment into the population as pregnant bears with low lipid stores
are less likely to leave the den with healthy young in the spring
(Atkinson and Ramsay 1995, pp. 565-566). Messier et al. (1994)
postulated that pregnant bears may reduce activity levels up to 2
months prior to denning to conserve energy.
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Bergen et al. (2007, p. 2) hypothesized that denning success is
inversely related to the distance a pregnant polar bear must travel to
reach denning habitat. These authors developed an approach using
observed sea ice distributions (1979-2006) and GCM-derived sea ice
projections (1975-2060) to estimate minimum distances that pregnant
polar bears would have to travel between summer sea ice habitats and a
terrestrial den location in northeast Alaska (Bergen et al. 2007, p. 2-
3). In this pilot assessment, calculations were made with and without
the constraint of least cost movement paths, which required bears to
optimally follow high-quality sea ice habitats. Although variation was
evident and considerable among the five GCMs analyzed, the smoothed
multi-model average distances aligned well with those derived from the
observational record. The authors found that between 1979 and 2006, the
minimum distance polar bears traveled to denning habitats in northeast
Alaska increased at an average linear rate of 6-8 km per year (3.7-5.0
mi per year), and almost doubled after 1992. They projected that travel
would increase threefold by 2060 (Bergen et al. 2007, p. 2-3).
Based on projected retraction of sea ice in the future, Bergen et
al. (2007, p. 2) states, ``thus, pregnant polar bears will likely incur
greater energetic expense in reaching traditional denning regions if
sea ice loss continues along the projected trajectory.'' Increased
travel distances could negatively affect individual fitness, denning
success, and ultimately populations of polar bears (Aars et al. 2006).
While the Bergen et al. (2007, p. 2) study focused on polar bears using
denning habitat in northern Alaska, other denning regions in the
Arctic, particularly within the polar basin region, are much farther
from
[[Page 28265]]
areas where summer ice is predicted to persist in the future. Polar
bears returning to other denning locales, such as Wrangel Island or the
Chukotka Peninsula, will likely have to travel greater distances than
those reported here. Most high-density denning areas are located at
more southerly latitudes (see Figure 8). For populations that den at
high latitudes in the Canadian archipelago islands, access to, and
availability of, suitable den sites may not currently be a problem.
However, access to historically-used den sites in the future may become
more problematic in the northern areas. The degree to which polar bears
may use nontraditional denning habitats at higher latitudes in the
future, through facultative adaptation, is largely unknown but is
possible.
Climate change could also impact populations where females den in
snow (Derocher et al. 2004). Insufficient snow would prevent den
construction or result in use of poor sites where the roof could
collapse (Derocher et al. 2004). Too much snow could necessitate the
reconfiguration of the den by the female throughout the winter
(Derocher et al. 2004). Changes in amount and timing of snowfall could
also impact the thermal properties of the dens (Derocher et al. 2004).
Since polar bear cubs are born helpless and need to nurse for three
months before emerging from the den, major changes in the thermal
properties of dens could negatively impact cub survival (Derocher et
al. 2004). Finally, unusual rain events are projected to increase
throughout the Arctic in winter (ACIA 2005), and increased rain in late
winter and early spring could cause den collapse (Stirling and Smith
2004). Den collapse following a warming period was observed in the
Beaufort Sea and resulted in the death of a mother and her two young
cubs (Clarkson and Irish 1991). After March 1990 brought unseasonable
rain south of Churchill, Manitoba, Canada, researchers observed large
snow banks along creeks and rivers used for denning that had collapsed
because of the weight of the wet snow, and noted that had there been
maternity dens in this area the bears likely would have been crushed
(Stirling and Derocher 1993).
Oil and Gas Exploration, Development, and Production
Each of the Parties to the 1973 Polar Bear Agreement (see
International Agreements and Oversight section below) has developed
detailed regulations pertaining to the extraction of oil and gas within
their countries. The greatest level of oil and gas activity within
polar bear habitat is currently occurring in the United States
(Alaska). Exploration and production activities are also actively
underway in Russia, Canada, Norway, and Denmark (Greenland). In the
United States, all such leasing and production activities are evaluated
as specified by the National Environmental Policy Act (42 U.S.C. 4321
et seq.) (NEPA), Outer Continental Shelf Lands Act (43 U.S.C. 1331 et
seq.) (OCSLA), and numerous other statutes, that evaluate and guide
exploration, development, and production in order to minimize possible
environmental impacts. In Alaska, the majority of oil and gas
development is on land; however, some offshore production sites have
been developed, and others are planned.
Historically, oil and gas activities have resulted in little direct
mortality to polar bears, and that mortality which has occurred has
been associated with human-bear interactions as opposed to a spill
event. However, oil and gas activities are increasing as development
continues to expand throughout the U.S. Arctic and internationally,
including in polar bear terrestrial and marine habitats. The greatest
concern for future oil and gas development is the effect of an oil
spill or discharges in the marine environment impacting polar bears or
their habitat. Disturbance from activities associated with oil and gas
activities can result in direct or indirect effects on polar bear use
of habitat. Direct disturbances include displacement of bears or their
primary prey (ringed and bearded seals) due to the movement of
equipment, personnel, and ships through polar bear habitat. Female
polar bears tend to select secluded areas for denning, presumably to
minimize disturbance during the critical period of cub development.
Direct disturbance may cause abandonment of established dens before
their cubs are ready to leave. For example, expansion of the network of
roads, pipelines, well pads, and infrastructure associated with oil and
gas activities may force pregnant females into marginal denning
locations (Lentfer and Hensel 1980, p. 106; Amstrup et al. 1986, p.
242). The potential effects of human activities are much greater in
areas where there is a high concentration of dens such as Wrangel
Island. Although bear behavior is highly variable among individuals and
the sample size was small, Amstrup (1993, pp. 247-249) found that in
some instances denning bears were fairly tolerant to some levels of
activity. Increased shipping may increase the amount of open water,
cause disturbance to polar bears and their prey, and increase the
potential for additional oil spills (Granier et al. 2006 p. 4). Much of
the North Slope of Alaska contains habitat suitable for polar bear
denning (Durner et al. 2001, p. 119). Furthermore, in northern Alaska
and Chukotka, Russia, polar bears appear to be using land areas with
greater frequency during the season of minimum sea ice. Some of these
areas coincide with areas that have traditionally been used for oil and
gas production and exploration. These events increase the potential for
interactions with humans (Durner et al. 2001, p. 115; National Research
Council (NRC) 2003, p. 168); however, current regulations minimize
these interactions by establishing buffer zones around active den
sites.
The National Research Council (NRC 2003, p. 169) evaluated the
cumulative effects of oil and gas development in Alaska and concluded
the following related to polar bears and ringed seals:
``Industrial activity in the marine waters of the Beaufort
Sea has been limited and sporadic and likely has not caused serious
cumulative effects to ringed seals or polar bears.
Careful mitigation can help to reduce the effects of oil
and gas development and their accumulation, especially if there are no
major oil spills. However, the effects of full-scale industrial
development of waters off the North Slope would accumulate through the
displacement of polar bears and ringed seals from their habitats,
increased mortality, and decreased reproductive success.
A major Beaufort Sea oil spill would have major effects on
polar bears and ringed seals.
Climatic warming at predicted rates in the Beaufort Sea
region is likely to have serious consequences for ringed seals and
polar bears, and those effects will accumulate with the effects of oil
and gas activities in the region.
Unless studies to address the potential accumulation of
effects on North Slope polar bears or ringed seals are designed,
funded, and conducted over long periods of time, it will be impossible
to verify whether such effects occur, to measure them, or to explain
their causes.''
Some alteration of polar bear habitat has occurred from oil and gas
development, seismic exploration, or other activities in denning areas,
and potential oil spills in the marine environment and expanded
activities increase the potential for additional alteration. Any such
impacts would be additive to other factors already or potentially
affecting polar bears and their habitat. However, mitigative
regulations that have been instituted,
[[Page 28266]]
and will be modified as necessary, have proven to be highly successful
in providing for polar bear conservation in Alaska.
Oil and gas exploration, development, and production activities do
not threaten the species throughout all or a significant portion of its
range based on: (1) mitigation measures in place now and likely to be
used in the future; (2) historical information on the level of oil and
gas development activities occurring within polar bear habitat within
the Arctic; (3) the lack of direct quantifiable impacts to polar bear
habitat from these activities noted to date in Alaska; (4) the current
availability of suitable alternative habitat; and (5) the limited and
localized nature of the development activities, or possible events,
such as oil spills.
Documented direct impacts on polar bears by the oil and gas
industry during the past 30 years are minimal. Polar bears spend a
limited amount of time on land, particularly in the southern Beaufort
Sea, coming ashore to feed, den, or move to other areas. At times, fall
storms deposit bears along the coastline where bears remain until the
ice returns. For this reason, polar bears have mainly been encountered
at or near most coastal and offshore production facilities, or along
the roads and causeways that link these facilities to the mainland.
During those periods, the likelihood of incidental interactions between
polar bears and industry activities increases. As discussed under our
Factor D analysis below, the MMPA has specific provisions for such
incidental take, including specific findings that must be made by the
Service and the provision of mitigation actions, which serve to
minimize the likelihood of impacts upon polar bears. We have found that
the polar bear interaction planning and training requirements set forth
in the incidental take regulations and required through the letters of
authorization (LOA) process, and the overall review of the regulations
every one to five years has increased polar bear awareness and
minimized these encounters in the United States. The LOA requirements
have also increased our knowledge of polar bear activity in the
developed areas.
Prior to issuance of regulations, lethal takes by industry were
rare. Since 1968, there have been two documented cases of lethal take
of polar bears associated with oil and gas activities. In both
instances, the lethal take was reported to be in defense of human life.
In the winter of 1968-1969, an industry employee shot and killed a
polar bear (Brooks et al. 1971, p. 15). In 1990, a female polar bear
was killed at a drill site on the west side of Camden Bay (USFWS
internal correspondence, 1990). In contrast, 33 polar bears were killed
in the Canadian Northwest Territories from 1976 to 1986 due to
encounters with industry (Stenhouse et al. 1988, p. 276). Since the
beginning of the incidental take program, which includes requirements
for monitoring, project design, and hazing of bears presenting a safety
problem, no polar bears have been killed due to encounters associated
with the current industry activities on the North Slope of Alaska.
Observed Demographic Effects of Sea Ice Changes on Polar Bear
The potential demographic effects of sea ice changes on polar bear
reproductive and survival rates (vital rates) and ultimately on
population size are difficult to quantify due to the need for extensive
time series of data. This is especially true for a long-lived and
widely dispersed species like the polar bear. Recent research by
Stirling et al. (2006), Regehr et al. (2007a, b), Hunter et al. (2007),
and Rode et al. (2007), however, evaluates these important
relationships and adds significantly to our understanding of how and to
what extent environmental changes influence essential life history
parameters. The key demographic factors for polar bears are physical
condition, reproduction, and survival. Alteration of these
characteristics has been associated with elevated risks of extinction
for other species (McKinney 1997, p. 496; Beissinger 2000, p. 11,688;
Owens and Bennett 2000, p. 12,145).
Physical condition of polar bears determines the welfare of
individuals, and, ultimately, through their reproduction and survival,
the welfare of populations (Stirling et al. 1999, p. 304; Regehr et al.
2007a, p. 13; Regehr et al 2007b, pp. 2,677-2,680; Hunter et al. 2007,
pp. 8-13). In general, Derocher et al. (2004, p. 170) predict that
declines in the physical condition will initially affect female
reproductive rates and juvenile survival and then under more severe
conditions adult female survival rates. Adult females represent the
most important sex and age class within the population regarding
population status (Taylor et al. 1987, p. 811).
Declines in fat reserves during critical times in the polar bear
life cycle detrimentally affect populations through delay in the age of
first reproduction, decrease in denning success, decline in litter
sizes with more single cub litters and fewer cubs, and lower cub body
weights and lower survival rates (Atkinson and Ramsay 1995, pp. 565-
566; Derocher et al. 2004, p. 170). Derocher and Stirling (1998, pp.
255-256) demonstrated that body mass of adult females is correlated
with cub mass at den emergence, with heavier females producing heavier
cubs and lighter females producing lighter cubs. Heavier cubs have a
higher rate of survival (Derocher and Stirling 1996, p. 1,249). A
higher proportion of females in poor condition do not initiate denning
or are likely to abandon their den and cub(s) mid-winter (Derocher et
al. 2004, p. 170). Females with insufficient fat stores or in poor
hunting condition in the early spring after den emergence could lead to
increased cub mortality (Derocher et al. 2004, p. 170). In addition,
sea ice conditions that include broken or more fragmented ice may
require young cubs to enter water more frequently and for more
prolonged periods of time, thus increasing mortality from hypothermia.
Blix and Lenter (1979, p. 72) and Larsen (1985, p. 325) indicate that
cubs are unable to survive immersion in icy water for more than
approximately 10 minutes. This is due to cubs having little insulating
fat, their fur losing its insulating ability when wet (though the fur
of adults sheds water and recovers its insulating properties quickly),
and the core body temperature dropping rapidly when they are immersed
in icy water (Blix and Lentfer 1979, p. 72).
Reductions in sea ice, as discussed in previous sections, will
alter ringed seal distribution, abundance, and availability for polar
bears. Such reductions will, in turn, decrease polar bear body
condition (Derocher et al. 2004, p. 165). Derocher et al. (2004, p.
165) projected that most females in the Western Hudson Bay population
may be unable to reach the minimum 189 kg (417 lbs) body mass required
to successfully reproduce by the year 2012. Stirling (Canadian Wildlife
Service, pers comm. 2006) indicates, based on the decline in weights of
lone and suspected pregnant females in the fall (Stirling and Parkinson
2006), that the 2012 date is likely premature. However, Stirling
(Canadian Wildlife Service, pers comm. 2006) found that the trend of
continuing weight loss by adult female polar bears in the fall is clear
and continuing, and, therefore, Stirling believed that the production
of cubs in these areas will probably be negligible within the next 15-
25 years.
Furthermore, with the extent of sea ice projected to be
substantially reduced in the future (e.g., Stroeve et al. 2007, pp. 1-
5), opportunities for increased feeding to recover fat stores during
the season of minimum ice may be limited
[[Page 28267]]
(Durner et al. 2007, p. 12). It should be noted that the models project
decreased ice cover in all months in the Arctic, but that (as has been
observed) the projected changes in the 21st century are largest in
summer (Holland et al. 2006, pp. 1-5; Stroeve et al. 2007, pp. 1-5;
Durner et al. 2007, p. 12; DeWeaver 2007, p. 2; IPCC 2007). Mortality
of polar bears is thought to be the highest in winter when fat stores
are low and energetic demands are greatest. Pregnant females are in
dens during this period using fat reserves and not feeding. The
availability and accessibility of seals to polar bears, which often
hunt at the breathing holes, is likely to decrease with increasing
amounts of open water or fragmented ice (Derocher et al. 2004, p. 167).
Demographic Effects on Polar Bear Populations with Long-term Data Sets
This section summarizes demographic effects on polar bear
populations for which long-term data sets are available. These
populations are: Western Hudson Bay, Southern Hudson Bay, Southern
Beaufort Sea, Northern Beaufort Sea, and, to a lesser extent, Foxe
Basin, Baffin Bay, Davis Strait, and Eastern Hudson Bay.
Western Hudson Bay
The Western Hudson Bay polar bear population occurs near the
southern limit of the species' range and is relatively discrete from
adjacent populations (Derocher and Stirling 1990, p. 1,390; Stirling et
al. 2004, p. 16). In winter and spring, polar bears of the Western
Hudson Bay population disperse over the ice-covered Bay to hunt seals
(Iverson et al. 2006, p. 98). In summer and autumn, when Hudson Bay is
ice-free, the population is confined to a restricted area of land on
the western coast of the Bay. There, nonpregnant polar bears are cut
off from their seal prey and must rely on fat reserves until freeze-up,
a period of approximately 4 months. Pregnant bears going into dens may
be food deprived for up to an additional 4 months (a total of 8
months).
In the past 50 years, spring air temperatures in western Hudson Bay
have increased by 2-3 degrees C (Skinner et al. 1998; Gagnon and Gough
2005, p. 289). Consequently, the sea ice on the Bay now breaks up
approximately 3 weeks earlier than it did 30 years ago (Stirling and
Parkinson 2006, p. 265). This forces the Western Hudson Bay polar bears
off the sea ice earlier, shortening the spring foraging period when
seals are most available, and reducing the polar bears' ability to
accumulate the fat reserves needed to survive while stranded onshore.
Previous studies have shown a correlation between rising air
temperatures, earlier sea ice break-up, and declining recruitment and
body condition for polar bears in western Hudson Bay (Derocher and
Stirling 1996, p. 1,250; Stirling et al. 1999, p. 294; Stirling and
Parkinson 2006, p. 266). Based on GCM projections of continued warming
and progressively earlier sea ice break-up (Zhang and Walsh 2006),
Stirling and Parkinson (2006, p. 271-272) predicted that conditions
will become increasingly difficult for the Western Hudson Bay
population.
Regehr et al. (2007a, p. 2,673) used capture-recapture models to
estimate population size and survival for polar bears captured from
1984 to 2004 along the western coast of Hudson Bay. During this period
the Western Hudson Bay population experienced a statistically
significant decline of 22 percent, from 1,194 bears in 1987 to 935
bears in 2004. Regehr et al. (2007a, p. 2,673) notes that while
survival of adult female and male bears was stable, survival of
juvenile, subadult, and senescent (nonreproductive) bears was
negatively correlated with the spring sea ice break-up date--a date
that occurred approximately 3 weeks earlier in 2004 than in 1984. Long-
term observations suggest that the Western Hudson Bay population
continues to exhibit a high degree of fidelity to the study area during
the early part of the sea ice-free season (Stirling et al. 1977, p.
1,126; Stirling et al. 1999, p. 301; Taylor and Lee 1995, p. 147),
which precludes permanent emigration as a cause for the population
decline. The authors (Regehr et al. 2007a, p. 2,673) attribute the
decline of the Western Hudson Bay population to increased natural
mortality associated with earlier sea ice break-up, and the continued
harvest of approximately 40 polar bears per year (Lunn et al. 2002, p.
104). No support for alternative explanations was found.
Southern Hudson Bay
Evidence of declining body condition for polar bears in the Western
Hudson Bay population suggests that there should be evidence of
parallel declines in adjacent polar bear populations experiencing
similar environmental conditions. In an effort to evaluate an adjacent
population, Obbard et al. (2006, p. 2) conducted an analysis of polar
bear condition in the Southern Hudson Bay population by comparing body
condition for two time periods, 1984-1986 and 2000-2005. The authors
found that the average body condition for all age and reproductive
classes combined was significantly poorer for Southern Hudson Bay bears
captured from 2000-2005 than for bears captured from 1984-1986 (Obbard
et al. 2006, p. 4). The results indicate a declining trend in condition
for all age and reproductive classes of polar bears since the mid-
1980s. The results further reveal that the decline has been greatest
for pregnant females and subadult bears--trends that will likely have
an impact on future reproductive output and subadult survival (Obbard
et al. 2006, p. 1).
Obbard et al (2006, p. 4) evaluated inter-annual variability in
body condition in relation to the timing of ice melt and to duration of
ice cover in the previous winter and found no significant relationship
despite strong evidence of a significant trend towards both later
freeze-up and earlier break-up (Gough et al. 2004, p. 298; Gagnon and
Gough 2005, p. 293). While southern Hudson Bay loses its sea ice cover
later in the year than western Hudson Bay, the authors believe that
other factors or combinations of factors (that likely also include
later freeze-up and earlier break-up) are operating to affect body
condition in southern Hudson Bay polar bears. These factors may include
unusual spring rain events that occur during March or April when ringed
seals are giving birth to pups in on-ice birthing lairs (Stirling and
Smith 2004, pp. 60-63), depth of snow accumulation and roughness of the
ice that vary over time and also affect polar bear hunting success
(Stirling and Smith 2004, p. 60-62; Ferguson et al. 2005, p. 131),
changes in the abundance and distribution of ringed seals, and reduced
pregnancy rates and of reduced pup survival in ringed seals from
western Hudson Bay during the 1990s (Ferguson et al. 2005, p. 132;
Stirling 2005, p. 381).
A more recent status assessment using open population capture-
recapture models was conducted to evaluate population trend in the
Southern Hudson Bay population (Obbard et al. 2007, pp. 3-9). The
authors found that the population and survival estimates for subadult
female and male polar bears were not significantly different between
1984-1986 and 1999-2005 respectively. There was weak evidence of lower
survival of cubs, yearlings, and senescent adults in the recent time
period (Obbard et al. 2007, pp. 10-11). As previously reported, no
association was apparent between survival and cub-of-the-year body
condition, average body condition for the age class, or extent of ice
cover. The authors indicate that lack of association could be real or
attributable to various factors--the coarse scale of average body
condition measure, or to limited sample size, or
[[Page 28268]]
limited years of intensive sampling (Obbard et al. 2007, pp. 11-12).
The decline in survival estimates, although not statistically
significantly, combined with the evidence of significant declines in
body condition for all age and sex classes, suggest that the Southern
Hudson Bay population may be under increased stress at this time
(Obbard et al. 2007, p. 14). The authors also indicated that if the
trend in earlier ice break-up and later freeze-up continues in this
area, it is likely that the population will exhibit changes similar to
the Western Hudson Bay population even though no current significant
relationships exist between extent of ice cover and the survival
estimates and the average body condition for each age class (Obbard et
al. 2007, p. 14).
Southern Beaufort Sea
The Southern Beaufort Sea population has also been subject to
dramatic changes in the sea ice environment, beginning in the winter of
1989-1990 (Regehr et al. 2006, p. 2). These changes were linked
initially through direct observation of distribution changes during the
fall open-water period. With the exception of the Western Hudson Bay
population, the Southern Beaufort Sea population has the most complete
and extensive time series of life history data, dating back to the late
1960s. A 5-year coordinated capture-recapture study of this population
to evaluate changes in the health and status of polar bears and life
history parameters such as reproduction, survival, and abundance was
completed in 2006. Results of this study indicate that the estimated
population size has gone from 1,800 polar bears (Amstrup et al. 1986,
p. 244; Amstrup 2000, p. 146) to 1,526 polar bears in 2006 (Regehr et
al. 2006, p. 16). The precision of the earlier estimate (1,800 polar
bears) was low, and consequently there is not a statistically
significant difference between the two point estimates. Amstrup et al.
(2001, p. 230) provided a population estimate of as many as 2,500 bears
for this population in the late 1980s, but the statistical variance of
this estimate could not be calculated and thus precludes the
comparative value of the estimate.
Survival rates, weights, and skull sizes were compared for two
periods of time, 1967-1989 and 1990-2006. In the later period,
estimates of cub survival declined significantly, from 0.65 to 0.43
(Regehr et al. 2006, p. 11). Cub weights also decreased slightly. The
authors believed that poor survival of new cubs may have been related
to declining physical condition of females entering dens and
consequently of cubs born during recent years, as reflected by smaller
skull measurements. In addition, body weights for adult males decreased
significantly, and skull measurements were reduced since 1990 (Regehr
et al. 2006, p 1). Because male polar bears continue to grow into their
teen years (Derocher et al. 2005, p. 898), if nutritional intake was
similar since 1990, the size of males should have increased (Regehr et
al. 2006, p. 18). The observed changes reflect a trend toward smaller
size adult male bears. Although a number of the indices of population
status were not independently significant, nearly all of the indices
illustrated a declining trend. In the case of the Western Hudson Bay
population, declines in cub survival and physical stature were recorded
for a number of years (Stirling et al. 1999, p. 300; Derocher et al.
2004, p. 165) before a statistically significant decline in the
population size was confirmed (Regehr et al. 2007, p. 2,673).
In further support of the interaction of environmental factors,
nutritional stress, and their effect on polar bears, several unusual
mortality events have been documented in the southern Beaufort Sea.
During the winter and early spring of 2004, three observations of polar
bear cannibalism were recorded (Amstrup et al. 2006b, p. 1). Similar
observations had not been recorded in that region despite studies
extending back for decades. In the fall of 2004, four polar bears were
observed to have drowned while attempting to swim between shore and
distant pack ice in the Beaufort Sea. Despite offshore surveys
extending back to 1987, similar observations had not previously been
recorded (Monnett and Gleason 2006, p. 3). In spring of 2006, three
adult female polar bears and one yearling were found dead. Two of these
females and the yearling had no fat stores and apparently starved to
death, while the third adult female was too heavily scavenged to
determine a cause of death. This mortality is suspicious because prime
age females have had very high survival rates in the past (Amstrup and
Durner 1995, p. 1,315). Similarly, the yearling that was found starved
was the offspring of another radio-collared prime age female whose
collar had failed prior to her yearling being found dead. Annual
survival of yearlings, given survival of their mother, was previously
estimated to be 0.86 (Amstrup and Durner 1995, p. 1,316). The
probability, therefore, that this yearling died while its mother was
still alive was only approximately 14 percent. Regehr et al. (2006, p.
27) indicate that these anecdotal observations, in combination with
changes in survival of young and declines in size and weights reported
above, suggest mechanisms by which a changing sea ice environment can
affect polar bear demographics and population status.
The work by Regehr et al. (2006, pp. 1, 5) described above
suggested that the physical stature (as measured by skull size and body
weight data) of some sex and age classes of bears in the Southern
Beaufort Sea population had changed between early and latter portions
of this study, but trends in or causes of those changes were not
investigated. Rode et al. (2007, pp. 1-28), using sea ice and polar
bear capture data from 1982 to 2006, investigated whether these
measurements changed over time or in relation to sea ice extent. Annual
variation in sea ice habitat important to polar bear foraging was
quantified as the percent of days between April to November when mean
sea ice concentration over the continental shelf was greater than or
equal to 50 percent. The 50 percent concentration threshold was used
because bears make little use of areas where sea ice concentration is
lower (Durner et al. 2004, p. 19). The April to November period was
used because it is believed to be the primary foraging period for polar
bears in the southern Beaufort Sea (Amstrup et al. 2000b, p. 963). The
frequency of capture events for individual bears was evaluated to
determine if this factor had an effect on bear size, mass, or
condition. Rode et al. (2007, pp. 5-8) found that mass, length, skull
size, and body condition indices (BCI) of growing males (aged 3-10),
mass and skull size of cubs-of-the year, and the number of yearlings
per female in the spring and fall were all positively and significantly
related to the percent of days in which sea ice covered the continental
shelf. Unlike Regehr et al. (2006, p. 1), Rode et al. (2007, p. 8) did
not document a declining trend in skull size or body size of cubs-of-
the-year when the date of capture was considered. Condition of adult
males 11 years and older and of adult females did not decline. There
was some evidence, based on capture dates, that females with cubs have
been emerging from dens earlier in recent years. Thus, though cubs were
smaller in recent years, they also were captured earlier in the year.
Why females may be emerging from dens earlier than they used to is not
certain and warrants additional research.
Skull sizes and/or lengths of adult and subadult males and females
decreased over time during the study (Rode et al. 2007, p. 1). Adult
body mass was not related to sea ice cover and did
[[Page 28269]]
not show a trend with time. The condition of adult females exhibited a
positive trend over time, reflecting a decline in length without a
parallel trend in mass. Though cub production increased over time, the
number of cubs-of-the-year per female in the fall and yearlings per
female in the spring declined (Rode et al. 2007, p. 1), corroborating
the reduced cub survival, as noted previously by Regehr et al. (2006,
p. 1). Males exhibited a stronger relationship with sea ice conditions
and more pronounced declines over time than females. The mean body mass
of males of ages 3-10 years (63 percent of all males captured over the
age of 3) declined by 2.2 kg (4.9 lbs) per year, consistent with Regehr
et al. (2006, p. 1), and was positively related to the percent of days
with greater than or equal to 50 percent mean ice concentration over
the continental shelf (Rode et al. 2007, p. 10). Because declines were
not apparent in older, fully grown males, but were apparent in younger,
fully grown males, the authors suggest that nutritional limitations may
have occurred only in more recent years after the time when older males
in the population were fully grown. Bears with prior capture history
were either larger or similar in stature and mass to bears captured for
the first time, indicating that research activities did not influence
trends in the data.
The effect of sea ice conditions on the mass and size of subadult
males suggests that, if sea ice conditions changed over time, this
factor could be associated with the observed declines in these
measures. While the sea ice metric used in Rode et al. (2007, p. 3) was
meaningful to the foraging success of polar bears, recent habitat
analyses have resulted in improvements in the understanding of
preferred sea ice conditions of bears in the Southern Beaufort Sea
population. Durner et al. (2007, pp. 6, 9) recently identified optimal
polar bear habitat based on bathymetry (water depth), proximity to
land, sea ice concentration, and distance to sea ice edges using
resource selection functions. The sum of the monthly extent of this
optimal habitat for each year within the range of the Southern Beaufort
Sea population (Amstrup et al. 2004, p. 670) was strongly correlated
with the Rode et al. (2007, p. 10) sea ice metric for the 1982-2006
period. This suggests that the Rode et al. (2007, p. 10) sea ice metric
effectively quantified important habitat value. While the Rode et al.
(2007, p. 10) sea ice metric did not exhibit a significantly negative
trend over time, the optimal habitat available to bears in the southern
Beaufort Sea as identified by Durner et al. (2007, pp. 5-6) did
significantly decline between 1982 and 2006. This further supports the
observation that the declining trend in bear size and condition over
time were associated with a declining trend in availability of foraging
habitat, particularly for subadult males whose mass and stature were
related to sea ice conditions.
Rode et al. (2007, p. 12) concludes that the declines in mass and
body condition index of subadult males, declines in growth of males and
females, and declines in cub recruitment and survival suggest that
polar bears of the Southern Beaufort Sea population have experienced a
declining trend in nutritional status. The significant relationship
between several of these measurements and sea ice cover over the
continental shelf suggests that nutritional limitations may be
associated with changing sea ice conditions.
Regehr et al. (2007b, p. 3) used multistate capture-recapture
models that classified individual polar bears by sex, age, and
reproductive category to evaluate the effects of declines in the extent
and duration of sea ice on survival and breeding probabilities for
polar bears in the Southern Beaufort Sea population. The study
incorporated data collected from 2001-2006. Key elements of the models
were the dependence of survival on the duration of the ice-free period
over the continental shelf in the southern Beaufort Sea region, and
variation in breeding probabilities over time. Other factors considered
included harvest mortality, uneven capture probability, and temporary
emigrations from the study area. Results of Regehr et al. (2007b, p. 1)
reveal that in 2001 and 2002, the ice-free period was relatively short
(mean 92 days) and survival of adult female polar bears was high
(approximately 0.99). In 2004 and 2005, the ice-free period was long
(mean 135 days) and survival of adult female polar bears was lower
(approximately 0.77). Breeding and cub-of-the-year litter survival also
declined from high rates in early years to lower rates in latter years
of the study. The short duration of the study (5 years) introduced
uncertainty associated with the logistic relationship between the sea
ice covariate and survival. However, the most supported noncovariate
models (i.e., that excluded ice as a covariate) also estimated declines
in survival and breeding from 2001 to 2005 that were in close agreement
to the declines estimated by the full model set.
Although the precision of vital rates estimated by Regehr et al.
(2007b, pp. 17-18) was low, subsequent analyses (Hunter et al. 2007, p.
6) indicated that the declines in vital rates associated with longer
ice-free periods have ramifications for the trend of the Southern
Beaufort Sea population (i.e., result in a declining population trend).
The Southern Beaufort Sea population occupies habitats similar to four
other populations (Chukchi, Laptev, Kara, and Barents Seas) which
represent over one-third of the world's polar bears. These areas have
experienced sea ice declines in recent years that have been more severe
than those experienced in the southern Beaufort Sea (Durner et al.
2007, pp. 32-33), and declining trends in status for these populations
are projected to be similar to or greater than those projected for the
Southern Beaufort Sea population (Amstrup et al. 2007, pp 7-8, 32).
Northern Beaufort Sea
The Northern Beaufort Sea population, unlike the Southern Beaufort
Sea and Western Hudson Bay populations, is located in a region where
sea ice converges on shorelines throughout most of the year. Stirling
et al. (2007, pp. 1-6) used open population capture-recapture models of
data collected from 1971-2006 to assess the relationship between polar
bear survival and sex, age, time period, and a number of environmental
covariates in order to assess population trends. Three covariates, two
related to sea ice habitat and yearly seal productivity, were used to
assess the recapture probability for estimates of long-term trends in
the size of the Northern Beaufort Sea population (Stirling et al. 2007,
pp. 4-8). Associations between survival estimates and the three
covariates (sea ice habitat variables and seal abundance) were not, in
general, supported by the data. Population estimates (model averaged)
from 2004-2006 (980) were not significantly different from estimates
for the periods of 1972-1975 (745) and 1985-1987 (867). The abundance
during the three sampling periods, 1972-1975, 1985-1987, and 2004-2006
may be slightly low because (1) some bears residing in the extreme
northern portions of the population may not have been equally available
for capture and (2) the number of polar bears around Prince Patrick
Island was not large relative to the rest of the population. Stirling
et al. (2007, p. 10) concluded that currently the Northern Beaufort Sea
population appears to be stable, probably because ice conditions remain
suitable for feeding through much of the summer and fall in most years
and harvest has not exceeded sustainable levels.
[[Page 28270]]
Other Populations
As noted earlier in the ``Distribution and Movement'' and the
``Polar Bear Seasonal Distribution Patterns Within Annual Activity
Areas'' sections of this final rule, Stirling and Parkinson (2006, pp.
261-275) investigated ice break-up relative to distribution changes in
five other polar bear populations in Canada: Foxe Basin, Baffin Bay,
Davis Strait, Western Hudson Bay, and Eastern Hudson Bay. They found
that sea-ice break-up in Foxe Basin has been occurring about 6 days
earlier each decade; ice break-up in Baffin Bay has been occurring 6 to
7 days earlier per decade; and ice break-up in Western Hudson Bay has
been occurring 7 to 8 days earlier per decade. Although long-term
results from Davis Strait were not conclusive, particularly because the
maximum percentage of ice cover in Davis Strait varies considerably
more between years than in western Hudson Bay, Foxe Basin, or Baffin
Bay, Stirling and Parkinson (2006, p. 269) did document a negative
shortterm trend from 1991 to 2004 in Davis Strait. In eastern Hudson
Bay, there was not a statistically significant trend toward earlier
sea-ice break-up.
In four populations, Western Hudson Bay, Foxe Basin, Baffin Bay,
and Davis Strait, residents of coastal settlements have reported seeing
more polar bears and having more problem bear encounters during the
open-water season, particularly in the fall. In those areas, the
increased numbers of sightings, as well as an increase in the number of
problem bears handled at Churchill, Manitoba, have been interpreted as
indicative of an increase in population size. As discussed earlier, the
declines in population size, condition, and survival of young bears in
the Western Hudson Bay population as a consequence of earlier sea ice
break-up brought about by climate warming have all been well documented
(Stirling et al. 1999, p. 294; Gagnon and Gough 2005; Regehr et al.
2007a, p. 2,680). In Baffin Bay, the available data suggest that the
population is being overharvested, so the reason for seeing more polar
bears is unlikely to be an increase in population size. Ongoing
research in Davis Strait (Peacock et al. 2007, pp. 6-7) indicates that
this population may be larger than previously believed, which may at
first seem inconsistent with the Stirling and Parkinson (2006, pp. 269-
270) hypothesis of declining populations over time. This observation,
however, is not equilavent to an indication of population growth. The
quality of previous population estimates for this region, and the lack
of complete coverage of sampling used to derive the previous estimates,
preclude establishment of a trend in numbers. Although the timing and
location of availability of sea ice in Davis Strait may have been
declining (Amstrup et al. 2007, p. 25), changes in numbers and
distribution of harp seals at this time may support large numbers of
polar bears even if ringed seals are less available (Stirling and
Parkinson 2006, p. 270; Iverson et al. 2006, p. 110). As stated
previously, continuing loss of sea ice ultimately will have negative
effects on this population and other populations in the Seasonal Ice
ecoregion.
Polar Bear Populations without Long-term Data Sets
The remaining circumpolar polar bear populations either do not have
data sets of sufficiently long time series or do not have data sets of
comparable information that would allow the analysis of population
trends or relationships to various environmental factors and other
variables over time.
Projected Effects of Sea Ice Changes on Polar Bears
This section reviews a study by Durner et al. (2007) that evaluated
polar bear habitat features and future habitat distribution and
seasonal availability into the future. Studies by Amstrup et al. (2007)
and Hunter et al. (2007) are also reviewed which included new analyses
and approaches to examine trends and relationships for populations or
groups of populations based on commonly understood relationships with
habitat features and environmental conditions.
Habitat loss has been implicated as the greatest threat to the
survival for most species (Wilcove et al. 1998, p. 614). Extinction
theory suggests that the most vulnerable species are those that are
specialized (Davis et al. 2004), long-lived with long generation times
and low reproductive output (Bodmer et al. 1997), and carnivorous with
large geographic extents and low population densities (Viranta 2003, p.
1,275). Because of their specialized habitats and life history
constraints (Amstrup 2003, p. 605), polar bears have many qualities
that make their populations susceptible to the potential negative
impacts of sea ice loss resulting from climate change.
As discussed in detail in the ``Sea Ice Habitat'' section of this
final rule, contemporary observations and state-of-the-art models point
to a warming global climate, with some of the most accelerated changes
in Arctic regions. In the past 30 years, average world surface
temperatures have increased 0.2 degrees C per decade, but parts of the
Arctic have experienced warming at a rate of 10 times the world average
(Hansen et al. 2006). Since the late 1970s there have been major
reductions in summer (multi-year) sea ice extent (Meier et al. 2007,
pp. 428-434) (see detailed discussion in section entitled ``Summer Sea
Ice''); decreases in ice age (Rigor and Wallace 2004; Belchansky et al.
2005) and thickness (Rothrock et al. 1999; Tucker et al. 2001) (see
detailed discussion in section entitled ``Sea Ice Thickness''); and
increases in length of the summer melt period (Belchansky et al. 2004;
Stroeve et al. 2005) (see detailed discussion in section entitled
``Length of the Melt Period''). Recent observations further indicate
that winter ice extent is declining (Comiso 2006) (see detailed
discussion in section entitled ``Winter Sea Ice''). Empirical evidence
therefore establishes that the environment on which polar bears depend
for their survival has already changed substantially.
Without sea ice, polar bears lack the platform that allows them to
access prey. Longer melt seasons and reduced summer ice extent will
force polar bears into habitats where their hunting success will be
compromised (Derocher et al. 2004, p. 167; Stirling and Parkinson 2006,
pp. 271-272). Increases in the duration of the summer season, when
polar bears are restricted to land or forced over relatively
unproductive Arctic waters, may reduce individual survival and
ultimately population size (Derocher et al. 2004, pp. 165-170). Ice
seals typically occur in open-water during summer and therefore are
inaccessible to polar bears during this time (Harwood and Stirling
1992, p. 897). Thus, increases in the length of the summer melt season
have the potential to reduce annual availability of prey. In addition,
unusual movements, such as long distance swims to reach pack ice or
land, place polar bears at risk and may affect mortality (Monnett and
Gleason 2006, pp. 4-6). Because of the importance of sea ice to polar
bears, projecting patterns of ice habitat availability has direct
implications on their future status. This section reports on recent
studies that project the effects of sea ice change on polar bears.
Polar Bear Habitat
Durner et al. (2007, pp. 4-10) developed resource selection
functions (RSFs) to identify ice habitat characteristics selected by
polar bears and used these selection criteria as a basis for projecting
the future availability of optimal polar bear habitat throughout the
21st century. Location
[[Page 28271]]
data from satellite-collared polar bears and environmental data (e.g.,
sea ice concentration, bathymetry, etc.) were used to develop RSFs
(Manly et al. 2002), which are considered to be a quantitative measure
of habitat selection by polar bears. Important habitat features
identified in the RSF models were then used to determine the
availability of optimal polar bear habitat in GCM projections of 21st
century sea ice distribution. The following information has been
excerpted or extracted from Durner et al. (2007).
Durner et al. (2007, p. 5) used the outputs from 10 GCMs from the
IPCC 4AR report as inputs into RSFs models to forecast future
distribution and quantities of preferred polar bear habitat. The 10
GCMs were selected based on their ability to accurately simulate actual
ice extent derived from passive microwave satellite observations (as
described in DeWeaver 2007). The area of the assessment was the pelagic
ecoregion of the Arctic polar basin comprised of the Divergent and
Convergent ecoregions described by Amstrup et al. (2007, pp. 5-7) as
described previously in introductory materials contained in the ``Polar
Bear Ecoregions'' section of this final rule. Predictions of the amount
and rate of change in polar bear habitat varied among GCMs, but all
predicted net losses in the polar basin during the 21st century.
Projected losses in optimal habitat were greatest in the peripheral
seas of the polar basin (Divergent ecoregion) and projected to be
greatest in the Southern Beaufort, Chukchi, and Barents Seas. Observed
losses of sea ice in the Southern Beaufort, Chukchi, and Barents Seas
are occurring more rapidly than projected and suggest that trajectories
may vary at regional scales. Losses were least in high-latitude regions
where the RSF models predicted an initial increase in optimal habitat
followed by a modest decline. Optimal habitat changes in the Queen
Elizabeth and Arctic Basin units of the Canada-Greenland group
(Convergent ecoregion) were projected to be negligible if not
increasing. Very little optimal habitat was observed or predicted to
occur in the deep water regions of the central Arctic basin.
Durner et al. (2007, p. 13) found that the largest seasonal
reductions in habitat were predicted for spring and summer. Based on
the multi-model mean of 10 GCMs, the average area of optimal polar bear
habitat during summer in the polar basin declined from an observed 1.0
million sq km (0.39 million sq mi) in 1985-1995 (baseline) to a
projected multi-model average of 0.58 million sq km (0.23 million sq
mi) in 2045-2054 (42 percent decline), 0.36 million sq km (0.14 million
sq mi) in 2070-2079 (64 percent decline), and 0.32 million sq km (0.12
million sq mi) in 2090-2099 (68 percent decline). After summer melt,
most regions of the polar basin were projected to refreeze throughout
the 21st century. Therefore, winter losses of polar bear habitat were
more modest, from 1.7 million sq km (0.54 million sq mi) in 1985-1995
to 1.4 million sq km (0.55 million sq mi) in 2090-2099 (17 percent
decline). Simulated and projected rates of habitat loss during the late
20th and early 21st centuries by many GCMs tend to be less than
observed rates of loss during the past two decades; therefore, habitat
losses based on GCM multi-model averages were considered to be
conservative.
Large declines in optimal habitat are projected to occur in the
Alaska-Eurasia region (Divergent ecoregion) where 60-80 percent of the
polar bear's historical area of spring and summer habitat may disappear
by the end of the century (Durner et al. 2007). The Canada-Greenland
region (Convergent ecoregion) has historically contained less total
optimal habitat area, since it is geographically smaller than the
Alaska-Eurasia region. In the Queen Elizabeth region, while there is a
similar seasonal pattern to the projected loss of optimal habitat, the
magnitude of habitat loss was much less because of the predicted
stability of ice in this region (Durner et al. 2007, p. 13). The
projected rates of habitat loss over the 21st century were not constant
over time (Durner et al. 2007). Rates of loss tended to be greatest
during the second and third quarters of the century and then diminish
during the last quarter.
Losses in optimal habitat between 1985-1995 and 1996-2006
established an observed trajectory of change that was consistent with
the GCM projections; however, the observed rate of change (established
over a 10-year period), when extrapolated over the first half of the
21st century, resulted in more habitat lost than that projected by the
GCM ensemble average (i.e., faster than projected) (Durner et al. 2007,
p. 13).
The recent findings regarding the record minimum summer sea ice
conditions for 2007 reported by the NSIDC in Boulder, Colorado, were
not considered in the analysis of sea ice conditions reported by Durner
et al. (2007) because the full 2007 data were not yet available when
the analyses in Durner et al. (2007) were conducted. In 2007, sea ice
losses in the Canadian Archipelago and the polar basin Convergent
ecoregions were the largest observed to date; these areas had
previously been observed to be relatively stable (Durner et al. 2007).
Durner et al. (2007, pp. 18-19) indicated that less available
habitat will likely result in reduced polar bear populations, although
the precise relationship between habitat loss and population
demographics remains unknown. Other authors (Stirling and Parkinson
2006, pp. 271-272; Regehr et al. 2007, pp. 14-18; Hunter et al. 2007,
pp. 14-18; Rode et al. 2007, pp. 5-8; Amstrup et al. 2007, pp. 19-31)
present detailed information regarding demographic effects of loss of
sea ice habitat. Durner et al. (2007, pp. 19-20) does hypothesize that
density effects may become more important as polar bears make long
distance annual migrations from traditional winter areas to remnant
high-latitude summer areas already occupied by polar bears. Further,
Durner et al. (2007, p. 19) indicate that declines and large seasonal
swings in habitat availability and distribution may impose greater
impacts on pregnant females seeking denning habitat or leaving dens
with cubs than on males and other age groups. Durner et al. (2007, p.
19) found that although most winter habitats would be replenished
annually, long distance retreat of summer habitat may ultimately
preclude bears from seasonally returning to their traditional winter
ranges. Please also see the section in this final rule entitled
``Access to and Alteration of Denning Areas.''
Polar Bear Population Projections--Southern Beaufort Sea
Recent demographic analyses and modeling of the Southern Beaufort
Sea population have provided insight about the current and future
status of this population (Hunter et al. 2007; Regehr et al. 2007b).
This population occupies habitats similar to four other populations in
the Divergent ecoregion (Barents, Chukchi, Kara and Laptev Seas), which
together represent over one-third of the current worldwide polar bear
population. Because these other populations have experienced more
severe sea ice changes than the southern Beaufort Sea, this assessment
may understate the severity of the demographic impact that polar bear
populations face in the Divergent ecoregion.
Hunter et al. (2007, pp. 2-6) conducted a demographic analysis of
the Southern Beaufort Sea population using a life-cycle model
parameterized with vital rates estimated from capture-recapture data
collected between 2001 and 2006 (Regehr et al. 2007b, pp. 12-
[[Page 28272]]
14). Population growth rates and resultant population sizes were
projected both deterministically (i.e., assuming that environmental
conditions remained constant over time) and stochastically (i.e.,
allowing for environmental conditions to vary over time).
The deterministic model produced positive point estimates of
population growth rate under the conditions in 2001-2003, ranging from
1.02 to 1.08 (i.e., 2 to 8 percent growth per year), and negative point
estimates of population growth rate under the conditions in 2004-2005
when the region was ice-free for much longer, ranging from 0.77 to 0.90
(i.e., 23 to 10 percent decline per year) (Hunter et al. 2007, p. 8).
The overall growth rate estimate for the study period was about 0.997,
i.e., a 0.3 percent decline per year. Population growth rate was most
affected by adult female survival, with secondary effects from reduced
breeding probability (Hunter et al. 2007, p. 8). A main finding of this
analysis was that when there are more than 125 ice-free days over the
continental shelf of the broad southern Beaufort Sea region, population
growth rate declines precipitously.
The stochastic model incorporated environmental variability by
partitioning observed data into ``good'' years (2001-2003, short ice-
free period) and ``bad'' years (2004-2005, long ice-free period), and
evaluating the effect of the frequency of bad years on population
growth rate (Hunter et al. 2007, p. 6). Stochastic projections were
made in two ways: (1) Assuming a variable environment with the
probability of bad years equal to what has been observed recently
(1979-2006); and (2) assuming a variable environment described by
projections of sea ice conditions in outputs of 10 selected general
circulation models, as described by DeWeaver (2007). In the first
analysis, Hunter et al. (2007, pp. 12-13) found that the stochastic
growth rate declined with an increase in frequency of bad years, and
that if the frequency of bad years exceeded 17 percent the result would
be population decline. The observed frequency of bad years since 1979
indicated a decline of about 1 percent per year for the Southern
Beaufort Sea population. The average frequency of bad ice years from
1979-2006 was approximately 21 percent and from 2001-2005 was
approximately 40 percent. In the second analysis, using outputs from 10
GCMs to determine the frequency of bad years, Hunter et al. (2007, p.
13) estimated a 55 percent probability of decline to 1 percent of
current population size in 45 years using the non-covariate model set,
and a 40 percent probability of decline to 0.1 percent of current
population size in 45 years, also using the non-covariate model set.
Under sea ice conditions predicted by each of the 10 GCMs, the Southern
Beaufort Sea population was projected to experience a significant
decline within the next century. The demographic analyses of Hunter et
al. (2007, pp. 3-9) incorporated uncertainty arising from demographic
parameter estimation, the short time-series of capture-recapture data,
the form of the population model, environmental variation, and climate
projections. Support for the conclusions come from the agreement of
results from different statistical model sets, deterministic and
stochastic models, and models with and without climate forcing.
Polar Bear Population Projections--Range-wide
Amstrup et al. (2007, pp. 5-6) used two modeling approaches to
estimate the future status of polar bears in the 4 ecoregions they
delineated (see section entitled ``Polar Bear Ecoregions'' and Figure 2
above). First, they used a deterministic Carrying Capacity Model (CM)
that applied current polar bear densities to future GCM sea ice
projections to estimate potential future numbers of polar bears in each
of the 4 ecoregions. The second approach, a Bayesian Network Model
(BM), included the same annual measure of sea ice area as well as
measures of the spatial and temporal availability of sea ice. In
addition, the BM incorporated numerous other stressors that might
affect polar bear populations that were not incorporated in the
carrying capacity model. The CM ``provided estimates of the maximum
potential sizes of polar bear populations based on climate modeling
projections of the quantity of their habitat--but in the absence of
effects of any additional stressors * * *'' while the BM ``provided
estimates of how the presence of multiple stressors * * * may affect
polar bears'' (Amstrup et al. 2007, p. 5).
For both modeling approaches, the 19 polar bear populations were
grouped into 4 ecoregions, which are defined by the authors on the
basis of observed temporal and spatial patterns of ice formation and
ablation (melting or evaporation), observations of how polar bears
respond to these patterns, and projected future sea ice patterns (see
``Current Population Status and Trends'' section). The four ecoregions
are: (1) the Seasonal Ice ecoregion (which occurs mainly at the
southern extreme of the polar bear range); (2) the Archipelago
ecoregion of the central Canadian Arctic; (3) the polar basin Divergent
ecoregion; and (4) the polar Basin Convergent ecoregion (see Figure 2
above). The ecoregions group polar bear populations that share similar
environmental conditions and are, therefore, likely to respond in a
similar fashion to projected future conditions.
Carrying Capacity Model (CM)
The deterministic Carrying Capacity Model (CM) developed by Amstrup
et al. (2007) was used to estimate present-day polar bear density in
each ecoregion based on estimates of the number of polar bears and
amount of sea ice in each ecoregion. These density estimates were
defined as ``carrying capacities'' and applied to projected future sea
ice availability scenarios using the assumption that current ``carrying
capacities'' will apply to available habitat in the future. This
density and habitat index, therefore, allows a straightforward
comparison between the numbers of bears that are present now and the
number of bears which might be present in the future.
Amstrup et al. (2007, p. 8) defined total available sea ice habitat
in the Divergent and Convergent ecoregions as the 12-month sum of sea
ice cover (in km2) over the continental shelves of the 2 polar basin
ecoregions; in the Archipelago and Seasonal Ice ecoregions, all sea
ice-covered areas were considered shelf areas and defined as available
habitat (Amstrup et al. 2007, p. 9). In the Divergent and Convergent
ecoregions, available sea ice habitat was further defined as either
optimal (according to the definition of Durner et al. 2007, p. 9) or
nonoptimal; this further subdivision was not applied in the Archipelago
and Seasonal Ice ecoregions, which used the one measure of total
available sea ice habitat. Projections of future sea ice availability
for each ecoregion were derived from 10 General Circulation Models
(GCMs) selected by DeWeaver (2007, p. 21). Projections of polar bear
status based on habitat availability were determined for each of the
four ecoregions for 4 time periods: the present (year 0); 45 years from
the present (the decade of 2045-2055); 75 years from the present (2070-
2080); and 100 years (2090-2100) from the present. For added
perspective, the authors also looked at 10 years in the past (1985-
1995). Three sea ice habitat availability estimates were derived for
each time period, based on the minimum, mean, and maximum sea ice
projections from the 10-model GCM ensemble. Changes in habitat were
defined in terms of direction (contracting, stable or expanding) and
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magnitude (slow or none, moderate, or fast), while changes in carrying
capacity were defined in terms of direction (decreasing, stable or
increasing) and magnitude (low to none, moderate, or high) (Amstrup et
al. 2007, pp. 10-12). ``Outcomes of habitat change and carrying
capacity change were categorized into 4 composite summary categories to
describe the status of polar bear populations: enhanced, maintained,
decreased, or toward extirpation'' (Amstrup et al. 2007, p. 12).
The range of projected carrying capacities (numbers of bears
potentially remaining assuming historic densities were maintained)
varied by ecoregion and to whether maximum or minimum ice values were
used. Table 1 below presents the range of projected change in carrying
capacity of sea ice habitats for polar bears by ecoregion based on sea
ice projections from GCMs. The range of percentages represents minimum
and maximum projected changes in carrying capacity based on minimum and
maximum projected changes in the total area of sea ice habitat at
various times.
[GRAPHIC] [TIFF OMITTED] TR15MY08.011
All CM runs projected declines in polar bear carrying capacity in
all four ecoregions (Amstrup et al. 2007, Figure 9). Some CM model runs
project that polar bear carrying capacity will be trending ``toward
extirpation'' (the term ``toward extirpation'' is defined as one of
three combinations of habitat change and carrying capacity change
(i.e., contracting moderate habitat change, decreasing fast carrying
capacity change; contracting fast, decreasing moderate; contracting
fast, decreasing high)) in some ecoregions at certain times, but that
less severe carrying capacity changes will occur in other ecoregions
(see Tables 2 and 6, and Figure 9 in Amstrup et al. 2007). Using the 4
composite summary categories of Amstrup et al. (2007, p. 12), the
minimum sea ice extent model results project that a trend toward
extirpation of polar bears will appear in the polar basin Divergent
ecoregion by year 45 and in the Seasonal Ice ecoregion by year 75. Mean
sea ice extent model results project that a trend toward extirpation of
bears will appear in the polar basin Divergent ecoregion by year 75 and
in the polar basin Convergent ecoregion by year 100. None of the model
results project that a trend toward extirpation will appear in the
Archipelago region by year 100. Likewise, none of the model results
project that polar bear carrying capacity will increase or remain
stable in any ecoregion beyond 45 years. Although the pattern of
projected carrying capacity varied greatly among regions, the summary
finding was for a range-wide decline in polar bear carrying capacity of
between 10 and 22 percent by year 45 and between 22 and 32 percent by
year 75 (Amstrup et al. 2007, p. 20). CM results provide a conservative
view of the potential magnitude of change in bear carrying capacity
over time and area, because these results are based solely on the area
of sea ice present at a given point in time and do not consider the
effects of other population stressors.
Bayesian Network Model (BM)
To address other variables in addition to sea ice habitat that may
affect polar bears, Amstrup et al. (2007, pp. 5-6) developed a
prototype Bayesian Network Model (BM). The BM incorporated empirical
data and GCM projections of annual and seasonal sea ice availability,
numerous other stressors, and expert judgment regarding known
relationships between these stressors and polar bear demographics to
obtain probabilistic estimates of future polar bear distributions and
relative numbers. Anthropogenic stressors included human activities
that could affect distribution or abundance of polar bears, such as
hunting, oil and gas development, shipping, and direct bear-human
interactions. Natural stressors included changes in the availability of
primary and alternate prey and foraging areas, and occurrence of
parasites, disease, and predation. Environmental factors included
projected changes in total ice and optimal habitat, changes in the
distance that ice retreats from traditional autumn or winter foraging
areas, and changes in the number of months per year that ice is absent
in the continental shelf regions. Habitat changes, natural and
anthropogenic stressors, and environmental factors were evaluated for
their potential effects on the density and distribution of polar bears
and survival throughout their range. BM outcomes were defined according
to their collective influence on polar bear
[[Page 28274]]
population distribution and relative numbers with respect to current
conditions (e.g., larger than now, the same as now, smaller than now,
rare, or extinct) (Amstrup et al. 2007).
As a caveat to their results, the authors note that, because a BM
combines expert judgment and interpretation with quantitative and
qualitative empirical information, inputs from multiple experts are
usually incorporated into the structure and parameterization of a
``final'' BM. Because the BM in Amstrup et al. (2007) incorporates the
input of a single polar bear expert, the model should be viewed as an
``alpha'' level prototype (Marcot et al. 2006, cited in Amstrup et al.
2007, p.27) that would benefit from additional development and
refinement. Given this caveat, it is extremely important, while
interpreting model outcomes, to focus on the general direction and
magnitude of the probabilities of projected outcomes rather than the
actual numerical probabilities associated with each outcome. For
example, situations with high probability of a particular outcome
(e.g., of extinction) or consistent directional effect across sea ice
scenarios suggest a higher likelihood of that outcome as opposed to
situations where the probability is evenly spread across outcomes or
where there is large disagreement among different sea ice scenarios.
These considerations were central to the authors' interpretation of BM
results (Amstrup et al. 2007).
The overall outcomes from the BM indicate that in each of the four
ecoregions polar bear populations in the future are very likely to be
smaller and have a higher likelihood of experiencing multiple stressors
in comparison to the past or present. In the future, multiple natural
and anthropogenic stressors will likely become important, and negative
effects on all polar bear populations will be apparent by year 45 with
generally increased effects through year 100.
In the Seasonal Ice ecoregion the dominant outcome of the BM was
``extinct'' at all future time periods under all three GCM scenarios
used in the analysis, with low probabilities associated with
alternative outcomes, except for the minimum GCM scenario at year 45
(when the probability of alternative outcomes was around 44 percent).
The small probabilities for outcomes other than extinct suggest a trend
in this ecoregion toward probable extirpation by the mid-21st century.
In the polar basin Divergent ecoregion, ``extinct'' was also the
predominant outcome, with very low probabilities associated with
alternative outcomes (i.e., less then 15 percent probability of not
becoming extinct). The small probabilities for outcomes other than
extinct also suggest a trend in this ecoregion toward probable
extirpation by the mid-21st century. In the polar basin Convergent
ecoregion, population persistence at ``smaller in numbers'' or ``rare''
was the predominant outcome at year 45, but the probability of
extinction came to predominate (i.e., was greater than 60 percent) at
year 75 and year 100. In the Archipelago ecoregion, a smaller
population was the most probable outcome at year 45 under all GCM
scenarios. By year 75, the most probable outcome for this ecoregion (as
in the other ecoregions) across all GCM ice scenarios was population
persistence, albeit in lower numbers. Even late in the century,
however, the probability of a smaller than present population in the
Archipelago Ecoregion was relatively high. Therefore, Amstrup et al.
(2007) concluded that polar bears, in reduced numbers, could occur in
the Archipelago Ecoregion through the end of the century. The authors
note that the projected changes in sea ice conditions could result in
loss of approximately two-thirds of the world's current polar bear
population by the mid-21st century. They further note that, because the
observed trajectory of Arctic sea ice decline appears to be
underestimated by currently available models, these projections may be
conservative.
As part of the BM, Amstrup et al. (2007, pp. 29-31) conducted a
sensitivity analysis to determine the influence of model inputs and
found that the overall projected population outcome was greatly
influenced by changes in sea ice habitat. The Bayesian sensitivity
analysis found that 91 percent of the variation in the overall
predicted population outcome was determined by six variables. Four of
these six were sea ice related, including patterns of seasonal and
spatial distribution. The fifth variable among these top six was the
ecoregion being considered. Outcomes varied for ecoregions as a result
of differences in their sea ice characteristics. The sixth ranked
variable, with regard to overall population outcome, was the level of
intentional takes or harvest (overutilization). The stressors that
related to bear-human interactions, parasites and disease and
predation, and other natural or man-made factors provided a nominal
influence of less than 9 percent contribution to the status outcome.
Amstrup et al. (2007, pp. 22-24) characterize the types and
implications of uncertainty inherent to the carrying capacity and BM
modeling in their report. Analyses in this report contain three main
categories of uncertainty: (1) uncertainty in our understandings of the
biological, ecological, and climatological systems; (2) uncertainty in
the representation of those understandings in models and statistical
descriptions; and (3) uncertainty in model predictions. In addition,
Amstrup et al. (2007) discussed potential consequences of and efforts
to evaluate and minimize uncertainty in the analyses. We reiterate the
caveat that a BM combines expert judgment and interpretation with
quantitative and qualitative empirical information, therefore
necessitating inputs from multiple experts (if available) before it can
be considered final. We note again that because the BM presented in
Amstrup et al. (2007) incorporates the input of a single polar bear
expert, it should be viewed as a first-generation prototype (Marcot et
al. 2006, cited in Amstrup et al. 2007, p.27) that would benefit from
additional development.
Because the BM includes numerous qualitative inputs (including
expert assessment) and requires additional development (Amstrup et al.
2007, p. 27), we are more confident in the general direction and
magnitude of the projected outcomes rather than the actual numerical
probabilities associated with each outcome, and we are also more
confident in outcomes within the 45-year foreseeable future than in
outcomes over longer timeframes (e.g., year 75 and year 100 in Amstrup
et al. (2007)). We conclude that the outcomes of the BM are consistent
with ``the increasing volume of data confirming negative relationships
between polar bear welfare and sea ice decline'' (Amstrup et al. 2007,
p. 31), and parallel other assessments of both the demographic
parameter changes as well as trends in various factors that threaten
polar bears as described by Derocher et al. (2004), and in the proposed
rule to list polar bears as a threatened species (72 FR 1064). However,
because of the preliminary nature of the BM and levels of uncertainty
associated with the initial Bayesian Modeling efforts, we do not find
that the projected outcomes derived from the BM to be as reliable as
the data derived from the ensemble of climate models used by the
Service to gauge the loss of sea ice habitat over the next 45 years.
Both the proposed rule and the status assessment (Range Wide Status
Review of the Polar Bear (Ursus maritimus), Schliebe et al. 2006a),
underwent extensive peer review by impartial experts within the
disciplines of polar bear ecology, climatology, toxicology, seal
ecology, and traditional ecological knowledge, and thereby
[[Page 28275]]
represent a consensus on the conclusions in these documents. The more
recent projections from the BM exercise conducted by Amstrup et al.
(2007) are consistent with conclusions reached in the earlier
assessments that polar bear populations will continue to decline in the
future.
Polar Bear Mortality
As changes in habitat become more severe and seasonal rates of
change more rapid, catastrophic mortality events that have yet to be
realized on a large scale are expected to occur. Observations of
drownings and starved animals may be a prelude to such events.
Populations experiencing compromised physical condition will be
increasingly prone to sudden die-offs. While no information currently
exists to evaluate such events, the possibility of other forms of
unanticipated mortality are mentioned here because they have been
observed in other species (e.g., canine distemper in Caspian seals
(Phoca caspica) (Kuiken et al. 2006, p. 321) and phocine distemper
virus in harbor seals (Heide-Jorgensen et al. 1992, cited in Goodman
1998).
Conclusion Regarding Current and Projected Demographic Effects of
Habitat Changes on Polar Bears
Polar bears have evolved in a sea ice environment that serves as an
essential platform from which they meet life functions. Polar bears
currently are exposed to a rapidly changing sea ice platform, and in
many regions of the Arctic already are being affected by these changes.
Sea ice changes are projected to continue and positive feedbacks are
expected to amplify changes in the arctic which will hasten sea ice
retreat. These factors will likely negatively impact polar bears by
increasing energetic demands of seeking prey. Remaining members of many
populations will be redistributed, at least seasonally, into
terrestrial or offshore habitats with marginal values for feeding, and
increasing levels of negative bear-human interactions. Increasing
nutritional stress will coincide with exposure to numerous other
potential stressors. Polar bears in some regions already are
demonstrating reduced physical condition, reduced reproductive success,
and increased mortality. As changes in habitat become more severe and
seasonal rates of change more rapid, catastrophic mortality events that
have yet to be realized on a large scale are expected to occur.
Observations of drownings and starved animals may be a prelude to such
events. These changes will in time occur throughout the world-wide
range of polar bears. Ultimately, these inter-related factors will
result in range-wide population declines. Populations in different
ecoregions will experience different rates of change and timing of
impacts. Within the foreseeable future, however, all ecoregions will be
affected.
Conclusion for Factor A
Rationale
Polar bears evolved over thousands of years to life in a sea ice
environment. They depend on the sea ice-dominated ecosystem to support
essential life functions. Sea ice provides a platform for hunting and
feeding, for seeking mates and breeding, for movement to terrestrial
maternity denning areas and occasionally for maternity denning, for
resting, and for long-distance movements. The sea ice ecosystem
supports ringed seals, primary prey for polar bears, and other marine
mammals that are also part of their prey base.
Sea ice is rapidly diminishing throughout the Arctic. Patterns of
increased temperatures, earlier onset of and longer melting periods,
later onset of freeze-up, increased rain-on-snow events, and potential
reductions in snowfall are occurring. In addition, positive feedback
systems (i.e., the sea-ice albedo feedback mechanism) and naturally
occurring events, such as warm water intrusion into the Arctic and
changing atmospheric wind patterns, can operate to amplify the effects
of these phenomena. As a result, there is fragmentation of sea ice, a
dramatic increase in the extent of open water areas seasonally,
reduction in the extent and area of sea ice in all seasons, retraction
of sea ice away from productive continental shelf areas throughout the
polar basin, reduction of the amount of heavier and more stable multi-
year ice, and declining thickness and quality of shore-fast ice. Such
events are interrelated and combine to decrease the extent and quality
of sea ice as polar bear habitat during all seasons and particularly
during the spring-summer period. Arctic sea ice will continue to be
affected by climate change. Due to the long persistence time of certain
GHGs in the atmosphere, the current and projected patterns of GHG
emissions over the next few decades, and interactions among climate
processes, climate changes for the next 40-50 years are already largely
set (IPCC 2007, p. 749; J. Overland, NOAA, in litt. to the Service,
2007). Climate change effects on sea ice and polar bears will continue
through this timeframe and very likely further into the future.
Changes in sea ice negatively impact polar bears by increasing the
energetic demands of movement in seeking prey, causing seasonal
redistribution of substantial portions of populations into marginal ice
or terrestrial habitats with limited values for feeding, and increasing
the susceptibility of bears to other stressors, some of which follow.
As the sea ice edge retracts to deeper, less productive polar basin
waters, polar bears will face increased competition for limited food
resources, increased open water swimming with increased risk of
drowning, increasing interaction with humans with negative
consequences, and declining numbers that may be unable to sustain
ongoing harvests.
Changes in sea ice will reduce productivity of most ice seal
species, result in changes in composition of seal species indigenous to
some areas, and eventually result in a decrease in seal abundance.
These changes will decrease availability or timing of availability of
seals as food for polar bears. Ringed seals will likely remain
distributed in shallower, more productive southerly areas that are
losing their seasonal sea ice and becoming characterized by vast
expanses of open water in the spring-summer-fall period. As a result,
the seals will remain unavailable as prey to polar bears during
critical times of the year. These factors will, in turn, result in a
steady decline in the physical condition of polar bears, which has
proven to lead to population-level demographic declines in reproduction
and survival.
The ultimate net effect of these inter-related factors will be that
polar bear populations will decline or continue to decline. Not all
populations will be affected evenly in the level, rate, and timing of
effects, but we have determined that, within the foreseeable future,
all polar bear populations will be negatively affected. This
determination is broadly supported by results of the USGS studies, and
within the professional community, including a majority of polar bear
experts who peer reviewed the proposed rule. The PBSG evaluated
potential impacts to the polar bear, and determined that the observed
and projected changes in sea ice habitat would negatively affect the
species (Aars et al. 2006, p. 47). The IUCN, based on the PBSG
assessment, reclassified polar bears as ``vulnerable.'' Similarly,
their justification for the classification was the projected change in
sea ice, effect of climate change on polar bear condition, and
corresponding effect on reproduction and survival, which have been
associated with a steady and persistent decline in abundance.
A series of analyses of the best available scientific information
on the
[[Page 28276]]
ecology and demography of polar bears were recently undertaken by the
USGS at the request of the Secretary of the Interior. These include
additional analyses of some specific populations (Southern Beaufort
Sea, Northern Beaufort Sea, Southern Husdon Bay), analysis of optimal
polar bear habitat and projections of optimal habitat through the 21st
century, projections of the status of populations into the future, and
information from a pilot study regarding the increase in travel
distance for pregnant females to reach denning areas on the North Slope
of Alaska with insights to potential consequences. Results of the
analyses are detailed within this final rule. This significant effort
enhanced and reaffirmed our understanding of the interrelationships of
ecological factors and the future status of polar bear populations.
The USGS report by Amstrup et al. (2007) synthesized historical and
recent scientific information and conducted two modeling exercises to
provide a range-wide assessment of the current and projected future
status of polar bears occupying four ecoregions. In this effort, using
two approaches and validation processes, the authors described four
``ecoregions'' based on current and projected sea ice conditions and
developed a suite of population projections by ecoregion. This
assessment helps inform us on the future fate of polar bear populations
subject to a rapidly changing sea ice environment. In summary, polar
bear populations within all ecoregions were not uniformly impacted, but
all populations within ecoregions declined, with the severity of
declines depending on the sea ice projections (minimal, mean, maximum),
season of the year, and area. Amstrup et al. (2007, p. 36) forecasts
the extirpation of populations in the Seasonal Ice, and polar basin
Divergent ecoregions by the mid-21st century. Because the BM presented
in the report be viewed as a first-generation prototype (Marcot et al.
2006, cited in Amstrup et al. 2007, p.27) that would benefit from
additional development, and because the BM includes numerous
qualitative inputs (including expert assessment), we are more confident
in the general direction and magnitude of the projected outcomes rather
than the actual numerical probabilities associated with each outcome,
and we are also more confident in outcomes within the 45-year
foreseeable future.
In the southerly populations (Seasonal Ice ecoregion) of Western
Hudson Bay, Southern Hudson Bay, Foxe Basin, Davis Strait, and Baffin
Bay, polar bears already experience stress from seasonal fasting due to
early sea ice retreat, and have or will be affected earliest (Stirling
and Parkinson 2006, p. 272; Obbard et al. 2006, pp. 6-7; Obbard et al.
2007, p. 14). Populations in the Divergent ecoregion, including the
Chukchi Sea, Barents Sea, Southern Beaufort Sea, Kara Sea, and Laptev
Sea will, or are currently, experiencing initial effects of changes in
sea ice (Rode et al. 2007, p. 12; Regehr et al. 2007b, pp. 18-19;
Hunter et al. 2007, p. 19; Amstrup et al. 2007, p. 36). These
populations are vulnerable to large-scale dramatic seasonal
fluctuations in ice movements, decreased abundance and access to prey,
and increased energetic costs of hunting. Polar bear populations
inhabiting the central island archipelago of Canada (Archipelago
ecoregion) will also be affected but to lesser degrees and later in
time. These more northerly populations (Norwegian Bay, Lancaster Sound,
M'Clintock Channel, Viscount Melville Sound, Kane Basin, and the Gulf
of Boothia) are expected to be affected last due to the buffering
effects of the island archipelago complex, which lessens effects of
oceanic currents and seasonal retractions of ice and retains a higher
proportion of heavy, more stable, multi-year sea ice. A caution in this
evaluation is that historical record minimum summer ice conditions in
September 2007 resulted in vast ice-free areas that encroached into the
area of permanent polar sea ice in the central Arctic Basin, and the
Northwest Passage was open for the first time in recorded history. The
record low sea ice conditions of 2007 are an extension of an
accelerating trend of minimum sea ice conditions and further support
the concern that current sea ice models may be conservative and
underestimate the rate and level of change expected in the future.
Although climate change may improve conditions for polar bears in
some high latitude areas where harsh conditions currently prevail,
these improvements will only be transitory. Continued warming will lead
to reduced numbers and reduced distribution of polar bears range-wide
(Regehr et al. 2007b, p. 18; Derocher et al. 2004, p. 19; Hunter et al.
2007, p. 14; Amstrup et al. 2007, p. 36). Projected declines in the sea
ice for most parts of the Arctic are long-term, severe, and occurring
at a pace that is unprecedented (Comiso 2003; ACIA 2004; Holland et al.
2006, pp. 1-5); therefore, the most northerly polar bear populations
will experience declines in demographic parameters similar to those
observed in the Western Hudson Bay population, along with changes in
distribution and other currently unknown ecological responses (Derocher
et al. 2004, p. 171; Aars et al. 2006, p. 47). Ultimately, all polar
bear populations will be affected within the foreseeable future, and
the species will likely become in danger of extinction throughout all
of its range.
It is possible, even with the total loss of summer sea ice, that a
small number of polar bears could survive, provided there is adequate
seasonal ice cover to serve as a platform for hunting opportunities,
and that sea ice is present for a period of time adequate for
replenishment of body fat stores and condition. However, this
possibility is difficult to evaluate. As a species, polar bears have
survived at least two warming periods, the Last Interglacial (140,000--
115,000 years Before Present (BP)), and the Holocene Thermal maximum
(ca 12,000--4,000 BP) (Dansgaard et al. 1993, p. 218; Dahl-Jensen et
al. 1998, p. 268). Greenland ice cores revealed that the climate was
much more variable in the past, and some of the historical shifts
between the warm and cold periods were rapid, suggesting that the
recent relative climate stability seen during the Holocene may be an
exception (Dansgaard et al. 1993, p. 218). While the precise impacts of
these warming periods on polar bears and the Arctic sea ice habitat are
unknown, the ability of polar bears to adapt to alternative food
sources seems extremely limited given the caloric requirements of adult
polar bears and the documented effects of nutritional stress on
reproductive success.
In addition to the effects of climate change on sea ice, we have
also evaluated changes to habitat in the Arctic as a result of
increased pressure from human activities. Increased human activities
include a larger footprint from the number of people resident to the
area, increased levels of oil and gas exploration and development and
expanding areas of interest, and potential increases in shipping.
Cumulatively, these activities may result in alteration of polar bear
habitat. Any potential impact from these activities would be additive
to other factors already or potentially affecting polar bears and their
habitat. We acknowledge that the sum total of documented direct impacts
from these activities in the past have been minimal. We also
acknowledge, as discussed further under the Factor D analysis in this
final rule, that national and local concerns for these activities has
resulted in the development and implementation of multi-layered
regulatory programs to monitor and eliminate or minimize potential
effects. Regarding potential
[[Page 28277]]
shipping activities within the Arctic, increased future monitoring is
necessary to enhance the understanding of potential effects from this
activity.
Determination for Factor A
We have evaluated the best available scientific and commercial
information on polar bear habitat and the current and projected effects
of various factors (including climate change) on the quantity and
distribution of polar bear habitat, and have determined that the polar
bear is threatened throughout its entire range by ongoing and projected
changes in sea ice habitat (i.e., the species is likely to become
endangered throughout all of its range within the foreseeable future
due to habitat loss).
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Use of polar bears for commercial, recreational, scientific, and
educational purposes is generally low, with the exception of harvest.
Use for nonlethal scientific purposes is highly regulated and does not
pose a threat to populations. Similarly, the regulated, low-level use
for educational purposes through placement of cubs or orphaned animals
into zoos or public display facilities or through public viewing is not
a threat to populations. Sport harvest of polar bears in Canada is
discussed in the harvest section below. For purposes of population
assessment, no distinction is made between harvest uses for sport or
subsistence. Take associated with defense of life, scientific research,
illegal take, and other forms of take are generally included in harvest
management statistics, so this section also addresses all forms of
take, including bear-human interactions.
Overview of Harvest
Polar bears historically have been, and continue to be, an
important renewable resource for coastal communities throughout the
Arctic (Lentfer 1976, p. 209; Amstrup and DeMaster 1988, p. 41;
Servheen et al. 1999, p. 257, Table 14.1; Schliebe et al. 2006a, p.
72). Polar bears and polar bear hunting remain an important part of
indigenous peoples' culture, and polar bear hunting is a source of
pride, prestige, and accomplishment. Polar bears provide a source of
meat and raw materials for handicrafts, including functional clothing
such as mittens, boots (mukluks), parka ruffs, and pants (Nageak et al.
1991, p. 6).
Prior to the 1950s, most hunting was by indigenous people for
subsistence purposes. Increased sport hunting in the 1950s and 1960s
resulted in population declines (Prestrud and Stirling 1994, p. 113).
International concern about the status of polar bears resulted in
biologists from the five polar bear range nations forming the Polar
Bear Specialist Group (PBSG) within the IUCN SSC (Servheen et al. 1999,
p. 262). The PBSG was largely responsible for the development and
ratification of the 1973 International Agreement on the Conservation of
Polar Bears (1973 Polar Bear Agreement) (Prestrud and Stirling 1994, p.
114) (see detailed discussion under Factor D, ``Inadequacy of Existing
Regulatory Mechanisms'' below). The 1973 Polar Bear Agreement and the
actions of the member nations are credited with the recovery of polar
bears following the previous period of overexploitation.
Harvest Management by Nation
Canada
Canada manages or shares management responsibility for 13 of the
world's 19 polar bear populations (Kane Basin, Baffin Bay, Davis
Strait, Foxe Basin, Western Hudson Bay, Southern Hudson Bay, Gulf of
Boothia, Lancaster Sound, Norwegian Bay, M'Clintock Channel, Viscount
Melville Sound, Northern Beaufort Sea, and Southern Beaufort Sea).
Wildlife management is a shared responsibility of the Provincial and
Territorial governments. The Federal government (Canadian Wildlife
Service) has an ongoing research program and is involved in management
of wildlife populations shared with other jurisdictions, especially
ones with other nations (e.g., where a polar bear stock ranges across
an international boundary). To facilitate and coordinate management of
polar bears, Canada has formed the Federal Provincial Technical
Committee for Polar Bear Research and Management (PBTC) and the Federal
Provincial Administrative Committee for Polar Bear Research and
Management (PBAC). These committees include Provincial, Territorial,
and Federal representatives who meet annually to review research and
management activities.
Polar bears are harvested in Canada by native residents and by
sport hunters employing native guides. All human-caused mortality
(i.e., hunting, defense of life, and incidental kills) is included in a
total allowable harvest. Inuit people from communities in Nunavut,
Northwest Territories (NWT), Manitoba, Labrador, Newfoundland, and
Quebec conduct hunting. In Ontario, the Cree and the Inuit can harvest
polar bears. In Nunavut and NWT, each community obtains an annual
harvest quota that is based on the best available scientific
information and monitored through distribution of harvest tags to local
hunter groups, who work with scientists to set quotas. Native hunters
may use their harvest tags to guide sport hunts. The majority of sport
hunters in Canada are U.S. citizens. In 1994 the MMPA was amended to
allow these hunters to import their trophies into the United States if
the bears had been taken in a legal manner from sustainably managed
populations.
The Canadian system places tight controls on the size and design of
harvest limits and harvest reporting. Quotas are reduced in response to
population declines (Aars et al. 2006, p. 11). In 2004, existing polar
bear harvest practices caused concern when Nunavut identified quota
increases for 8 populations, 5 of which are shared with other
jurisdictions (Lunn et al. 2005, p. 3). Quota increases were largely
based on indigenous knowledge (the Nunavut equivalent of traditional
ecological knowledge) and the perception that some populations were
increasing from historic levels. Nunavut did not coordinate these
changes with adjacent jurisdictions that share management
responsibility. This action resulted in an increase in the quota of
allowable harvest from 398 bears in 2003-2004 to 507 bears in 2004-2005
(Lunn et al. 2005, p. 14, Table 6). Discussions between jurisdictions,
designed to finalize cooperative agreements regarding the shared
quotas, continue.
Greenland
The management of polar bear harvest in Greenland is through a
system introduced in 1993 that allows only full-time hunters living a
subsistence lifestyle to hunt polar bears. Licenses are issued annually
for a small fee contingent upon reporting harvest during the prior 12
months. Until 2006, no quotas were in place, but harvest statistics
were collected through Piniarneq, a local reporting program (Born and
Sonne 2005, p. 137). In January 2006, a new harvest monitoring and
quota system was implemented (L[oslash]nstrup 2005, p. 133). Annual
quotas are determined in consideration of international agreements,
biological advice, user knowledge, and consultation with the Hunting
Council. However, for the Baffin Bay and Kane Basin populations, which
are shared with Canada, evaluation of quota levels, harvest levels for
shared populations occurring in other jurisdictions, and best available
estimates of population numbers indicate that the quotas and combined
jurisdictions harvest levels are not sustainable and the enforcement of
harvest quotas may not be effective
[[Page 28278]]
(Aars et al. 2006). These populations are thought to be reduced and the
trend is thought to be declining. Greenland is considering the
allocation of part of the quota for sport hunting (L[oslash]nstrup
2005, p. 133).
Norway
Norway and Russia share jurisdiction over the Barents Sea
population of polar bears. Management in Norway is the responsibility
of the Ministry of the Environment (Wiig et al. 1995, p. 110). The
commercial, subsistence, or sport hunting of polar bears in Norway is
prohibited (Wiig et al. 1995, p. 110). Bears may only be killed in
self-defense or protection of property, and all kills, including
``mercy'' kills, must be reported and recorded (Gjertz and Scheie 1998,
p. 337).
Russia
The commercial, subsistence, or sport hunting of polar bears in
Russia is prohibited. Some bears are killed in defense of life, and a
small number of cubs (1 or 2 per year) have been taken in the past for
zoos. Despite the 1956 ban on hunting polar bears, illegal harvest is
occurring in the Chukchi Sea region and elsewhere where there is
limited monitoring or enforcement (Aars et al. 2007, p. 9; Belikov et
al. 2005, p. 153). The level of illegal harvest in Russian populations
is unknown. There is a significant interest in reopening subsistence
hunting by indigenous people. The combined ongoing illegal hunting in
Russia and legal subsistence harvest in Alaska is a concern for the
Chukchi Sea population, which may be in decline (USFWS 2003, p. 1).
This mutual concern resulted in the United States and Russia signing
the ``Agreement between the United States of America and the Russian
Federation on the Conservation and Management of the Alaska-Chukotka
Polar Bear Population'' (Bilateral Agreement) on October 16, 2000. On
January 12, 2007, the President of the United States signed into law
the ``Magnuson-Stevens Fishery Conservation and Management
Reauthorization Act of 2006.'' This Act added Title V to the MMPA,
which implements the Bilateral Agreement. On September 22, 2007, the
governments of the United States and Russian Federation exchanged
instruments of ratification. Full implementation of the Bilateral
Agreement is intended to address overharvest, but implementation has
not yet occurred (Schliebe et al. 2005, p. 75). In the United States,
Presidential appointment of Commissioners necessary to implement the
Bilateral Agreement is pending. Accordingly, we have not relied on
implementation of the Bilateral Agreement in our assessment of the
threat of overutilization of polar bears (see ``International
Agreements and Oversight'' section under Factor D below).
United States
Polar bear subsistence hunting by coastal Alaska Natives has
occurred for centuries (Lentfer 1976, p. 209). Polar bear hunting and
the commercial sale of skins took on increasing economic importance to
Alaskan Natives when whaling began in the 1850s, and a market for pelts
emerged (Lentfer 1976, p. 209). Trophy hunting using aircraft began in
the late 1940s. In the 1960s, State of Alaska hunting regulations
became more restrictive, and in 1972 aircraft-assisted hunting was
stopped altogether (Lentfer 1976, p. 209). Between 1954 and 1972, an
average of 222 polar bears was harvested annually, resulting in a
population decline (Amstrup et al. 1986, p. 246).
Passage of the MMPA in 1972 established a moratorium on the sport
or commercial hunting of polar bears in Alaska. However, the MMPA
exempts harvest, conducted in a nonwasteful manner, of polar bears by
coastal dwelling Alaska Natives for subsistence and handicraft
purposes. The MMPA and its implementing regulations also prohibit the
commercial sale of any marine mammal parts or products except those
that qualify as authentic articles of handicrafts or clothing created
by Alaska Natives. The Service cooperates with the Alaska Nanuuq
Commission, an Alaska Native organization that represents Native
villages in North and Northwest Alaska on matters concerning the
conservation and sustainable subsistence use of the polar bear, to
address polar bear subsistence harvest issues. In addition, for the
Southern Beaufort Sea population, hunting is regulated voluntarily and
effectively through an agreement between the Inuvialuit of Canada and
the Inupiat of Alaska (Brower et al. 2002, p. 371) (see ``International
Agreements and Oversight'' section under Factor D below). The harvest
is monitored by the Service's marking and tagging program. Illegal take
or trade is monitored by the Service's law enforcement program.
The MMPA was amended in 1994 to allow for the import into the
United States of sport-hunted polar bear trophies legally taken by the
importer in Canada. Prior to issuing a permit for import of such
trophies, the Service must have found that Canada has a monitored and
enforced sport-hunting program consistent with the purposes of the 1973
Polar Bear Agreement, and that the program is based on scientifically
sound quotas ensuring the maintenance of the population at a
sustainable level. Six populations were approved for import of polar
bear trophies (62 FR 7302, 64 FR 1529, 66 FR 50843) under regulations
implementing section 104(c)(5) of the MMPA (50 CFR 18.30). However, as
of the effective date of the threatened listing, authorization for the
import of sport hunted polar bear trophies is no longer available under
section 104(c)(5) of the MMPA.
Harvest Summary
A thorough review and evaluation of past and current harvest,
including other forms of removal, for all populations has been
described in the Polar Bear Status Review (Schliebe et al. 2006a, pp.
108-127). The Status Review is available on our Marine Mammal website
(http://alaska.fws.gov/fisheries/mmm/polarbear/issues.htm). Table 2 of
the Status Review provides a summary of harvest statistics from the
populations and is included herein as a reference. The total harvest
and other forms of removal were considered in the summary analysis.
Five populations (including four that are hunted) have no estimate
of potential risk from overharvest, since adequate demographic
information necessary to conduct a population viability analysis and
risk assessment are not available (see Table 1 below). For one of the
populations, Chukchi Sea, severe overharvest is suspected to have
occurred during the past 10-15 years, and anecdotal information
suggests the population is in decline (Aars et al. 2006, pp. 34-35).
The Chukchi Sea, Baffin Bay, Kane Basin, and Western Hudson Bay
populations may be overharvested (Aars et al. 2006, pp. 40, 44-46). In
other populations, including East Greenland and Davis Strait,
substantial harvest occurs annually in the absence of scientifically
derived population estimates (Aars et al. 2006, pp. 39, 46).
Considerable debate has occurred regarding the recent changes in
population estimates based on indigenous or local knowledge (Aars et
al. 2006, p. 57) and subsequent quota increases for some populations in
Nunavut (Lunn et al. 2005, p. 20). The PBSG (Aars et al. 2006, p. 57),
by resolution, recommended that ``polar bear harvest can be increased
on the basis of local and traditional knowledge only if supported by
scientifically collected information.'' Increased polar bear
observations along the coast may be attributed to changes in bear
distribution due to lack of suitable ice habitat rather than to
increased
[[Page 28279]]
population size (Stirling and Parkinson 2006, p. 266). Additional data
are needed to reconcile these differing interpretations.
As discussed in Factor A, Amstrup et al. (2007, p.30) used a first-
generation BM model to forecast the range-wide status of polar bears
during the 21st century, factoring in a number of stressors, including
intentional take or harvest. The authors conducted a sensitivity
analysis to determine the importance and influence of the stressors on
the population forecast. Their analysis indicated that intentional take
was the 4th ranked .potential stressor, and could exacerbate the
effects of habitat loss in the future. Because of the preliminary
nature of the BM results, we are more confident in the general
direction and magnitude of the projected outcomes rather than the
actual numerical probabilities associated with each outcome.
Nonetheless, the relatively high ranking for this stressor indicates
that effective management of hunting and evaluation of sustainable
harvest levels will continue to be important to minimize effects for
populations experiencing increased stress.
[GRAPHIC] [TIFF OMITTED] TR15MY08.012
Bear-Human Interactions
Polar bears come into conflict with humans when they scavenge for
food at sites of human habitation, and also because they occasionally
prey or attempt to prey upon humans (Stirling 1988, p. 182). ``Problem
bears,'' the bears most associated with human conflicts, are most often
subadult bears that are inexperienced hunters and, therefore, that
scavenge more frequently than adult bears (Stirling 1988, p. 182).
Following subadults, females with cubs are most likely to interact with
humans, because females with cubs are likely to be thinner and hungrier
than single adult bears, and starving bears are more likely to interact
with humans in their pursuit of food (Stirling 1988, p. 182). For
example, in Churchill, Manitoba, Canada, an area of high polar bear
use, the occurrence of females with cubs feeding at the town's garbage
dump in
[[Page 28280]]
the fall increased during years when bears came ashore in poorer
condition (Stirling 1988, p. 182). Other factors that may influence
bear-human encounters include increased land use activities, increased
human populations in areas of high polar bear activity, increased polar
bear concentrations on land, and earlier polar bear departure from ice
habitat to terrestrial habitats.
Increased bear-human interactions and defense-of-life kills may
occur under predicted climate change scenarios where more bears are on
land and in contact with human settlements (Derocher et al. 2004, p.
169). Direct interactions between people and bears in Alaska have
increased markedly in recent years, and this trend is expected to
continue (Amstrup 2000, p. 153). Since the late 1990s, the timing of
complete ice formation in the fall has occurred later in November or
early December than it formerly did (September and October), resulting
in an increased amount of time polar bears spend on land. This
consequently increases the probability of bear-human interactions
occurring in coastal villages. Adaptive management programs that focus
on the development of community or ecotourism based polar bear-human
interaction plans (that include polar bear patrols, deterrent and
hazing programs, efforts to manage and minimize sources of attraction,
and education about polar bear behavior and ecology) are ongoing in a
number of Alaska North Slope communities and should be expanded or
further developed for other communities in the future. In four Canadian
populations-Western Hudson Bay, Foxe Basin, Baffin Bay, and Davis
Strait-Inuit hunters reported seeing more bears in recent years around
settlements, hunting camps, and sometimes locations where they had not
(or only rarely) been seen before, resulting in an increase in threats
to human life and damage to property (Stirling and Parkinson 2006, p.
262).
As discussed in Factor A, Amstrup et al. (2007, p.30) used a first-
generation BM model to forecast the range-wide status of polar bears
during the 21st century, factoring in a number of stressors, including
bear-human interactions. The authors conducted a sensitivity analysis
to determine the importance and influence of the stressors on the
population forecast. Their analysis indicated that bear-human
interactions ranked 7th of potential stressors. Because of the
preliminary nature of the BM results, we are more confident in the
general direction and magnitude of the projected outcomes rather than
the actual numerical probabilities associated with each outcome.
Although this factor's singular contribution to a declining population
trend was relatively small, it could operate with other mortality
factors (such as harvest) in the future to exacerbate the effects of
habitat loss. Thus, bear-human interactions should be monitored, and
may require additional management actions in the future.
Conclusion for Factor B
Rationale
Polar bears are harvested in Canada, Alaska, Greenland, and Russia.
Active harvest management or reporting programs are in place for
populations in Canada, Greenland, and Alaska. Principles of sustainable
yield are instituted through harvest quotas or guidelines for a number
of Canadian populations. Other forms of removal, such as defense-of-
life take are considered through management actions by the responsible
jurisdictions. Hunting or killing polar bears is illegal in Russia,
although an unknown level of harvest occurs, and harvest impacts on
Russian populations are generally unknown. While overharvest is
occurring for some populations, laws and regulations for most
management programs have been instituted and are flexible enough to
allow adjustments in order to ensure that harvests are sustainable.
These actions are largely viewed as having succeeded in reversing
widespread overharvests by many jurisdictions that resulted in
population depletion during the period prior to signing of the
multilateral 1973 Polar Bear Agreement (Prestrud and Stirling 1994) see
additional discussion under Factor D below). For the internationally-
shared populations in the Chukchi Sea, Baffin Bay, Kane Basin, and
Davis Strait, conservation agreements have been developed (United
States-Russia) or are in development (Canada-Greenland), but in making
our finding we have not relied on agreements that have not been
implemented.
We realize that management agencies will be challenged in the
future with managing populations that are declining and under stress
from loss of sea ice. We also note that the sensitivity anlaysis
conducted by Amstrup et al. (2007, pp. 35, 58) suggests that, for some
populations, the effects of habitat and environmental changes will far
outweigh the effects of harvest, and consequently, that harvest
regulation may have little effect on the ultimate population outcome.
For other populations affected to a lesser degree by environmental
changes and habitat impacts, effective implementation of existing
regulatory mechanisms is necessary to address issues related to
overutilization.
Determination for Factor B
We have evaluated the best available scientific and commercial
information on the utilization of polar bears for commercial,
recreational, scientific, or educational purposes. Harvest, increased
bear-human interaction levels, defense-of-life take, illegal take, and
take associated with scientific research live-capture programs are
occurring for several populations. We have determined that harvest is
likely exacerbating the effects of habitat loss in several populations.
In addition, polar bear mortality from harvest and negative bear-human
interactions may in the future approach unsustainable levels for
several populations, especially those experiencing nutritional stress
or declining population numbers as a consequence of habitat change. The
PBSG (Aars et al. 2006, p. 57), through resolution, urged that a
precautionary approach be instituted when setting harvest limits in a
warming Arctic environment. Continued efforts are necessary to ensure
that harvest or other forms of removal do not exceed sustainable
levels. We find, however, that overutilization does not currently
threaten the polar bear throughout all or a significant portion of its
range.
Factor C. Disease and Predation
Disease
The occurrence of diseases and parasites in polar bears is rare
compared to other bears, with the exception of the presence of
Trichinella larvae, Trichinella has been documented in polar bears
throughout their range, and, although infestations can be quite high,
they are normally not fatal (Rausch 1970, p. 360; Dick and Belosevic
1978, p. 1,143; Larsen and Kjos-Hanssen 1983, p. 95; Taylor et al.
1985, p. 303; Forbes 2000, p. 321). Although rabies is commonly found
in Arctic foxes, there has been only one documented case in polar bears
(Taylor et al. 1991, p. 337). Morbillivirus has been documented in
polar bears from Alaska and Russia (Garner et al. 2000, p. 477; C.
Kirk, University of Alaska, Fairbanks, pers. comm. 2006). Antibodies to
the protozoan parasite, Toxoplasma gondii, were found in Alaskan polar
bears; whether this is a health concern for polar bears is unknown (C.
Kirk, University of Alaska, Fairbanks, pers. comm. 2006).
[[Page 28281]]
Whether polar bears are more susceptible to new pathogens due to
their lack of previous exposure to diseases and parasites is also
unknown. Many different pathogens and viruses have been found in seal
species that are polar bear prey (Duignan et al. 1997, p. 7; Measures
and Olson 1999, p. 779; Dubey et al. 2003, p. 278; Hughes-Hanks et al.
2005, p. 1,226), so the potential exists for transmission of these
diseases to polar bears. . As polar bears become more nutritionally
stressed, they may eat more of the intestines and internal organs of
their prey than they presently do, thus increasing potential exposure
to parasites and viruses (Derocher et al. 2004, p. 170; Amstrup et al.
2006b, p. 3). In addition, new pathogens may expand their range
northward from more southerly areas under projected climate change
scenarios (Harvell et al. 2002, p. 60). A warming climate has been
associated with increases in pathogens in other marine organisms
(Kuiken et al. 2006, p. 322).
Amstrup et al. (2007, p. 87) considered a host of potential
stressors, including diseases and parasites, in their status evaluation
of polar bears. The influence of parasites and disease agents evaluated
in the sensitivity analysis ranked 8th, and made very minor
contributions to the projected population status. The authors note,
however, that the potential effect of disease and parasites on polar
bears would likely increase if the climate continues to warm (Amstrup
et al. 2007, p. 21). Parasitic agents that have developmental stages
outside the bodies of warm-blooded hosts (e.g., nematodes) will likely
benefit from the warmer and wetter weather projected for the Arctic
(Macdonald et al. 2005). Significant impacts from such parasites on
some Arctic ungulates have been noted. Improved conditions for such
parasites already have had significant impacts on some terrestrial
mammals (Kutz et al. 2001, p. 771; Kutz et al. 2004). Bacterial
parasites also are likely to benefit from a warmer and wetter Arctic.
Although increases in disease and parasite agents have not yet been
reported in polar bears, they are anticipated, if temperatures continue
to warm as projected. Amstrup et al. (2007, p. 31) also indicated that
diseases and parasites could operate to exacerbate the effects of
habitat loss. Continued monitoring of pathogens and parasites in polar
bears is appropriate.
Intraspecific Predation
Intraspecific killing has been reported among all North American
bear species (Derocher and Wiig 1999, p. 307; Amstrup et al. 2006b, p.
1). Reasons for intraspecific predation in bear species are poorly
understood but thought to include nutrition, and enhanced breeding
opportunities in the case of predation on cubs. Although occurrences of
infanticide by male polar bears have been well documented (Hansson and
Thomassen 1983, p. 248; Larsen 1985, p. 325; Taylor et al. 1985, p.
304; Derocher and Wiig 1999, p. 307), this activity accounts for a
small percentage of the cub mortality.
Cannibalism has also been documented in polar bears (Derocher and
Wiig 1999, p. 307; Amstrup et al. 2006b, p. 1). Amstrup et al. (2006b,
p. 1) observed three instances of cannibalism in the southern Beaufort
Sea during the spring of 2004; two involved adult females (one an
unusual mortality of a female in a den) and third involved a yearling.
This is notable because, throughout a combined 58 years of research,
there are no similar observations recorded. Active stalking or hunting
preceded the attacks, and all three of the killed bears were wholly or
partly consumed. Adult males were believed to be the predator in both
attacks. Amstrup et al. (2006b, p. 43) indicated that in general a
greater proportion of polar bears in the area where the predation
events occurred were in poorer physical condition compared to bears
captured in other areas. The authors hypothesized that large adult
males may be the first to show effects of nutritional stress which is
expected to occur first in more southerly areas, due to significant ice
retreat (Skinner et al. 1988, p. 3; Comiso and Parkinson 2004, p. 43;
Stroeve et al. 2005, p. 1) . Adult males may be the first to show the
effects of nutritional stress because they feed little during the
spring mating season and enter the summer in poorer condition than
other sex/age classes. Derocher and Wiig (1999, p. 308) documented a
similar intraspecific killing and consumption of another polar bear in
Svalbard, Norway, which was attributed to relatively high population
densities and food shortages. Taylor et al. (1985, p. 304) documented
that a malnourished female killed and consumed her own cubs, and Lunn
and Stenhouse (1985, p. 1,516) found an emaciated male consuming an
adult female polar bear. The potential importance of cannibalism and
infanticide for polar bear population regulation is unknown. However,
given our current knowledge of disease and predation, we do not believe
that these factors are currently having population-level effects.
Another form of intraspecific stress is cross-breeding, or
hybridization. The first documented instance of cross-breeding in the
wild was reported in the spring of 2006. Rhymer and Simberloff (1996,
pp. 83-84) express concerns for cross-breeding in the wild, noting that
habitat modification contributing to cross breeding may cause the
break-down of reproductive isolation between native species, leading to
mixing of gene pools and potential loss of genotypically distinct
populations. The authors generally viewed hybridization through
introgression (defined as gene flow between populations through
hybridization when hybrids cross back to one of the parental
populations) as a threat to plant and animal taxa, particularly for
morphologically well-defined and evolutionarily isolated taxa. Cross-
breeding in the wild is thought to be extremely rare, but cross-
breeding may pose additional concerns for population and species
viability in the future should the rate of occurrence increase.
Conclusion for Factor C
Rationale
Disease pathogen titers are present in polar bears; however, no
epizootic outbreaks have been detected. In addition, forms of
intraspecific stress and cannibalism are known to be present with bear
species and within polar bears. For polar bears, there is no indication
that these stressors have operated to influence population levels in
the past. Cannibalism is an indication of intraspecific stress, however
we do not believe it has resulted in population level effects.
Determination for Factor C
We have evaluated the best available scientific information on
disease and predation, and have determined that disease and predation
(including intraspecific predation) do not threaten the species
throughout all or any significant portion of its range. Potential for
disease outbreaks, an increased possibility of pathogen exposure from
changed diet or the occurrence of new pathogens that have moved
northward with a warming environment, and increased mortality from
cannibalism all warrant continued monitoring and may become more
significant threat factors in the future for polar bear populations
experiencing nutritional stress or declining population numbers.
Factor D. Inadequacy of Existing Regulatory Mechanisms
Regulatory mechanisms directed specifically at managing many of the
threats to polar bears, such as overharvest or disturbance, exist in
all of the countries states where the species
[[Page 28282]]
occurs, as well as between (bilateral and multilateral) range
countries.
IUCN/SSC Polar Bear Specialist Group
The Polar Bear Specialist Group (PBSG) is not a regulatory
authority nor do they provide any regulatory mechanisms. However, the
PBSG contributed significantly to the negotiation and development of
the International Agreement on the Conservation of Polar Bears (1973
Polar Bear Agreement), and has been instrumental in monitoring the
worldwide status of polar bear populations. Therefore, we believe a
discussion of the PBSG is relevant to a current understanding of the
status of polar bears worldwide. We did not rely on the PBSG or any
actions of the PBSG for determining the status of the polar bear under
the Act.
The PBSG operates under the IUCN Species Survival Commission (SSC),
and was formed in 1968. The PBSG meets periodically at 3-to 5-year
intervals in compliance with Article VII of the 1973 Polar Bear
Agreement; said article instructs member parties to conduct national
research programs on polar bears, particularly research relating to the
conservation and management of the species and, as appropriate,
coordinate such research with the research carried out by other
parties, consult with other parties on management of migrating polar
bear populations, and exchange information on research and management
programs, research results, and data on bears taken. The PBSG first
evaluated the status of all polar bear populations in 1980. In 1993,
1997, and 2001, the PBSG conducted circumpolar status assessments of
polar bear populations, and the results of those assessments were
published as part of the proceedings of the relevant PBSG meeting. The
PBSG conducted its fifth polar bear status assessment in June 2005.
The PBSG also evaluates the status of polar bears under the IUCN
Red List criteria. Previously, polar bears were classified under the
IUCN Red List program as: ``Less rare but believed to be threatened/
requires watching'' (1965); ``Vulnerable'' (1982, 1986, 1988, 1990,
1994); and ``Lower Risk/Conservation Dependent'' (1996). During the
2005 PBSG working group meeting, the PBSG re-evaluated the status of
polar bears and unanimously agreed that a status designation of
``Vulnerable'' was warranted.
International Agreements and Oversight
International Agreement on the Conservation of Polar Bears
Canada, Denmark (on behalf of Greenland), Norway, the Russian
Federation, and the United States are parties to the Agreement on the
Conservation of Polar Bears (1973 Polar Bear Agreement) signed in 1973;
by 1976, the Agreement was ratified by all parties. The 1973 Polar Bear
Agreement requires the parties to take appropriate action to protect
the ecosystem of which polar bears are a part, with special attention
to habitat components such as denning and feeding sites and migration
patterns, and to manage polar bear populations in accordance with sound
conservation practices based on the best available scientific data. The
1973 Polar Bear Agreement relies on the efforts of each party to
implement conservation programs and does not preclude a party from
establishing additional controls (Lentfer 1974, p. 1).
The 1973 Polar Bear Agreement is viewed as a success in that polar
bear populations recovered from excessive harvests and severe
population reductions in many areas (Prestrud and Stirling 1994). At
the same time, implementation of the terms of the 1973 Polar Bear
Agreement varies across the member parties. Efforts are needed to
improve current harvest management practices, such as restricting
harvest of females and cubs, establishing sustainable harvest limits,
and controlling illegal harvests (Derocher et al. 1998, pp. 47-48). In
addition, a lack of protection of key habitats by member parties, with
few notable exceptions for some denning areas, is a weakness (Prestrud
and Stirling 1994, p. 118).
Inupiat-Inuvialuit Agreement for the Management of Polar Bears of the
Southern Beaufort Sea
In January 1988, the Inuvialuit of Canada and the Inupiat of
Alaska, groups that both harvest polar bears for cultural and
subsistence purposes, signed a management agreement for polar bears of
the southern Beaufort Sea. This agreement, based on the understanding
that the two groups harvested animals from a single population shared
across the international boundary, provides a joint responsibility for
conservation and harvest practices (Treseder and Carpenter 1989, p. 4;
Nageak et al. 1991, p. 341). Provisions of the agreement include:
annual quotas (which may include problem kills); hunting seasons;
protection of bears in dens or while constructing dens, and protection
of females accompanied by cubs and yearlings; collection of specimens
from killed bears to facilitate monitoring of the sex and age
composition of the harvest; agreement to meet annually to exchange
information on research and management and to set priorities; agreement
on quotas for the coming year; and prohibition of hunting with aircraft
or large motorized vessels and of trade in products taken in violation
of the agreement. In Canada, recommendations and decisions from the
Commissioners are then implemented through Community Polar Bear
Management Agreements, Inuvialuit Settlement Region Community Bylaws,
and NWT Big Game Regulations. In the United States, this agreement is
implemented at the local level. Adherence to the agreement's terms in
Alaska is voluntary, and levels of compliance may vary. There are no
Federal, State, or local regulations that limit the number or type
(male, female, cub) of polar bear that may be taken. Brower et al.
(2002) analyzed the effectiveness of the Inupiat-Inuvialuit Agreement,
and found that it had been successful in maintaining the total harvest
and the proportion of females in the harvest within sustainable levels.
The authors noted the need to improve harvest monitoring in Alaska and
increase awareness of the need to prevent overharvest of females for
both countries.
Agreement between the United States of America and the Russian
Federation on the Conservation and Management of the Alaska-Chukotka
Polar Bear Population
On October 16, 2000, the United States and the Russian Federation
signed a bilateral agreement for the conservation and management of
polar bear populations shared between the two countries. The Agreement
between the United States of America and the Russian Federation on the
Conservation and Management of the Alaska-Chukotka Polar Bear
Population (Bilateral Agreement) expands upon the progress made through
the multilateral 1973 Polar Bear Agreement by implementing a unified
conservation program for this shared population. The Bilateral
Agreement reiterates requirements of the 1973 Polar Bear Agreement and
includes restrictions on harvesting denning bears, females with cubs or
cubs less than 1 year old, and prohibitions on the use of aircraft,
large motorized vessels, and snares or poison for hunting polar bears.
The Bilateral Agreement does not allow hunting for commercial purposes
or commercial
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uses of polar bears or their parts. It also commits the parties to the
conservation of ecosystems and important habitats, with a focus on
conserving polar bear habitats such as feeding, congregating, and
denning areas. The Russian government indicates that it is prepared to
implement the Bilateral Agreement. On December 9, 2006, the Congress of
the United States passed the ``United States--Russia Polar Bear
Conservation and Management Act of 2006.'' This Act provides the
necessary authority to regulate and manage the harvest of polar bears
from the Chukchi Sea population, an essential conservation measure.
Ratification documents have been exchanged between the countries, but
the United States has yet to designate representatives to the
Commission, and we did not rely on this treaty in our assessment as it
is not formally implemented. Implementation of the Act will provide
numerous conservation benefits for this population, however it does not
provide authority or mechanisms to address ongoing loss of sea ice.
Convention on International Trade in Endangered Species of Wild Fauna
and Flora (CITES)
The Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES) is a treaty aimed at protecting species at risk
from international trade. The CITES regulates international trade in
animals and plants by listing species in one of its three appendices.
The level of monitoring and regulation to which an animal or plant
species is subject depends on the appendix in which the species is
listed. Appendix I includes species threatened with extinction that are
or may be affected by trade; trade of Appendix I species is only
allowed in exceptional circumstances. Appendix II includes species not
necessarily now threatened with extinction, but for which trade must be
regulated in order to avoid utilization incompatible with their
survival. Appendix III includes species that are subject to regulation
in at least one country, and for which that country has asked other
CITES Party countries for assistance in controlling and monitoring
international trade in that species.
Polar bears were listed in Appendix II of CITES on July 7, 1975. As
such, CITES parties must determine, among other things, that any polar
bear, polar bear part, or product made from polar bear was legally
obtained and that the export will not be detrimental to the survival of
the species, prior to issuing a permit authorizing the export of the
animal, part, or product. The CITES does not itself regulate take or
domestic trade of polar bears; however, through its process of
monitoring trade in wildlife species and requisite findings prior to
allowing international movement of listed species and monitoring
programs, the CITES is effective in ensuring that the international
movement of listed species does not contribute to the detriment of
wildlife populations. All polar bear range states are members to the
CITES and have in place the CITES-required Scientific and Management
Authorities. The Service therefore has determined that the CITES is
effective in regulating the international trade in polar bear, or polar
bear parts or products, and provides conservation measures to minimize
those potential threats to the species.
Domestic Regulatory Mechanisms
United States
Marine Mammal Protection Act of 1972, as amended
The Marine Mammal Protection Act of 1972, as amended (16 U.S.C.
1361 et seq.) (MMPA) was enacted to protect and conserve marine mammals
so that they continue to be significant functioning elements of the
ecosystem of which they are a part. The MMPA set forth a national
policy to prevent marine mammal species or population stocks from
diminishing to the point where they are no longer a significant
functioning element of the ecosystems.
The MMPA places an emphasis on habitat and ecosystem protection.
The habitat and ecosystem goals set forth in the MMPA include: (1)
Management of marine mammals (including of polar bears) to ensure they
do not cease to be a significant element of the ecosystem to which they
are a part; (2) protection of essential habitats, including rookeries,
mating grounds, and areas of similar significance ``from the adverse
effects of man's action''; (3) recognition that marine mammals ``affect
the balance of marine ecosystems in a manner that is important to other
animals and animal products,'' and that marine mammals and their
habitats should therefore be protected and conserved; and (4) direction
that the primary objective of marine mammal management is to maintain
``the health and stability of the marine ecosystem.'' Congressional
intent to protect marine mammal habitat is also reflected in the
definitions section of the MMPA. The terms ``conservation'' and
``management'' of marine mammals are specifically defined to include
habitat acquisition and improvement.
The MMPA established a general moratorium on the taking and
importing of marine mammals and a number of prohibitions, which are
subject to a number of exceptions. Some of these exceptions include
take for scientific purposes, for purposes of public display, for
subsistence use by Alaska Natives, and unintentional incidental take
coincident with conducting otherwise lawful activities. The Service,
prior to issuing a permit authorizing the taking or importing of a
polar bear, or a polar bear part or product, for scientific or public
display purposes submits each request to a rigorous review, including
an opportunity for public comment and consultation with the U.S. Marine
Mammal Commision (MMC), as described at 50 CFR 18.31. In addition, in
1994, Congress amended the MMPA to allow for the import of polar bear
trophies taken in Canada for personal use providing certain
requirements are met. Import permits may only be issued to hunters that
are citizens of the United States for trophies they have legally taken
from those Canadian polar bear populations the Service has approved as
meeting the MMPA requirements, as described at 50 CFR 18.30. The
Service has determined that there is sufficient rigor under the
regulations at 50 CFR 18.30 and 18.31 to ensure that any activities so
authorized are consistent with the conservation of this species and are
not a threat to the species.
Take is defined in the MMPA to include the ``harassment'' of marine
mammals. ``Harassment'' includes any act of pursuit, torment, or
annoyance that ``has the potential to injure a marine mammal or marine
mammal stock in the wild'' (Level A harassment), or ``has the potential
to disturb a marine mammal or marine mammal stock in the wild by
causing disruption of behavioral patterns, including, but not limited
to, migration, breathing, nursing, breeding, feeding, or sheltering''
(Level B harassment).
The Secretaries of Commerce and of the Interior have primary
responsibility for implementing the MMPA. The Department of Commerce,
through the National Oceanic and Atmospheric Administration (NOAA), has
authority with respect to whales, porpoises, seals, and sea lions. The
remaining marine mammals, including polar bears, walruses, sea otters,
dugongs, and manatees are managed by the Department of the Interior
through the U.S. Fish and Wildlife Service. Both agencies are ``* * *
responsible for the promulgation of regulations, the issuance of
permits, the conduct of scientific research, and enforcement as
[[Page 28284]]
necessary to carry out the purposes of [the MMPA].''
Citizens of the United States who engage in a specified activity
other than commercial fishing (which is specifically and separately
addressed under the MMPA) within a specified geographical region may
petition the Secretary of the Interior to authorize the incidental, but
not intentional, taking of small numbers of marine mammals within that
region for a period of not more than five consecutive years (16 U.S.C.
1371(a)(5)(A)). The Secretary ``shall allow'' the incidental taking if
the Secretary finds that ``the total of such taking during each five-
year (or less) period concerned will have no more than a negligible
impact on such species or stock and will not have an unmitigable
adverse impact on the availability of such species or stock for taking
for subsistence uses.'' If the Secretary makes the required findings,
the Secretary also prescribes regulations that specify (1) permissible
methods of taking, (2) means of affecting the least practicable adverse
impact on the species, their habitat, and their availability for
subsistence uses, and (3) requirements for monitoring and reporting.
The regulatory process does not authorize the activities themselves,
but authorizes the incidental take of the marine mammals in conjunction
with otherwise legal activities.
Similar to promulgation of incidental take regulations, the MMPA
also established an expedited process by which citizens of the United
States can apply for an authorization to incidentally take small
numbers of marine mammals where the take will be limited to harassment
(16 U.S.C. 1371(a)(5)(D)). These authorizations are limited to one year
and as with incidental take regulations, the Secretary must find that
the total of such taking during the period will have no more than a
negligible impact on such species or stock and will not have an
unmitigable adverse impact on the availability of such species or stock
for taking for subsistence uses. The Service refers to these
authorizations as Incidental Harassment Authorizations.
Examples and descriptions of how the Service has analyzed the
effects of oil and gas activities and applied the general provisions of
the MMPA described above to polar bear conservation programs in the
Beaufort and Chukchi Seas are decribed in the Range Wide Status Review
of the Polar Bear (Ursus maritimus) (Schliebe et al. 2006a). These
regulations include an evaluation of the cumulative effects of oil and
gas industry activities on polar bears from noise, physical
obstructions, human encounters, and oil spills. The likelihood of an
oil spill occurring and the risk to polar bears is modeled
quantitatively and factored into the evaluation. The results of
previous industry monitoring programs, and the effectiveness of past
detection and deterrent programs that have a beneficial record of
protecting polar bears, as well as providing for the safety of oil
field workers, are also considered. Based on the low likelihood of an
oil spill occurring and the effectiveness of industry mitigation
measures within the Beaufort Sea region, the Service has found that oil
and gas industry activities have not affected the rates of recruitment
or survival for the polar bear populations over the period of the
regulations.
General operating conditions in specific authorizations include the
following: (1) Protection of pregnant polar bears during denning
activities (den selection, birthing, and maturation of cubs) in known
and confirmed denning areas; (2) restrictions on industrial activities,
areas, time of year; and (3) development of a site-specific plan of
operation and a site-specific polar bear interaction plan. Additional
requirements may include: pre-activity surveys (e.g., aerial surveys,
infra-red thermal aerial surveys, or polar bear scent-trained dogs) to
determine the presence or absence of dens or denning activity and, in
known denning areas, enhanced monitoring or flight restrictions, such
as minimum flight elevations. These and other safeguards and
coordination with industry have served to minimize industry effects on
polar bears.
Outer Continental Shelf Lands Act
The Outer Continental Shelf Lands Act (43 U.S.C. 1331 et seq.)
(OCSLA) established Federal jurisdiction over submerged lands on the
Outer Continental Shelf (OCS) seaward of the State boundaries (3-mile
limit) in order to expedite exploration and development of oil/gas
resources on the OCS in a manner that minimizes impact to the living
natural resources within the OCS. Implementation of OCSLA is delegated
to the Minerals Management Service (MMS) of the Department of the
Interior. The OCS projects that could adversely impact the Coastal Zone
are subject to Federal consistency requirements under terms of the
Coastal Zone Management Act, as noted below. The OCSLA also mandates
that orderly development of OCS energy resources be balanced with
protection of human, marine, and coastal environments. The OCSLA does
not itself regulate the take of polar bears, although through
consistency determinations it helps to ensure that OCS projects do not
adversely impact polar bears or their habitats.
Oil Pollution Act of 1990
The Oil Pollution Act of 1990 (33 U.S.C. 2701) established new
requirements and extensively amended the Federal Water Pollution
Control Act (33 U.S.C. 1301 et. seq.) to provide enhanced capabilities
for oil spill response and natural resource damage assessment by the
Service. It requires us to consult on developing a fish and wildlife
response plan for the National Contingency Plan, input to Area
Contingency Plans, review of Facility and Tank Vessel Contingency
Plans, and to conduct damage assessments associated with oil spills.
Coastal Zone Management Act
The Coastal Zone Management Act of 1972 (16 U.S.C. 1451 et seq.)
(CZMA) was enacted to ``preserve, protect, develop, and where possible,
to restore or enhance the resources of the Nation's coastal zone.'' The
CZMA provides for the submission of a State program subject to Federal
approval. The CZMA requires that Federal actions be conducted in a
manner consistent with the State's CZM plan to the maximum extent
practicable. Federal agencies planning or authorizing an activity that
affects any land or water use or natural resource of the coastal zone
must provide a consistency determination to the appropriate State
agency. The CZMA applies to polar bear habitats of northern and western
Alaska. The North Slope Borough and Alaska Coastal Management Programs
assist in protection of polar bear habitat through the project review
process. The CZMA does not itself regulate the take of polar bears,
and, overall, is not determined to be effective at this time in
addressing the threats identified in the five factor analysis.
Alaska National Interest Lands Conservation Act
The Alaska National Interest Lands Conservation Act of 1980 (16
U.S.C. 3101 et seq.) (ANILCA) created or expanded National Parks and
National Wildlife Refuges in Alaska, including the expansion of the
Arctic National Wildlife Refuge (NWR). One of the establishing purposes
of the Arctic NWR is to conserve polar bears. Section 1003 of ANILCA
prohibits production of oil and gas in the Arctic NWR, and no leasing
or other development leading to production of oil and gas may take
place unless authorized by an Act of Congress. Most of the Arctic NWR
is a federally
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designated Wilderness, but the coastal plain of Arctic NWR, which
provides important polar bear denning habitat, does not have Wilderness
status. The ANILCA does not itself regulate the take of polar bears,
although through its designations it has provided recognition of, and
various levels of protection for, polar bear habitat. In the case of
polar bear habitat, the Bureau of Land Management (BLM) is responsible
for vast land areas on the North Slope, including the National
Petroleum Reserve, Alaska (NPRA). Habitat suitable for polar bear
denning and den sites have been identified within NPRA. The BLM
considers fish and wildlife values under its multiple use mission in
evaluating land use authorizations and prospective oil and gas leasing
actions. Provisions of the MMPA regarding the incidental take of polar
bears on land areas and waters within the jurisdiction of the United
States continue to apply to activities conducted by the oil and gas
industry on BLM lands.
Marine Protection, Research and Sanctuaries Act
The Marine Protection, Research and Sanctuaries Act (33 U.S.C. 1401
et seq.) (MPRSA) was enacted in part to ``prevent or strictly limit the
dumping into ocean waters of any material that would adversely affect
human health, welfare, or amenities, or the marine environment,
ecological systems, or economic potentialities.'' The MPRSA does not
itself regulate the take of polar bears. There are no designated marine
sanctuaries within the range of the polar bear.
Canada
Canada's constitutional arrangement specifies that the Provinces
and Territories have the authority to manage terrestrial wildlife,
including the polar bear, which is not defined as a marine mammal in
Canada. The Canadian Federal Government is responsible for CITES-
related programs and provides both technical (long-term demographic,
ecosystem, and inventory research) and administrative (Federal-
Provincial Polar Bear Technical Committee (PBTC), Federal-Provincial
Polar Bear Administrative Committee (PBAC), and the National Database)
support to the Provinces and Territories. The Provinces and Territories
have the ultimate authority for management, although in several areas,
the decision-making process is shared with aboriginal groups as part of
the settlement of land claims. Regulated hunting by aboriginal people
is permissible under Provincial and Territorial statutes (Derocher et
al. 1998, p. 32) as described in Factor B.
In Manitoba, most denning areas have been protected by inclusion
within the boundaries of Wapusk National Park. In Ontario, some denning
habitat and coastal summer sanctuary habitat are included in Polar Bear
Provincial Park. Some polar bear habitat is included in the National
Parks and National Park Reserves and territorial parks in the Northwest
Territories, Nunavut, and Yukon Territory (e.g., Herschel Island).
While these parks and preserves provide some protection for terrestrial
habitat, subsistence hunting activities are allowed in these areas.
Additional habitat protection measures in Manitoba include restrictions
on harassment and approaching dens and denning bears, and a land use
permit review that considers potential impacts of land use activities
on wildlife (Derocher et al. 1998, p. 35). The measures adopted by the
Government of Manitoba have been effective on a site-specific basis. In
addition, the Government of Manitoba has recently listed the polar bear
as a threatened species in that province; however, we have no
information on whether this designation provides any additional
regulatory protection for the species.
Species at Risk Act
Canada's Species at Risk Act (SARA) became law on December 12,
2002, and went into effect on June 1, 2004 (Walton 2004, p. M1-17).
Prior to SARA, Canada's oversight of species at risk was conducted
through the Committee on the Status of Endangered Wildlife in Canada
(COSEWIC) which continues to function under SARA and through the
Ministry of Environment. COSEWIC evaluates species status and provides
recommendations to the Minister of the Environment, who makes final
listing decisions and identifies species-specific management actions.
The SARA provides a number of protections for wildlife species placed
on the List of Wildlife Species at Risk, or ``Schedule 1'' (SARA
Registry 2005). The listing criteria used by COSEWIC are based on the
2001 IUCN Red List assessment criteria (Appendix 3). Currently, under
SARA the polar bear is designated as a Schedule 3 species, ``Species of
Special Concern,'' awaiting re-assessment and public consultation for
possible up-listing to Schedule 1 (Environment Canada 2005). A Schedule
3 listing under SARA does not include protection measures, whereas a
Schedule 1 listing under SARA may include protection measures. We did
not rely on this potential in our analysis as the action has not yet
occurred.
Intra-jurisdiction Polar Bear Agreements Within Canada
Polar bears occur in the Northwest Territories (NWT), Nunavut,
Yukon Territory, and in the Provinces of Manitoba, Ontario, Quebec,
Newfoundland, and Labrador (see Figure 1 above). All 13 Canadian polar
bear populations lie within or are shared with the NWT or Nunavut. The
NWT and Nunavut geographical boundaries include all Canadian lands and
marine environment north of the 60th parallel (except the Yukon
Territory), and all islands and waters in Hudson Bay and Hudson Strait
up to the low water mark of Manitoba, Ontario, and Quebec. The offshore
marine areas along the coast of Newfoundland and Labrador are under
Federal jurisdiction. Although Canada manages each of the 13
populations of polar bear as separate units, there is a complex sharing
of responsibilities. While wildlife management has been delegated to
the Provincial and Territorial Governments, the Federal Government
(Environment Canada's Canadian Wildlife Service) has an active research
program and is involved in management of wildlife populations shared
with other jurisdictions, especially ones with other nations. In the
NWT, Native Land Claims resulted in Co-management Boards for most of
Canada's polar bear populations. Canada formed the PBTC and PBAC to
ensure a coordinated management process consistent with internal and
international management structures and the International Agreement.
The committees meet annually to review research and management of polar
bears in Canada and have representation from all Provincial and
Territorial jurisdictions with polar bear populations and the Federal
Government. Beginning in 1984, the Service and biologists from Norway
and Denmark have, with varying degrees of frequency, participated in
annual PBTC meetings. The annual meetings of the PBTC provide for
continuing cooperation between jurisdictions and for recommending
management actions to the PBAC (Calvert et al. 1995, p. 61).
The NWT Polar Bear Management Program (GNWT) manages polar bears in
the Northwest Territories. A 1960 ``Order-in-Council'' granted
authority to the Commissioner in Council (NWT) to pass ordinances to
protect polar bears, including the establishment of a quota system. The
Wildlife Act, 1988, and Big Game Hunting Regulations provide supporting
legislation which addresses each polar bear population. The Inuvialuit
and Nunavut Land Claim
[[Page 28286]]
Agreements supersede the Northwest Territories Act (Canada) and the
Wildlife Act. The Government of Nunavut passed a new Wildlife Act in
2004 and has management and enforcement authority for polar bears in
their jurisdiction. Under the umbrella of this authority, polar bears
are now co-managed through wildlife management boards made up of Land
Claim Beneficiaries and Territorial and Federal representatives. The
Boards may develop Local Management Agreements (LMAs) between the
communities that share a population of polar bears. Management
agreements are in place for all Nunavut populations. The LMAs are
signed between the communities, regional wildlife organizations, and
the Government of Nunavut (Department of Environment) but can be over-
ruled by the Nunavut Wildlife Management Board (NWMB).
In the case of populations that Nunavut shares with Quebec and
Ontario, the management agreement is not binding upon residents of
communities outside of Nunavut jurisdiction. Similarly, in the case of
populations that Nunavut shares with Manitoba, or Newfoundland and
Labrador, the management agreement is not binding upon residents of
communities outside of Nunavut jurisdiction. Regulations implementing
the LMAs specify who can hunt, season timing and length, age and sex
classes that can be hunted, and the total allowable harvest for a given
population. The Department of Environment in Nunavut and the Department
of Environment and Natural Resources in the NWT have officers to
enforce the regulations in most communities of the NWT. The officers
investigate and prosecute incidents of violation of regulations, kills
in defense of life, or exceeding a quota (USFWS 1997). Canada's inter-
jurisdictional requirements for consultation and development of LMAs
and oversight through the PBTC and PBAC have resulted in conservation
benefits for polar bear populations. Although there are some localized
instances where changes in management agreements may be necessary,
these arrangements and provisions have operated to minimize the threats
of overharvest to the species.
The Service analyzed the overall efficacy of Canada's management of
polar bears in 1997 (62 FR 7302) and 1999 (64 FR 1529) and determined,
at those times, that the species was managed by Canada using sound
scientific principles and in such a manner that existing populations
would be sustained. We continue to believe that, in general, Canada
manages polar bears in an effective and sustainable manner. However, as
discussed above (see ``Harvest Management by Nation''), the Territory
of Nunavut has recently adopted changes to polar bear management,
including some increased harvest quotas, that may place a greater
significance on indigenous knowledge than on scientific data and
analysis. Management improvements may be desirable for some Canadian
populations. The Service will continue to monitor polar bear management
in Canada and actions taken by the Nunavut Government. This is
particularly important for populations that are currently in decline or
may decline in the near future.
Russian Federation
Polar bears are listed in the second issue of the Red Data Book of
the Russian Federation (2001). The Red Data Book establishes official
policy for protection and restoration of rare and endangered species in
Russia. Polar bear populations inhabiting the Barents Sea and part of
the Kara Sea (Barents-Kara population) are designated as Category IV
(uncertain status); polar bears in the eastern Kara Sea, Laptev Sea,
and the western Eastern Siberian Sea (Laptev population) are listed as
Category III (rare); and polar bears inhabiting the eastern part of the
Eastern Siberian Sea, Chukchi Sea, and the northern portion of the
Bering Sea (Chukchi population) are listed as Category V (restoring).
The main government body responsible for management of species listed
in the Red Data Book is the Ministry of Natural Resources of the
Russian Federation. Russia Regional Committees of Natural Resources are
responsible for managing polar bear populations consistent with Federal
legislation (Belikov et al. 2002, p. 86).
Polar bear hunting has been totally prohibited in the Russian
Arctic since 1956 (Belikov et al. 2002, p. 86). The only permitted take
of polar bears is catching cubs for public zoos and circuses. There are
no data on illegal trade of polar bears, and parts and products derived
from them, although considerable concern persists for unquantified
levels of illegal harvest that is occurring (Belikov et al. 2002, p.
87).
In the Russian Arctic, Natural Protected Areas (NPAs) have been
established that protect marine and associated terrestrial ecosystems,
including polar bear habitats. Wrangel and Herald Islands have high
concentrations of maternity dens and polar bears, and were included in
the Wrangel Island State Nature Reserve (zapovednik) in 1976. A 1997
decree by the Russian Federation Government established a 12-nautical
mile (nm) (22.2 km) marine zone to the Wrangel Island State Nature
Reserve; the marine zone was extended an additional 24-nm (44.4-km) to
a total of 36-nm (66.7-km) by a decree from the Governor of Chukotsk
Autonomous Okruga (Belikov et al. 2002, p. 87). The Franz Josef Land
State Nature Refuge was established in 1994. In 1996, a federal nature
reserve (zakaznik) was established on Severnaya Zemlya archipelago. In
Chukotka, efforts are underway to establish new protected areas where
polar bears aggregate seasonally; other special protected areas are
proposed for the Russian High Arctic including the Novosibirsk Islands,
Severnaya Zemlya, and Novaya Zemlya. However, because they have not yet
been designated, protections that may be afforded the polar bear under
these designations have not been considered in our evaluation of the
adequacy of existing regulatory mechanisms. Within these protected
areas, conservation and restoration of terrestrial and marine
ecosystems, and plant and animal species (including the polar bear),
are the main goals. In 2001, the Nenetskiy State Reserve, which covers
313,400 ha (774,428 ac), and includes the mouth of the Pechora River
and adjacent waters of the Barents Sea, was established.
In May 2001, the Federal law ``Concerning territories of
traditional use of nature by small indigenous peoples of North,
Siberia, and Far East of the Russian Federation'' was passed. This law
established areas for traditional use of nature (TTUN) within NPAs of
Federal, regional, and local levels to support traditional life styles
and traditional subsistence use of nature resources for indigenous
peoples. This law and the law ``Concerning natural protected
territories'' (1995) regulate protection of plants and animals on the
TTUNs. The latter also regulates organization, protection and use of
other types of NPAs: State Nature Reserves (including Biosphere
Reserves), National Parks, Natural Parks, and State Nature Refuges.
Special measures on protection of polar bears or other resources may be
governed by specific regulations of certain NPAs.
Outside NPAs, protection and use of marine renewable natural
resources are regulated by Federal legislation; Acts of the President
of the Russian Federation; regulations of State Duma, Government, and
Federal Senate of the Russian Federation; and regulations issued by
appropriate governmental departments. The most important Federal laws
for nature protection are: ``About environment protection'' (2002),
``About
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animal world'' (1995), ``About continental shelf of the Russian
Federation'' (1995), ``About exclusive economical zone of the Russian
Federation'' (1998), and ``About internal sea waters, territorial sea,
and adjacent zone of the Russian Federation'' (1998) (Belikov et al.
2002, p. 87). The effectiveness of laws protecting marine and nearshore
environments is unknown.
Norway
According to the Svalbard Treaty of February 9, 1920, Norway
exercises full and unlimited sovereignty over the Svalbard Archipelago.
Polar bears have complete protection from harvest under the Svalbard
Treaty (Derocher et al. 2002b, p. 75), which is effectively
implemented. The Svalbard Treaty applies to all the islands situated
between 10 degree and 35 degrees East longitude and between 74 degrees
and 81 degrees North latitude, and includes the waters up to 4 nm
offshore. Beyond this zone, Norway claims an economic zone to the
continental shelf areas to which Norwegian law applies. Under Norwegian
Game Law, all game, including polar bears, are protected unless
otherwise stated (Derocher et al. 2002b, p. 75). The main
responsibility for the administration of Svalbard lies with the
Norwegian Ministry of Justice. Norwegian civil and penal laws and
various other regulations are applicable to Svalbard. The Ministry of
Environment deals with matters concerning the environment and nature
conservation. The Governor of Svalbard (Sysselmannen), who has
management responsibilities for freshwater fish and wildlife, pollution
and oil spill protection, and environmental monitoring, is the cultural
and environmental protection authority in Svalbard (Derocher et al.
2002b, p. 75).
Approximately 65 percent of the land area of Svalbard is totally
protected, including all major regions of denning by female bears;
however, protection of habitat is only on land and to 4 nm offshore.
Marine protection was increased in 2004, when the territorial border of
the existing protected areas was increased to 12 nm (Aars et al. 2006,
p. 145). Norway claims control of waters out to 200 nm and regards
polar bears as protected within this area.
In 2001, the Norwegian Parliament passed a new Environmental Act
for Svalbard which went into effect in July 2002. This Act was designed
to ensure that wildlife, including polar bears, is protected, although
hunting of some other species is allowed. The only permitted take of
polar bears is for defense of life. The regulations included specific
provisions on harvesting, motorized traffic, remote camps and camping,
mandatory leashing of dogs, environmental pollutants, and environmental
impact assessments in connection with planning development or
activities in or near settlements. Some of these regulations were
specific to the protection of polar bears, e.g., through enforcement of
temporal and spatial restrictions on motorized traffic and through
provisions on how and where to camp to ensure adequate bear security
(Aars et al. 2006, p. 145).
In 2003, Svalbard designated six new protected areas, two nature
reserves, three national parks and one ``biotope protection area.'' The
new protected areas are mostly located around Isfjord, the most
populated fjord on the west side of the archipelago. Another protected
area, Hopen, is an important denning area (Aars et al. 2006, p. 145).
Kong Karls Land is the main denning area and has the highest level of
protection under the Norwegian land management system. These new
protected areas cover 4,449 sq km (1,719 sq mi) which is 8 percent of
the Archipelago's total area (http://www.norway.org/News/archive/2003/
200304svalbard.htm), and increase the total area under protection to 65
percent of the total land area.
Denmark/Greenland
Under terms of the Greenland Home Rule (1979), the government of
Greenland is responsible for management of all renewable resources,
including polar bears. Greenland is also responsible for providing
scientific data for sound management of polar bear populations and for
compliance with terms of the 1973 Polar Bear Agreement. Regulations for
the management and protection of polar bears in Greenland that were
introduced in 1994 have been amended several times (Jensen 2002, p.
65). Hunting and reporting regulations include who can hunt polar bears
(residents who live off the land), protection of family groups with
cubs of the year, prohibition of trophy hunting, mandatory reporting
requirements, and regulations on permissible firearms and means of
transportation (Jensen 2002, p. 65). In addition, there are specific
regulations that apply to traditional take within the National Park of
North and East Greenland and the Melville Bay Nature Reserve. A large
amount of polar bear habitat occurs within the National Park of North
and East Greenland. One preliminary meeting between Greenland Home Rule
Government and Canada (with the participation of the government of
Nunavut) has occurred to discuss management of shared populations.
Greenland introduced a quota system that took effect on January 1, 2006
(L[deg]nstrup 2005, p. 133), although no scientifically supportable
quotas have yet been developed. Some reconsideration to allow a limited
sport hunt is under discussion within the Greenland governmental
organizations. We have no information upon which to base a finding that
Greenland is managing polar bear hunting activities in a manner that
provides for sustainable populations.
Regulatory Mechanisms to Limit Sea Ice Loss
Although there are regulatory mechanisms for managing many of the
threats to polar bears in all countries where the species occurs, as
well as among range countries through bilateral and multilateral
agreements, there are no known regulatory mechanisms that are directly
and effectively addressing reductions in sea ice habitat at this time.
National and international regulatory mechanisms to comprehensively
address the causes of climate change are continuing to be developed.
International efforts to address climate change globally began with the
United Nations Framework Convention on Climate Change (UNFCCC), adopted
in May 1992. The stated objective of the UNFCCC is the stabilization of
GHG concentrations in the atmosphere at a level that would prevent
dangerous anthropogenic interference with the climate system. The Kyoto
Protocol, negotiated in 1997, became the first additional agreement
added to the UNFCCC to set GHG emissions targets. The Kyoto Protocol
entered into force in February 2005 for signatory countries.
Domestic U.S. efforts relative to climate change focus on
implementation of the Clean Air Act, and continued studies programs,
support for developing new technologies and use of incentives for
supporting reductions in emissions.
The recent publication by Canadell et al. (2007) underscores the
current deficiencies of regulatory mechanisms in addressing root causes
of climate change. This paper, in the Proceedings of the National
Academy of Sciences, indicates that the growth rate of atmospheric
carbon dioxide (CO2), the largest anthropogenic source of
GHGs, is increasing rapidly. Increasing atmospheric CO2
concentration is consistent with the results of climate-carbon cycle
models, but the magnitude of the observed CO2 concentration
is larger than that estimated by models. The authors suggest that these
changes ``characterize a carbon cycle that is generating stronger-than-
expected and
[[Page 28288]]
sooner-than-expected climate forcing'' (Canadell et al. 2007).
Conclusion for Factor D
Rationale
Our review of existing regulatory mechanisms at the national and
international level has led us to determine that potential threats to
polar bears from direct take, disturbance by humans, and incidental or
harassment take are, for the most part, adequately addressed through
international agreements, national, State, Provincial or Territorial
legislation, and other regulatory mechanisms.
As described under Factor A, the primary threat to the survival of
the polar bear is loss of sea ice habitat and its consequences to polar
bear populations. Our review of existing regulatory mechanisms has led
us to determine that, although there are some existing regulatory
mechanisms to address anthropogenic causes of climate change, there are
no known regulatory mechanisms in place at the national or
international level that directly and effectively address the primary
threat to polar bears-the rangewide loss of sea ice habitat.
Determination for Factor D
After evaluating the best available scientific information, we have
determined that existing regulatory mechanisms at the national and
international level are adequate to address actual and potential
threats to polar bears from direct take, disturbance by humans, and
incidental or harassment take.
We note that GHG loading in the atmosphere can have a considerable
lag effect on climate, so that what has already been emitted will have
impacts out to 2050 and beyond (IPCC 2007, p. 749; J. Overland, NOAA,
in litt. to the Service, 2007)). This is reflected in the similarity of
low, medium, and high SRES emissions scenarios out to about 2050 (see
Figure 5). As noted above, the publication of Canadell et al. (2007)
underscores the current deficiencies of regulatory mechanisms in
addressing root causes of climate change. This paper indicates that the
growth rate of atmospheric carbon dioxide (CO2), the largest
anthropogenic source of GHGs, is increasing rapidly. Increasing
atmospheric CO2 concentration is consistent with the results
of climate-carbon cycle models, but the magnitude of the observed
CO2 concentration is larger than that estimated by models
(Canadell et al. 2007). We have determined that there are no known
regulatory mechanisms in place at the national or international level
that directly and effectively address the primary threat to polar
bears-the rangewide loss of sea ice habitat within the foreseeable
future. We also acknowledge that there are some existing regulatory
mechanisms to address anthropogenic causes of climate change, and these
mechanisms are not expected to be effective in counteracting the
worldwide growth of GHG emissions within the foreseeable future.
Factor E. Other Natural or Manmade Factors Affecting the Polar Bear's
Continued Existence
Contaminants
Understanding the potential effects of contaminants on polar bears
in the Arctic is confounded by the wide range of contaminants present,
each with different chemical properties and biological effects, and the
differing geographic, temporal, and ecological exposure regimes
impacting each of the 19 polar bear populations. Further, contaminant
concentrations in polar bear tissues differ with polar bears' age, sex,
reproductive status, and other factors. Contaminant sources and
transport; geographical, temporal patterns and trends; and biological
effects are detailed in several recent Arctic Monitoring and Assessment
Program (AMAP) publications (AMAP 1998; AMAP 2004a; AMAP 2004b; AMAP
2005). Three main groups of contaminants in the Arctic are thought to
present the greatest potential threat to polar bears and other marine
mammals: petroleum hydrocarbons, persistent organic pollutants (POPS),
and heavy metals.
Petroleum Hydrocarbons
The principal petroleum hydrocarbons in the Arctic include crude
oil, refined oil products, polynuclear aromatic hydrocarbons, and
natural gas and condensates (AMAP 1998, p. 661). Petroleum hydrocarbons
come from both natural and anthropogenic sources. The primary natural
source is oil seeps. AMAP (2007, p. 18) notes that ``natural seeps are
the major source of petroleum hydrocarbon contamination in the Arctic
environment.'' Anthropogenic sources include activities associated with
exploration, development, and production of oil (well blowouts,
operational discharges), ship- and land-based transportation of oil
(oil spills from pipelines, accidents, leaks, and ballast washings),
discharges from refineries and municipal waste water, and combustion of
wood and fossil fuels. In addition to direct contamination, petroleum
hydrocarbons are transported from more southerly areas to the Arctic
via long range atmospheric and oceanic transport, as well as by north-
flowing rivers (AMAP 1998, p. 671).
Polar bears are particularly vulnerable to oil spills due to their
inability to effectively thermoregulate when their fur is oiled, and to
poisoning that may occur from ingestion of oil while from grooming or
eating contaminated prey (St. Aubin 1990, p. 237). In addition, polar
bears are curious and are likely to investigate oil spills and oil-
contaminated wildlife. Under some circumstances polar bears are
attracted to offshore drilling platforms (Stirling 1988, p. 6; Stirling
1990, p. 230). Whether healthy polar bears in their natural environment
would avoid oil spills and contaminated seals is unknown; hungry polar
bears are likely to scavenge contaminated seals, as they have shown no
aversion to eating and ingesting oil (St. Aubin 1990, p. 237; Derocher
and Stirling 1991, p. 56). Polar bears are generally known to be
attracted to various refined hydrocarbon products such as anti-freeze,
hydraulic fluids, etc., and may consume them, which in some instances
has resulted in death (Amstrup et al. 1989).
The most direct exposure of polar bears to petroleum hydrocarbons
would come from direct contact with and ingestion of oil from acute and
chronic oil spills. Polar bears' range overlaps with many active and
planned oil and gas operations within 40 km (25 mi) of the coast or
offshore. In the past, no large volume major oil spills of more than
3,000 barrels have occurred in the marine environment within the range
of polar bears. Oil spills associated with terrestrial pipelines have
occurred in the vicinity of polar bear habitat, including denning areas
(e.g., Russian Federation, Komi Republic, 1994 oil spill, http://
www.american.edu/ted/KOMI.HTM). Despite numerous safeguards to prevent
spills, smaller spills do occur. An average of 70 oil and 234 waste
product spills per year occurred between 1977 and 1999 in the North
Slope oil fields (71 FR 14456). Many spills are small (less than 50
barrels) by oil and gas industry standards, but larger spills (greater
than or equal to 500 barrels) account for much of the annual volume.
The largest oil spill to date on the North Slope oil fields in Alaska
(estimated volume of approximately 4,786 barrels) occurred on land in
March 2006, and resulted from an undetected leak in a corroded pipeline
(see State of Alaska Prevention and Emergency Response web site (http:/
/www.dec.state.ak.us/spar/perp/
[[Page 28289]]
response/sum--fy06/060302301/060302301--index.htm).
The MMS (2004, pp. 10, 127) estimated an 11 percent chance of a
marine spill greater than 1,000 barrels in the Beaufort Sea from the
Beaufort Sea Multiple Lease Sale in Alaska. The Minerals Management
Service (MMS) prepared an EIS on the Chukchi Sea Planning Area; Oil and
Gas Lease Sale 193 and Seismic Surveying Activities in the Chukchi Sea;
they determined that polar bears could be affected by both routine
activities and a large oil spill (MMS 2007, pp. ES 1-10). Regarding
routine activities, the EIS determined that small numbers of polar
bears could be affected by ``noise and other disturbance caused by
exploration, development, and production activities'' (MMS 2007, p. ES-
4). In addition, the EIS evaluated events that would be possible over
the life of the hypothetical development and production that could
follow the lease sale, and estimated that ``the chance of a large spill
greater than or equal to 1,000 barrels occurring and entering offshore
waters is within a range of 33 to 51 percent.'' If a large spill were
to occur, the analysis conducted as part of the EIS process identified
potentially significant impacts to polar bears occurring in the area
affected by the spill; the evaluation was done without regard to the
effect of mitigating measures (MMS 2007, p. ES-4).
Oil spills in the fall or spring during the formation or break-up
of sea ice present a greater risk because of difficulties associated
with clean up during these periods, and the presence of bears in the
prime feeding areas over the continental shelf. Amstrup et al. (2000a,
p. 5) concluded that the release of oil trapped under the ice from an
underwater spill during the winter could be catastrophic during spring
break-up if bears were present. During the autumn freeze-up and spring
break-up periods, any oil spilled in the marine environment would
likely concentrate and accumulate in open leads and polynyas, areas of
high activity for both polar bears and seals (Neff 1990, p. 23). This
would result in an oiling of both polar bears and seals (Neff 1990, pp.
23-24; Amstrup et al. 2000a, p. 3; Amstrup et al. 2006a, p. 9).
The MMS operating regulations require that Outer Continental Shelf
(OCS) activities are carried out in a safe and environmentally sound
manner to prevent harm, damage or waste of, any natural resources any
life (including marine mammals such as the polar bear), property, or
the marine, coastal, or human environment. Regulations for exploration,
development, and production operations on the OCS are specified in 30
CFR part 250. These regulations provide measures for pollution
prevention and control, including drilling procedures specific to
individual wells, redundant safety and pollution prevention equipment,
blowout preventers and subsurface safety valves, training of the
drilling crews, and structural and safety system review of production
facilities. Regulations related to oil-spill prevention and response
are specified in 30 CFR part 254.
As previously discussed in the ``Oil and Gas Exploration,
Development, and Production'' section, the actual history of oil and
gas activities in the Beaufort and Chukchi Seas demonstrate that
operations have been done safely and with a negligible effect on
wildlife and the environment. On the Beaufort and Chukchi OCS, 35
exploratory wells have been drilled. During this drilling period,
approximately 26.7 barrels of petroleum product have been spilled, and,
of those 26.7 barrels, approximately 24 barrels were recovered or
cleaned up. MMS and industry standards require strict protection
measures during production of energy resources. For example, although
it is located in State of Alaska waters, the shared State/Federal
Northstar production facility used a specially-fabricated pipe that was
buried 7-11 ft below the sea floor to prevent damage from ice keels, is
pigged (the practice of using pipeline inspection gauges or 'pigs' to
perform various operations on a pipeline without stopping the flow of
the product in the pipeline), and has several different monitoring
systems to detect spills.
In addition, NOAA and the Service require monitoring and avoidance
measures for marine mammals during critical times during exploration
and production. The Marine Mammal Observers (MMO) are required by NOAA
and the Service to be on deck watching for animals. Depending on the
activity and the particular circumstances, operations may be
temporarily halted or modified. In some circumstances, hazing may be
used to keep the polar bears away from operations. There are specific
guidelines the MMO follow for observing and hazing. Hazing is only used
to protect the safety of humans or the marine mammal.
Prior to any exploration, development, or production activities,
companies must submit an Exploration Plan or a Development/Production
Plan to MMS for review and approval. In Alaska, MMS provides a copy of
all such plans to the Service for review. Prior to conducting drilling
operations, the operator must also obtain approval for an Application
for Permit to Drill (APD). The APD requires detailed information on the
seafloor and shallow seafloor conditions for the drill site from
shallow geophysical and, if necessary, archaeological and biological
surveys. The APD requires detailed information about the drilling
program to allow evaluation of operational safety and pollution-
prevention measures. The lessee must use the best available and safest
technology to minimize the potential for uncontrolled well flow,
through the use of blowout preventers. For example, the operator also
must identify procedures to curtail operations during critical ice or
weather conditions.
In addition, the MMS identifies additional protection measures for
the polar bear through the use of Information to Lessees (ITL). Lessees
are advised that incidental take of marine mammals is prohibited unless
authorization is received under the MMPA. For example, for Sale 193 in
the Chukchi Sea, potential lessees were advised to obtain MMPA
authorizations from FWS and to consult with the Service, local Native
communities and the Alaska Nanuuq Commission during exploration,
production and spill response planning, to assure adequate protection
for the polar bear. Lessees are specifically advised to conduct their
activities in a way that will limit potential encounters and
interaction between lease operations and polar bears.
For production, the lessee must design, fabricate, install, use,
inspect, and maintain all platforms and structures on the OCS to ensure
their structural integrity for the safe conduct of operations at
specific locations. All tubing installations open to hydrocarbon-
bearing zones below the surface must be equipped with safety devices
that will shut off the flow from the well in the event of an emergency,
unless the well is incapable of flowing. All surface production
facilities must be designed, installed, and maintained in a manner that
provides for efficiency, safety of operations, and protection of the
environment, including marine mammals.
Pipeline-permit applications to MMS include the pipeline location
drawing, profile drawing, safety schematic drawing, pipe-design data to
scale, a shallow-hazard-survey report, and an archaeological report.
The MMS evaluates the design and fabrication of the pipeline. No
pipeline route will be approved by MMS if any bottom-disturbing
activities (from the pipeline
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itself or from the anchors of lay barges and support vessels) encroach
on any biologically sensitive areas. The operators are required to
monitor and inspect pipelines by methods prescribed by MMS for any
indication of pipeline leakage.
MMS conducts onsite inspections to ensure compliance with plans and
with the MMS pollution prevention regulations. It has been practice in
Alaska to have an MMS inspector onboard drilling vessels during key
drilling procedures.
In compliance with 30 CFR part 254, all owners and operators of
oil-handling, oil-storage, or oil-transportation facilities located
seaward of the coastline must submit an Oil Spill Response Plan to MMS
for approval. Owners or operators of offshore pipelines are required to
submit a plan for any pipeline that carries oil, condensate that has
been injected into the pipeline, or gas and naturally occurring
condensate.
Increases in circumpolar Arctic oil and gas development, coupled
with increases in shipping and/or development of offshore and land-
based pipelines, increase the potential for an oil spill to negatively
affect polar bears and/or their habitat. Future declines in the Arctic
sea ice may result in increased tanker traffic in high bear use areas
(Frantzen and Bambulyak 2003, p. 4), which would increase the chances
of an oil spill from a tanker accident, ballast discharge, or
discharges during the loading and unloading of oil at the ports.
Amstrup et al. (2007, p. 31) assumed that human activities related to
oil and gas exploration and development are likely to increase with
disappearance of sea ice from many northern areas. At the same time,
less sea ice will facilitate an increase in offshore developments. More
offshore development will increase the probability of hydrocarbon
discharges into polar bear habitat (Stirling 1990, p. 228). The record
of over 30 years of predominantly terrestrial oil and gas development
in Alaska suggests that with proper management, potential negative
effects of these activities on polar bears can be minimized (Amstrup
1993, p. 250; Amstrup 2000, pp. 150-154; Amstrup 2003, pp. 597, 604;
Amstrup et al. 2004, p. 23) (for details see the ``Oil and Gas
Exploration, Development, and Production'' section of this final rule).
Increased industrial activities in the marine environment will require
additional monitoring.
Amstrup et al. (2006) evaluated the potential effects of a
hypothetical 5,912-barrel oil spill (the largest spill thought possible
from a pipeline spill) on polar bears from the Northstar offshore oil
production facility in the southern Beaufort Sea, and found that there
is a low probability that a large number of bears (e.g., 25-60) might
be affected by such a spill. For the purposes of this scenario, it was
assumed that a polar bear would die if it came in contact with the oil.
Amstrup et al. (2006a, p.21) found that 0-27 bears could potentially be
oiled during the open water conditions in September, and from 0-74
bears in mixed ice conditions during October. If such a spill occurred,
particularly during the broken ice period, the impact of the spill
could be significant to the Southern Beaufort Sea polar bear population
(Amstrup et al. 2006a, pp. 7, 22; 65 FR 16833). The sustainable harvest
yield per year for the Southern Beaufort Sea population, based on a
stable population size of 1,800 bears, was estimated to be 81.1 bears
(1999-2000 to 2003-2004) (Lunn et al. 2005, p. 107). For the same time
period, the average harvest was 58.2 bears, leaving an additional
buffer of 23 bears that could have been removed from the population.
Therefore, an oil spill that resulted in the death of greater than 23
bears, which was possible based on the range of oil spill-related
mortalities from the previous analysis, could have had population level
effects for polar bears in the southern Beaufort Sea. However, the
harvest figure of 81 bears may no longer be sustainable for the
Southern Beaufort Sea population, so, given the average harvest rate
cited above, fewer than 23 oil spill-related mortalities could result
in population-level effects.
The number of polar bears affected by an oil spill could be
substantially higher if the spill spread to areas of seasonal polar
bear concentrations, such as the area near Kaktovik, Alaska, in the
fall, and could have a significant impact to the Southern Beaufort Sea
polar bear population. It seems likely that an oil spill would affect
ringed seals the same way the Exxon Valdez oil spill affected harbor
seals (Frost et al. 1994a, pp. 108-110; Frost et al. 1994b, pp. 333-
334, 343-344, 346-347; Lowry et al. 1994, pp. 221-222; Spraker et al.
1994, pp. 300-305). As with polar bears, the number of animals killed
would vary depending upon the season and spill size (NRC 2003, pp. 168-
169). Oil spills remain a concern for polar bears throughout their
range. Increased industrial activities in the marine environment will
require additional monitoring. Oil and gas exploration, development,
and production effects on polar bears and their habitat are discussed
under Factor A.
Persistent Organic Pollutants (POPs)
Contamination of the Arctic and sub-Arctic regions through long-
range transport of persistent organic pollutants has been recognized
for over 30 years (Bowes and Jonkel 1975, p. 2,111; de March et al.
1998, p. 184; Proshutinsky and Johnson 2001, p. 68; MacDonald et al.
2003, p. 38). These compounds are transported via large rivers, air,
and ocean currents from the major industrial and agricultural centers
located at more southerly latitudes (Barrie et al. 1992; Li et al.
1998, pp. 39-40; Proshutinsky and Johnson 2001, p. 68; Lie et al. 2003,
p. 160). The presence and persistence of these contaminants within the
Arctic is dependent on many factors, including transport routes,
distance from source, and the quantity and chemical composition of the
releases. Climate change may increase long-range marine and atmospheric
transport of contaminants (Macdonald et al. 2003, p. 5; Macdonald et al
2005, p.15). For example, increased rainfall in northern regions has
increased river discharges into the Arctic marine environment. Many
north-flowing rivers originate in heavily industrialized regions and
carry heavy contaminant burdens (Macdonald et al. 2005, p. 31).
The Arctic ecosystem is particularly sensitive to environmental
contamination due to the slower rate of breakdown of persistent organic
pollutants, including organochlorine (OC) compounds, the relatively
simple food chains, and the presence of long-lived organisms with low
rates of reproduction and high lipid levels. The persistence and
tendency of OCs to reside and concentrate in fat tissues of organisms
increases the potential for bioaccumulation and biomagnification at
higher trophic levels (Fisk et al. 2001, pp. 225-226). Polar bears,
because of their position at the top of the Arctic marine food chain,
have some of the highest concentrations of OCs of any Arctic mammals
(Braune et al. 2005, p. 23). Considering the potential for increases in
both local and long-range transport of contaminants to the Arctic, with
warmer climate and less sea ice, the influence these activities have on
polar bears is likely to increase.
The most studied POPs in polar bears include polychlorinated
biphenyls (PCBs), chlordanes (CHL), DDT and its metabolites, toxaphene,
dieldrin, hexachloroabenzene (HCB), hexachlorocyclohexanes (HCHs), and
chlorobenzenes (ClBz). Overall, the relative proportion of the more
recalcitrant compounds, such as PCB 153 and [beta]-HCH, appears to be
increasing in polar bears (Braune et al. 2005, p. 50).
[[Page 28291]]
Although temporal trend information is lacking, newer compounds, such
as polybrominated diphenyl ethers (PBDEs), polychlorinated naphthalenes
(PCNs), perflouro-octane sulfonate (PFOsS), perfluoroalkyl acids
(PFAs), and perflourocarboxylic acids (PFCAs), have been recently found
in polar bears (Braune et al. 2005, p. 5). Of this relatively new suite
of compounds, there is concern that both PFOsS, which are increasing
rapidly, and PBDEs are a potential risk to polar bears (Ikonomou et al.
2002, p. 1,886; deWit 2002, p. 583; Martin et al. 2004, p. 373; Braune
et al. 2005, p. 25; Smithwick et al. 2006, p. 1,139).
Currently, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans
(PCDFs) and dioxin-like PCBs are at relatively low concentrations in
polar bears (Norstrom et al. 1990, p. 14). The highest PCB
concentrations have been found in polar bears from the Russian Arctic
(Franz Joseph Land and the Kara Sea), with decreasing concentrations to
the east and west (Andersen et al. 2001, p. 231). Overall, there is
evidence of declines in PCBs for most polar bear populations. The
pattern of distribution for most other chlorinated hydrocarbons and
metabolites generally follows that of PCBs, with the highest
concentrations of DDT-related compounds and CHLs in Franz Joseph Land
and the Kara Sea, followed by East Greenland, Svalbard, the eastern
Canadian Arctic populations, the western Canadian populations, the
Siberian Sea, and finally the lowest concentrations in Alaska
populations (Bernhoft et al. 1997; Norstrom et al. 1998, p. 361;
Andersen et al. 2001, p. 231; Kucklick et al. 2002, p. 9; Lie et al.
2003, p. 159; Verreault et al. 2005, pp. 369-370; Braune et al. 2005,
p. 23).
The polybrominated diphenyl ethers (PBDEs) share similar physical
and chemical properties with PCBs (Wania and Dugani 2003, p. 1,252;
Muir et al. 2006, p. 449), and are thought to be transported to the
Arctic by similar pathways. Muir et al. (2006, p. 450) analyzed
archived samples from Dietz et al. (2004) and Verreault et al. (2005)
for PBDE concentrations, finding the highest mean PBDE concentrations
in female polar bear adipose tissue from East Greenland and Svalbard.
Lower concentrations of PBDEs were found in adipose tissue from the
Canadian and Alaskan populations (Muir et al. 2006, p. 449).
Differences between the PBDE concentrations and composition in liver
tissue between the Southern Beaufort Sea and the Chukchi Seas
populations in Alaska suggest differences in the sources of PBDEs
exposure (Kannan et al. 2005, p. 9057). Overall, the sum of the PBDE
concentrations are much lower and less of a concern compared to PCBs,
oxychlordane, and some of the more recently discovered perflouorinated
compounds. PBDEs are metabolized to a high degree in polar bears and
thus do not bioaccumulate as much as PCBs (Wolkers et al. 2004, p.
1,674).
Although baseline information on contaminant concentrations is
available, determining the biological effects of these contaminants in
polar bears is difficult. Field observations of reproductive impairment
in females and males, lower survival of cubs, and increased mortality
of females in Svalbard, Norway, however, suggest that high
concentrations of PCBs may have contributed to population level effects
in the past (Wiig 1998, p. 28; Wiig et al. 1998, p. 795; Skaare et al.
2000, p. 107; Haave et al. 2003, pp. 431, 435; Oskam et al. 2003, p.
2134; Derocher et al. 2003, p. 163). At present, however, PCB
concentrations are not thought to be resulting population level effects
on polar bears. Organochlorines may adversely affect the endocrine
system as metabolites of these compounds are toxic and some have
demonstrated endocrine disrupting activity (Letcher et al. 2000; Braune
et al. 2005, p. 23). High concentrations of organochlorines may also
affect the immune system, resulting in a decreased ability to produce
antibodies (Lie et al. 2004, pp. 555-556).
Despite the regulatory steps taken to decrease the production or
emissions of toxic chemicals, increases in some relatively new
compounds are cause for concern. Some of these compounds have increased
in the last decade (Ikonomou et al. 2002, p. 1,886; Muir et al. 2006,
p. 453).
Metals
Numerous essential and non-essential elements have been reported on
for polar bears and the most toxic or abundant elements in marine
mammals are mercury, cadmium, selenium, and lead. Of these, mercury is
of greatest concern because of its potential toxicity at relatively low
concentrations, and its ability to biomagnify and bioaccumulate in the
food web. Polar bears from the western Canadian Arctic and southwest
Melville Island, Canada (Braune et al. 1991, p. 263; Norstrom et al.
1986, p. 195; AMAP 2005, pp. 42, 62, 134), and ringed seals from the
western Canadian Arctic (Wagemann et al. 1996, p. 41; Deitz et al.
1998, p. 433; Dehn et al. 2005, p. 731; Riget et al. 2005, p. 312),
have some of the highest known mercury concentrations. Wagemann et al.
(1996, pp. 51, 60) observed an increase in mercury from eastern to
western Canadian ringed seal populations and attributed this pattern to
a geologic gradient in natural mercury deposits.
Although the contaminant concentrations of mercury found in marine
mammals often exceed those found to cause effects in terrestrial
mammals (Fisk et al. 2003, p. 107), most marine mammals appear to have
evolved effective biochemical mechanisms to tolerate high
concentrations of mercury (AMAP 2005, p.123). Polar bears are able to
break down methylmercury and accumulate higher levels than their
terrestrial counterparts without detrimental effects (AMAP 2005, p.
123). Evidence of mercury poisoning is rare in marine mammals, but
Dietz et al. (1990, p. 49) noted that sick marine mammals often have
higher concentrations of methylmercury, suggesting that these animals
may no longer be able to detoxify methylmercury. Hepatic mercury
concentrations are well below those expected to cause biological
effects in most polar bear populations (AMAP 2005, p. 118). Only two
polar bear populations have concentrations of mercury close to the
biological threshold levels of 60 micrograms wet weight reported for
marine mammals (AMAP 2005, p. 121): the Viscount Melville population
(southwest Melville Sound), Canada, and the Southern Beaufort Sea
population (eastern Beaufort Sea) (Dietz et al. 1998, p. 435, Figure 7-
52).
Shipping and Transportation
Observations over the past 50 years show a decline in Arctic sea
ice extent in all seasons, with the most prominent retreat in the
summer. Climate models project an acceleration of this trend with
periods of extensive melting in spring and autumn, thus opening new
shipping routes and extending the period that shipping is practical
(ACIA 2005, p. 1,002). Notably, the navigation season for the Northern
Sea Route (across northern Eurasia) is projected to increase from 20-30
days per year to 90-100 days per year. Russian scientists cite
increasing use of a Northern Sea Route for transit and regional
development as a major source of disturbance to polar bears in the
Russian Arctic (Wiig et al. 1996, pp. 23-24; Belikov and Boltunov 1998,
p. 113; Ovsyanikov 2005, p. 171). Commercial navigation on the Northern
Sea Route could disturb polar bear feeding and other behaviors, and
would increase the risk of oil spills (Belikov et al. 2002, p. 87).
Increased shipping activity may disturb polar bears in the marine
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environment, adding additional energetic stresses. If ice-breaking
activities occur, they may alter habitats used by polar bears, possibly
creating ephemeral lead systems and concentrating ringed seals within
the refreezing leads. This, in turn, may allow for easier access to
ringed seals and may have some beneficial values. Conversely, this may
cause polar bears to use areas that may have a higher likelihood of
human encounters as well as increased likelihood of exposure to oil,
waste products, or food wastes that are intentionally or accidentally
released into the marine environment. If shipping involved the tanker
transport of crude oil or oil products, there would be some increased
likelihood of small to large volume spills and corresponding oiling of
polar bears, as well as potential effects on seal prey species (AMAP
2005, pp. 91, 127).
The PBSG (Aars et al. 2006, pp. 22, 58, 171) recognized the
potential for increased shipping and marine transportation in the
Arctic with declining seasonal sea ice conditions. The PBSG recommended
that the parties to the 1973 Polar Bear Agreement take appropriate
measures to monitor, regulate, and mitigate ship traffic impacts on
polar bear populations and habitats (Aars et al. 2006, p. 58).
Ecotourism
Properly regulated ecotourism will likely not have a negative
effect on polar bear populations, although increasing levels of
ecotourism and photography in polar bear viewing areas and natural
habitats may lead to increased polar bear-human conflicts. Ecotourists
and photographers may inadvertently displace bears from preferred
habitats or alter natural behaviors (Lentfer 1990, p.19; Dyck and
Baydack 2004, p. 344). Polar bears are inquisitive animals and often
investigate novel odors or sights. This trait can lead to polar bears
being killed at cabins and remote stations where they investigate food
smells (Herrero and Herrero 1997, p. 11). Conversely, ecotourism has
the effect of increasing the worldwide constituency of people with an
interest in polar bears and their conservation.
Conclusion for Factor E
Rationale
Contaminant concentrations are not presently thought to have
population level effects on most polar bear populations. However,
increased exposure to contaminants has the potential to operate in
concert with other factors, such nutritional stress from loss or
degradation of the sea ice habitat or decreased prey availability and
accessibility, to lower recruitment and survival rates that ultimately
would have negative population level effects. Despite the regulatory
steps taken to decrease the production or emissions of toxic chemicals,
use of some relatively new compounds has increased recently in the last
decade (Ikonomou et al. 2002, p. 1,886; Muir et al. 2006, p. 453).
Several populations, such as the Svalbard, East Greenland, and Kara Sea
populations, that currently have some of the highest contaminant
concentrations may be affected, but we do not believe these effects
will be significant within the foreseeable future. Increasing levels of
ecotourism and shipping may lead to greater impacts on polar bears. The
potential extent of impact is related to changing sea ice conditions
and resulting changes to polar bear distribution.
Determination for Factor E
We have evaluated the best available scientific information on
other natural or manmade factors that are affecting polar bears, and
have determined that contaminants, ecotourism, and shipping do not
threaten the polar bear throughout all or any significant portion of
its range. Some of these, particularly contaminants and shipping, may
become more significant threats in the future for polar bear
populations experiencing declines related to nutritional stress brought
on by sea ice and environmental changes.
Finding
We have carefully considered all available scientific and
commercial information past, present, and future threats faced by the
polar bear. We reviewed the petition, information available in our
files, scientific journals and reports, and other published and
unpublished information submitted to us during the public comment
periods following our February 9, 2006 (71 FR 6745) 90-day petition
finding, the January 9, 2007 (72 FR 1064), 12-month Finding and
proposed rule, and during public hearings held in Washington, DC and
Alaska. In addition, at the request of the Secretary of the Interior,
the USGS analyzed and integrated a series of studies on polar bear
population dynamics, range-wide habitat use and changing sea ice
conditions in the Arctic, and provided the Service with nine scientific
reports on the results of their studies. We carefully evaluated these
new reports and other published and unpublished information submitted
to us following the public comment period on these reports, initially
opened for 15 days (September 20, 2007; 72 FR 53749), but then extended
until October 22, 2007 (72 FR 56979).
In accordance with our policy published on July 1, 1994 (59 FR
34270), we solicited and received expert opinions on both the Range
Wide Status Review of the Polar Bear (Ursus maritimus) (Schliebe et al.
2006a), and subsequently on the 12-month finding and proposed rule (72
FR 1064). We received reviews of the draft Status Review from 10
independent experts and on the proposed rule from 14 independent
experts in the fields of polar bear ecology, contaminants and
physiology, climatic science and physics, Arctic ecology, pinniped
(seal) ecology, and traditional ecological knowledge (TEK). We also
consulted with recognized polar bear experts and other Federal, State,
and range country resource agencies.
In making this finding, we recognize that polar bears evolved in
the ice-covered waters of the circumpolar Arctic, and are reliant on
sea ice as a platform to hunt and feed on ice-seals, to seek mates and
breed, to move to feeding sites and terrestrial maternity denning
areas, and for long-distance movements. The rapid retreat of sea ice in
the summer and overall diminishing sea ice throughout the year in the
Arctic is unequivocal and extensively documented in scientific
literature. Further extensive recession of sea ice is projected by the
majority of state-of-the-art climate models, with a seasonally ice-free
Arctic projected by the middle of the 21st century by many of those
models. Sea ice habitat will be subjected to increased temperatures,
earlier melt periods, increased rain-on-snow events, and shifts in
atmospheric and marine circulation patterns.
Under Factor A (``Present or Threatened Destruction, Modification,
or Curtailment of its habitat or range''), we have determined that
ongoing and projected loss of the polar bear's crucial sea ice habitat
threatens the species throughout all of its range. Productivity,
abundance, and availability of ice seals, the polar bear's primary prey
base, would be diminished by the projected loss of sea ice, and
energetic requirements of polar bears for movement and obtaining food
would increase. Access to traditional denning areas would be affected.
In turn, these factors would cause declines in the condition of polar
bears from nutritional stress and reduced productivity. As already
evidenced in the Western Hudson Bay and Southern Beaufort Sea
populations, polar bears would experience reductions in survival and
recruitment rates. The eventual effect is that polar bear populations
would
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decline. The rate and magnitude of decline would vary among
populations, based on differences in the rate, timing, and magnitude of
impacts. However, within the foreseeable future, all populations would
be affected, and the species is likely to become in danger of
extinction throughout all of its range due to declining sea ice
habitat.
Under Factor B (``Overutilization for Commercial, Recreational,
Scientific, or Educational Purposes'') we note that polar bears are
harvested in Canada, Alaska, Greenland, and Russia, and we acknowledge
that harvest is the consumptive use of greatest importance and
potential effect to polar bear. Further we acknowledge that forms of
removal other than harvest (such as defense-of-life take) have been
considered in this analysis. While overharvest occurs for some
populations, laws and regulations for most management programs have
been instituted to provide sustainable harvests over the long term. As
the status of populations declines, it may be necessary for management
entitites to implement harvest reductions in order to limit the
potential effect of harvest. This capability has a proven track record
in Canada, and is adaptive to future needs. Further, bilateral
agreements or conservation agreements have been developed to address
issues of overharvest. Conservation benefits from agreements that are
in development or have not yet been implemented are not considered in
our evaluation. We also acknowledge that increased levels of bear-human
encounters are expected in the future and that encounters may result in
increased mortality to bears at some unknown level. Adaptive management
programs, such as implementing polar bear patrols, hazing programs, and
efforts to minimize attraction of bears to communities, to address
future bear-human interaction issues, including on-the-land ecotourism
activities, are anticipated.
Harvest is likely exacerbating the effects of habitat loss in
several populations. In addition, continued harvest and increased
mortality from bear-human encounters or other forms of mortality may
become a more significant threat factor in the future, particularly for
populations experiencing nutritional stress or declining population
numbers as a consequence of habitat change. Although harvest, increased
bear-human interaction levels, defense-of-life take, illegal take, and
take associated with scientific research live-capture programs are
occurring for several populations, we have determined that
overutilization does not currently threaten the species throughout all
or a significant portion of its range.
Under Factor C (``Disease and Predation'') we acknowledge that
disease pathogens are present in polar bears; no epizootic outbreaks
have been detected; and intra-specific stress through cannibalism may
be increasing; however, population level effects have not been
documented. Potential for disease outbreaks, an increased possibility
of pathogen exposure from changed diet or the occurrence of new
pathogens that have moved northward with a warming environment, and
increased mortality from intraspecific predation (cannibalism) may
become more significant threat factors in the future for polar bear
populations experiencing nutritional stress or declining population
numbers. We have determined that disease and predation (including
intraspecific predation) do not threaten the species throughout all or
a significant portion of its range.
Under Factor D (``Inadequacy of Existing Regulatory Mechanisms''),
we have determined that existing regulatory mechanisms at the national
and international level are generally adequate to address actual and
potential threats to polar bears from direct take, disturbance by
humans, and incidental or harassment take. We have determined that
there are no known regulatory mechanisms in place at the national or
international level that directly and effectively address the primary
threat to polar bears--the rangewide loss of sea ice habitat within the
foreseeable future.
We acknowledge that there are some existing regulatory mechanisms
to address anthropogenic causes of climate change, and these mechanisms
are not expected to be effective in counteracting the worldwide growth
of GHG emissions in the foreseeable future.
Under Factor E (``Other Natural or Manmade Factors Affecting the
Polar Bear's Continued Existence'') we reviewed contaminant
concentrations and find that, in most populations, contaminants have
not been found to have population level effects. We further evaluated
increasing levels of ecotourism and shipping that may lead to greater
impacts on polar bears. The extent of potential impact is related to
changing ice conditions, polar bear distribution changes, and relative
risk for a higher interaction between polar bears and ecotourism or
shipping. Certain factors, particularly contaminants and shipping, may
become more significant threats in the future for polar bear
populations experiencing declines related to nutritional stress brought
on by sea ice and environmental changes. We have determined, however,
that contaminants, ecotourism, and shipping do not threaten the polar
bear throughout all or a significant portion of its range.
On the basis of our thorough evaluation of the best available
scientific and commercial information regarding present and future
threats to the polar bear posed by the five listing factors under the
Act, we have determined that the polar bear is threatened throughout
its range by habitat loss (i.e., sea ice recession). We have determined
that there are no known regulatory mechanisms in place at the national
or international level that directly and effectively address the
primary threat to polar bears--the rangewide loss of sea ice habitat.
We have determined that overutilization does not currently threaten the
species throughout all or a significant portion of its range, but is
exacerbating the effects of habitat loss for several populations and
may become a more significant threat factor within the foreseeable
future. We have determined that disease and predation, in particular
intraspecific predation, and contaminants do not currently threaten the
species throughout all or a significant portion of its range, but may
become more significant threat factors for polar bear populations,
especially those experiencing nutritional stress or declining
population levels, within the foreseeable future.
Distinct Population Segment (DPS) and Significant Portion of the Range
(SPR) Evaluation
The Act defines an endangered species as a species in danger of
extinction throughout all or a significant portion of its range, and a
threatened species as a species that is likely to become an endangered
species within the foreseeable future throughout all or a significant
portion of its range.
In our analysis for this final rule we initially evaluated the
status of and threats to the species throughout its entire range. The
polar bear is broadly distributed throughout the circumpolar Arctic,
occurring in five countries and numbering from 20,000-25,000 in total
population. The species has been delineated into 19 populations for
management purposes by the PBSG (Aars et al. 2006, p. 33), and these
populations have been aggregated into four ecoregions for population
and habitat modeling exercises by Amstrup et al. (2007). In our
evaluation of threats to the polar bear, we determined that populations
are being affected, and will continue being affected, at different
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times, rates, and magnitudes depending on where they occur. Some of
these differential effects can be distinguished at the ecoregional
level, as demonstrated by Amstrup et al. (2007). On the basis of this
evaluation, we determined that the entire species meets the definition
of threatened under the Act due to the loss of sea ice habitat. The
basis of this determination is captured within the analysis of each of
the five listing factors, and the ``Finding'' immediately preceding
this section.
Recognizing the differences in the timing, rate, and magnitude of
threats, we evaluated whether there were any specific areas or
populations that may be disproportionately threatened such that they
currently meet the definition of an endangered species versus a
threatened species. We first considered whether listing one or more
Distinct Population Segments (DPS) as endangered may be warranted. We
then considered whether there are any significant portions of the polar
bear's range (SPR) where listing the species as endangered may be
warranted. Our DPS and SPR analyses follow.
Our ``Policy Regarding the Recognition of Distinct Vertebrate
Population Segments under the Act'' (61 FR 4725; February 7, 1996)
outlines three elements that must be considered with regard to the
potential recognition of a DPS as endangered or threatened: (1)
Discreteness of the population segment in relation to the remainder of
the species to which it belongs; (2) significance of the population
segment in relation to the remainder of the taxon; and (3) conservation
status of the population segment in relation to the Act's standards for
listing (i.e., when treated as if it were a species, is the population
segment endangered or threatened?).
Under our DPS Policy, a population segment of a vertebrate species
may be considered discrete if it satisfies either one of the following
conditions: (1) It is markedly separated from other populations of the
same taxon as a consequence of physical, physiological, ecological, or
behavioral factors (quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation); or (2) it is
delimited by international governmental boundaries within which
differences in control of exploitation, management of habitat,
conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the Act.
Genetic studies of polar bears have documented that within-
population genetic variation is similar to black and grizzly bears
(Amstrup 2003, p. 590), but that among populations, genetic structuring
or diversity is low (Paetkau et al. 1995, p. 347; Cronin et al. 2006,
pp. 658-659). The latter has been attributed to extensive population
mixing associated with large home ranges and movement patterns, as well
as the more recent divergence of polar bears in comparison to grizzly
and black bears (Talbot and Shields 1996a, p. 490; Talbot and Shields
1996b, p. 574; Paetkau et al. 1999, p. 1580). Genetic analyses support
delineated boundaries between some populations (Paetkau et al. 1999, p.
1,571; Amstrup 2003, p. 590), while confirming the existence of overlap
and mixing among others (Paetkau et al. 1999, p. 1,571; Cronin et al.
2006, p. 655). We have concluded that these small genetic differences
are not sufficient to distinguish population segments under the DPS
Policy. Moreover, there are no morphological or physiological
differences across the range of the species that may indicate
adaptations to environmental variations. Although polar bears within
different populations or ecoregions (as defined by Amstrup et al. 2007)
may have minor differences in demographic parameters, behavior, or life
history strategies, in general polar bears have a similar dependence
upon sea ice habitats, rely upon similar prey, and exhibit similar life
history characteristics throughout their range.
Consideration might be given to utilizing international boundaries
to satisfy the discreteness portion of the DPS Policy. However, each
range country shares populations with other range countries, and many
of the shared populations are also co-managed. Given that the threats
to the polar bear's sea ice habitat is global in scale and not limited
to the confines of a single country, and that populations are being
managed collectively by the range countries (through bi-lateral and
multi-lateral agreements), we do not find that differences in
conservation status or management for polar bears across the range
countries is sufficient to justify the use of international boundaries
to satisfy the discreteness criterion of the DPS Policy. Therefore, we
conclude that there are no population segments that satisfy the
discreteness criterion of the DPS Policy. As a consequence, we could
not identify any geographic areas or populations that would qualify as
a DPS under our 1996 DPS Policy (61 FR 4722).
Having determined that the polar bear meets the definition of a
threatened species rangewide and that there are no populations that
meet the discreteness criteria under our DPS policy (and, therefore,
that there are no Distinct Population Segments for the polar bear), we
then considered whether there are any significant portions of its range
where the species is in danger of extinction.
On March 16, 2007, a formal opinion was issued by the Solicitor of
the Department of the Interior, ``The Meaning of `In Danger of
Extinction Throughout All or a Significant Portion of Its Range'''
(USDI 2007c). We have summarized our interpretation of that opinion and
the underlying statutory language below. A portion of a species' range
is significant if it is part of the current range of the species and it
contributes substantially to the representation, resiliency, or
redundancy of the species. The contribution must be at a level such
that its loss would result in a decrease in the ability to conserve the
species.
Some may argue that lost historical range should be considered by
the Service when evaluating effects posed to a significant portion of
the species' range. While we disagree with this argument, we note that
the polar bear currently occupies its entire historical range.
In determining whether a species is threatened or endangered in a
significant portion of its range, we first identify any portions of the
range of the species that warrant further consideration. The range of a
species can theoretically be divided into portions in an infinite
number of ways. However, there is no purpose to analyzing portions of
the range that are not reasonably likely to be significant and
threatened or endangered. To identify those portions that warrant
further consideration, we determine whether there is substantial
information indicating that (i) the portions may be significant and
(ii) the species may be in danger of extinction there or likely to
become so within the foreseeable future. In practice, a key part of
this analysis is whether the threats are geographically concentrated in
some way. If the threats to the species are essentially uniform
throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the range that are unimportant to the conservation of
the species, such portions will not warrant further consideration.
If we identify any portions that warrant further consideration, we
then determine whether in fact the species is threatened or endangered
in any significant portion of its range. Depending on the biology of
the species, its range, and the threats it faces, it may be more
efficient for the Service to
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address the significance question first, or the status question first.
Thus, if the Service determines that a portion of the range is not
significant, the Service need not determine whether the species is
threatened or endangered there. If the Service determines that the
species is not threatened or endangered in a portion of its range, the
Service need not determine if that portion is significant. If the
Service determines that both a portion of the range of a species is
significant and the species is threatened or endangered there, the
Service will specify that portion of the range as threatened or
endangered pursuant to section 4(c)(1) of the Act.
The terms ``resiliency,'' ``redundancy,'' and ``representation''
are intended to be indicators of the conservation value of portions of
the range. Resiliency of a species allows the species to recover from
periodic disturbance. A species will likely be more resilient if large
populations exist in high-quality habitat that is distributed
throughout the range of the species in such a way as to capture the
environmental variability found within the range of the species. In
addition, the portion may contribute to resiliency for other reasons--
for instance, it may contain an important concentration of certain
types of habitat that are necessary for the species to carry out its
life-history functions, such as breeding, feeding, migration,
dispersal, or wintering. Redundancy of populations may be needed to
provide a margin of safety for the species to withstand catastrophic
events. This does not mean that any portion that provides redundancy is
a significant portion of the range of a species. The idea is to
conserve enough areas of the range such that random perturbations in
the system act on only a few populations. Therefore, each area must be
examined based on whether that area provides an increment of redundancy
that is important to the conservation of the species. Adequate
representation ensures that the species' adaptive capabilities are
conserved. Specifically, the portion should be evaluated to see how it
contributes to the genetic diversity of the species. The loss of
genetically based diversity may substantially reduce the ability of the
species to respond and adapt to future environmental changes. A
peripheral population may contribute meaningfully to representation if
there is evidence that it provides genetic diversity due to its
location on the margin of the species' habitat requirements.
To determine whether any portions of the range of the polar bear
warrant further consideration as possible endangered significant
portions of the range, we reviewed the entire supporting record for
this final listing determination with respect to the geographic
concentration of threats and the significance of portions of the range
to the conservation of the species. As previously mentioned, we
evaluated whether substantial information indicated that (i) the
portions may be significant and (ii) the species in that portion may
currently be in danger of extinction. We recognize that the level,
rate, and timing of threats are uneven across the Arctic and, thus,
that polar bear populations will be affected at different rates and
magnitudes depending on where they occur and the resiliency of each
specific population. On this basis, we determined that some portions of
the polar bear's range might warrant further consideration as possible
endangered significant portions of the range.
To determine which areas may warrant further consideration, we
initially evaluated the four ecoregions defined by Amstrup et al.
(2007), each of which consists of a subset of the 19 IUCN-defined
management populations, plus a new population--the Queen Elizabeth
Islands--created by the authors. The four ecoregions are: (1) the
Seasonal Ice ecoregion; (2) the Archipelago ecoregion of the central
Canadian Arctic; (3) the polar basin Divergent ecoregion; and (4) the
polar basin Convergent ecoregion. On the basis of observational results
from long-term studies of polar bear populations and sea ice
conditions, plus projections from GCM climate simulations and the
results of preliminary Carrying Capacity and Bayesian Network modeling
exercises by Amstrup et al. (2007), we have determined that there is
substantial information that polar bear populations in the Seasonal Ice
and polar basin Divergent ecoregions may face a greater level of threat
than populations in the Archipelago and polar basin Convergent
ecoregions (see detailed discussion under Factor A). The large
geographic area included in each of these ecoregions, plus the
substantial proportion of the total polar bear population inhabiting
those ecoregions, also indicate that they may be significant portions
of the range. Having met these two initial tests, a further evaluation
was deemed necessary to determine if these two portions of the range
are both significant and endangered (that analysis follows below). We
determined that the Archipelago and polar Convergent ecoregions do not
satisfy the two initial tests, because there is not substantial
information to suggest that the species in those portions may currently
be in danger of extinction.
After reviewing the four ecoregions, we proceeded to an evaluation
of the 19 populations delineated for management purposes by the IUCN
PBSG (Aars et al. 2006, p. 33) plus the Queen Elizabeth Island
population created by Amstrup et al. (2007). For fourteen of the PBSG-
defined populations, population status is considered stable,
increasing, or data deficient, and there is not substantial information
indicating that they may currently be in danger of extinction. We
eliminated these populations from further consideration. We also
eliminated the Queen Elizabeth Island population because there is no
current evidence of decline in the population, and because it occurs in
the polar basin Convergent ecoregion where sea ice is projected to
persist longest into the future (along with the Archipelago ecoregion).
Thus, there is not substantial information indicating that this
population may currently be in danger of extinction. For the remaining
five populations, there is some information indicating actual or
projected population declines according to the most recent
subpopulation viability analysis conducted by the PBSG (i.e., Southern
Beaufort Sea, Norwegian Bay, Western Hudson Bay, Kane Basin, Baffin
Bay) (Aars et al. 2006, pp. 34-35). Two of these populations--Norwegian
Bay and Kane Basin--occur within the Archipelago ecoregion, and are
small both in terms of geographic area included within their boundaries
and number of polar bears in the population. Even if these two
populations are considered together, the overall geographic area they
occupy and overall population size are still small. On this basis we
determined that these two populations do not satisfy one portion of the
initial test, because there is not substantial information to suggest
that these areas are significant portions of the range. In addition,
the two populations occur in the Archipelago ecoregion, where sea ice
is projected to persist the longest into the future. In addition,
available population estimates for these two populations are less
reliable because they are older (circa 1998) and are based on limited
years and incomplete coverage of sampling. Because of the projected
persistence of sea ice in this area throughout the foreseeable future,
and the lack of reliable information on population trends, we have
determined that there is not substantial information to indicate that
these populations are currently in danger of extinction. Having not
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satisfied either of the two initial tests, we have determined that
these two populations do not warrant any further consideration in this
analysis.
The relatively larger area and population size of each of the three
remaining populations--Southern Beaufort Sea, Western Hudson Bay,
Baffin Bay--indicate that they may be significant portions of the
range. For these three populations there is information indicating
actual or potential population declines according to the most recent
subpopulation viability analysis conducted by the PBSG (Baffin Bay) and
other recent studies (Regehr et al. 2007a for Western Hudson Bay;
Regehr et al. 2007b for Southern Beaufort Sea), as well as projected
population declines based on recent modeling exercises (Hunter et al.
2007; Amstrup et al. 2007). Having met these two initial tests, a
further evaluation was deemed necessary to determine if these three
populations are both significant and endangered (that analysis follows
below). Based on our review of the record, we did not find substantial
information indicating that any other portions of the polar bear's
range might be considered significant and qualify as endangered.
Having identified the five portions of the range that warrant
further consideration (two ecoregions and three populations), we then
proceeded to determine whether any of those portions are both
significant and endangered. We initially discuss our evaluation of the
two ecoregions identified above, and then proceed to discuss our
evaluation of the three populations identified above.
On an ecoregional level, the most significant results suggesting
that the two ecoregions may be endangered comes from the results of
Bayesian network modeling (BM) exercises by Amstrup et al. (2007). In
particular, the BM exercise results suggest that polar bear populations
in the Seasonal Ice and polar basin Divergent ecoregions may be lost by
the mid-21st century given rates of sea ice recession projected in the
10-GCM ensemble used by the authors. As previously discussed above
under the heading ``Bayesian Network Model'' within Factor A, we
believe that this initial effort has several limitations that reduce
our confidence in the actual numerical probabilities associated with
each outcome of the BM, as opposed to the general direction and
magnitude of the projected outcomes. The BM analysis is a preliminary
effort that requires additional development (Amstrup et al. 2007, p.
27). The current prototype is based on qualitative input from a single
expert, and input from additional polar bear experts is needed to
advance the model beyond the alpha prototype stage. There are also
uncertainties associated with statistical estimation of various
parameters such as the extent of sea ice or size of polar bear
populations (Amstrup et al. 2007, p. 23). In addition, the BM needs
further refinement to develop variance estimates to go with its
outcomes. Because of these uncertainties associated with the complex
BM, it is more appropriate to focus on the general direction and
magnitude of the projected outcomes rather than the actual numerical
probabilities associated with each outcome. Because of these
limitations, we have determined that the BM model outcomes are not a
sufficient basis, in light of the other available scientific
information, to find that threats to polar bears currently warrant a
determination of endangered status for the two ecoregions. However,
despite these limitations, we also recognize that the BM results are a
useful contribution to the overall weight of evidence and likelihood
regarding changing sea ice, population stressors, and effects. We
believe that the results are consistent with other available scientific
information, including results of the CM (see discussion under
``Carrying Capacity Model'' under Factor A), and quantitative evidence
of the gradual rate of population decline in three populations within
the ecoregions. We further note that, although these Seasonal Ice and
polar basin Divergent ecoregions face differential threats, both
ecoregions currently are estimated to have large numbers of polar
bears, and there is no evidence of any population currently undergoing
a precipitous decline. Therefore, we find that the polar bear is not
currently in danger of extinction in either the Seasonal Ice ecoregion
or the polar basin Divergent ecoregion.
The three populations identified above as actually or potentially
declining are the Western Hudson Bay, Southern Beaufort Sea, and Baffin
Bay populations. Over an 18-year period, Regehr et al. (2007, p. 2,673)
documented a statistically significant decline in the Western Hudson
Bay polar bear population of 22 percent. For this period, the mean
annual growth rate was 0.986 (with a 95 percent confidence interval of
0.978-0.995), indicative of a gradual population decline. The decline
has been attributed primarily to the effects of climate change (earlier
break-up of sea ice in the spring), with harvest also playing a role
(see discussion of ``Western Hudson Bay'' under Factor A). A reduction
in harvest quota in this population (from 54 to 38) for the 2007-2008
harvest season might begin to reduce the effect of harvest; however, we
expect continued population declines from earlier and earlier break-up
of sea ice and corresponding longer fasting periods of bears on land
(Stirling and Parkinson 2006). Nonetheless, we note that the Western
Hudson Bay population remains greater than 900 bears, and that
reproduction and recruitment are still occurring in the population
(Regehr et al. 2006). Because the current rate of decline for the
Western Hudson Bay population is gradual rather than precipitous,
reproduction and recruitment are still occurring, and the current size
of the population remains reasonably large, we have determined that the
population is not currently in danger of extinction, but is likely to
become so within the foreseeable future.
The apparent decline in the Southern Beaufort Sea population,
documented over a 20-year period, has not been demonstrated to be
statistically significant. However, available information indicates
that there will be a statistically-significant population decline in
the coming decades. Hunter et al. (2007) conducted a sophisticated
demographic analysis of the Southern Beaufort Sea population using both
deterministic and stochastic demographic models, and parameters
estimated from capture-recapture data collected between 2001 and 2006.
The authors focused on measures of long-term population growth rate and
on projections of population size over the next 100 years. Taking the
average observed frequency of bad sea ice years (0.21), they predicted
a gradual population decline of about one percent per year (similar to
the rate of decline observed in Western Hudson Bay), and an extinction
probability of around 35-40 percent at year 45 (see Figure 14 of Hunter
et al. 2007). However, the precision of vital rates used in the
analysis (estimated by Regehr et al. (2007b, pp. 17-18)) was subject to
large degrees of sampling and model selection uncertainty (Hunter et
al. 2007, p. 6), the length of the study period (5 years) was short,
and the spatial resolution of the GCMs at the scale of the southern
Beaufort Sea is less reliable than at the scale of the entire range of
the polar bear. These sources of uncertainty lead us to have greater
confidence in the general direction and magnitude of the trend of the
model outcomes in Hunter et al. (2007) than in the specific percentages
associated with each
[[Page 28297]]
outcome. In addition, we note that the Southern Beaufort Sea population
remains fairly large, that reproduction and recruitment is still
occurring in the population, and that changes in the sea ice have not
yet been associated with changes in the size of the population (Regehr
et al. 2007, p. 2). These results all indicate that this population is
not currently in danger of extinction but is likely to become so in the
foreseeable future.
As regards Baffin Bay, the recent population estimates of 2,074
bears in 1998 and 1,546 bears in 2004 have limited reliability because
of the population survey methods used. There is clear evidence that the
population has been overharvested (Aars et al. 2006). Although the PBSG
subpopulation viability analysis projects a declining trend, most
likely as a result of overharverst, there is no reliable estimate of
population trend based on valid population survey results. In recent
years, some efforts have been made to reduce harvest of the Baffin Bay
population. Greenland put a quota system in place for Baffin Bay in
2006; its current quota is 75 bears. Stirling and Parkinson (2006, p.
268) have documented earlier spring sea ice break-up dates in Baffin
Bay since 1978 (i.e., ice breakup has been occurring 6 to 7 days
earlier per decade since late 1978). Earlier breakup is likely to lead
to longer periods of fasting onshore, with concomitant effects on bear
body condition as documented in other populations. However, there are
no data on body condition of polar bears or the survival of cubs or
subadults from Baffin Bay (Stirling and Parkinson 2006, p. 269) that
would allow an analysis of the relationship between changes in body
condition and changes in sea ice habitat. In terms of projecting sea
ice trends in Baffin Bay in the foreseeable future, Overland and Wang
(2007) evaluated a suite of the 12 most applicable GCMs, and found
that, ``according to these models, Baffin Bay does not show significant
ice loss by 2050.'' These results are at apparent odds with observed
sea ice trends, which further complicates projecting future effects of
sea ice loss on polar bears. Without statistically reliable indices of
declines in survival, body condition indices, or population size, and
with evidence of earlier spring breakup dates but equivocal information
on future sea ice conditions, we cannot conclude that the species is
currently in danger of extinction in Baffin Bay, but can conclude it is
likely to become so in the foreseeable future.
Therefore, on the basis of the discussion presented in the previous
three paragraphs, we find that the polar bear populations of Western
Hudson Bay, Southern Beaufort Sea, and Baffin Bay are not currently in
danger of extinction, but are likely to become so in the foreseeable
future.
As a result, while the best scientific data available allows us to
make a determination as to the rangewide status of the polar bear, we
have determined that when analyzed on a population or even an ecoregion
level, the available data show that there are no significant portions
of the range in which the species is currently in danger of extinction.
Because we find that the polar bear is not endangered in the five
portions of the range that we previously determined to warrant further
consideration (two ecoregions and three populations), we need not
address the question of significance for those five portions.
Critical Habitat
Critical habitat is defined in section 3(5) of the Act as: (i) the
specific areas within the geographical area occupied by a species, at
the time it is listed in accordance with the Act, on which are found
those physical or biological features (I) essential to the conservation
of the species and (II) that may require special management
considerations or protection; and (ii) specific areas outside the
geographical area occupied by a species at the time it is listed, upon
a determination that such areas are essential for the conservation of
the species. ``Conservation'' is defined in section 3(3) of the Act as
meaning the use of all methods and procedures needed to bring the
species to the point at which listing under the Act is no longer
necessary. The primary regulatory effect of critical habitat is the
requirement, under section 7(a)(2) of the Act, that Federal agencies
shall ensure that any action they authorize, fund, or carry out is not
likely to result in the destruction or adverse modification of
designated critical habitat.
Section 4(a)(3) of the Act and implementing regulations (50 CFR
424.12) require that, to the maximum extent prudent and determinable,
we designate critical habitat at the time a species is determined to be
endangered or threatened. Critical habitat may only be designated
within the jurisdiction of the United States, and may not be designated
for jurisdictions outside of the United States (50 CFR 424(h)). Our
regulations (50 CFR 424.12(a)(1)) state that designation of critical
habitat is not prudent when one or both of the following situations
exist: (1) the species is threatened by taking or other activity and
the identification of critical habitat can be expected to increase the
degree of threat to the species; or (2) such designation of critical
habitat would not be beneficial to the species. Our regulations (50 CFR
424.12(a)(2)) further state that critical habitat is not determinable
when one or both of the following situations exist: (1) Information
sufficient to perform required analysis of the impacts of the
designation is lacking; or (2) the biological needs of the species are
not sufficiently well known to permit identification of an area as
critical habitat.
Delineation of critical habitat requires, within the geographical
area occupied by the polar bear, identification of the physical and
biological features essential to the conservation of the species. In
general terms, physical and biological features essential to the
conservation of the polar bear may include (1) annual and perennial
marine sea ice habitats that serve as a platform for hunting, feeding,
traveling, resting, and to a limited extent, for denning, and (2)
terrestrial habitats used by polar bears for denning and reproduction
for the recruitment of new animals into the population, as well as for
seasonal use in traveling or resting. The most important polar bear
life functions that occur in these habitats are feeding (obtaining
adequate nutrition) and reproduction. These habitats may be influenced
by several factors and the interaction among these factors, including:
(1) water depth; (2) atmospheric and oceanic currents or events; (3)
climatologic phenomena such as temperature, winds, precipitation and
snowfall; (4) proximity to the continental shelf; (5) topographic
relief (which influences accumulation of snow for denning); (6)
presence of undisturbed habitats; and (7) secure resting areas that
provide refuge from extreme weather or other bears or humans. Unlike
some other marine mammal species, polar bears generally do not occur at
high-density focal areas such as rookeries and haulout sites. However,
certain terrestrial areas have a history of higher use, such as core
denning areas, or are experiencing an increasing tendancy of use for
resting, such as coastal areas during the fall open water phase for
which polar bear use has been increasing in duration for additional and
expanded areas. During the winter period, when energetic demands are
the greatest, nearshore lead systems (linear openings or cracks in the
sea ice) and emphemeral or recurrent polynyas (areas of open sea
surrounded by sea ice) are areas of importance for seals
[[Page 28298]]
and, correspondingly for polar bears that hunt seals for nutrition.
During the spring period, nearshore lead systems continue to be
important habitat for bears for hunting seals and feeding. Also the
shorefast ice zone where ringed seals construct subnivean birth lairs
for pupping is an important feeding habitat during this season. In
northern Alaska, while denning habitat is more diffuse than in other
areas where core, high-density denning has been identified, certain
areas such as barrier islands, river bank drainages, much of the North
Slope coastal plain (including the Arctic NWR), and coastal bluffs that
occur at the interface of mainland and marine habitat receive
proportionally greater use for denning than other areas. Habitat
suitable for the accumulation of snow and use for denning has been
delineated on the North Slope.
While information regarding important polar bear life functions and
habitats associated with these functions has expanded greatly in Alaska
during the past 20 years, the identification of specific physical and
biological features and specific geographic areas for consideration as
critical habitat is complicated, and the future values of these
habitats may change in a rapidly changing environment. Arctic sea ice
provides a platform for critical life-history functions, including
hunting, feeding, travel, and nuturing cubs. That habitat is projected
to be significantly reduced within the next 45 years, and some models
project complete absence of sea ice during summer months in shorter
timeframes.
A careful assessment of the designation of marine areas as critical
habitat will require additional time to fully evaluate physical and
biological features essential to the conservation of the polar bear and
how those features are likely to change over the foreseeable future. In
addition, near-shore and terrestrial habitats that may qualify for
designation as critical habitat will require a similar thorough
assessment and evaluation in light of projected climate change and
other threats. Additionally, we have not gathered sufficient economic
and other data on the impacts of a critical habitat designation. These
factors must be considered as part of the designation procedure. Thus,
we find that critical habitat is not determinable at this time.
Available Conservation Measures
The Service will continue to work with other countries that have
jurisdiction in the Arctic, the IUCN/SSC Polar Bear Specialist Group,
U.S. government agencies (e.g., NASA, NOAA), species experts, Native
organizations, and other parties as appropriate to consider new
information as it becomes available to track the status of polar bear
populations over time, to develop a circumpolar monitoring program for
the species, and to develop management actions to conserve the polar
bear. Using current ongoing and future monitoring programs for the 19
IUCN-designated populations we will continue to evaluate the status of
the species in relation to its listing under the Act. In addition,
status of domestic populations will continue to be evaluated as
required under the MMPA.
Conservation measures provided to species listed as endangered or
threatened under the Act include recognition of the status, increased
priority for research and conservation funding, recovery actions,
requirements for Federal protection, and prohibitions against certain
activities. Recognition through listing results in public awareness and
conservation actions by Federal, State, and local agencies, private
organizations, and individuals. The Act provides for possible land
acquisition and cooperation with the States, and for conservation
actions to be carried out for listed species.
The listing of the polar bear will lead to the development of a
recovery plan for this species in Alaska. The recovery plan will bring
together international, Federal, State, and local agencies, and private
efforts, for the conservation of this species. A recovery plan for
Alaska will establish a framework for interested parties to coordinate
activities and to cooperate with each other in conservation efforts.
The plan will set recovery priorities, identify responsibilities, and
estimate the costs of the tasks necessary to accomplish the priorities.
Under section 6 of the Act, we would be able to grant funds to the
State of Alaska for management actions promoting the conservation of
the polar bear.
Additionally, the Service will pursue conservation strategies among
all countries that share management of polar bears. The existing
multilateral agreement provides an international framework to pursue
such strategies, and the outcome of the June 2007 meeting of polar bear
range countries (held at the National Conservation Training Center in
West Virginia) clearly documents the shared interest by all to pursue
such an effort. Range-wide strategies will be particularly important as
the sea ice habitat likely to persist the longest is not in U.S.
jurisdiction and collaborative efforts to support ongoing research and
management actions for purposes of restoring or supplementing the most
dramatically affected population will be important. The PBSG is
recognized as the technical advisor for the 1973 Agreement for the
Conservation of Polar Bears and provides recommendations to each of the
range states on conservation and management; recommendations from this
group will be sought throughout the entire process.
Section 7(a) of the Act, as amended, requires Federal agencies to
evaluate their actions with respect to any species that is listed as
endangered or threatened and with respect to its critical habitat, if
any is designated. Regulations implementing this interagency
cooperation provision of the Act are codified at 50 CFR part 402. For
threatened species such as the polar bear, section 7(a)(2) of the Act
requires Federal agencies to ensure that activities they authorize,
fund, or carry out are not likely to jeopardize the continued existence
of the species. If a Federal action may affect a polar bear, the
responsible Federal agency must consult with us under the provisions of
section 7(a)(2) of the Act.
Several Federal agencies are expected to have involvement under
section 7 of the Act regarding the polar bear. The National Marine
Fisheries Service may become involved, such as if a joint rulemaking
for the incidental take of marine mammals is undertaken. The EPA may
become involved through its permitting authority under the Clean Water
Act and Clean Air Act for activities conducted in Alaska. The U.S Army
Corps of Engineers may become involved through its responsibilities and
permitting authority under section 404 of the Clean Water Act and
through future development of harbor projects. The MMS may become
involved through administering their programs directed toward offshore
oil and gas development, and the BLM for onshore activities in NPRA.
The Denali Commission may be involved through its potential funding of
fuel and power generation projects. The U.S. Coast Guard may become
involved through their deployment of icebreakers in the Arctic Ocean.
Much of Alaska oil and gas development occurs within the range of
polar bears, and the Service has worked effectively with the industry
for a number of years to minimize impacts to polar bears through
implementation of the incidental take program authorized under the
MMPA. Under the MMPA, incidental take cannot be authorized unless the
Service finds that any take that is reasonably likely to occur will
have no more than a negligible impact on the species. Incidental take
[[Page 28299]]
authorization has been in place for the Beaufort Sea region since 1993
and for the Chukchi Sea in 2006 and 2007. New MMPA incidental take
authorization covering oil and gas exploration activities in the
Chukchi Sea was proposed in June 2007. Mitigation measures required
under these authorizations minimize potential impacts to polar bears
and ensure that any take remains at the negligible level; these
measures are implemented on a case-by-case basis through Letters of
Authorization (LOAs) under the MMPA. Because the MMPA negligible impact
standard is a tighter management standard than ensuring that an
activity is not likely to jeopardize the continued existence of the
species under section 7 of the Act, we do not anticipate that any
entity holding incidental take authorization for polar bears under the
MMPA and in compliance with all mitigation measures under that
authorization will be required to implement further measures under the
section 7 consultation process.
Regulatory Implications for Consultations under Section 7 of the Act
When a species is listed as threatened under the Act, section
7(a)(2) provides that Federal agencies must insure that any actions
they authorize, fund, or carry out are not likely to jeopardize the
continued existence of any listed species or result in the destruction
or adverse modification of designated critical habitat. Furthermore,
under the authority of section 4(d), the Secretary shall establish
regulatory provisions on the take of threatened species that are
``necessary and advisable to provide for the conservation of the
species'' (16 U.S.C. 1533(d)).
The coverage of the section 9 taking prohibition is much broader
than a simple prohibition against killing an individual of the species.
Section 3(19) of the Act defines the term ``take'' as ``* * * harass,
harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or
attempt to engage in any such conduct.'' Federal regulations
promulgated by the Service (50 CFR 17.3) define the terms ``harm'' and
``harass'' as:
Harass in the definition of ``take'' in the Act means an
intentional or negligent act or omission which creates the likelihood
of injury to wildlife by annoying it to such an extent as to
significantly disrupt normal behavioral patterns which include, but are
not limited to, breeding, feeding, or sheltering. This definition, when
applied to captive wildlife does not include generally accepted: (1)
animal husbandry practices that meet or exceed the minimum standards
for facilities and care under the Animal Welfare Act, (2) breeding
procedures, or (3) provisions of veterinary care for confining,
tranquilizing, or anesthetizing, when such practices, procedures, or
provisions are not likely to result in injury to the wildlife.
Harm in the definition of ``take'' in the Act means an act that
actually kills or injures wildlife. Such act may include significant
habitat modification or degradation where it actually kills or injures
wildlife by significantly impairing essential behaviorial patterns,
including breeding, feeding, or sheltering.
Certain levels of incidental take may be authorized through
provisions under section 7(b)(4) and (o)(2) (incidental take statements
for Federal agency actions) and section 10(a)(1)(B) (incidental take
permits).
In making a determination to authorize incidental take under
section 7 or section 10, the Service must assess the effects of the
proposed action to evaluate the potential negative and positive impacts
that are expected to occur as a result of the action. Under Section 7,
this would be done through a consultation between the Service and the
Federal agency on a specific proposed agency action. Section 7
consultation regulations generally limit the Service's review of the
effects of the proposed action to the direct and indirect effects of
the action and any activities that are interrelated or interdependent
with the proposed action. ``Indirect'' effects are caused by the
proposed action, later in time, and are ``reasonably certain to
occur.'' Essentially, the Service evaluates those effects that would
not occur ``but for'' the action under consultation and that are also
reasonably certain to occur. Cumulative effects, which are the effects
of future non-Federal actions that are also reasonably certain to occur
within the action area of the proposed action, must also be taken into
consideration. The direct, indirect, and cumulative effects are then
analyzed along with the status of the species and the environmental
baseline to determine whether the action under consultation is likely
to reduce appreciably both the survival and recovery of the listed
species or result in the destruction or adverse modification of
critical habitat. If the Service determines that the action is not
likely to jeopardize the continued existence of a listed species, a
``no jeopardy'' opinion will be issued, along with an incidental take
statement. The purpose of the incidental take statement is to identify
the amount or extent of take that is reasonably likely to result from
the proposed action and to minimize the impact of any take through
reasonable and prudent measures (RPMs). The regulations require,
however, that any RPM's be only a ``minor change'' to the proposed
action. If the Federal agency and any applicant comply with the terms
and conditions of the incidental take statement, then section 7(o)(2)
of the Act provides an exception to the take prohibition.
The 9th Circuit Court of Appeals has determined that the Service
cannot use the consultation process or the issuance of an Incidental
Take Statement as a form of regulation limiting what are otherwise
legal activities by action agencies, if no incidental take is
reasonably likely to occur as a result of the Federal action (Arizona
Cattle Growers' Association v. U.S. Fish and Wildlife Service, 273 F.3d
1229 (9th Cir. 2001)). In that case, the court reviewed several
biological opinions that were the result of consultations on numerous
grazing permits. The 9th Circuit analyzed the Service's discussion of
effects and the incidental take statements for several specific grazing
allotments. The court found that the Service, in some allotments,
assumed there would be ``take'' without explaining how the agency
action (in this case, cattle grazing) would cause the take of specific
individuals of the listed species. Further, for other permits the court
did not see evidence or argument to demonstrate how cattle grazing in
one part of the permit area would take listed species in another part
of that permit area. The court concluded that the Service must
``connect the dots'' between its evaluation of effects of the action
and its assessment of take. That is, the Service cannot simply
speculate that take may occur. The Service must first articulate the
causal connection between the effects of the action under consultation
and the anticipated take. It must then demonstrate that the take is
reasonably likely to occur.
The significant cause of the decline of the polar bear, and thus
the basis for this action to list it as a threatened species, is the
loss of arctic sea ice that is expected to continue to occur over the
next 45 years. The best scientific information available to us today,
however, has not established a causal connection between specific
sources and locations of emissions to specific impacts posed to polar
bears or their habitat.
Some commenters to the proposed rule suggested that the Service
should require other agencies (e.g., the Environmental Protection
Agency) to
[[Page 28300]]
regulate emissions from all sources, including automobile and power
plants. The best scientific information available today would neither
allow nor require the Service to take such action.
First, the primary substantive mandate of section 7(a)(2)--the duty
to avoid likely jeopardy to an endangered or threatened species--rests
with the Federal action agency and not with the Service. The Service
consults with the Federal action agency on proposed Federal actions
that may affect an endangered or threatened species, but its
consultative role under section 7 does not allow for encroachment on
the Federal action agency's jurisdiction or policy-making role under
the statutes it administers.
Second, the Federal action agency decides when to initiate formal
consultation on a particular proposed action, and it provides the
project description to the Service. The Service may request the Federal
action agency to initiate formal consultation for a particular proposed
action, but it cannot compel the agency to consult, regardless of the
type of action or the magnitude of its projected effects.
Recognizing the primacy of the Federal action agency's role in
determining how to conform its proposed actions to the requirements of
section 7, and taking into account the requirement to examine the
``effects of the action'' through the formal consultation process, the
Service does not anticipate that the listing of the polar bear as a
threatened species will result in the initiation of new section 7
consultations on proposed permits or licenses for facilities that would
emit GHGs in the conterminous 48 States. Formal consultation is
required for proposed Federal actions that ``may affect'' a listed
species, which requires an examination of whether the direct and
indirect effects of a particular action meet this regulatory threshold.
GHGs that are projected to be emitted from a facility would not, in and
of themselves, trigger formal section 7 consultation for a particular
licensure action unless it is established that such emissions
constitute an ``indirect effect'' of the proposed action. To constitute
an ``indirect effect,'' the impact to the species must be later in
time, must be caused by the proposed action, and must be ``reasonably
certain to occur'' (50 CFR 402.02 (definition of ``effects of the
action'')). As stated above, the best scientific data available today
are not sufficient to draw a causal connection between GHG emissions
from a facility in the conterminous 48 States to effects posed to polar
bears or their habitat in the Arctic, nor are there sufficient data to
establish that such impacts are ``reasonably certain to occur'' to
polar bears. Without sufficient data to establish the required causal
connection--to the level of ``reasonable certainty''--between a new
facility's GHG emissions and impacts to polar bears, section 7
consultation would not be required to address impacts to polar bears.
A question has also been raised regarding the possible application
of section 7 to effects posed to polar bears that may arise from oil
and gas development activities conducted on Alaska's North Slope or in
the Chukchi Sea. It is clear that any direct effects from oil and gas
development operations, such as drilling activities, vehicular traffic
to and from drill sites, and other on-site operational support
activities, that pose adverse effects to polar bears would need to be
evaluated through the section 7 consultation process. It is also clear
that any ``indirect effects'' from oil and gas development activities,
such as impacts from the spread of contaminants (accidental oil spills,
or the unintentional release of other contaminants) that result from
the oil and gas development activities and that are ``reasonably
certain to occur,'' that flow from the ``footprint'' of the action and
spread into habitat areas used by polar bears would also need to be
evaluated through the section 7 consultation process.
However, the future effects of any emissions that may result from
the consumption of petroleum products refined from crude oil pumped
from a particular North Slope drilling site would not constitute
``indirect effects'' and, therefore, would not be considered during the
section 7 consultation process. The best scientific data available to
the Service today does not provide the degree of precision needed to
draw a causal connection between the oil produced at a particular
drilling site, the GHG emissions that may eventually result from the
consumption of the refined petroleum product, and a particular impact
to a polar bear or its habitat. At present there is a lack of
scientific or technical knowledge to determine a relationship between
an oil and gas leasing, development, or production activity and the
effects of the ultimate consumption of petroleum products (GHG
emissions). There are discernible limits to the establishment of a
causal connection, such as uncertainties regarding the productive yield
from an oil and gas field; whether any or all of such production will
be refined for plastics or other products that will not be burned; what
mix of vehicles or factories might use the product; and what mitigation
measures would offset consumption. Furthermore, there is no traceable
nexus between the ultimate consumption of the petroleum product and any
particular effect to a polar bear or its habitat. In short, the
emissions effects resulting from the consumption of petroleum derived
from North Slope or Chukchi Sea oil fields would not constitute an
``indirect effect'' of any federal agency action to approve the
development of that field.
Other Provisions of the Act
Section 9 of the Act, except as provided in sections 6(g)(2) and 10
of the Act, prohibits take (within the United States and on the high
seas) and import into or export out of the United States of endangered
species. The Act defines take to mean harass, harm, pursue, hunt,
shoot, wound, kill, trap, capture, or collect, or to attempt to engage
in any such conduct. However, the Act also provides for the
authorization of take and exceptions to the take prohibitions. Take of
endangered wildlife species by non-Federal property owners can be
permitted through the process set forth in section 10 of the Act. The
Service has issued regulations (50 CFR 17.31) that generally afford to
fish and wildlife species listed as threatened the prohibitions that
section 9 of the Act establishes with respect to species listed as
endangered.
The Service may also develop a special rule specifically tailored
to the conservation needs of a threatened species instead of applying
the general threatened species regulations. In today's Federal Register
we have published a special rule for the polar bear that generally
adopts existing conservation regulatory requirements under the MMPA and
the Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES) as the appropriate regulatory provisions for
this threatened species.
Section 10(e) of the Act provides an exemption for any Indian,
Aleut, or Eskimo who is an Alaskan Native and who resides in Alaska to
take a threatened or endangered species if such taking is primarily for
subsistence purposes and the taking is not accomplished in a wasteful
manner. Non-native permanent residents of an Alaska native village are
also covered by this exemption, but since such persons are not covered
by the similar exemption under the MMPA, take of polar bears for
subsistence purposes by non-native permanent residents of an Alaskan
native village would not be lawful. While the collaborative co-
[[Page 28301]]
management mechanisms to institute sustainable harvest levels are in
place, the challenges of managing harvest for declining populations are
new and will require extensive dialogue with the Alaska Native hunting
community and their leadership organizations. Development of risk
assessment models that describe the probability and effect of a range
of harvest levels interrelated to demographic population life tables
are needed. Any future consideration of harvest regulation will be done
with the full involvement of the subsistence community through the
Alaska Nanuuq Commission and North Slope Borough and should build upon
the co-management approach to harvest management that we have developed
through the Inupiat-Inuvialuit Agreement and which we will work to
expand through the United States-Russia Bilateral Agreement. The
Inupiat-Inuvialuit Agreement is a voluntary harvest agreement between
the native peoples of Alaska and Canada who share access to the
Southern Beaufort Sea polar bear population. The agreement includes
harvest restrictions, including a quota. A 10-year review of the
agreement published in 2002 revealed high compliance rates and support
for the agreement. The United States-Russia Bilateral Agreement calls
for the active involvement of the United States, Russian Federation,
and native people of both countries in managing subsistence harvest.
The Service is currently developing recommendations for the Bilateral
Commission that will direct research and establish sustainable and
enforceable harvest limits needed to address current potential
population declines due to overharvest of the stock. Development of
population estimates and harvest monitoring protocols must be developed
in a cooperative bilateral manner. The Alaska Nanuuq Commission, the
North Slope Borough, USGS, and the Alaska Department of Fish and Game
(ADF&G) have indicated support for these future efforts and wish to be
a part of implementation of this agreement.
Under the section 10(e) exemption, nonedible byproducts of species
taken pursuant to this section may be sold in interstate commerce when
made into authentic native articles of handicrafts and clothing. It is
illegal to possess, sell, deliver, carry, transport, or ship any such
wildlife that has been taken illegally. Further, it is illegal for any
person to commit, to solicit another person to commit, or cause to be
committed, any of these acts. Certain exceptions to the prohibitions
apply to our agents and State conservation agencies. See our special
rule published in today's edition of the Federal Register that would
align allowable activities with authentic native articles of
handicrafts and clothing made from polar bear parts with existing
provisions under the MMPA.
Under the general threatened species regulations at 50 CFR 17.32,
permits to carry out otherwise prohibited activities may be issued for
particular purposes, including scientific purposes, enhancement of the
propagation or survival of the species, zoological exhibitions,
educational purposes, incidental take in the course of otherwise lawful
activities, or special purposes consistent with the purposes of the
Act. However, see today's Federal Register for our rule that presents
provisions specifically tailored to the conservation needs of the polar
bear that generally adopts provisions of the MMPA and CITES. Requests
for copies of the regulations that apply to the polar bear and
inquiries about prohibitions and permits may be addressed to the
Endangered Species Coordinator, U.S. Fish and Wildlife Service, 1011
East Tudor Road, Anchorage, AK 99503.
It is our policy, published in the Federal Register on July 1, 1994
(59 FR 34272), to identify, to the maximum extent practicable at the
time a species is listed, those activities that would or would not
likely constitute a violation of regulations at 50 CFR 17.31. The
intent of this policy is to increase public awareness of the effects of
the listing on proposed and ongoing activities within a species' range.
For the polar bear we have not yet determined which, if any,
provisions under section 9 would apply, provided these activities are
carried out in accordance with existing regulations and permit
requirements. Some permissible uses or actions have been identified
below. Note that the special rule for polar bears (see the special rule
published in today's Federal Register) affects certain activities
otherwise regulated under the Act.
(1) Possession and noncommercial interstate transport of authentic
native articles of handicrafts and clothing made from polar bears taken
for subsistence purposes in a nonwasteful manner by Alaska Natives;
(2) Any action authorized, funded, or carried out by a Federal
agency that may affect the polar bear, when the action is conducted in
accordance with the terms and conditions of authorizations under
section 101(a)(5) of the MMPA and the terms and conditions of an
incidental take statement issued by us under section 7 of the Act;
(3) Any action carried out for scientific purposes, to enhance the
propagation or survival of polar bears, for zoological exhibitions, for
educational purposes, or for special purposes consistent with the
purposes of the Act that is conducted in accordance with the conditions
of a permit issued by us under 50 CFR 17.32; and
(4) Any incidental take of polar bears resulting from an otherwise
lawful activity conducted in accordance with the conditions of an
incidental take permit issued under 50 CFR 17.32. Non-Federal
applicants may design a habitat conservation plan (HCP) for the species
and apply for an incidental take permit. HCPs may be developed for
listed species and are designed to minimize and mitigate impacts to the
species to the greatest extent practicable. See also requirements for
incidental take of a polar bear under (3) above.
We believe the following activities could potentially result in a
violation of the special rule for polar bears; however, possible
violations are not limited to these actions alone:
(1) Unauthorized killing, collecting, handling, or harassing of
individual polar bears;
(2) Possessing, selling, transporting, or shipping illegally taken
polar bears or their parts;
(3) Unauthorized destruction or alteration of denning, feeding, or
resting habitats, or of habitats used for travel, that actually kills
or injures individual polar bears by significantly impairing their
essential behavioral patterns, including breeding, feeding, or
sheltering; and
(4) Discharge or dumping of toxic chemicals, silt, or other
pollutants (i.e., sewage, oil, pesticides, and gasoline) into the
marine environment that actually kills or injures individual polar
bears by significantly impairing their essential behavioral patterns,
including breeding, feeding, or sheltering.
We will review other activities not identified above on a case-by-
case basis to determine whether they may be likely to result in a
violation of 50 CFR 17.31. We do not consider these lists to be
exhaustive and provide them as information to the public. You may
direct questions regarding whether specific activities may constitute a
violation of the Act to the Field Supervisor, U.S. Fish and Wildlife
Service, Fairbanks Fish and Wildlife Field Office, 101 12th Avenue, Box
110, Fairbanks, Alaska 99701.
Regarding ongoing importation of sport-hunted polar bear trophies
from Canada, under sections 101(a)(3)(B) and 102(b) of the MMPA, it is
unlawful to
[[Page 28302]]
import into the United States any marine mammal that has been
designated as a depleted species or stock unless the importation is for
the purpose of scientific research or enhancement of the survival or
recovery of the species. Under the MMPA, the polar bear will be a
depleted species as of the effective date of the rule. Under sections
102(b) and 101(a)(3)(B) of the MMPA therefore, as a depleted species,
polar bears and their parts cannot be imported into the United States
except for scientific research or enhancement. Therefore, sport-hunted
polar bear trophies from Canada cannot be imported after the effective
date of this listing rule. Nothing in the special rule for polar bears
published in today's Federal Register affects these provisions under
the MMPA.
Future Opportunities
Earlier in the preamble to this final rule, we determined that
polar bear habitat--principally sea ice--is declining throughout the
species' range, that this decline is expected to continue for the
foreseeable future, and that this loss threatens the species throughout
all of its range. We also determined that there are no known regulatory
mechanisms in place, and none that we are aware of that could be put in
place, at the national or international level, that directly and
effectively address the rangewide loss of sea ice habitat within the
foreseeable future. We also acknowledged that existing regulatory
mechanisms to address anthropogenic causes of climate change are not
expected to be effective in counteracting the worldwide growth of GHG
emissions within the foreseeable future, as defined in this rule.
Fully aware of the current situation and projected trends within
the foreseeable future, and recognizing the great challenges ahead of
us, we remain optimistic that the future can be a bright one for the
polar bear. The root causes and consequences of the loss of Arctic sea
ice extend well beyond the five countries that border the Arctic and
comprise the range of the polar bear, and will extend beyond the
foreseeable future as determined in this rule. This is a global issue
and will be resolved as the global community comes together and acts in
concert to achieve that resolution. Polar bear range countries are
working, individually and cooperatively, to conserve polar bears and
alleviate stressors on polar bear populations that may exacerbate the
threats posed by sea ice loss. The global community is also beginning
to act more cohesively, by developing national and international
regulatory mechanisms and implementing measures to mitigate the
anthropogenic causes of climate change.
In December 2007, the United States joined other Nations at the
United Nations (UN) Climate Change Conference in Bali to launch a
comprehensive ``roadmap'' for global climate negotiations. The Bali
Action Plan is a critical step in moving the UN negotiation process
forward toward a comprehensive and effective post-2012 arrangement by
2009. (Please note that measures in the Bali Action Plan, in and of
themselves, were not considered as offsetting or otherwise dimishing
the risk of sea ice loss in our determination of the appropriate
listing classification for the polar bear.) In December 2007, President
Bush signed the Energy Independence and Security Act of 2007, which
responded to his ``Twenty in Ten'' challenge in his 2006 State of the
Union Address to improve vehicle fuel economy and increase alternative
fuels. This bill will help improve energy efficiency and cut GHG
emissions.
With the world community acting in concert, we are confident the
future of the polar bear can be secured.
National Environmental Policy Act
We have determined that we do not need to prepare an environmental
assessment or an environmental impact statement as defined under the
authority of the National Environmental Policy Act of 1969, in
connection with regulations adopted under section 4(a) of the Act. We
published a notice outlining our reasons for this determination in the
Federal Register on October 25, 1983 (48 FR 49244).
Government-to-Government Relationship with Tribes
In accordance with the President's memorandum of April 29, 1994,
``Government-to-Government Relations with Native American Tribal
Governments'' (59 FR 22951), Executive Order 13175, Secretarial Order
3225, and the Department of Interior's manual at 512 DM 2, we readily
acknowledge our responsibility to communicate meaningfully with
recognized Federal Tribes on a government-to-government basis. Since
1997, we have signed cooperative agreements annually with The Alaska
Nanuuq Commission (Commission) to fund their activities. The Commission
was established in 1994 to represent the interests of subsistence users
and Alaska Native polar bear hunters when working with the Federal
government on the conservation of polar bears in Alaska. We attended
Commission board meetings during the preparation of the proposed rule
and subsequent public comment period, regularly briefing the board of
commissioners and staff on relevant issues. We also requested the
Commission to act as a peer reviewer of the Polar Bear Status Review
(Schliebe et al. 2006a) and the proposed rule to list the species
throughout its range (72 FR 1064). In addition to working closely with
the Commission, we sent copies of the proposed rule (72 FR 1064) to, or
contacted directly, 46 Alaska Native Tribal Councils and specifically
requested their comments on the proposed listing action. As such, we
believe that we have and will continue to coordinate with affected
Tribal entities in compliance with the applicable Executive and
Secretarial Orders.
References Cited
A complete list of all references cited in this rule is available
upon request. You may request a list of all references cited in this
document from the Supervisor, Marine Mammals Management Office (see
ADDRESSES section).
Authors
The primary authors of this rule are Scott Schliebe, Marine Mammals
Management Office (see ADDRESSES section), and Kurt Johnson, PhD,
Branch of Listing, Endangered Species Program, Arlington, VA.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Final Regulation Promulgation
0
Accordingly, part 17, subchapter B of chapter I, title 50 of the Code
of Federal Regulations, is amended as set forth below:
PART 17--[AMENDED]
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.
0
2. Amend Sec. 17.11(h) by adding an entry for ``Bear, polar'' in
alphabetical order under MAMMALS, to the List of Endangered and
Threatened Wildlife to read as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
[[Page 28303]]
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Species Vertebrate
------------------------------------------------------ population where Critical Special
Historic Range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mammals
* * * * * * * *
Bear, polar..................... Ursus maritimus.... U.S.A. (AK), Entire............. T ........... NA NA
Canada, Russia,
Denmark
(Greenland),
Norway.
* * * * * * * *
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Dated: May 14, 2008.
Dirk Kempthorne,
Secretary of the Interior.
[FR Doc. E8-11105 Filed 5-14-08; 3:15 pm]
BILLING CODE 4310-55-P