[Federal Register: September 8, 2010 (Volume 75, Number 173)]
[Proposed Rules]
[Page 54707-54753]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08se10-31]
[[Page 54707]]
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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; Revised 12-Month Finding
to List the Upper Missouri River Distinct Population Segment of Arctic
Grayling as Endangered or Threatened; Proposed Rule
[[Page 54708]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2009-0065]
[MO 92210-0-0008-B2]
Endangered and Threatened Wildlife and Plants; Revised 12-Month
Finding to List the Upper Missouri River Distinct Population Segment of
Arctic Grayling as Endangered or Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of revised 12-month finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service/USFWS),
announce a revised 12-month finding on a petition to list the upper
Missouri River Distinct Population Segment (Missouri River DPS) of
Arctic grayling (Thymallus arcticus) as endangered or threatened under
the Endangered Species Act of 1973, as amended. After review of all
available scientific and commercial information, we find that listing
the upper Missouri River DPS of Arctic grayling as endangered or
threatened is warranted. However, listing the upper Missouri River DPS
of Arctic grayling is currently precluded by higher priority actions to
amend the Lists of Endangered and Threatened Wildlife and Plants. Upon
publication of this 12-month finding, we will add the upper Missouri
River DPS of Arctic grayling to our candidate species list. We will
develop a proposed rule to list this DPS as our priorities allow. We
will make any determination on critical habitat during development of
the proposed listing rule. In the interim, we will address the status
of this DPS through our annual Candidate Notice of Review (CNOR).
DATES: The finding announced in this document was made on September 8,
2010.
ADDRESSES: This finding is available on the Internet at http://
www.regulations.gov at Docket Number FWS-R6-ES-2009-0065. Supporting
documentation we used in preparing this finding is available for public
inspection, by appointment, during normal business hours at the U.S.
Fish and Wildlife Service, Montana Field Office, 585 Shepard Way,
Helena, MT 59601. Please submit any new information, materials,
comments, or questions concerning this finding to the above street
address (Attention: Arctic grayling).
FOR FURTHER INFORMATION CONTACT: Mark Wilson, Field Supervisor, Montana
Field Office (see ADDRESSES); by telephone at 406-449-5225; or by
facsimile at 406-449-5339. Persons who use a telecommunications device
for the deaf (TDD) may call the Federal Information Relay Service
(FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (ESA) (16 U.S.C. 1531 et seq.), requires that, for any petition
containing substantial scientific or commercial information indicating
that listing the species may be warranted, we make a finding within 12
months of the date of receipt of the petition. In this finding, we
determine that the petitioned action is: (a) Not warranted, (b)
warranted, or (c) warranted, but immediate proposal of a regulation
implementing the petitioned action is precluded by other pending
proposals to determine whether species are endangered or threatened,
and expeditious progress is being made to add or remove qualified
species from the Federal Lists of Endangered and Threatened Wildlife
and Plants. Section 4(b)(3)(C) of the ESA requires that we treat a
petition for which the requested action is found to be warranted but
precluded as though resubmitted on the date of such finding, that is,
requiring a subsequent finding to be made within 12 months. We must
publish these 12-month findings in the Federal Register.
Previous Federal Actions
We have published a number of documents on Arctic grayling and have
been involved in litigation over previous findings. We describe our
actions relevant to this notice below.
We initiated a status review for the Montana Arctic grayling
(Thymallus arcticus montanus) in a Federal Register notice on December
30, 1982 (47 FR 58454). In that notice, we designated the purported
subspecies, Montana Arctic grayling, as a Category 2 species. At that
time, we designated a species as Category 2 if a listing as endangered
or threatened was possibly appropriate, but we did not have sufficient
data to support a proposed rule to list the species.
On October 9, 1991, the Biodiversity Legal Foundation and George
Wuerthner petitioned us to list the fluvial (riverine populations) of
Arctic grayling in the upper Missouri River basin as an endangered
species throughout its historical range in the coterminous United
States. We published a notice of a 90-day finding in the January 19,
1993, Federal Register (58 FR 4975), concluding the petitioners
presented substantial information indicating that listing the fluvial
Arctic grayling of the upper Missouri River in Montana and northwestern
Wyoming may be warranted. This finding noted that taxonomic recognition
of the Montana Arctic grayling (Thymallus arcticus montanus) as a
subspecies (previously designated as a category 2 species) was not
widely accepted, and that the scientific community generally considered
this population a geographically isolated member of the wider species
(T. arcticus).
On July 25, 1994, we published a notice of a 12-month finding in
the Federal Register (59 FR 37738), concluding that listing the DPS of
fluvial Arctic grayling in the upper Missouri River was warranted but
precluded by other higher priority listing actions. This DPS
determination predated our DPS policy (61 FR 4722, February 7, 1996),
so the entity did not undergo a DPS analysis as described in the
policy. The 1994 finding placed fluvial Arctic grayling of the upper
Missouri River on the candidate list and assigned it a listing priority
of 9. On May 4, 2004, we elevated the listing priority number of the
fluvial Arctic grayling to 3 (69 FR 24881).
On May 31, 2003, the Center for Biological Diversity and Western
Watersheds Project (Plaintiffs) filed a complaint in U.S. District
Court in Washington, D.C., challenging our ``warranted but precluded''
determination for Montana fluvial Arctic grayling. On July 22, 2004,
the Plaintiffs amended their complaint to challenge our failure to
emergency list this population. We settled with the Plaintiffs in
August 2005, and we agreed to submit a final determination on whether
this population warranted listing as endangered or threatened to the
Federal Register on or before April 16, 2007.
On April 24, 2007, we published a revised 12-month finding on the
petition to list the upper Missouri River DPS of fluvial Arctic
grayling (72 FR 20305) (``2007 finding''). In this finding, we
determined that fluvial Arctic grayling of the upper Missouri River did
not constitute a species, subspecies, or DPS under the ESA. Therefore,
we found that the upper Missouri River population of fluvial Arctic
grayling was not a listable entity under the ESA, and as a result,
listing was not warranted. With that notice, we withdrew the fluvial
Arctic grayling from the candidate list.
[[Page 54709]]
On November 15, 2007, the Center for Biological Diversity,
Federation of Fly Fishers, Western Watersheds Project, George
Wuerthner, and Pat Munday filed a complaint (CV-07-152, in the District
Court of Montana) to challenge our 2007 finding. We settled this
litigation on October 5, 2009. In the stipulated settlement, we agreed
to: (a) Publish, on or before December 31, 2009, a notice in the
Federal Register soliciting information on the status of the upper
Missouri River Arctic grayling; and (b) submit, on or before August 30,
2010, a new 12-month finding for the upper Missouri River Arctic
grayling to the Federal Register.
On October 28, 2009, we published a notice of intent to conduct a
status review of Arctic grayling (Thymallus arcticus) in the upper
Missouri River system (74 FR 55524). To ensure the status review was
based on the best available scientific and commercial data, we
requested information on the taxonomy, biology, ecology, genetics, and
population status of the Arctic grayling of the upper Missouri River
system; information relevant to consideration of the potential DPS
status of Arctic grayling of the upper Missouri River system; threats
to the species; and conservation actions being implemented to reduce
those threats in the upper Missouri River system. The notice further
specified that the status review may consider various DPS designations
that include different life histories of Arctic grayling in the upper
Missouri River system. Specifically, we may consider DPS configurations
that include: Fluvial, adfluvial (lake populations), or all life
histories of Arctic grayling in the upper Missouri River system.
This notice constitutes the revised 12-month finding (``2010
finding'') on whether to list the upper Missouri River DPS of Arctic
grayling (Thymallus arcticus) as endangered or threatened.
Taxonomy and Species Description
The Arctic grayling (Thymallus arcticus) belongs to the family
Salmonidae (salmon, trout, charr, whitefishes), subfamily Thymallinae
(graylings), and it is represented by a single genus, Thymallus. Scott
and Crossman (1998, p. 301) recognize four species within the genus: T.
articus (Arctic grayling), T. thymallus (European grayling), T.
brevirostris (Mongolian grayling), and T. nigrescens (Lake Kosgol,
Mongolia). Recent research focusing on Eurasian Thymallus (Koskinen et
al. 2002, entire; Froufe et al. 2003, entire; Froufe et al. 2005,
entire; Weiss et al. 2006, entire) indicates that the systematic
diversity of the genus is greater than previously thought, or at least
needs better description (Knizhin et al. 2008, pp. 725-726, 729;
Knizhin and Weiss 2009, pp. 1, 7-8; Weiss et al. 2007, p. 384).
Arctic grayling have elongate, laterally compressed, trout-like
bodies with deeply forked tails, and adults typically average 300-380
millimeters (mm) (12-15 inches (in.)) in length. Coloration can be
striking, and varies from silvery or iridescent blue and lavender, to
dark blue (Behnke 2002, pp. 327-328). The sides are marked with a
varying number of V-shaped or diamond-shaped spots (Scott and Crossman
1998, p. 301). During the spawning period, the colors darken and the
males become more brilliantly colored than the females. A prominent
morphological feature of Arctic grayling is the sail-like dorsal fin,
which is large and vividly colored with rows of orange to bright green
spots, and often has an orange border (Behnke 2002, pp. 327-328).
Distribution
Arctic grayling are native to Arctic Ocean drainages of Alaska and
northwestern Canada, as far east as Hudson's Bay, and westward across
northern Eurasia to the Ural Mountains (Scott and Crossman 1998, pp.
301-302; Froufe et al. 2005, pp. 106-107; Weiss et al. 2006, pp. 511-
512; see Figure 1 below). In North America, they are native to northern
Pacific Ocean drainages as far south as the Stikine River in British
Columbia (Nelson and Paetz 1991, pp. 253-256; Behnke 2002, pp. 327-
331).
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FIGURE 1. Approximate world-wide distribution of Arctic grayling
(Thymallus arcticus) at the end of the most recent glacial cycle. The
Missouri River distribution is based on Kaya (1992, pp. 47-51). The
distribution of the extinct Michigan population is based on Vincent
(1962, p. 12) and the University of Michigan (2010). The North American
distribution in Canada and Alaska is based on Behnke (2002, p. 330) and
Scott and Crossman (1998, pp. 301-302). The Eurasian distribution is
based on Knizhin (2009, p. 32) and Knizhin (2010, pers. comm.).
Arctic grayling remains widely distributed across its native range,
but within North America, the species has experienced range decline or
contraction at the southern limits of its distribution. In British
Columbia, Canada, populations in the Williston River watershed are
designated as a provincial ``red list'' species, meaning the population
is a candidate for further evaluation to determine if it should be
granted endangered (facing imminent extirpation or extinction) or
threatened status (likely to become endangered) (British Columbia
Conservation Data Centre 2010). In Alberta, Canada, Arctic grayling are
native to the Athabasca, Peace, and Hay River drainages. In Alberta,
the species has undergone a range contraction of about 40 percent, and
half of the province's subpopulations have declined in abundance by
more than 90 percent (Alberta Sustainable Resource Development (ASRD)
2005, p. iv).
Distribution in the Conterminous United States
Two disjunct groups of Arctic grayling were native to the
conterminous United States: One in the upper Missouri River basin in
Montana and Wyoming (extant in Montana, see Figure 2), and another in
Michigan that was extirpated in the late 1930s (Hubbs and Lagler 1949,
p. 44). Michigan grayling formerly occurred in the Otter River of the
Lake Superior drainage in northern Michigan and in streams of the lower
peninsula of Michigan in both the Lake Michigan and Lake Huron
drainages including the Au Sable, Cheboygan, Jordan, Pigeon, and Rifle
Rivers (Vincent 1962, p. 12).
Introduced Lake Dwelling Arctic Grayling in the Upper Missouri
River
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System and western U.S. populations of Arctic grayling have been
established in lakes outside their native range in Arizona, Colorado,
Idaho, Montana, New Mexico, Utah, Washington, and Wyoming (Vincent
1962, p. 15; Montana Fisheries Information System (MFISH) 2009;
NatureServe 2010). Stocking of hatchery grayling in Montana has been
particularly extensive, and there are thought to be up to 78 introduced
lacustrine (lake-dwelling) populations resulting from these
introductions (see Table 1 below). Over three-quarters of these
introductions (79.5 percent) were established outside the native
geographic range of upper Missouri River grayling, while only 16 (20.5
percent) were established within the watershed boundary of the upper
Missouri River system.
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FIGURE 2. Historical (dark grey lines) and current distribution
(stars and circled portion of Big Hole River) of native Arctic grayling
in the upper Missouri River basin. White bars denote mainstem river
dams that are total barriers to upstream passage by fish.
TABLE 1. Introduced Lake-dwelling Populations of Arctic Grayling in
Montana. The primary data source for these designations is MFISH (2009).
------------------------------------------------------------------------
Number of Introduced
River Basin (Exotic) Populations\a\
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Outside Native Geographic Range In Montana
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Columbia River 23
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Middle Missouri River 2
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Saskatchewan River 1
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Yellowstone River 36\b\
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Within Watershed Boundary Of Native Geographic Range In Montana
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Upper Missouri River 16
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Total Exotic Populations 78
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\a\List of populations does not include lake populations derived from
attempts to re-establish fluvial populations in Montana, native
adfluvial populations, or genetic reserves of Big Hole River grayling.
\b\Many of these populations may not reproduce naturally and are only
sustained through repeated stocking (Montana Fish, Wildlife and Parks
2009, entire).
For the purposes of this finding, we are analyzing a petitioned
entity that includes, at its maximum extent, populations of Arctic
grayling considered native to the upper Missouri River. Introduced
populations present in Montana (e.g., Table 1) or elsewhere are not
considered as part of the listable entity because we do not consider
them to be native populations. Neither the Act nor our implementing
regulations expressly address whether introduced populations should be
considered part of an entity being evaluated for listing, and no
Service policy addresses the issue. Consequently, in our evaluation of
whether or not to include introduced populations in the potential
listable entity we considered the following: (1) Our interpretation of
the intent of the Act with respect to the disposition of native
populations, (2) a policy used by the National Marine Fishery Service
(NMFS) to evaluate whether hatchery-origin populations warrant
inclusion in the listable entity, and (3) a set of guidelines from
another organization (International Union for Conservation of Nature
and Natural Resources (IUCN)) with specific criteria for evaluating the
conservation contribution of introduced populations.
Intent of the Endangered Species Act
The primary purpose of the Act is to provide a means whereby the
ecosystems upon which endangered species and threatened species depend
may be conserved. The Service has interpreted the Act to provide a
statutory directive to conserve species in their native ecosystems (49
FR 33890, August 27, 1984) and to conserve genetic resources and
biodiversity over a representative portion of a taxon's historical
occurrence (61 FR 4723, February 7, 1996). This priority on natural
populations is evident in the Service's DPS policy within the third
significance criteria. In that, a discrete population segment may be
significant if it represents the only surviving natural occurrence of
the taxon that may be more abundant elsewhere as an introduced
population outside of its historical range.
National Marine Fishery Service Hatchery Policy
In 2005, the NMFS published a final policy on the consideration of
hatchery-origin fish in Endangered Species Act listing determinations
for Pacific salmon and steelhead (anadromous Oncorhynchus spp.) (NMFS
2005, entire). A central tenet of this policy is the primacy of the
conservation of naturally spawning salmon populations and the
ecosystems on which they depend, consistent with the intent of the Act
(NMFS 2005, pp. 37211, 37214). The policy recognizes that properly
managed hatchery programs may provide some conservation benefit to the
evolutionary significant unit (ESU, which is analogous to a DPS but
applied to Pacific salmon) (NMFS 2005, p. 37211), and that hatchery
stocks that contribute to survival and recovery of an ESU are
considered during a listing decision (NMFS 2005, p. 37209). The policy
states that since hatchery stocks are established and maintained with
the intent of furthering the viability of wild populations in the ESU,
that those hatchery populations have an explicit conservation value.
Genetic divergence is the preferred metric to determine if hatchery
fish should be included in the ESU, but NMFS recognizes that these data
may be lacking in most cases (NMFS 2005, p. 37209). Thus, proxies for
genetic divergence can be used, such as the length of time a stock has
been isolated from its source population, the degree to which natural
broodstock has been regularly incorporated into the hatchery
population, the history of non-ESU fish or eggs in the hatchery
population, and the attention given to genetic considerations in
selecting and mating broodstocks (NMFS 2005, p. 37209).
The NMFS policy applies to artificially propagated (hatchery)
populations. In this finding, however, the Service is deciding whether
self-sustaining populations introduced outside its natural range should
be included in the listable entity. Thus, the NMFS policy is not
directly applicable. Nonetheless, if the NFMS policy's criteria are
applied to the introduced lake-dwelling populations of Arctic grayling
in Montana and elsewhere, these populations do not appear to warrant
inclusion in the entity being evaluated for listing. First, there does
not appear to be any formally recognized conservation value for the
[[Page 54713]]
introduced populations of Arctic grayling, and they are not being used
in restoration programs. Recent genetic analysis indicates that many of
the introduced Arctic grayling populations in Montana are derived, in
part, from stocks in the Red Rock Lakes system (Peterson and Ardren
2009, p. 1767). Nonetheless, there have been concerns that introduced,
lake-dwelling populations could pose genetic risks to the native
fluvial population (Arctic Grayling Workgroup (AGW) 1995, p. 15), and
in practice, these introduced populations have not been used for any
conservation purpose. In fact, efforts are currently underway to
establish a genetically pure brood reserve population of Red Rock Lakes
grayling to be used for conservation purposes (Jordan 2010, pers.
comm.), analogous to the brood reserves maintained for Arctic grayling
from the Big Hole River (Rens and Magee 2007, pp. 22-24).
Second, introduced populations in lakes have apparently been
isolated from their original source stock for decades without any
supplementation from the wild. These populations were apparently
established without any formal genetic consideration to selecting and
mating broodstock, the source populations were not well documented
(Peterson and Ardren 2009, p. 1767), and the primary intent of
culturing and introducing these grayling appears to have been to
provide recreational fishing opportunities in high mountain lakes.
Guidelines Used in Other Evaluation Systems
The IUCN uses its Red List system to evaluate the conservation
status and relative risk of extinction for species, and to catalogue
and highlight plant and animal species that are facing a higher risk of
global extinction (http://www.iucnredlist.org). IUCN does not use the
term ``listable entity'' as the Service does; however, IUCN does
clarify that their conservation ranking criteria apply to any taxonomic
group at the species level or below (IUCN 2001, p.4). Further, the IUCN
guidelines for species status and scope of the categorization process
focus on wild populations inside their natural range (IUCN 2001, p. 4;
2003, p. 10) or so-called ``benign'' or ``conservation introductions,''
which are defined as attempts to establish a species, for the purpose
of conservation, outside its recorded distribution, when suitable
habitat is lacking within the historical range (IUCN 1998, p. 6; 2003,
pp. 6, 10). Guidelines for evaluating conservation status under the
IUCN exclude introduced populations located outside the recorded
distribution of the species if such populations were established for
commercial or sporting purposes (IUCN 1998, p. 5; 2003, p. 24). In
effect, the IUCN delineates between introduced and native populations
in that non-benign introductions do not qualify for evaluation under
the IUCN Red List system. Naturalized populations of Arctic grayling in
lakes thus do not meet the IUCN criterion for a wild population that
should be considered when evaluating the species status for two
reasons. First, there remains `suitable habitat' for Arctic grayling in
its native range, as evidenced by extant native populations in the Big
Hole River, Madison River, Miner Lake, Mussigbrod Lake, and Red Rock
Lakes. Second, the naturalized populations derived from widespread
stocking were apparently aimed at establishing recreational fisheries.
Our interpretation is that the ESA is intended to preserve native
populations in their ecosystems. While hatchery or introduced
populations of fishes may have some conservation value, this does not
appear to be the case with introduced populations of Arctic grayling in
the conterminous United States. These populations were apparently
established to support recreational fisheries, and without any formal
genetic consideration to selecting and mating broodstock, and are not
part of any conservation program to benefit the native populations.
Consequently, we do not consider the introduced populations of Arctic
grayling in Montana and elsewhere in the conterminous United States,
including those in lakes and in an irrigation canal (Sun River Slope
Canal), to be part of the listable entity.
Native Distribution in the Upper Missouri River System
The first Euro-American ``discovery'' of Arctic grayling in North
America is attributed to members of the Lewis and Clark Expedition, who
encountered the species in the Beaverhead River in August 1805 (Nell
and Taylor 1996, p. 133). Vincent (1962, p. 11) and Kaya (1992, pp. 47-
51) synthesized accounts of Arctic grayling occurrence and abundance
from historical surveys and contemporary monitoring to determine the
historical distribution of the species in the upper Missouri River
system (Figure 2). We base our conclusions on the historical
distribution of Arctic grayling in the upper Missouri River basin on
these two reviews. Arctic grayling were widely but irregularly
distributed in the upper Missouri River system above the Great Falls in
Montana and in northwest Wyoming within the present-day location of
Yellowstone National Park (Vincent 1962, p. 11). They were estimated to
inhabit up to 2,000 kilometers (km) (1,250 miles (mi)) of stream
habitat until the early 20th century (Kaya 1992, pp. 47-51). Arctic
grayling were reported in the mainstem Missouri River, as well as in
the Smith, Sun, Jefferson, Madison, Gallatin, Big Hole, Beaverhead, and
Red Rock Rivers (Vincent 1962, p. 11; Kaya 1992, pp. 47-51; USFWS 2007;
72 FR 20307, April 24, 2007). ``Old-timer'' accounts report that the
species may have been present in the Ruby River, at least seasonally
(Magee 2005, pers. comm.), and were observed as recently as the early
1970s (Holton, undated).
Fluvial Arctic grayling were historically widely distributed in the
upper Missouri River basin, but a few adfluvial populations also were
native to the basin. For example, Arctic grayling are native to Red
Rock Lakes, in the headwaters of the Beaverhead River (Vincent 1962,
pp. 112-121; Kaya 1992, p. 47). Vincent (1962, p. 120) stated that Red
Rock Lakes were the only natural lakes in the upper Missouri River
basin accessible to colonization by Arctic grayling, and concluded that
grayling there were the only native adfluvial population in the basin.
However, it appears that Arctic grayling also were native to Elk Lake
(in the Red Rocks drainage; Kaya 1990, p. 44) and a few small lakes in
the upper Big Hole River drainage (Peterson and Ardren 2009, p. 1768).
The distribution of native Arctic grayling in the upper Missouri
River went through a dramatic reduction in the first 50 years of the
20th century, especially in riverine habitats (Vincent 1962, pp. 86-90,
97-122, 127-129; Kaya 1992, pp. 47-53). The native populations that
formerly resided in the Smith, Sun, Jefferson, Beaverhead, Gallatin,
and mainstem Missouri Rivers are considered extirpated, and the only
remaining indigenous fluvial population is found in the Big Hole River
and some if its tributaries (Kaya 1992, pp. 51-53). The fluvial form
currently occupies only 4 to 5 percent of its historic range in the
Missouri River system (Kaya 1992, p. 51). Other remaining native
populations in the upper Missouri River occur in two small, headwater
lakes in the upper Big Hole River system (Miner and Mussigbrod Lakes);
the Madison River upstream from Ennis Reservoir; and the Red Rock Lakes
in the headwaters of the Beaverhead River system (Everett 1986, p. 7;
Kaya 1992, p. 53; Peterson and Ardren 2009, pp. 1762, 1768; Figure 1
above, and Table 2 below).
[[Page 54714]]
TABLE 2. Extant Native Arctic Grayling Populations in the Upper Missouri
River Basin.
------------------------------------------------------------------------
Big Hole River Drainage\a\
-------------------------------------------------------------------------
1. Big Hole River
------------------------------------------------------------------------
2. Miner Lake
------------------------------------------------------------------------
3. Mussigbrod Lake
------------------------------------------------------------------------
Madison River Drainage
------------------------------------------------------------------------
4. Madison River-Ennis Reservoir
------------------------------------------------------------------------
Beaverhead River Drainage
------------------------------------------------------------------------
5. Red Rock Lakes
------------------------------------------------------------------------
\a\Arctic grayling also occur in Pintler Lake in the Big Hole River
drainage, but this population has not been evaluated with genetic
markers to determine whether it constitutes a native remnant
population.
Origins, Biogeography, and Genetics of Arctic Grayling in North America
North American Arctic grayling are most likely descended from
Eurasian Thymallus that crossed the Bering land bridge during or before
the Pleistocene glacial period (Stamford and Taylor 2004, pp. 1533,
1546). A Eurasian origin is suggested by the substantial taxonomic
diversity found in the genus in that region. There were multiple
opportunities for freshwater faunal exchange between North America and
Asia during the Pleistocene, but genetic divergence between North
American and Eurasian Arctic grayling suggests that the species could
have colonized North America as early as the mid-late Pliocene (more
than 3 million years ago) (Stamford and Taylor 2004, p. 1546).
The North American distribution of Arctic grayling was strongly
influenced by patterns of glaciation. Genetic studies of grayling using
mitochondrial DNA (mtDNA, maternally-inherited DNA located in cellular
organelles called mitochondria) and microsatellite DNA (repeating
sequences of nuclear DNA) have shown that North American Arctic
grayling consist of at least three major lineages that originated in
distinct Pleistocene glacial refugia (Stamford and Taylor 2004, p.
1533). These three groups include a South Beringia lineage found in
western Alaska to northern British Columbia, Canada; a North Beringia
lineage found on the North Slope of Alaska, the lower Mackenzie River,
and to eastern Saskatchewan; and a Nahanni lineage found in the lower
Liard River and the upper Mackenzie River drainage (Stamford and Taylor
2004, pp. 1533, 1540). The Nahanni lineage is the most genetically
distinct group (Stamford and Taylor 2004, pp. 1541-1543). Arctic
grayling from the upper Missouri River basin were tentatively placed in
the North Beringia lineage because a small sample (three individuals)
of Montana grayling shared a mtDNA haplotype (form of the mtDNA) with
populations in Saskatchewan and the lower Peace River, British Columbia
(Stamford and Taylor 2004, p. 1538).
The existing mtDNA data suggest that Missouri River Arctic grayling
share a common ancestry with the North Beringia lineage, but other
genetic markers and biogeographic history indicate that Missouri River
grayling have been physically and reproductively isolated from northern
populations for millennia. The most recent ancestors of Missouri River
Arctic grayling likely spent the last glacial cycle in an ice-free
refuge south of the Laurentide and Cordilleran ice sheets. Pre-glacial
colonization of the Missouri River basin by Arctic grayling was
possible because the river flowed to the north and drained into the
Arctic-Hudson Bay prior to the last glacial cycle (Cross et al. 1986,
pp. 374-375; Pielou 1991, pp. 194-195). Low mtDNA diversity observed in
a small number of Montana grayling samples and a shared ancestry with
Arctic grayling from the north Beringia lineage suggest a more recent,
post-glacial colonization of the upper Missouri River basin. In
contrast, microsatellite DNA show substantial divergence between
Montana and Saskatchewan (i.e., same putative mtDNA lineage) (Peterson
and Ardren 2009, entire). Differences in the frequency and size
distribution of microsatellite alleles between Montana populations and
two Saskatchewan populations indicate that Montana grayling have been
isolated long enough for mutations (i.e., evolution) to be responsible
for the observed genetic differences.
Additional comparison of 21 Arctic grayling populations from
Alaska, Canada, and the Missouri River basin using 9 of the same
microsatellite loci as Peterson and Ardren (2009, entire) further
supports the distinction of Missouri River Arctic grayling relative to
populations elsewhere in North America (USFWS, unpublished data).
Analyses of these data using two different methods clearly separates
sample fish from 21 populations into two clusters: one cluster
representing populations from the upper Missouri River basin, and
another cluster representing populations from Canada and Alaska (USFWS,
unpublished data). These new data, although not yet peer reviewed,
support the interpretation that the previous analyses of Stamford and
Taylor (2004, entire) underestimated the distinctiveness of Missouri
River Arctic grayling relative to other sample populations, likely
because of the combined effect of small sample sizes and the lack of
variation observed in the Missouri River for the markers used in that
study (Stamford and Taylor 2004, pp. 1537-1538). Thus, these recent
microsatellite DNA data suggest that Arctic grayling may have colonized
the Missouri River before the onset of Wisconsin glaciation (more than
80,000 years ago).
Genetic relationships among native and introduced populations of
Arctic grayling in Montana have recently been investigated (Peterson
and Ardren 2009, entire). Introduced, lake-dwelling populations of
Arctic grayling trace much of their original ancestry to Red Rock Lakes
(Peterson and Ardren 2009, p. 1767), and stocking of hatchery grayling
did not appear to have a large effect on the genetic composition of the
extant native populations (Peterson and Ardren 2009, p. 1768).
Differences between native populations of the two grayling ecotypes
(adfluvial, fluvial) do not appear to be as large as differences
resulting from geography (i.e., drainage of origin).
[[Page 54715]]
Habitat
Arctic grayling generally require clear, cold water. Selong et al.
(2001, p. 1032) characterized Arctic grayling as belonging to a
``coldwater'' group of salmonids, which also includes bull trout
(Salvelinus confluentus) and Arctic char (Salvelinus alpinus). Hubert
et al. (1985, p. 24) developed a habitat suitability index study for
Arctic grayling and concluded that thermal habitat was optimal between
7 to 17 [deg]C (45 to 63 [deg]F), but became unsuitable above 20[deg]C
(68[deg]F). Arctic grayling fry may be more tolerant of high water
temperature than adults (LaPerriere and Carlson 1973, p. 30; Feldmeth
and Eriksen 1978, p. 2041).
Having a broad, nearly-circumpolar distribution, Arctic grayling
occupy a variety of habitats including small streams, large rivers,
lakes, and even bogs (Northcote 1995, pp. 152-153; Scott and Crossman
1998, p. 303). They may even enter brackish water (less than or equal
to 4 parts per thousand) when migrating between adjacent river systems
(West et al. 1992, pp. 713-714). Native populations are found at
elevations ranging from near sea level, such as in Bristol Bay, Alaska,
to high-elevation montane valleys (more than 1,830 meters (m) or 6,000
feet (ft)), such as the Big Hole River and Centennial Valley in
southwestern Montana. Despite this broad distribution, Arctic grayling
have specific habitat requirements that can constrain their local
distributions, especially water temperature and channel gradient. At
the local scale, Arctic grayling prefer cold water and are often
associated with spring-fed habitats in regions with warmer climates
(Vincent 1962, p. 33). Arctic grayling are generally not found in
swift, high-gradient streams, and Vincent (1962, p. 36-37, 41-43)
characterized typical Arctic grayling habitat in Montana (and Michigan)
as low-to-moderate gradient (less than 4 percent) streams and rivers
with low-to-moderate water velocities (less than 60 centimeters/sec).
Juvenile and adult Arctic grayling in streams and rivers spend much of
their time in pool habitat (Kaya 1990 and references therein, p. 20;
Lamothe and Magee 2003, pp. 13-14).
Breeding
Arctic grayling typically spawn in the spring or early summer,
depending on latitude and elevation (Northcote 1995, p. 149). In
Montana, Arctic grayling generally spawn from late April to mid-May by
depositing adhesive eggs over gravel substrate without excavating a
nest (Kaya 1990, p. 13; Northcote 1995, p. 151). In general, the
reproductive ecology of Arctic grayling differs from other salmonid
species (trout and salmon) in that Arctic grayling eggs tend to be
comparatively small; thus, they have higher relative fecundity (females
have more eggs per unit body size). Males establish and defend spawning
territories rather than defending access to females (Northcote 1995,
pp. 146, 150-151). The time required for development of eggs from
embryo until they emerge from stream gravel and become swim-up fry
depends on water temperature (Northcote 1995, p. 151). In the upper
Missouri River basin, development from embryo to fry averages about 3
weeks (Kaya 1990, pp. 16-17). Small, weakly swimming fry (typically 1-
1.5 centimeters (cm) (0.4-0.6 in.) at emergence) prefer low-velocity
stream habitats (Armstrong 1986, p. 6; Kaya 1990, pp. 23-24; Northcote
1995, p. 151).
Arctic grayling of all ages feed primarily on aquatic and
terrestrial invertebrates captured on or near the water surface, but
also will feed opportunistically on fish and fish eggs (Northcote 1995,
pp. 153-154; Behnke 2002, p. 328). Feeding locations for individual
fish are typically established and maintained through size-mediated
dominance hierarchies where larger individuals defend favorable feeding
positions (Hughes 1992, p. 1996).
Life History Diversity
Migratory behavior is a common life-history trait in salmonid
fishes such as Arctic grayling (Armstrong 1986, pp. 7-8; Northcote
1995, pp. 156-158; 1997, pp. 1029, 1031-1032, 1034). In general,
migratory behavior in Arctic grayling and other salmonids results in
cyclic patterns of movement between refuge, rearing-feeding, and
spawning habitats (Northcote 1997, p. 1029).
Arctic grayling may move to refuge habitat as part of a regular
seasonal migration (e.g., in winter), or in response to episodic
environmental stressors (e.g., high summer water temperatures). In
Alaska, Arctic grayling in rivers typically migrate downstream in the
fall, moving into larger streams or mainstem rivers that do not
completely freeze (Armstrong 1986, p. 7). In Arctic rivers, fish often
seek overwintering habitat influenced by groundwater (Armstrong 1986,
p. 7). In some drainages, individual fish may migrate considerable
distances (greater than 150 km or 90 mi) to overwintering habitats
(Armstrong 1986, p. 7). In the Big Hole River, Montana, similar
downstream and long-distance movement to overwintering habitat has been
observed in Arctic grayling (Shepard and Oswald 1989, pp. 18-21, 27).
In addition, Arctic grayling in the Big Hole River may move downstream
in proximity to colder tributary streams in summer when thermal
conditions in the mainstem river become stressful (Lamothe and Magee
2003, p. 17).
In spring, mature Arctic grayling leave overwintering areas and
migrate to suitable spawning sites. In river systems, this typically
involves an upstream migration to tributary streams or shallow riffles
within the mainstem (Armstrong 1986, p. 8). Arctic grayling in lakes
typically migrate to either the inlet or outlet to spawn (Armstrong
1986, p. 8; Northcote 1997, p. 148). In either situation, Arctic
grayling typically exhibit natal homing, whereby individuals spawn in
or near the location where they were born (Northcote 1997, pp. 157-
160).
Fry from river populations typically seek feeding and rearing
habitats in the vicinity where they were spawned (Armstrong 1986, pp.
6-7; Northcote 1995, p. 156), while those from lake populations migrate
downstream (inlet spawners) or upstream (outlet spawners) to the
adjacent lake. Following spawning, adults move to appropriate feeding
areas if they are not adjacent to spawning habitat (Armstrong 1986, pp.
7-8). Juvenile Arctic grayling may undertake seasonal migrations
between feeding and overwintering habitats until they reach maturity
and add the spawning migration to this cycle (Northcote 1995, pp. 156-
157).
Life History Diversity in Arctic Grayling in the Upper Missouri River
Two general life-history forms or ecotypes of native Arctic
grayling occur in the upper Missouri River Arctic: Fluvial and
adfluvial. Fluvial fish use river or stream (lotic) habitat for all of
their life cycles and may undergo extensive migrations within river
habitat. Adfluvial fish live in lakes and migrate to tributary streams
to spawn. These same life-history forms also are expressed by Arctic
grayling elsewhere in North America (Northcote 1997, p. 1030).
Historically, the fluvial life-history form predominated in the
Missouri River basin above the Great Falls, perhaps because there were
only a few lakes accessible to natural colonization of Arctic grayling
that would permit expression of the adfluvial ecotype (Kaya 1992, p.
47). The fluvial and adfluvial life-history forms of Arctic grayling in
the upper Missouri River do not appear to represent distinct
evolutionary lineages. Instead, they appear to represent an example of
adaptive radiation (Schluter 2000, p. 1), whereby the forms
[[Page 54716]]
differentiated from a common ancestor developed traits that allowed
them to exploit different habitats. The primary evidence for this
conclusion is genetic data that indicate that within the Missouri River
basin the two ecotypes are more closely related to each other than they
are to the same ecotype elsewhere in North America (Redenbach and
Taylor 1999, pp. 27-28; Stamford and Taylor 2004, p. 1538; Peterson and
Ardren 2009, p. 1766). Historically, there may have been some genetic
exchange between the two life-history forms as individuals strayed or
dispersed into different populations (Peterson and Ardren 2009, p.
1770), but the genetic structure of current populations in the upper
Missouri River basin is consistent with reproductive isolation.
The fluvial and adfluvial forms of Arctic grayling appear to differ
in their genetic characteristics, but there appears to be some
plasticity in behavior where individuals from a population can exhibit
a range of behaviors. Arctic grayling fry in Montana can exhibit
heritable, genetically-based differences in swimming behavior between
fluvial and adfluvial ecotypes (Kaya 1991, pp. 53, 56-58; Kaya and
Jeanes 1995, pp. 454, 456). Progeny of Arctic grayling from the fluvial
ecotype exhibited a greater tendency to hold their position in flowing
water relative to progeny from adfluvial ecotypes (Kaya 1991, pp. 53,
56-58; Kaya and Jeanes 1995, pp. 454, 456). Similarly, young grayling
from inlet and outlet spawning adfluvial ecotypes exhibited an innate
tendency to move downstream and upstream, respectively (Kaya 1989, pp.
478-480). All three studies (Kaya 1989, entire; 1991, entire; Kaya and
Jeanes 1995, entire) demonstrate that the response of fry to flowing
water depended strongly on the life-history form (ecotype) of the
source population, and that this behavior has a genetic basis. However,
behavioral responses also were mediated by environmental conditions
(light--Kaya 1991, pp. 56-57; light and water temperature--Kaya 1989,
pp. 477-479), and some progeny of each ecotype exhibited behavior
characteristic of the other; for example some individuals from the
fluvial ecotype moved downstream rather than holding position, and some
individuals from an inlet-spawning adfluvial ecotype held position or
moved upstream (Kaya 1991, p. 58). These observations indicate that
some plasticity for behavior exists, at least for very young Arctic
grayling.
However, the ability of one ecotype of Arctic grayling to give rise
to a functional population of the other ecotype within a few decades is
much less certain, and may parallel the differences in plasticity that
have evolved between river- and lake-type European grayling (Salonen
2005, entire). Circumstantial support for reduced plasticity in
adfluvial Arctic grayling comes from observations that adfluvial fish
stocked in river habitats almost never establish populations (Kaya
1990, pp. 31-34). In contrast, a population of Arctic grayling in the
Madison River that would have presumably expressed a fluvial ecotype
under historical conditions has apparently adapted to an adfluvial
life-history after construction of an impassible dam, which impounded
Ennis Reservoir (Kaya 1992, p. 53; Jeanes 1996, pp. 54). We note that
adfluvial Arctic grayling retain some life-history flexibility--at
least in lake environments--as naturalized populations derived from
inlet-spawning stocks have established outlet-spawning demes (a deme is
a local populations that shares a distinct gene pool) in Montana and in
Yellowstone National Park (Kruse 1959, p. 318; Kaya 1989, p. 480).
While in some cases Arctic grayling may be able to adapt or adjust
rapidly to a new environment, the frequent failure of introductions of
Arctic grayling suggest a cautionary approach to the loss of particular
life-history forms is warranted. Healey and Prince (1995, entire)
reviewed patterns of genotypic and phenotypic variation in Pacific
salmon and warn that recovery of lost life-history forms may not follow
directly from conservation of the genotype (p. 181), and reason that
the critical conservation unit is the population within its habitat (p.
181).
Age and Growth
Age at maturity and longevity in Arctic grayling varies regionally
and is probably related to growth rate, with populations in colder,
northern latitudes maturing at later ages and having a greater lifespan
(Kruse 1959, pp. 340-341; Northcote 1995 and references therein, pp.
155-157). Arctic grayling in the upper Missouri River typically mature
at age 2 (males) or age 3 (females), and individuals greater than age 6
are rare (Kaya 1990, p. 18; Magee and Lamothe 2003, pp. 16-17).
Similarly, Nelson (1954, pp. 333-334) observed that the majority of the
Arctic grayling spawning in two tributaries in the Red Rock Lakes
system, Montana, were age 3, and the oldest individuals aged from a
larger sample were age 6. Mogen (1996, pp. 32-34) found that Arctic
grayling spawning in Red Rock Creek were mostly ages 2 to 5, but he did
encounter some individuals age 7.
Generally, growth rates of Arctic grayling are greatest during the
first years of life then slow dramatically after maturity. Within that
general pattern, there is substantial variation among populations from
different regions. Arctic grayling populations in Montana (Big Hole
River and Red Rock Lakes) appear to have very high growth rates
relative to those from British Columbia, Asia, and the interior and
North Slope of Alaska (Carl et al. 1992, p. 240; Northcote 1995, pp.
155-157; Neyme 2005, p. 28). Growth rates of Arctic grayling from
different management areas in Alberta are nearly as high as those
observed in Montana grayling (ASRD 2005, p. 4).
Distinct Population Segment
In its stipulated settlement with Plaintiffs, the Service agreed to
consider the appropriateness of DPS designations for Arctic grayling
populations in the upper Missouri River basin that included: (a) All
life ecotypes or histories, (b) the fluvial ecotype, and (c) the
adfluvial ecotype. The fluvial ecotype has been the primary focus of
past Service action and litigation, but the Service also has alluded to
the possibility of alternative DPS designations in previous candidate
species assessments (USFWS 2005, p. 11). Since the 2007 finding (72 FR
20305), additional research has been conducted and new information on
the genetics of Arctic grayling is available. This finding contains a
more comprehensive and robust distinct population segment analysis than
the 2007 finding.
Distinct Population Segment Analysis for Native Arctic Graying in the
Upper Missouri River
Discreteness
The discreteness standard under the Service's and National Oceanic
and Atmospheric Administration's (NOAA) joint Policy Regarding the
Recognition of Distinct Vertebrate Population Segments Under the
Endangered Species Act (61 FR 4722) requires an entity to be adequately
defined and described in some way that distinguishes it from other
representatives of its species. A segment is discrete if it is: (1)
Markedly separated from other populations of the same taxon as
consequence of physical, physiological, ecological, or behavioral
factors (quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation); or (2)
delimited by international
[[Page 54717]]
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 ESA.
Arctic grayling native to the upper Missouri River are isolated
from populations of the species inhabiting the Arctic Ocean, Hudson
Bay, and north Pacific Ocean drainages in Asia and North America (see
Figure 1). Arctic grayling native to the upper Missouri River occur as
a disjunct group of populations approximately 800 km (500 mi) to the
south of the next-nearest Arctic grayling population in central
Alberta, Canada. Missouri River Arctic grayling have been isolated from
other populations for at least 10,000 years based on historical
reconstruction of river flows at or near the end of the Pleistocene
(Cross et al. 1986, p. 375; Pileou 1991, pp. 10-11;). Genetic data
confirm Arctic grayling in the Missouri River basin have been
reproductively isolated from populations to the north for millennia
(Everett 1986, pp. 79-80; Redenbach and Taylor 1999, p. 23; Stamford
and Taylor 2004, p. 1538; Peterson and Ardren 2009, pp. 1764-1766;
USFWS, unpublished data). Consequently, we conclude that Arctic
grayling native to the upper Missouri River are markedly separated from
other native populations of the taxon as a result of physical factors
(isolation), and therefore meet the first criterion of discreteness
under the DPS policy. As a result, Arctic grayling native to the upper
Missouri River are considered a discrete population according to the
DPS policy. Because the entity meets the first criterion (markedly
separated), an evaluation with respect to the second criterion
(international boundaries) is not needed.
Significance
If we determine that a population meets the DPS discreteness
element, we then consider whether it also meets the DPS significance
element. The DPS policy states that, if a population segment is
considered discrete under one or more of the discreteness criteria, its
biological and ecological significance will be considered in light of
congressional guidance that the authority to list DPSs be used
``sparingly'' while encouraging the conservation of genetic diversity
(see U.S. Congress 1979, Senate Report 151, 96\th\ Congress, 1st
Session). In making this determination, we consider available
scientific evidence of the discrete population's importance to the
taxon to which it belongs. Since precise circumstances are likely to
vary considerably from case to case, the DPS policy does not describe
all the classes of information that might be used in determining the
biological and ecological importance of a discrete population. However,
the DPS policy does provide four possible reasons why a discrete
population may be significant. As specified in the DPS policy, this
consideration of significance may include, but is not limited to, the
following: (1) Persistence of the discrete population segment in a
unique or unusual ecological setting; (2) evidence that loss of the
discrete segment would result in a significant gap in the range of the
taxon; (3) evidence that the discrete population segment represents the
only surviving natural occurrence of the taxon that may be more
abundant elsewhere as an introduced population outside of its historic
range; or (4) evidence that the discrete population segment differs
markedly from other populations of the species in its genetic
characteristics.
Unique Ecological Setting
Water temperature is a key factor influencing the ecology and
physiology of ectothermic (body temperature regulated by ambient
environmental conditions) salmonid fishes, and can dictate reproductive
timing, growth and development, and life-history strategies.
Groundwater temperatures can be related to air temperatures (Meisner
1990, p. 282), and thus reflect the regional climatic conditions.
Warmer groundwater influences ecological factors such as food
availability, the efficiency with which food is converted into energy
for growth and reproduction, and ultimately growth rates of aquatic
organisms (Allan 1995, pp. 73-79). Aquifer structure and groundwater
temperature is important to salmonid fishes because groundwater can
strongly influence stream temperature, and consequently egg incubation
and fry growth rates, which are strongly temperature-dependent (Coutant
1999, pp. 32-52; Quinn 2005, pp. 143-150).
Missouri River Arctic grayling occur within the 4 to 7 [deg]C (39
to 45 [deg]F) ground water isotherm (see Heath 1983, p. 71; an isotherm
is a line connecting bands of similar temperatures on the earth's
surface), whereas most other North American grayling are found in
isotherms less than 4 [deg]C, and much of the species' range is found
in areas with discontinuous or continuous permafrost (Meisner et al.
1988, p. 5). Much of the historical range of Arctic grayling in the
upper Missouri River is encompassed by mean annual air temperature
isotherms of 5 to 10 [deg]C (41 to 50 [deg]F) (USGS 2009), with the
colder areas being in the headwaters of the Madison River in
Yellowstone National Park. In contrast, Arctic grayling in Canada,
Alaska, and Asia are located in regions encompassed by air temperature
isotherms 5 [deg]C and colder (41 [deg]F and colder), with much of the
species distributed within the 0 to -10 [deg]C isolines (32 to 14
[deg]F). This difference is significant because Arctic grayling in the
Missouri River basin have evolved in isolation for millennia in a
generally warmer climate than other populations. The potential for
thermal adaptations makes Missouri River Arctic grayling a significant
biological resource for the species under expected climate change
scenarios.
TABLE 3. Differences Between the Ecological Setting of the Upper
Missouri River and Elsewhere in the Species' Range of Arctic Grayling.
------------------------------------------------------------------------
Ecological Setting Variable Missouri River Rest of Taxon
------------------------------------------------------------------------
Ocean watershed Gulf of Mexico- Hudson Bay, Arctic
Atlantic Ocean Ocean, or north
Pacific
------------------------------------------------------------------------
Bailey's Ecoregion Dry Domain: Polar Domain:
Temperate Steppe Tundra &
Subarctic Humid
Temperate:
Marine,
Prairie, Warm
Continental
Mountains
------------------------------------------------------------------------
Air temperature (isotherm) 5 to 10 [deg]C -15 to 5 [deg]C
(41 to 50 [deg]F). (5 to 41 [deg]F)
------------------------------------------------------------------------
[[Page 54718]]
Groundwater temperature 4 to 7[deg]C Less than 4 [deg]C
(isotherm) (39 to 45 [deg]F). (less than 39
[deg]F)
------------------------------------------------------------------------
Native occurrence of large- None, in most of Bull trout, lake
bodied fish predators on the range\a\ trout, northern
salmonids pike, taimen
------------------------------------------------------------------------
\a\Lake trout are native to two small lakes in the upper Missouri River
basin (Twin Lakes and Elk Lake), where their distributions presumably
overlapped with the native range of Arctic grayling, so they would not
have interacted with most Arctic grayling populations in the basin
that were found in rivers.
Arctic grayling in the upper Missouri River basin occur in a
temperate ecoregion distinct from all other Arctic grayling populations
worldwide, which occur in Arctic or sub-Arctic ecoregions dominated by
Arctic flora and fauna. An ecoregion is a continuous geographic area
within which there are associations of interacting biotic and abiotic
features (Bailey 2005, pp. S14, S23). These ecoregions delimit large
areas within which local ecosystems recur more or less in a predictable
fashion on similar sites (Bailey 2005, p. S14). Ecoregional
classification is hierarchical, and based on the study of spatial
coincidences, patterning, and relationships of climate, vegetation,
soil, and landform (Bailey 2005, p. S23). The largest ecoregion
categories are domains, which represent subcontinental areas of similar
climate (e.g., polar, humid temperate, dry, and humid tropical) (Bailey
1994; 2005, p. S17). Domains are divided into divisions that contain
areas of similar vegetation and regional climates. Arctic grayling in
the upper Missouri River basin are the only example of the species
naturally occurring in a dry domain (temperate steppe division; see
Table 3 above). The vast majority of the species' range is found in the
polar domain (all of Asia, most of North America), with small portions
of the range occurring in the humid temperate domain (northern British
Columbia and southeast Alaska). Occupancy of Missouri River Arctic
grayling in a temperate ecoregion is significant for two primary
reasons. First, an ecoregion represents a suite of factors (climate,
vegetation, landform) influencing, or potentially influencing, the
evolution of species within that ecoregion. Since Missouri River Arctic
grayling have existed for thousands of years in an ecoregion quite
different from the majority of the taxon, they have likely developed
adaptations during these evolutionary timescales that distinguish them
from the rest of the taxon, even if we have yet to conduct the proper
studies to measure these adaptations. Second, the occurrence of
Missouri River Arctic grayling in a unique ecoregion helps reduce the
risk of species-level extinction, as the different regions may respond
differently to environmental change.
Arctic grayling in the upper Missouri River basin have existed for
at least 10,000 years in an ecological setting quite different from
that experienced by Arctic grayling elsewhere in the species' range.
The most salient aspects of this different setting relate to
temperature and climate, which can strongly and directly influence the
biology of ectothermic species (like Arctic grayling). Arctic grayling
in the upper Missouri River have experienced warmer temperatures than
most other populations. Physiological and life-history adaptation to
local temperature regimes are regularly documented in salmonid fishes
(Taylor 1991, pp. 191-193), but experimental evidence for adaptations
to temperature, such as unusually high temperature tolerance or lower
tolerance to colder temperatures, is lacking for Missouri River Arctic
grayling because the appropriate studies have not been conducted. Lohr
et al. (1996, p. 934) studied the upper thermal tolerances of Arctic
grayling from the Big Hole River, but their research design did not
include other populations from different thermal regimes, so it was not
possible to make between-population contrasts under a common set of
conditions. Arctic grayling from the upper Missouri River demonstrate
very high growth rates relative to other populations (Northcote 1995,
p. 157). Experimental evidence obtained by growing fish from
populations under similar conditions would be needed to measure the
relative influence of genetics (local adaptation) versus environment.
An apex fish predator that preys successfully on salmonids has been
largely absent from most of the upper Missouri River basin over
evolutionary time scales (tens of thousands of years). This suggests
that Arctic grayling in the upper Missouri River basin have faced a
different selective pressure than Arctic grayling in many other areas
of the species' range, at least with respect to predation by fishes.
Predators can exert a strong selective pressure on populations. One
noteworthy aspect of the aquatic biota experienced by Arctic grayling
in the upper Missouri River is the apparent absence of a large-bodied
fish that would be an effective predator on juvenile and adult
salmonids. In contrast, one or more species of large predatory fishes
like northern pike (Esox lucius), bull trout, taimen (Hucho taimen),
and lake trout (Salvelinus namaycush) are broadly distributed across
much of the range of Arctic grayling in Canada and Asia (Northern
pike--Scott and Crossman 1998, pp. 302, 358; taimen--VanderZanden et
al. 2007, pp. 2281-2282; Esteve et al. 2009, p. 185; bull trout--Behnke
2002, pp. 296, 330; lake trout --Behnke 2002, pp. 296, 330). The only
exceptions to this general pattern are where Arctic grayling formerly
coexisted with lake trout native to Twin Lakes and Elk Lake (Beaverhead
County) (Vincent 1963, pp. 188-189), but both of these Arctic grayling
populations are thought to be extirpated (Oswald 2000, pp. 10, 16;
Oswald 2006, pers. comm.). The burbot (Lota lota) is a freshwater fish
belonging to the cod family and is native to the Missouri, Big Hole,
Beaverhead, Ruby, and Madison Rivers in Montana (MFISH 2010); thus its
distribution significantly overlapped the historical and current ranges
of Arctic grayling in the upper Missouri River system. Burbot are
voracious predators, but tend to be benthic (bottom-oriented) and
apparently prefer the deeper portions of larger rivers and lakes. A few
studies have investigated the diet of burbot where they overlap with
native Arctic grayling in Montana, but did not detect any predation on
Arctic grayling (Streu 1990, pp. 16-20; Katzman 1998, pp. 98-100).
Burbot apparently do not consume salmonids in significant amounts, even
when they are very abundant (Katzman 1998 and references therein, p.
106). The response of Arctic grayling in the Missouri River basin to
introduced,
[[Page 54719]]
nonnative trout suggests they were not generally pre-adapted to cope
with the presence of a large-bodied salmonid predator. Missouri River
Arctic grayling lack a co-evolutionary history with brown trout, and
there are repeated observations that the two species tend not to
coexist and that brown trout displace Arctic grayling (Kaya 1992, p.
56; 2000, pp. 14-15). We caution that competition with and predation by
brown trout has not been directly studied with Arctic grayling, but at
least some circumstantial evidence indicates that Missouri River Arctic
grayling may not coexist well with brown trout.
We conclude that the occurrence of Arctic grayling in the upper
Missouri River is biogeographically important to the species, that
grayling there have occupied a distinctly different ecological setting
relative to the rest of the species (see Table 3 above), and that they
have been on a different evolutionary trajectory for at least 10,000
years. Consequently, we believe that Arctic grayling in the upper
Missouri River occupy a unique ecological setting. The role that this
unique setting plays in influencing adaptations or determining unique
traits is unclear, and therefore a determination of the significance of
this ecological setting to the taxon is unknown.
Gap in the Range
Arctic grayling in the upper Missouri River basin occur in an ocean
drainage basin that is distinct from all other Arctic grayling
populations worldwide. All other Arctic grayling occur in drainages of
Hudson Bay, the Arctic Ocean, or the north Pacific Ocean; the Missouri
River is part of the Gulf of Mexico-Atlantic Ocean drainage. The
significance of occupancy of this drainage basin is that the upper
Missouri River basin represents an important part of the species' range
from a biogeographic perspective. The only other population of Arctic
grayling to live in a non-Arctic environment was the Michigan-Great
Lakes population that was extirpated in the 1930s.
Arctic grayling in Montana (southern extent is approximately
44[deg]36[min]23[sec] N latitude) represent the southern-most extant
population of the species' distribution since the Pleistocene
glaciation (Figure 1). The next-closest native Arctic grayling
population outside the Missouri River basin is found in the Pembina
River (approximately 52[deg]55[min]6.77[sec] N latitude) in central
Alberta, Canada, west of Edmonton (Blackburn and Johnson 2004, pp. ii,
17; ASRD 2005, p. 6). Loss of the native Arctic grayling of the upper
Missouri River would shift the southern distribution of Arctic grayling
by more than 8[deg] latitude. Such a dramatic range constriction would
constitute a significant geographic gap in the species' range, and
eliminate a genetically distinct group of Arctic grayling, which may
limit the species' ability to cope with future environmental change.
Marginal populations, defined as those on the periphery of the
species' range, are believed to have high conservation significance
(see reviews by Scudder 1989, entire; Lesica and Allendorf 1995,
entire; Fraser 2000, entire). Peripheral populations may occur in
suboptimal habitats and thus be subjected to very strong selective
pressures (Fraser 2000, p. 50). Consequently, individuals from these
populations may contain adaptations that may be important to the taxon
in the future. Lomolino and Channell (1998, p. 482) hypothesize that
because peripheral populations should be adapted to a greater variety
of environmental conditions, then they may be better suited to deal
with anthropogenic (human-caused) disturbances than populations in the
central part of a species' range. Arctic grayling in the upper Missouri
River have, for millennia, existed in a climate warmer than that
experienced by the rest of the taxon. If this selective pressure has
resulted in adaptations to cope with increased water temperatures, then
the population segment may contain genetic resources important to the
taxon. For example, if northern populations of Arctic grayling are less
suited to cope with increased water temperatures expected under climate
warming, then Missouri River Arctic grayling might represent an
important population for reintroduction in those northern regions. We
believe that Arctic grayling from the upper Missouri River's occurrence
at the southernmost extreme of the range contributes to its
significance that may increased adaptability and contribute to the
resilience of the overall taxon.
Only Surviving Natural Occurrence of the Taxon that May be More
Abundant Elsewhere as an Introduced Population Outside of its
Historical Range
This criterion does not directly apply to the Arctic grayling in
the upper Missouri River because it is not the only surviving natural
occurrence of the taxon; there are native Arctic grayling populations
in Canada, Alaska, and Asia. That said, there are introduced Lake
Dwelling Arctic Grayling within the native range in the Upper Missouri
River System and Arctic grayling have been established in lakes outside
their native range in Arizona, Colorado, Idaho, Montana, New Mexico,
Utah, Washington, and Wyoming (Vincent 1962, p. 15; Montana Fisheries
Information System (MFISH) 2009; NatureServe 2010).
Differs Markedly in Its Genetic Characteristics
Differences in genetic characteristics can be measured at the
molecular genetic or phenotypic level. Three different types of
molecular markers (allozymes, mtDNA, and microsatellites) demonstrate
that Arctic grayling from the upper Missouri River are genetically
different from those in Canada, Alaska, and Asia (Everett 1986, pp. 79-
80; Redenbach and Taylor 1999, p. 23; Stamford and Taylor 2004, p.
1538; Peterson and Ardren 2009, pp. 1764-1766; USFWS, unpublished
data). These data confirm the reproductive isolation among populations
that establishes the discreteness of Missouri River Arctic grayling
under the DPS policy. Here, we speak to whether these data also
establish significance.
Allozymes
Using allozyme electrophoretic data, Everett (1986, entire) found
marked genetic differences among Arctic grayling collected from the
Chena River in Alaska, those descended from fish native to the
Athabasca River drainage in the Northwest Territories, Canada, and
native upper Missouri River drainage populations or populations
descended from them (see Leary 2005, pp. 1-2). The Canadian population
had a high frequency of a unique isocitrate dehydrogenase allele (form
of a gene) and a unique malate dehydrogenase allele, which strongly
differentiated them from all the other samples (Everett 1986, p. 44).
With the exception one introduced population in Montana that is
believed to have experienced extreme genetic bottlenecks, the Chena
River (Alaskan) fish were highly divergent from all the other samples
as they possessed an unusually low frequency of superoxide dismutase
(Everett 1986, p. 60; Leary 2005, p. 1), and contained a unique variant
of the malate dehydrogenase (Leary 2005, p. 1). Overall, each of the
four native Missouri River populations examined (Big Hole, Miner,
Mussigbrod, and Red Rock) exhibited statistically significant
differences in allele frequencies relative to both the Chena River
(Alaska) and Athabasca River (Canada) populations (Everett 1986, pp.
15, 67).
Combining the data of Everett (1986, entire), Hop and Gharrett
(1989, entire), and Leary (1990, entire) results in
[[Page 54720]]
information from 21 allozyme loci (genes) from the five native upper
Missouri River drainage populations, five native populations in the
Yukon River drainage in Alaska, and the one population descended from
the Athabasca River drainage in Canada (Leary 2005, pp. 1-2).
Examination of the genetic variation in these samples indicated that
most of the genetic divergence is due to differences among drainages
(29 percent) and comparatively little (5 percent) results from
differences among populations within a drainage (Leary 2005, p. 1).
Mitochondrial DNA
Analysis using mtDNA suggest that Arctic grayling in North America
represent at least three evolutionary lineages that are associated with
distinct glacial refugia (Redenbach and Taylor 1999, entire; Stamford
and Taylor 2004, entire). Arctic grayling in the Missouri River basin
belong to the so-called North Beringia lineage (Redenbach and Taylor
1999, pp. 27-28; Samford and Taylor 2004, pp. 1538-1540). Analysis of
Arctic grayling using restriction enzymes and DNA sequencing indicated
that the fish from the upper Missouri River drainage possessed, in
terms of North American fish, an ancestral form of the molecule
(different forms of mtDNA molecules are referred to as haplotypes) that
was generally absent from populations collected from other locations
within the species' range in North America (Redenbach and Taylor 1999,
pp. 27-28; Stamford and Taylor 2004, p. 1538). The notable exceptions
were that some fish from the lower Peace River drainage in British
Columbia, Canada (2 of 24 individuals in the population), and all
sampled individuals from the Saskatchewan River drainage Saskatchewan,
Canada (a total of 30 individuals from 2 populations), also possessed
this haplotype (Stamford and Taylor 2004, p. 1538).
Variation in mtDNA haplotypes based on sequencing a portion of the
`control region' of the mtDNA molecule of Arctic grayling from 26
different populations seems to support the groupings proposed by
Stamford and Taylor (2004, entire) (USFWS unpublished data). Two
haplotypes were common in the five native Missouri River populations
(Big Hole, Red Rock, Madison, Miner, and Mussigbrod - total sample size
143 individuals; USFWS unpublished data). Fish from three populations
in Saskatchewan or near Hudson's Bay also had one of these Missouri
River haplotypes at very high frequency (50 of 51 individuals sequenced
had the same haplotype; USFWS unpublished data). The two ``common''
Missouri River haplotypes also occurred at low frequency in handful of
other populations elsewhere in Canada and Alaska. For example, there a
total of five such populations where a few individuals contained had
one or the other of the two common Missouri River haplotypes (25 of 107
individuals sequenced; USFWS unpublished data). Also similar to the
earlier study by Stamford and Taylor (2004, entire), a few individuals
(9 of 40 individuals) from two populations from the Lower Peace River
and the Upper Yukon River also had one or the other of the two common
Missouri River haplotypes (USFWS unpublished data).
The distribution of the common Missouri River haplotype compared to
others suggested that Arctic grayling native to the upper Missouri
River drainage probably originated from a glacial refuge in the
drainage and subsequently migrated northwards when the Missouri River
temporarily flowed into the Saskatchewan River and was linked to an
Arctic drainage (Cross et al. 1986, pp. 374-375; Pielou 1991, p. 195).
When the Missouri River began to flow southwards because of the advance
of the Laurentide ice sheet (Cross et al. 1986, p. 375; Pileou 1991, p.
10), the Arctic grayling in the drainage became physically and
reproductively isolated from the rest of the species' range (Leary
2005, p. 2; Campton 2006, p. 6), which would have included those
populations in Saskatchewan. Alternatively, the Missouri River Arctic
grayling could have potentially colonized Saskatchewan or the Lower
Peace River (in British Columbia) or both post-glacially (Stamford
2001, p. 49) via a gap in the Cordilleran and Laurentide ice sheets
(Pielou 1991, pp. 10-11), which also might explain the low frequency of
one or the other of the `Missouri River' haplotypes in grayling in the
Lower Peace River and Upper Yukon River.
We do not interpret the observation that Arctic grayling in Montana
and Saskatchewan, and to lesser extent those from the Lower Peace and
Upper Yukon River systems, share a mtDNA haplotype to mean that these
groups of fish are genetically identical. Rather, we interpret it to
mean that these fish shared a common ancestor tens to hundreds of
thousands of years ago.
Microsatellite DNA
Recent analysis of microsatellite DNA (highly variable portions of
nuclear DNA that exhibit tandem repeats of DNA base pairs) that
included samples from five native Missouri River populations and two
from Saskatchewan showed substantial divergence between these groups
(Peterson and Ardren 2009, entire). Genetic differentiation between
sample populations can be compared in terms of the genetic variation
within relative to among populations, measured in terms of allele
frequencies, a metric called Fst (Allendorf and Luikart
2007, pp. 52-54, 198-199). An analogous metric, named Rst,
also measures genetic differentiation between populations based on
microsatellite DNA, but differs from Fst in that it also
considers the size differences between alleles (Hardy et al. 2003, p.
1468). An Fst or Rst of 0 indicates that
populations are the same genetically (all genetic diversity within a
species is shared by all populations), whereas a value of 1 indicates
the populations are completely different (all the genetic diversity
within a species is found as fixed differences among populations).
Fst values ranged from 0.13 to 0.31 (average 0.18) between
Missouri River and Saskatchewan populations (Peterson and Ardren 2009,
pp. 1758, 1764-1765), whereas Rst values ranged from 0.47 to
0.71 (average 0.54) for the same comparisons (Peterson and Ardren 2009,
pp. 1758, 1764-1765). This indicates that the two groups (Missouri vs.
Saskatchewan populations) differ significantly in allele frequency and
also in the size differences, and therefore divergence, among those
alleles. This indicates that the observed genetic differences are not
simply due to random loss of genetic variation because the populations
are isolated (genetic drift), but they also are due to mutational
differences, which suggests the groups may have been separated for
millennia (Peterson and Ardren 2009, pp. 1767-1768).
Comparison of 435 individuals from 21 Arctic grayling populations
from Alaska, Canada, and the Missouri River basin using nine of the
same microsatellite loci as Peterson and Ardren (2009, entire) further
supports the distinction of Missouri River Arctic grayling relative to
populations elsewhere in North America (USFWS, unpublished data). A
statistical analysis that determines the likelihood that an individual
fish belongs to a particular group (e.g., STRUCTURE) (Pritchard et al.
2000, entire), clearly separated the sample fish from 21 populations
into two clusters: one cluster representing populations from the upper
Missouri River basin, and another cluster representing populations from
across Canada and Alaska (USFWS, unpublished data). Factorial
correspondence analysis (FCA) plots of individual fish also separated
the fish
[[Page 54721]]
into two groups, or clouds of data points when visualized in a three-
dimensional space (USFWS, unpublished data). The FCA is a multivariate
data analysis technique used to simplify presentation of complex data
and to identify systematic relations between variables, in this case
the multi-locus genotypes of Arctic grayling. As with the other
analysis, the FCA plots clearly distinguished Missouri River Arctic
grayling from those native to Canada and Alaska (USFWS, unpublished
data). Divergence in size among these alleles further supports the
distinction between Missouri River grayling from those in Canada and
Alaska (USFWS, unpublished data). The interpretation of these data is
that the Missouri River populations and the Canada/Alaska populations
are most genetically distinct at the microsatellite loci considered.
Phenotypic Characteristics Influenced by Genetics--Meristics
Phenotypic variation can be evaluated by counts of body parts
(i.e., meristic counts of the number of gill rakers, fin rays, and
vertebrae characteristics of a population) that can vary within and
among species. These meristic traits are influenced by both genetics
and the environment (Allendorf and Luikart 2007, pp. 258-259). When the
traits are controlled primarily by genetic factors, then meristic
characteristics can indicate significant genetic differences among
groups. Arctic grayling north of the Brooks Range in Alaska and in
northern Canada had lower lateral line scale counts than those in
southern Alaska and Canada (McCart and Pepper 1971, entire). These two
scale-size phenotypes are thought to correspond to fish from the North
and South Beringia glacial refuges, respectively (Stamford and Taylor
2004, p. 1545). Arctic grayling from the Red Rock Lakes drainage had a
phenotype intermediate to the large- and small-scale types (McCart and
Pepper 1971, pp. 749, 754). Arctic grayling populations from the
Missouri River (and one each from Canada and Alaska) could be correctly
assigned to their group 60 percent of the time using a suite of seven
meristic traits (Everett 1986, pp. 32-35). Those native Missouri River
populations that had high genetic similarity also tended to have
similar meristic characteristics (Everett 1986, pp. 80, 83).
Arctic grayling from the Big Hole River showed marked differences
in meristic characteristics relative to two populations from Siberia,
and were correctly assigned to their population of origin 100 percent
of the time (Weiss et al. 2006, pp. 512, 515-516, 518). The populations
that were significantly different in terms of their meristic
characteristics also exhibited differences in molecular genetic markers
(Weiss et al. 2006, p. 518).
Inference Concerning Genetic Differences in Arctic Grayling of the
Missouri River Relative to Other Examples of the Taxon
We believe the differences between Arctic grayling in the Missouri
River and sample populations from Alaska and Canada measured using
microsatellite DNA markers (Peterson and Ardren 2009, pp. 1764-1766;
USFWS, unpublished data) represent ``marked genetic differences'' in
terms of the extent of differentiation (e.g., Fst,
Rst) and the importance of that genetic legacy to the rest
of the taxon. The presence of morphological characteristics separating
Missouri River Arctic grayling from other populations also likely
indicates genetic differences, although this conclusion is based on a
limited number of populations (Everett 1986, pp. 32-35; Weiss et al.
2006, entire), and we cannot entirely rule out the influence of
environmental variation.
The intent of the DPS policy and the ESA is to preserve important
elements of biological and genetic diversity, not necessarily to
preserve the occurrence of unique alleles in particular populations. In
Arctic grayling of the Missouri River, the microsatellite DNA data
indicate that the group is evolving independently from the rest of the
species. The extirpation of this group would mean the loss of the
genetic variation in one of the two most distinct groups identified in
the microsatellite DNA analysis, and the loss of the future
evolutionary potential that goes with it. Thus, the genetic data
support the conclusion that Arctic grayling of the upper Missouri River
represent a unique and irreplaceable biological resource of the type
the ESA was intended to preserve. Thus, we conclude that Missouri River
Arctic grayling differ markedly in their genetic characteristics
relative to the rest of the taxon.
Conclusion
We find that a population segment that includes all native ecotypes
of Arctic grayling in the upper Missouri River basin satisfies the
discreteness standard of the DPS policy. The segment is physically
isolated, and genetic data indicates that Arctic grayling in the
Missouri River basin have been separated from other populations for
thousands of years. The population segment occurs in an ocean drainage
different from all other Arctic grayling populations worldwide, and we
find that loss of this population segment would create a significant
gap in the species' range. Molecular genetic data clearly differentiate
Missouri River Arctic grayling from other Arctic grayling populations,
including those in Canada and Alaska. We conclude that because Arctic
grayling of the upper Missouri River basin satisfy the criteria for
being discrete and significant under our DPS policy, we determined that
this population constitutes a DPS under our policy and the Act.
In our stipulated settlement agreement, we also agreed to consider
the appropriateness of distinct population segments based on the two
different ecotypes (fluvial and adfluvial) expressed by native Arctic
grayling of the upper Missouri River. We acknowledge there are cases
where the Service has designated distinct population segments primarily
on life-history even when they co-occur with another ecotype that can
be part of the same gene pool (e.g., anadromous steelhead and resident
rainbow trout, Oncorhynchus mykiss (71 FR 838, January 5, 2006).
However, we conclude that designation of a single population segment
for Arctic grayling in the upper Missouri River is more appropriate
than designating two separate distinct population segments delineated
by life-history type. In the Missouri River basin, the two ecotypes
share a common evolutionary history, and do not cluster genetically
based strictly on ecotype. As we discussed above, the fluvial and
adfluvial life-history forms of Arctic grayling in the upper Missouri
River do not appear to represent distinct evolutionary lineages. There
appears to be some plasticity in behavior where individuals from a
population can exhibit a range of behaviors. From a practical
standpoint, we observe that only five native Arctic grayling
populations remain in the Missouri River basin, and we believe that
both fluvial and adfluvial native ecotypes have a role in the
conservation of the larger population segment. We believe that the
intent of the ESA and the DPS policy, and our obligation to assess the
appropriateness of alternate DPS designations in the settlement
agreement are best served by designating a single distinct population
segment, rather than multiple population segments.
As we described above, we are not including introduced populations
that occur in lakes in the Upper Missouri River basin in the DPS. The
Service has interpreted the Act to provide a statutory directive to
conserve species in their native ecosystems (49 FR 33890,
[[Page 54722]]
August 27, 1984) and to conserve genetic resources and biodiversity
over a representative portion of a taxon's historical occurrence (61 FR
4723, February 7, 1996). The introduced Arctic grayling occur in lakes
apart from native fluvial environments and from lakes where native
adfluvial grayling occur. These introduced populations have not been
used for any conservation purpose and could pose genetic risks to the
native Arctic grayling population.
We find that the Arctic grayling of the upper Missouri River basin
constitute a distinct population segment. We define the historical
range of this population segment to include the major streams, lakes,
and tributary streams of the upper Missouri River (mainstem Missouri,
Smith, Sun, Beaverhead, Jefferson, Big Hole, and Madison Rivers, as
well as their key tributaries, as well as a few small lakes where
Arctic grayling are or were believed to be native (Elk Lake, Red Rock
Lakes, Miner Lake, and Mussigbrod Lake, all in Beaverhead County,
Montana). We define the current range of the DPS to consist of extant
native populations in the Big Hole River, Miner Lake, Mussigbrod Lake,
Madison River-Ennis Reservoir, and Red Rock Lakes. We refer to this DPS
as the native Arctic grayling of the upper Missouri River. The
remainder of this finding will thus focus on the population status of
and threats to this entity.
Population Status and Trends for Native Arctic Grayling in the Upper
Missouri River
We identified a DPS for Arctic grayling in the upper Missouri River
basin that includes five extant populations: (1) Big Hole River, (2)
Miner Lake, (3) Mussigbrod Lake, (4) Madison River-Ennis Reservoir, and
(5) Red Rock Lakes. In general, we summarize what is known about the
historical distribution and abundance of each of these populations,
describe their current distributional extent, summarize any available
population monitoring data, identify the best available information
that we use to infer the current population status, and summarize the
current population status and trends.
TABLE 4. Extent and current estimated effective population sizes (Ne) of native Arctic grayling populations in the Missouri River basin. Values in
parentheses represent 95 percent confidence intervals.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated Adult Population Size Assuming:
--------------------------------------------------------------------------------------------------------------------------------------------------------
Biological Date of
Population Name Population Ne \b\ Population Size Ne/N ratio 0.25 \d\ Ne/N ratio 0.14 \e\
Extent\a\ \c\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Big Hole River 158 mi 208 (176 to 251) 2000-2003 828 (704 to 1,004) 1,486 (1,257 to 1,793)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Miner Lakes 26.9 ha 286 (143 to 4,692) 2001-2003 1,144 (572 to 18,768) 2,043 (1,021 to 33,514)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mussigbrod Lake 42.5 ha 1,497 (262 to 2001-2003 5,988 (1,048 to [infin]) 10,693 (1,871 to
[infin]) [infin])
--------------------------------------------------------------------------------------------------------------------------------------------------------
Madison River-Ennis Reservoir 1,469 ha 162 (76 to 1991-1993 648 (304 to [infin]) 1,157 (543 to [infin])
[infin])
--------------------------------------------------------------------------------------------------------------------------------------------------------
Red Rock Lakes 890 ha 228 (141 to 547) 2000-2002 912 (564 to 2,188) 1,629 (1,007 to 3,907)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Approximate maximum spatial extent over which Arctic grayling are encountered in a given water.
\b\ Effective population size estimates from Peterson and Ardren (2009, p.1767). Confidence intervals that include infinity ([infin]) can result from
statistical artifacts of the linkage disequilibrium method (Waples and Do 2007, p. 10; Russell and Fewster 2009, pp. 309-310). The usual
interpretation is that there is no evidence for any disequilibrium caused by genetic drift due to a finite number of parents--it can all be explained
by sampling error (Waples and Do 2007, p. 10). Thus, the effective size is infinitely large. Small sample sizes may influence estimates in some cases
(e.g., Madison River-Ennis Reservoir).
\c\ Approximate date to which the Ne estimate refers. For example, Ne for the Big Hole River based on genotyping a sample of fish from 2005-2006, but
the interpretation of Ne is the number of breeding adults that produced the fish in the observed sample. Thus the true biological date of the Ne
estimate is one generation before 2005-2006, or approximately 2000-2003.
\d\ Adult population size estimated from Ne assuming Ne /N = 0.25. This value was the midpoint of a range of values (0.2-0.3) commonly cited for Ne /N
ratios in salmonid fishes (Allendorf et al. 1997, p. 143; McElhahey et al. 2000, p. 63; Rieman and Allendorf 2001, p. 762; Palm et al. 2003, p. 260).
\e\ Adult population size estimated from Ne assuming Ne /N = 0.14. This value was the median Ne /N ratio based on a meta analysis of 83 studies for 65
different species (Palstra and Ruzzante 2008, p. 3428).
Big Hole River
Historically, Arctic grayling presumably had access to and were
distributed throughout much of the Big Hole River, including the lower
reaches of many tributary streams, such as Big Lake, Deep, Doolittle,
Fishtrap, Francis, Governor, Johnson, LaMarche, Miner, Mussigbrod,
Odell, Pintlar, Rock, Sand Hollow, Swamp, Seymour, Steel, Swamp, and
Wyman Creeks, as well as the Wise River (Liknes 1981, p. 11; Liknes and
Gould 1987, p. 124; Kaya 1990, pp. 36-40). Presently, Arctic grayling
are found primarily in the mainstem Big Hole River between the towns of
Glen and Jackson, Montana, a distance of approximately 181 river km
(113 mi), and in 11 tributaries, totaling an additional 72 river km (45
mi) (Magee 2010a, pers. comm.; see Table 4 above). The total current
maximum extent of Arctic grayling occurrence in the Big Hole River is
approximately 250 river km (156 mi). However, the fish are not
continuously distributed across this distance, and instead tend to be
concentrated in discrete patches (Magee et al. 2006, pp. 27-28; Rens
and Magee 2007, p. 15) typically associated with spawning and rearing
habitats or cold-water sites that provide a thermal refuge from high
summer water temperatures.
Kaya (1992, pp. 50-52) noted the general lack of monitoring data
for the Big Hole River fluvial Arctic grayling population prior to the
late 1970s, but data collected since that time indicate the overall
range has contracted over the last 2 decades. During 1978 and 1979
Arctic grayling were observed in Governor Creek (in the headwaters of
the Big Hole River) and downstream in the Big Hole River near Melrose,
Montana (Liknes 1981, p. 11). Arctic grayling have not recently been
encountered in Governor Creek (Rens and Magee 2007, p. 15; Montana
Fish, Wildife and Parks (MFWP), unpublished data), but are occasionally
[[Page 54723]]
encountered in the Big Hole River downstream of Divide, Montana, at
very low densities and as far downstream as Melrose or Glen, Montana
(Oswald 2005a, pers. comm.). More recently, Arctic grayling have become
less abundant in historical spawning and rearing locations in the upper
watershed near Wisdom, Montana, and also in downstream river segments
with deep pool habitats considered important for overwintering (Magee
and Lamothe 2003, pp. 18-21; MFWP unpublished data). Comparatively,
greater numbers of Arctic grayling are encountered in the lower reaches
of tributaries to the upper Big Hole River, including LaMarche,
Fishtrap, Steel, and Swamp Creeks (Rens and Magee 2007, p. 13).
Based on the best available data, the adult population declined by
one half between the early 1990s and the early 2000s (see Figure 3,
USFWS unpublished data), which is equivalent to a decline of 7 percent
per year, on average. Monitoring data collected by MFWP also support
the conclusion that the Arctic grayling population in the Big Hole
River declined during this time period (Byorth 1994a, p. 11; Rens and
Magee 2007, entire; MFPW, unpublished data).
[GRAPHIC] [TIFF OMITTED] TP08SE10.002
FIGURE 3. Effective population size (Ne) of Big Hole
River Arctic grayling based on microsatellite DNA genotypes from fish
collected in three time periods (USFWS, unpublished data). The
Ne are estimated using the linkage disequilibrium method of
Waples and Do (2008, entire), and error bars represent 95% confidence
intervals estimated by the jackknife method.
Miner Lakes
The Miner Lakes are a complex of small lakes in the upper Big Hole
River drainage. Lower Miner Lakes are two small lakes in the middle of
the Miner Creek drainage connected by a narrow section approximately
100 m (330 ft) in length, functionally representing a single lake for
fish populations. Arctic grayling occur in Lower Miner Lakes (hereafter
Miner Lakes population), which has a total surface area of 26.7
hectares (ha) or 0.267 km\2\ (66 acres (ac)). Arctic grayling primarily
reside in the lake, and presumably move into the inlet or outlet
tributary to spawn. Surveys conducted upstream and downstream of the
Lower Miner Lakes in 1992 and 1994, respectively, captured no Arctic
grayling (Downing 2006, pers. comm.). Apparently, adults do not remain
in the stream long after spawning and young-of-the-year (YOY) move into
Lower Miner Lakes.
The MFWP conducted limited surveys in Lower Miner Lakes, but the
abundance of the population has not been estimated by traditional
fishery methods. Arctic grayling are classified as ``common'' in Lower
Miner Lakes (MFISH 2010). Introduced brook trout also are present.
The best available information on the abundance of Miner Lakes
Arctic grayling comes from a genetic assessment of that population.
Based on a sample of fish from 2006, Peterson and Ardren (2009, p.
1767) estimated an effective population size of 286. This estimate
represents an approximation of abundance of breeding adults at a single
point in time, and there are no data on which to base an assessment of
the population trend.
Mussigbrod Lake
Mussigbrod Lake has a surface area of 42.5 ha (105 ac), and is
found in the middle reaches of Mussigbrod Creek, a tributary to the
North Fork Big Hole River. Arctic grayling primarily reside in the
lake. We do not know whether Arctic grayling spawn in the inlet stream
or within the lake (Magee and
[[Page 54724]]
Olsen 2010, pers. comm.). Arctic grayling occasionally pass over a
diversion structure downstream at the outlet of Mussigbrod Lake, and
become trapped in a pool that is isolated because of stream dewatering.
The MFWP periodically capture grayling in this pool and return them to
the lake.
Data for the Mussigbrod Lake population of Arctic grayling is
minimal. The MFWP has conducted very limited surveys and the abundance
of the population has not been estimated by traditional fishery
methods. Genetic data indicate that Arctic grayling are comparatively
abundant (see Table 4 above). Based on a sample from 2006, Peterson and
Ardren (2009, p. 1767) estimated an effective size of 1,497. The best
available data indicate that the Mussigbrod Lake population is
comparatively large, but we have no data about the population trend.
Madison River - Ennis Reservoir
Historically, Arctic grayling were reported to be abundant in the
middle and upper Madison River, but have undergone a dramatic decline
in the past 100 years with the species becoming rare by the 1930s
(Vincent 1962, pp. 11, 85-87). Native Arctic grayling are thought be
extirpated from the upper Madison River. A major impact to fish in that
area was the construction of Hebgen Dam, which flooded Horsethief
Springs, a small tributary that was reportedly one of the most
important streams for Arctic grayling (Vincent 1962, pp. 40-41, 128).
In the middle Madison River, Arctic grayling were apparently common to
plentiful in the mainstem River near Ennis, Montana, and some
associated tributaries (Jack, Meadow, and O'Dell Creeks) (Vincent 1962,
p. 128). In 1906, construction of Ennis Dam blocked all upstream
movement of fishes, and apparently had a large negative effect on
Arctic grayling. Vincent (1962) noted that ``early settlers reported
scooping up boxes full of grayling at the base of Ennis Dam the year
after it was constructed'' (p. 128), and that the species apparently
became quite rare by the late 1930s (Vincent 1962, p. 85).
The current distribution of Arctic grayling in the Madison River is
primarily restricted to the Ennis Reservoir and upstream into the river
approximately 6.5 km (approximately 4 mi) to the Valley Garden Fishing
Access Site (Byorth and Shepard 1990, p. 21). Arctic grayling are
occasionally encountered in the Madison River downstream and upstream
from Ennis Reservoir (Byorth and Shepard 1990, p. 25; Clancey 2004, p.
22; 2008, p. 21). Arctic grayling migrate from the reservoir into the
river to spawn, then return to the reservoir (Byorth and Shepard 1990,
pp. 21-22; Rens and Magee 2007, pp. 20-21). The YOY Arctic grayling
spawned in the Madison River migrate downstream into Ennis Reservoir
about 1 month after emergence, but while they are in the river, they
are typically encountered in backwater or slackwater habitat (Jeanes
1996, pp. 31-34).
The MFWP has sporadically monitored Arctic grayling in the Madison
River near Ennis Reservoir since about 1990. Despite sparse data,
declining catches for both spawning adults and YOY indicate the
population is less abundant now compared to the early 1990s. The
highest numbers of YOY Arctic grayling were encountered in the early
1990s, and no more than two have been captured in any given year since
that time. Our interpretation of this information is that Arctic
grayling in the Madison River-Ennis Reservoir population have declined
during the past 20 years and are presently at very low abundance.
Abundance of the Madison River-Ennis Reservoir Arctic grayling has
been estimated twice. In 1990, the adult population was estimated to be
545, but the authors cautioned that the accuracy of the estimate was
questionable as it was based on recapturing only. From a sample of fish
collected mostly in 1996, the effective size of the population
(breeding adults) was estimated as 162 (Peterson and Ardren 2009, p.
1767). The average number of Arctic grayling captured per unit effort
(CPUE) declined by approximately a factor of 10 between the early 1990s
and recent samples (Clancey 1998, p. 10; Clancey 2007, p.16; Clancey
2008, pp. ii, 21, A2-2; Clancey and Lohrenz 2009, pp. 30, B2; Clancey
2010a, pers. comm.; Clancey 2010b, pers. comm.). Adult Arctic grayling
may currently exist at only 10 to 20 percent of the abundance observed
in the early 1990s. Based on the best available data, we conclude that
this Arctic grayling population has been in a decline during the past
20 years and may only consist of a few hundred adults.
Red Rocks Lakes
Arctic grayling are native to waters of the upper Beaverhead River
system, including the Red Rock River drainage. During the past 50 to
100 years, both the distribution and abundance of Arctic grayling in
the Centennial Valley, Beaverhead County, Montana (which contains the
Red Rock River), has severely declined (Vincent 1962, pp. 115-121;
Unthank 1989, pp. 13-17; Mogen 1996, pp. 2-5, 75-84). As of about 50
years ago, Arctic grayling spawned in at least 12 streams in the
Centennial Valley (Mogen 1996, p. 17), but they appear to have been
extirpated from all but 2 streams (Boltz 2006, p. 6). Presently, Arctic
grayling spawn in two locations within the Red Rock River drainage:
Odell Creek, a tributary to Lower Red Rock Lake; and Red Rock Creek,
the primary tributary to Upper Red Rock Lake (Mogen 1996, pp. 47-48;
Boltz 2006, p. 1). Lower and Upper Red Rock Lakes are connected by a
short segment of river, and both lakes are contained within the
boundaries of the Red Rock Lakes National Wildlife Refuge (NWR). The
upper lake appears to be the primary rearing and overwintering habitat
for Arctic grayling. Red Rock Creek is the only stream where Arctic
grayling spawn in appreciable numbers (Mogen 1996, pp. 45-48).
Collectively, we refer to this population as the Red Rocks Lakes Arctic
grayling, and characterize it as having the adfluvial ecotype.
Arctic grayling in the Red Rock Lakes have been monitored
intermittently since the 1970s. Most of that effort focused on Red Rock
Creek, but periodic sampling also occurred in Odell Creek. The MFWP and
the Service occasionally sampled for Arctic grayling in Odell Creek,
where grayling abundance declined over the past few decades. On
average, the minimum sizes of the spawning runs in Red Rock Creek since
1994 are about half of those recorded 4 decades ago (i.e., 623 vs. 308
per year) (data summarized from Mogen 1996, p. 70 and Boltz 2006, p.
7). The spawning runs into Red Rock Creek fluctuated during the 1990s
and early 2000s, but about 450 or fewer adult Arctic grayling have been
captured in 6 of 7 years in which weirs traps were operated.
Electrofishing surveys conducted in Red Rock Creek by MFWP seem to
corroborate a decline in the spawning population, as total catches
decreased even as sampling effort increased (Rens and Magee 2007, pp.
16-18).
Based on a sample of fish from Red Rock Creek in 2005, Peterson and
Ardren (2009, pp. 1761, 1767) estimated an effective size of 228, which
is interpreted as the number of breeding adults that produced the fish
sampled in 2005. The best available data indicate that the Red Rock
Lakes Arctic grayling population has declined over the past 2 decades.
Population viability analysis (PVA) of native Missouri River Arctic
grayling
To gauge the probability that the different native populations of
Arctic grayling in the upper Missouri River
[[Page 54725]]
basin will go extinct from unpredictable events in the foreseeable
future, we conducted a simple population viability analysis (PVA) (see
Dennis et al. (1991, entire) in Morris and Doak 2002, pp. 85-87 for
details on the PVA model and the software code to run the model). We
assumed that a population with 50 or fewer adults is likely influenced
by demographic stochasticity (chance variation in the fates of
individuals within a given year) and genetic stochasticity (random
changes in a population's genetic makeup), and would not be expected to
persist long as a viable population. For the different PVA scenarios,
we assume either the population has stabilized, or the estimated
decline will continue at a constant rate.
We considered the probability of extinction individually by
population, as populations appear to be reproductively isolated. The
relative risk of extinction in the foreseeable future (30 years based
on the observation that the variability in predictions for extinction
risk from the PVA model increases substantially after 30 years) varies
among the different populations, with the largest population,
Mussigbrod Lake, having a very low probability of extinction (less than
1 percent) in the foreseeable future, even given a population decline.
The other four populations have comparatively greater probabilities of
extinction in the foreseeable future, with all being roughly similar in
magnitude (13-55 percent across populations) when considering only
stochastic (random or chance) processes. The Madison River has the
greatest probability of extinction by stochastic processes (36-55
percent), followed by Big Hole (33-42 percent), Red Rocks (31-40
percent), and Miner (13-37 percent).
Overall, the PVA analyses indicate that four populations (Madison,
Big Hole, Red Rocks, and Miner) appear to be at risk from chance
environmental variation because of low population abundance. This is a
general conclusion, and the actual risk may vary substantially among
populations (USFWS unpublished data). For example, Arctic grayling in
the Big Hole River population spawn in different locations, which would
reduce the risk that an environmental catastrophe would simultaneously
kill all breeding adults, relative to a situation where adults appear
to be primarily in a single location or reach of river (e.g., Red Rocks
and Madison populations).
Arctic Grayling Conservation Efforts
Native Arctic Grayling Genetic Reserves and Translocation
Given concern over the status of native Arctic grayling, the
Montana Arctic Grayling Recovery Program (AGRP) was formed in 1987, to
address conservation concerns for primarily the fluvial ecotype in Big
Hole River, and to a lesser extent the native adflvuial population in
Red Rock Lakes (Memorandum of Understanding (MOU) 2007, p. 2). The AGW
was established as an ad hoc technical workgroup of the AGRP. In 1995,
the AGW finalized a restoration plan that outlined an agenda of
restoration tasks and research, including management actions to secure
the Big Hole River population, brood stock development, and a program
to re-establish four additional fluvial populations (AGW 1995, pp. 7-
17).
Consequently, the State of Montana established genetic reserves of
Big Hole River grayling (Leary 1991, entire), and has used the progeny
from those reserves in efforts to re-establish additional fluvial
populations within the historical native range in the Missouri River
basin (Rens and Magee 2007, pp. 21-38). Currently, brood (genetic)
reserves of Big Hole River grayling are held in two closed-basin lakes
in south-central Montana (Rens and Magee 2007, p. 22). These fish are
manually spawned to provide gametes for translocation efforts in
Montana (Rens and Magee 2007, p. 22). Functionally, these brood
reserves are hatchery populations maintained in a natural setting, and
we do not consider them wild populations for the purposes of evaluating
the status of native Arctic grayling in the Missouri River basin.
However, they are important to recovery efforts.
For more than 13 years, MFWP has attempted to re-establish
populations of fluvial Arctic grayling in various locations in the
Missouri River basin, including the Ruby, Sun, Beaverhead, Missouri,
Madison, Gallatin, and Jefferson Rivers (Lamothe and Magee 2004a, pp.
2, 28). A self-sustaining population has not yet been established from
these reintroductions (Lamothe and Magee 2004a, p. 28; Rens and Magee
2007, pp. 35-36, 38). Recent efforts have focused more intensively on
the Ruby and Sun Rivers, and have used methods that should improve
reintroduction success (Rens and Magee 2007, pp. 24-36). Encouragingly,
natural reproduction by Arctic grayling in the Ruby River was confirmed
during fall 2009 (Magee 2010b, pp. 6-7, 22). Monitoring will continue
in subsequent years to determine whether the population has become a
stable and viable population, as defined by the guidance and
implementation documents of the translocation programs (AGW 1995, p. 1;
Memorandum of Agreement (MOA) 1996, p. 2). Consequently, we do not
consider the Ruby River to represent a self-sustaining population for
the purposes of evaluating the population status of Missouri River
grayling in this finding. Arctic grayling presumably from previous
translocations are occasionally encountered near translocation sites in
other waters (Rens and Magee 2007, pp. 35-38; MFWP, unpublished data).
There is no evidence that these individuals represent progeny from a
re-established population, so we cannot consider them elements of a
stable and viable population for the purposes of evaluating the
population status of Missouri River Arctic grayling in this finding.
Big Hole River Candidate Conservation Agreement with Assurances
On August 1, 2006, the Service issued ESA section 10(a)(1)(A)
enhancement of survival permit (TE-104415-0) to Montana Fish, Wildlife
and Parks (MFWP) to implement a Candidate Conservation Agreement with
Assurances for Arctic grayling in the upper Big Hole River (Big Hole
Grayling CCAA) (MFWP et al. 2006, entire). This permit is valid through
August 1, 2026. The goal of the Big Hole Grayling CCAA is to secure and
enhance a population of fluvial Arctic grayling within the upper
reaches of their historic range in the Big Hole River drainage by
working with non-Federal property owners to implement conservation
measures on their lands. The guidelines of this CCAA will be met by
implementing conservation measures that improve stream flows, protect
and restore riparian habitats, identify and reduce or eliminate
entrainment (inadvertent capture) of grayling in irrigation ditches,
and remove human-made barriers to grayling migration (MFWP et al. 2006,
p. 3). Currently, 32 landowners representing 64,822 ha (160,178 ac) in
the upper Big Hole River drainage are participating in the CCAA
(Lamothe 2009, p. 5). The MFWP leads the Big Hole Grayling CCAA
implementation effort, and is supported by Montana Department of
Natural Resources and Conservation (MDNRC), USDA Natural Resources
Conservation Service (NRCS), and the Service. Other groups helping
implement the CCAA include the Big Hole Watershed Committee, the Big
Hole River Foundation, Montana Trout Unlimited, the Western Water
Project (affiliated with Trout Unlimited), and
[[Page 54726]]
The Nature Conservancy (Lamothe 2008, p. 23). Detailed information on
conservation actions and restoration projects implemented under the
plan are available in various reports (AGW 2010, p. 4; Everett 2010,
entire; Lamothe et al. 2007, pp. 6-35; Lamothe 2008, pp. 7-21; Lamothe
2009, entire; Lamothe 2010, entire; Magee 2010b, entire; Roberts 2010,
entire).
Biological Effectiveness of the Ongoing Conservation Programs
The current and anticipated effects of the aforementioned
conservation programs on the biological status and threats to Arctic
grayling of the upper Missouri River are discussed elsewhere in the
document (see Summary of Information Pertaining to the Five Factors and
Finding sections, below). We continue to encourage and promote
collaborative efforts to secure existing populations, and to increase
the distribution of the Arctic grayling within its historical range in
the upper Missouri River basin.
Summary of Information Pertaining to the Five Factors
Section 4 of the ESA (16 U.S.C. 1533) and implementing regulations
(50 CFR 424) set forth procedures for adding species to the Federal
Lists of Endangered and Threatened Wildlife and Plants. Under section
4(a)(1) of the ESA, a species may be determined to be endangered or
threatened based on any of the following five factors: (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,
information pertaining to the Missouri River DPS of Arctic grayling in
relation to the five factors provided in section 4(a)(1) of the Act is
discussed below.
In considering what factors might constitute threats to a species,
we must look beyond the exposure of the species to a factor to evaluate
whether the species may respond to the factor in a way that causes
actual impacts to the species. If there is exposure to a factor and the
species responds negatively, the factor may be a threat and we attempt
to determine how significant a threat it is. The threat is significant
if it drives, or contributes to, the risk of extinction of the species
such that the species warrants listing as endangered or threatened as
those terms are defined in the Act.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
Curtailment of Range and Distribution
The number of river kilometers (miles) occupied by the fluvial
ecotype of Arctic grayling in the Missouri River has been reduced by
approximately 95 percent during the past 100 to 150 years (Kaya 1992,
p. 51). The fluvial life history is only expressed in the population
residing in the Big Hole River; the remnant population in the Madison
River near Ennis Reservoir has apparently diverged toward an adfluvial
life history. Arctic grayling distribution within the Centennial Valley
in the upper Beaverhead River also has been severely curtailed during
the last 50 to 100 years, such that the only remaining example of the
species in that drainage is an adfluvial population associated with the
Red Rock Lakes. Indigenous populations in the Big Hole River, Madison
River, and Red Rock Lakes all exist at reduced densities on both
contemporary and historical timescales. The Miner Lakes and Mussigbrod
Lake populations appear to have been reproductively isolated for
hundreds of years (USFWS, unpublished data), so a restricted
distribution may represent the natural historical condition for these
populations. The curtailment of range and distribution is a current
threat, because the probability of extirpation of the DPS is related to
the number of populations and their resilience. Since the DPS currently
exists as a set of generally small, isolated populations that cannot
naturally re-found or `rescue' another population. Thus, the
curtailment of range and distribution will remain a threat in the
foreseeable future, absent the reestablishment of additional
populations within the DPS' historical range. Reintroduction attempted
under the auspices of the 1995 Restoration Plan (AGW 1995, entire) have
been underway since 1997, but have not yet resulted in re-establishment
of populations or the expansion of the DPS' current range.
Dams on Mainstem Rivers
The majority of the historical range of the Upper Missouri River
DPS of Arctic grayling has been altered by the construction of dams and
reservoirs that created barriers obstructing migrations to spawning,
wintering, or feeding areas; inundated grayling habitat; and impacted
the historical hydrology of river systems (Kaya 1990, pp. 51-52; Kaya
1992, p. 57). The construction of large dams on mainstem river habitats
throughout the upper Missouri River system fragmented river corridors
necessary for the expression of migratory life histories. Construction
of dams that obstructed fish passage on the mainstem Missouri River
(Hauser, Holter, Canyon Ferry, and Toston), Madison River (Madison-
Ennis, Hebgen), Beaverhead River and its tributary Red Rock River
(Clark Canyon, Lima), Ruby River (Ruby), and Sun River (Gibson) all
contributed to the rangewide decline of this DPS (Vincent 1962, pp.
127-128; Kaya 1992, p. 57; see Figure 2).
Dams also may continue to impact the extant population in the
Madison River. The Madison Dam (also known as Ennis Dam), as with the
aforementioned dams, is a migration barrier with no fish passage
facilities. Anglers have reported encountering Arctic grayling in pools
below the dam, implying that fish occasionally pass (downstream) over
or through the dam. These fish would be ``lost'' to the population
residing above the dam because they cannot return upstream, but have
apparently not established populations downstream. Operational
practices of the Madison Dam also have been shown to affect the
resident fishes. A population decline of Arctic grayling coincided with
a reservoir drawdown in winter 1982-1983 that was intended to reduce
the effects of aquatic vegetation on the hydroelectric operations at
the dam (Byorth and Shepard 1990, pp. 52-53). This drawdown likely
affected the forage base, rearing habitat, and spawning cycle of Arctic
grayling in the reservoir.
The presence of mainstem dams is a historical, current, and future
threat to the DPS. Lack of fish passage at these dams contributed to
the extirpation of Arctic grayling from some waters by blocking
migratory corridors (Vincent 1962, p. 128), curtailing access to
important spawning and rearing habitats, and impounding water over
former spawning locations (Vincent 1962, p. 128). These dams are an
impediment to fish migration and limit the ability of fish to disperse
between existing populations or recolonize habitat fragments, and will
continue to act in this manner for the foreseeable future. We believe
the presence of a mainstem dam is an immediate and imminent threat to
the Madison River population, as the remaining grayling habitat is
adjacent to Ennis Dam (see Figure 2). We not aware of any plans to
retrofit the Ennis Dam or any other mainstem dam to provide upstream
fish passage, so we expect the current situation to continue. The
Federal Energy Regulatory Commission (FERC) license for hydroelectric
generation at Ennis Dam will not expire until the year
[[Page 54727]]
2040 (FERC 2010, entire). The upper Missouri River basin dam having the
FERC license with the latest expiration date is Clark Canyon Dam, which
will not expire until 2059 (FERC 2010, entire). Thus, mainstem dams
will remain a threat in the foreseeable future, which is 30 to 50 years
based on the duration of existing FERC licenses in the upper basin.
Agriculture and Ranching
The predominant use of private lands in the upper Missouri River
basin is irrigated agriculture and ranching, and these activities had
and continue to have significant effects on aquatic habitats. In
general, these effects relate to changes in water availability and
alteration to the structure and function of aquatic habitats. The
specific activities and their impacts are discussed below.
Smaller Dams and Fish Passage Barriers
Smaller dams or diversions associated with irrigation structures
within specific watersheds continue to pose problems to Arctic grayling
migratory behavior, especially in the Big Hole River drainage. In the
Big Hole River, numerous diversion structures have been identified as
putative fish migration barriers (Petersen and Lamothe 2006, pp. 8, 12-
13, 29) that may limit the ability of Arctic grayling to migrate to
spawning, rearing, or sheltering habitats under certain conditions. The
Divide Dam on the Big Hole River near the town of Divide, Montana, has
existed for nearly 80 years and is believed to be at least a partial
barrier to upstream movement by fishes (Kaya 1992, p. 58). As with the
larger dams, these smaller fish passage barriers can reduce
reproduction (access to spawning habitat is blocked), reduce growth
(access to feeding habitat is blocked), and increase mortality (access
to refuge habitat is blocked). A number of planned or ongoing
conservation actions to address connectivity issues on the Big Hole
River and its tributaries may reduce the threat posed by movement
barriers for Arctic grayling in that habitat. The Divide Dam is being
replaced with a new structure that provides fish passage, and
construction began in July 2010 (Nicolai 2010, pers. comm.). At least
17 fish ladders have been installed at diversion structures in the Big
Hole River since 2006 as part of the Big Hole Grayling CCAA (AGW 2010,
p. 4), and a culvert barrier at a road crossing on Governor Creek
(headwaters of Big Hole River) was replaced with a bridge that is
expected to provide upstream passage for aquatic organisms under all
flow conditions (Everett 2010, pp. 2-6). Non-Federal landowners who
control approximately 50 to 70 percent of the points of irrigation
diversion in the upper Big Hole River are enrolled in the CCAA (Roberts
and Lamothe 2010, pers. comm.), so the threats posed by fish passage
barriers should be substantially reduced in the Big Hole River during
the next 10 to 20 years (foreseeable future) based on the minimum
duration of site-specific plans for landowners enrolled in the CCAA and
the duration of the ESA section 10(a)(1)(A) enhancement of survival
permit (TE 104415-0) associated with the CCAA (MFWP et al. 2006, p.
75).
Fish passage barriers also have been noted in the Red Rock Lakes
system (Unthank 1989, p. 9). Henshall (1907, p. 5) noted that spawning
Arctic grayling migrated from the Jefferson River system, through the
Beaverhead River and Red Rock River through the Red Rock Lakes and into
the upper drainage, and then returned downstream after spawning. The
construction of a water control structure (sill) at the outlet of Lower
Red Rock Lake in 1930 (and reconstructed in 1957 (USFWS 2009, p. 74))
created an upstream migration barrier that blocked these migrations
(Unthank 1989, p. 10; Gillin 2001, p. 4-4). This structure, along with
mainstem dams at Lima and Clark Canyon, extirpated spawning runs of
Arctic grayling that historically migrated through the Beaverhead and
Red Rock Rivers (see Figure 2; USFWS 2009, p. 72). All of these
structures preclude upstream movement by fishes, and continue to
prohibit immigration of Arctic grayling from the Big Hole River (see
Figure 2). Because recovery of Arctic grayling will necessitate
expansion into unoccupied habitat, and the Big Hole River includes some
of the best remaining habitat for the species, these dams constitute a
threat to Arctic grayling now and in the foreseeable future, which is
30 to 50 years based on the duration of existing FERC licenses in the
upper basin.
In Mussigbrod Lake, Arctic grayling occasionally pass downstream
over a diversion structure at the lake outlet, and become trapped in a
pool that is isolated because of stream dewatering (Magee and Olsen
2010, pers. comm.). However, the potential for mortality in these fish
is partially mitigated by MFWP, which periodically captures Arctic
grayling in this pool and returns them to the lake.
In the Red Rock Lakes system, the presence of fish passage barriers
represents a past and present threat. The magnitude of the threat may
be reduced in the next 15 years as a result of implementation of the
Red Rock Lakes NWR Comprehensive Conservation Plan (CCP) (USFWS 2009,
entire -- see Factor D discussion below), but we conclude that not all
barriers that potentially affect the population will addressed during
this time (e.g., Lower Red Rock Lake Water Control Structure) (USFWS
2009, p. 43). Thus, fish passage barriers will remain a threat to the
Red Rock Lakes grayling in the foreseeable future.
In the Big Hole River, fish passage barriers represent a past and
present threat. The magnitude of the threat in the Big Hole River
should decrease appreciably during the next 10 to 20 years, which
represents the foreseeable future in terms of the potential for the Big
Hole Grayling CCAA to address the threat. Additional projects, such as
the replacement of the Divide Dam, also should reduce the threat in the
foreseeable future.
Dewatering From Irrigation and Consequent Increased Water Temperatures
Demand for irrigation water in the semi-arid upper Missouri River
basin has dewatered many rivers formerly or currently occupied by
Arctic grayling. The primary effects of this dewatering are: 1)
Increased water temperatures, and 2) reduced habitat capacity. In
ectothermic species like salmonid fishes, water temperature sets basic
constraints on species distribution and physiological performance, such
as activity and growth (Coutant 1999, pp. 32-52). Increased water
temperatures can reduce the growth and survival of Arctic grayling
(physiological stressor). Reduced habitat capacity can concentrate
fishes and thereby increase competition and predation (ecological
stressor).
In the Big Hole River system, surface-water (flood) irrigation has
substantially altered the natural hydrologic function of the river and
has led to acute and chronic stream dewatering (Shepard and Oswald
1989, p. 29; Byorth 1993, p. 14; 1995, pp. 8-10; Magee et al. 2005, pp.
13-15). Most of the Big Hole River mainstem exceeds water quality
standards under the Clean Water Act (33. U.S.C. 1251 et seq.; see
discussion under Factor D, below) because of high summer water
temperatures (Flynn et al. 2008, p. 2). Stream water temperature is
affected by flow volume, stream morphology, and riparian shading, along
with other factors, but an inverse relationship between flow volume and
water temperature is apparent in the Big Hole River (Flynn et al. 2008,
pp. 18-19). Summer water temperatures exceeding 21 [deg]C (70 [deg]F)
are
[[Page 54728]]
considered to be physiologically stressful for cold-water fish species,
such as Arctic grayling (Hubert et al. 1985, pp. 7, 9). Summer water
temperatures consistently exceed 21 [deg]C (70 [deg]F) in the mainstem
of Big Hole River (Magee and Lamothe 2003, pp. 13-14; Magee et al.
2005, p. 15; Rens and Magee 2007, p. 11). Recently, summer water
temperatures have consistently exceeded the upper incipient lethal
temperature (UILT) for Arctic grayling (e.g., 25 [deg]C or 77 [deg]F)
(Lohr et al. 1996) at a number of monitoring stations throughout the
Big Hole River (Magee and Lamothe 2003, pp. 13-14; Magee et al. 2005,
p. 15; Rens and Magee 2007, p. 11). The UILT is the temperature that is
survivable indefinitely (for periods longer than 1 week) by 50 percent
of the ``test population'' in an experimental setting. Fish kills are a
clear result of high water temperature and have been documented in the
Big Hole River (Lohr et al. 1996, p. 934). Consequently, water
temperatures that are high enough to cause mortality of fish in the Big
Hole River represent a clear threat to Arctic grayling because of the
potential to directly and quickly reduce the size of the population.
Water temperatures below that which can lead to instant mortality
also can affect individual fish. At water temperatures between 21
[deg]C (70 [deg]F) and 25 [deg]C (77 [deg]F), Arctic grayling can
survive but experience chronic stress that can impair feeding and
growth, reduce physiological performance, and ultimately reduce
survival and reproduction. As described above, the Big Hole River
periodically experiences summer water temperatures high enough to cause
morality and chronic stress to Arctic grayling. Increased water
temperature also appears to be a threat to Arctic grayling in the
Madison River and Red Rock watershed. Mean and maximum summer water
temperatures can exceed 21 [deg]C (70 [deg]F) in the Madison River
below Ennis Reservoir (U.S. Geological Survey (USGS) 2010), and have
exceeded 22 [deg]C (72 [deg]F) in the reservoir, and 24 [deg]C (75
[deg]F) in the reservoir inlet (Clancey and Lohrenz 2005, p. 34).
Similar or higher temperatures have been noted at these same locations
in recent years (Clancey 2002, p. 17; 2003, p. 25; 2004, pp. 29-30).
Surface water temperatures in Upper Red Rock Lake as high as 24 [deg]C
(75 [deg]F) have been recorded (Gillin 2001, p. 4-6), and presence of
Arctic grayling in the lower 100 m (328 ft) of East Shambow Creek in
1994 was attributed to fish seeking refuge from high water temperatures
in the lake (Mogen 1996, p. 44). Mean summer water temperatures in Red
Rock Creek can occasionally exceed 20[deg]C or 68[deg]F during drought
conditions (Mogen 1996, pp. 19, 45). Arctic grayling can survive but
experience chronic stress that can impair feeding and growth, reduce
physiological performance, and ultimately reduce survival and
reproduction.
Experimental data specifically linking hydrologic alteration and
dewatering to individual and population-level effects for Arctic
grayling is generally lacking (Kaya 1992, p. 54), but we can infer
effects from observations that the abundance and distribution of Arctic
grayling has declined concurrent with reduced streamflows (MFWP et al.
2006, pp. 39-40) and increased water temperatures associated with low
streamflows.
In the Big Hole River system, early-season (April through May)
irrigation withdrawals may dewater grayling spawning sites (Byorth
1993, p. 22), preventing spawning or causing egg mortality; can prevent
juvenile grayling from accessing cover in the vegetation along the
shoreline; and may reduce connectivity between necessary spawning,
rearing, and refuge habitats. Severe dewatering reduces habitat volume
and may concentrate fish, increasing the probability of competition and
predation among and between species. Nonnative trout species presently
dominate the salmonid community in the Big Hole River, so dewatering
would tend to concentrate Arctic grayling in habitats where
interactions with these nonnative trout would be likely.
Especially in the Big Hole River, dewatering from irrigation
represents a past and present threat to Arctic grayling. Thermal
loading has apparently been a more frequent occurrence in the Big Hole
River than in other locations containing native Arctic grayling (e.g.,
Red Rock Creek and Madison River-Ennis Reservoir). Implementation of
the Big Hole Grayling CCAA during the next 20 years, which requires
conservation measures to increase stream flows and restore riparian
habitats (MFWP 2006, pp. 22-48), should significantly reduce the threat
of thermal loading for Big Hole River grayling in the foreseeable
future. While we expect agricultural and ranching-related use of water
to continue, we expect that the threat will be reduced, but not
eliminated, in the foreseeable future in the Big Hole River as a
consequence of the CCAA. The ability of the Big Hole Grayling CCAA to
augment streamflows should be substantial, as non-Federal landowners
who control approximately 50 to 70 percent of the points of irrigation
diversion in the upper Big Hole River are enrolled in the CCAA (Roberts
and Lamothe 2010, pers. comm.). However, the Big Hole River constitutes
one population in the DPS and high water temperatures are likely to
continue to affect grayling in the Madison River and Red Rock Lakes.
Thus, stream dewatering and high water temperatures are expected to
remain a threat to the DPS in the foreseeable future.
Entrainment
Entrainment can permanently remove individuals from the natural
population and strand them in a habitat that lacks the required
characteristics for reproduction and survival. Irrigation ditches may
dry completely when irrigation headgates are closed, resulting in
mortality of entrained grayling. Entrainment of individual Arctic
grayling in irrigation ditches occurs in the Big Hole River (Skarr
1989, p. 19; Streu 1990, pp. 24-25; MFWP et al. 2006, p. 49; Lamothe
2008, p. 22). Over 1,000 unscreened diversion structures occur in the
upper Big Hole River watershed, and more than 300 of these are located
in or near occupied grayling habitat (MFWP et al. 2006, pp. 48-49).
The magnitude of entrainment at unscreened diversions can depend on
a variety of physical and biological factors, including the volume of
water diverted (Kennedy 2009, p. iv, 36-38; but see Post et al. 2007,
p. 885), species-specific differences in the timing of migratory
behavior relative to when water is being diverted (Carlson and Rahel
2007, pp. 1340-1341), and differences in vulnerability among body size
or life-stage (Gale 2005, pp. 30-47; Post et al. 2006, p. 975; Carlson
and Rahel 2007 pp. 1340-1341). Studies of other salmonid species in a
river basin in southwestern Wyoming determined that ditches typically
entrain a small proportion (less than 4 percent) of the total estimated
trout in the basin (Carlson and Rahel 2007, p. 1335) and that this
represented a very small percentage of the total mortality for those
populations (Post et al. 2006, pp. 875, 884; Carlson and Rahel 2007,
pp. 1335, 1339). Whether or not this amount of mortality can cause
population instability is unclear (Post et al. 2006, p. 886; Carlson
and Rahel 2007, pp. 1340-1341). However, in some cases, even small
vital rate changes in a trout population can theoretically cause
population declines (Hilderbrand 2003, pp. 260-261).
The overall magnitude and population-level effect of entrainment on
Arctic grayling in the Big Hole River
[[Page 54729]]
is unknown but possibly significant given the large number of
unscreened surface-water diversions in the system and the large volumes
of water diverted for irrigation. Given the low abundance of the
species, even a small amount of entrainment may be biologically
significant and is unlikely to be offset by compensatory effects (i.e.,
higher survival in Arctic grayling that are not entrained).
Entrainment also may be a problem for Arctic grayling at some
locations within the Red Rock Lakes system (Unthank 1989, p. 10; Gillin
2001, pp. 2-4, 3-18, 3-25), particularly outside of the Red Rock Lakes
NWR (Boltz 2010, pers. comm.).
Entrainment has been a past threat to Arctic grayling in the Big
Hole River and the Red Rock Lakes system. It remains a current threat
as most, if not all, irrigation diversions located in occupied habitat
do not have any devices to exclude fish (i.e., fish screens).
Entrainment will remain a threat in the foreseeable future unless
diversion structures are modified to exclude fish. The Big Hole
Grayling CCAA has provisions to reduce entrainment at diversions
operated by enrolled landowners (MFWP et al. 2006, pp. 50-52). Non-
Federal landowners enrolled in the CCAA control approximately 50 to 70
percent of the points of irrigation diversion in the upper Big Hole
River (Roberts and Lamothe 2010, pers. comm.), so the threat of
entrainment in the Big Hole River should be significantly reduced in
the foreseeable future. We consider the foreseeable future to represent
approximately 20 years based on the duration of the Big Hole Grayling
CCAA. Under the auspices of the Red Rock Lakes NWR CCP, a fish screen
is planned to be installed on at least one diversion on the Red Rock
Creek (USFWS 2009, p. 72), which is the primary spawning tributary for
Arctic grayling in the Red Rock Lakes system. Overall, we anticipate it
may take years to design and install fish screens on all the diversions
that can entrain grayling in the Big Hole River and Red Rock Lakes
systems; thus we conclude that entrainment remains a current threat
that will continue to exist, but will decline in magnitude during the
foreseeable future (next 10 to 20 years) because of implementation of
the CCAA and CCP.
Degradation of Riparian Habitat
Riparian corridors are important for maintaining habitat for Arctic
grayling in the upper Missouri River basin, and in general are critical
for the ecological function of aquatic systems (Gregory et al. 1991,
entire). These riparian zones are important for Arctic grayling because
of their effect on water quality and role in creating and maintaining
physical habitat features (pools) used by the species.
Removal of willows and riparian clearing concurrent with livestock
and water management along the Big Hole River has apparently
accelerated in recent decades, and, in conjunction with streamside
cattle grazing, has led to localized bank erosion, channel instability,
and channel widening (Confluence Consulting et al. 2003, pp. 24-26;
Petersen and Lamothe 2006, pp. 16-17; Bureau of Land Management (BLM)
2009a, pp. 14-21). Arctic grayling abundance in the upper Big Hole
River is positively related to the presence of overhanging vegetation,
primarily willows, which are associated with pool habitat (Lamothe and
Magee 2004b, pp. 21-22). Degradation of riparian habitat in the upper
Big Hole River has led to a shift in channel form (from multiple
threads to a single wide channel), increased erosion rates, reduced
cover, increased water temperatures, and reduced recruitment of large
wood into the active stream channel (Confluence Consulting et al. 2003,
pp. 24-26). All of these combine to reduce the suitability of the
habitat for species like Arctic grayling, and likely reduce grayling
growth, survival, and reproduction.
Livestock grazing both within the Red Rock Lakes NWR and on
adjacent private lands has negatively affected the condition of
riparian habitats on tributaries to the Red Rock Lakes (Mogen 1996, pp.
75-77; Gillin 2001, pp. 3-12, 3-14). In general, degraded riparian
habitat limits the creation and maintenance of aquatic habitats,
especially pools, that are preferred habitats for adult Arctic grayling
(Lamothe and Magee 2004b, pp. 21-22; Hughes 1992, entire). Loss of
pools likely reduces growth and survival of adult grayling. Loss of
riparian vegetation increases bank erosion, which can lead to siltation
of spawning gravels, which may in turn harm grayling by reducing the
extent of suitable spawning habitat and reducing survival of Arctic
grayling embryos already present in the stream gravels. The condition
of riparian habitats upstream from the Upper and Lower Red Rock Lakes
may have improved during the 1990s (Mogen 1996, p. 77), and ongoing
efforts to improve grazing management and restore riparian habitats are
ongoing both inside the Red Rock Lakes NWR (USFWS 2009, pp. 67, 75) and
upstream (AGW 2010, p. 7; Korb 2010, pers. comm.). However, the
existing condition of riparian habitats continues to constitute a
threat to Arctic grayling because the loss of pool habitat and the
deposition of fine sediments may take some time to be reversed after
the recovery of riparian vegetation.
Much of the degradation of riparian habitats in the Big Hole River
and Red Rock Lakes systems has occurred within the past 50 to 100
years, but the influence of these past actions continues to affect the
structure and function of aquatic habitats in these systems. Thus,
while the actual loss of riparian vegetation has presumably slowed
during the past 10 years, the effect of reduced riparian vegetation
continues to promote channel widening and sedimentation, and limits the
creation and maintenance of pool habitats. Thus, degradation of
riparian habitats is a current threat. Degradation of riparian habitats
will remain a threat in the foreseeable future until riparian
vegetation recovers naturally or through direct restoration, which may
occur during the next 20 years in the Big Hole River and portions of
the Red Rock Lakes system. Protection and direct restoration of
riparian habitats in the Big Hole River is occurring on a fairly large
scale under the provisions of the Big Hole Grayling CCAA (Lamothe et
al. 2007, pp. 13-26; Everett 2010, pp. 10-23), which should
substantially reduce threats from riparian habitat degradation on
private lands. Protection and restoration of riparian habitats
implemented under the Red Rock Lakes NWR's CCP (see discussion under
Factor D, below) should reduce threats from riparian habitat
degradation within the NWR's boundary, but similar actions need to be
taken on private lands adjacent to it (AGW 2010, p. 7; Korb 2010, pers.
comm.) to appreciably reduce these threats in the foreseeable future
and to expand the distribution of the species into formerly occupied
habitat within that drainage.
Sedimentation
Sedimentation has been proposed as a mechanism behind the decline
of Arctic grayling and its habitat in the Red Rock Lakes (Unthank 1989,
p. 10; Mogen 1996, p. 76). Livestock grazing upstream has led to
accelerated sediment transport in tributary streams, and deposition of
silt in both stream and lakes has likely led to loss of fish habitat by
filling in pools, covering spawning gravels, and reducing water depth
in Odell and Red Rock Creeks, where Arctic grayling are still believed
to spawn (MFWP 1981, p. 105; Mogen 1996, pp. 73-76).
Sedimentation in the Upper and Lower Red Rock Lakes is believed to
[[Page 54730]]
affect Arctic grayling by, in winter, reducing habitat volume (e.g.,
lakes freezing to the bottom) and promoting hypoxia (low oxygen), which
generally concentrates fish in specific locations which have suitable
depth, and thus increases the probability of competition and predation,
and, in summer, causing thermal loading stress (see Dewatering From
Irrigation and Consequent Increased Water Temperatures discussion,
above). Depths in the Red Rock Lakes have decreased significantly, with
a decline in maximum depth from 7.6 to 5.0 m (25 to 16.4 ft) to less
than 2 m (6.5 ft) noted in Upper Red Rock Lake over the past century
(Mogen 1996, p. 76). Lower Red Rock Lake has a maximum depth of
approximately 0.5 m (1.6 ft), and freezes within a few inches of the
bottom or freezes solid (Unthank 1989, p. 10). Consequently, the Lower
Red Rock Lake does not appear to provide suitable overwintering habitat
for adfluvial Arctic grayling and may be devoid of grayling except for
the few individuals that may migrate between Odell Creek and Upper Red
Rock Lake (Mogen, 1996, p. 47).
Dissolved oxygen levels in Upper Red Rock Lake during winter 1994-
1995 dropped as low as 0.5 to 0.15 parts per million (ppm; Gangloff
1996, pp. 41-42, 72), well below the critical minimum of 1.3 to 1.7 ppm
measured for adult Arctic grayling acclimated to water temperatures
less than or equal to 8 [deg]C (46 [deg]F) (Feldmeth and Eriksen 1978,
pp. 2042-2043). Thus, lethally low oxygen levels can occur during
winter in Upper Red Rock Lake, the primary overwintering area for
adfluvial Arctic grayling in the system. Winter kill of invertebrates
and fishes (e.g., suckers Catostomus spp.) has been recorded in Upper
Red Rock Lake (Gangloff 1996, pp. 39-40). Gangloff (1996, pp. 71, 79)
hypothesized that Arctic grayling in Upper Red Rock Lake exhibit
behavioral mechanisms or physiological adaptations that permit them to
survive otherwise lethally low oxygen levels. Oxygen conditions in the
lake during winter are related to the effect of snowpack and ice cover
on light penetration and the density of macrophytes (rooted aquatic
plants) during the preceding growing season (Gangloff 1996, pp. 72-74).
Arctic grayling under winter ice seek areas of higher oxygen
concentration (oxygen refugia) within the lake or near inlet streams of
Upper Red Rock Lake (Gangloff 1996, pp. 78-79). Consequently, we expect
factors leading to reduced lake depth due to upstream erosion and
sedimentation within the lake, or factors that promote eutrophication
due to macrophyte growth, to lead to more frequent winter hypoxia (low
dissolved oxygen concentrations detrimental to aquatic organsims) in
Upper Red Rock Lake, which is the most important overwintering habitat
for adfluvial Arctic grayling in the system.
The effects of erosion and sedimentation on spawning gravels and
reduction of habitat volume in Upper and Lower Red Rock Lakes are past
and current threats. Improved land use may be reducing the rates of
erosion in tributary streams (USFWS 2009, pp. 75-76; Korb 2010, pers.
comm.). However, sedimentation of the lakes will likely remain a threat
(because of reduced overwintering habitat, and high water temperatures
in summer) in the foreseeable future unless some event mobilizes these
sediments and transports them out of the lakes.
Protection and restoration of riparian habitats implemented under
the Red Rock Lakes NWR's CCP (see discussion under Factor D, below)
should reduce the magnitude of sedimentation within the NWR's
boundaries, but similar actions need to be taken on private lands
adjacent to it (AGW 2010, p. 7; Korb 2010, pers. comm.) to appreciably
reduce threats in the foreseeable future.
Summary of Factor A
Based on the best available information, we find that the
historical range of the Missouri River DPS of Arctic grayling has been
greatly reduced, and the remaining native populations continue to face
significant threats to their habitat. Large-scale habitat fragmentation
by dams was likely a significant historical factor causing the range-
wide decline of the DPS. The most significant current threats to the
DPS are from land and water use activities that have affected the
structure and function of aquatic systems, namely stream dewatering
from irrigation withdrawals, which reduces habitat volume and increases
summer water temperatures; potential loss of individuals in irrigation
ditches (entrainment); degraded riparian habitats promoting erosion,
sedimentation, increased water temperatures, and loss of pool habitat;
and migration barriers that restrict movement to and from spawning,
feeding, and sheltering habitats. These are among the significant
current threats to Arctic grayling populations in the Big Hole River,
Madison River-Ennis Reservoir, and Red Rock Lakes system. The habitat-
related threats to the Big Hole River population should be reduced in
the foreseeable future by implementation of the Big Hole Grayling CCAA,
a formalized conservation plan with 32 private landowners currently
enrolled. The Big Hole Grayling CCAA is expected to reduce threats from
dewatering, high water temperatures, barriers to fish passage, and
entrainment in irrigation ditches that are associated with land and
water use in the upper Big Hole River watershed during the foreseeable
future (next 20 years based on the duration of the CCAA). Non-Federal
landowners enrolled in the Big Hole Grayling CCAA control or own
approximately 50 to 70 percent of the points of irrigation diversion in
the upper Big Hole River, so these landowners should have the ability
to reduce habitat-related threats to Arctic grayling in the Big Hole
River by a corresponding amount. However, the present or threatened
destruction, modification, or curtailment of habitat remains a threat
to the DPS overall. This factor is expected to continue to be a threat
to the species in the foreseeable future because it is not
comprehensively addressed for other populations, especially those in
the Madison River and Red Rock Lakes systems where ongoing habitat-
related threats (described above) may be making unoccupied habitat
unsuitable for Arctic grayling, and may thus limit the recovery
potential of the DPS.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Arctic grayling of the upper Missouri River are handled for
recreational angling; and for scientific, population monitoring, and
restoration purposes.
Recreational Angling
Arctic grayling are highly susceptible to capture by angling (ASRD
2005, pp. 19-20), and intense angling pressure can reduce densities and
influence the demography of exploited populations (Northcote 1995, pp.
171-172). Overfishing likely contributed to the rangewide decline of
the DPS in the upper Missouri River system (Vincent 1962, pp. 49-52,
55; Kaya 1992, pp. 54-55). In 1994, concern over the effects of angling
on fluvial Arctic grayling led the State of Montana to implement catch-
and-release regulations for Arctic grayling captured in streams and
rivers within its native range, and those regulations remain in effect
(MFWP 2010, p. 52). Catch-and-release regulations for Arctic grayling
in the Big Hole River have been in effect since 1988 (Byorth 1993, p.
8). Catch-and-release regulations also are in effect for Ennis
Reservoir on the Madison River (MFWP 2010, p. 61). Angling is not
[[Page 54731]]
permitted in either of the Red Rock Lakes to protect breeding waterfowl
and trumpeter swans (Cygnus buccinator) (USFWS 2009, p. 147), and
catch-and-release regulations remain in effect for any Arctic grayling
captured in streams (e.g., Odell Creek or Red Rock Creek) in the Red
Rock Lakes system (MFWP 2010, p. 56).
In Miner and Mussigbrod Lakes, anglers can keep up to 5 Arctic
grayling per day and have up to 10 in possession, in accordance with
standard daily and possession limits for that angling management
district (MFWP 2010, p. 52). The current abundance of Arctic grayling
in Mussigbrod Lake (see Table 4 above) suggests that present angling
exploitation rates are not a threat to that population. Miner Lakes
grayling are less abundant compared to Mussigbrod Lake, but we are not
sure whether angling exploitation constitutes a threat to Miner Lakes
grayling.
Repeated catch-and-release angling may harm individual fish,
causing physiological stress and injury (i.e., hooking wounds). Catch-
and-release angling also can result in mortality at a rate dependent on
hooking location, hooking duration, fish size, water quality, and water
temperature (Faragher et al. 2004, entire; Bartholomew and Bohnsack
2005, p. 140). Repeated hooking (up to five times) of Arctic grayling
in Alaska did not result in significant additional mortality (rates 0
to 1.4 percent; Clark 1991, pp. 1, 25-26). In Michigan, hooking
mortality of Arctic grayling in lakes averaged 1.7 percent per capture
event based on 355 individuals captured with artificial flies and lures
(Nuhfer 1992, pp. 11, 29). Higher mortality rates (5 percent) have been
reported for Arctic grayling populations in the Great Slave Lake area,
Canada (Falk and Gillman 1975, cited in Casselman 2005, p. 23).
Comparatively high catch rates for Arctic grayling have been observed
in the Big Hole River, Montana (Byorth 1993, pp. 26-27, 36), and
average hooking wound rates ranged from 15 to 30 percent among study
sections (Byorth 1993, p. 28). However, overall hooking mortality from
single capture events was low (1.4 percent), which led Byorth to
conclude that the Big Hole River population was not limited by angling
(Byorth 1994b, entire).
Compared to the average catch-and-release mortality rates of 4.2 to
4.5 percent in salmonids as reported by Schill and Scarpella (1997, p.
873), and the mean and median catch-and-release mortality rates of 18
percent and 11 percent from a meta-analysis of 274 studies (Bartholomew
and Bohnsack 2005, pp. 136-137), the catch-and-release mortality rates
for Arctic grayling are comparatively low (Clark 1991, pp. 1, 25-26;
Nuhfer 1992, pp. 11, 29; Byorth 1994b, entire). We are uncertain
whether these lower observed rates reflect an innate resistance to
effects of catch-and-release angling in Arctic grayling or whether they
reflect differences among particular populations or study designs used
to estimate mortality. Even if catch-and-release angling mortality is
low (e.g., 1.4 percent as reported in Byorth 1994b, entire), the high
catchability of Arctic grayling (ASRD 2005, pp. 19-20) raises some
concern about the cumulative mortality of repeated catch-and-release
captures. For example, based on the Arctic grayling catch rates and
angler pressure reported by Byorth (1993, pp. 25-26) and the population
estimate for the Big Hole River reported in Byorth (1994a, p. ii), a
simple calculation suggests that age 1 and older grayling susceptible
to recreational angling may be captured and released 3 to 6 times per
year.
The MFWP closes recreational angling in specific reaches of the Big
Hole River when environmental conditions are considered stressful.
Specific streamflow and temperature thresholds initiate mandatory
closure of the fishery (Big Hole Watershed Committee 1997, entire).
Such closures have been implemented in recent years. For example, the
upper segment of the Big Hole River between Rock Creek Road to the
confluence of the North Fork Big Hole River has been closed to angling
at various times during 2004 (Magee et al. 2005, p. 7), 2005 (Magee et
al. 2006, p. 20), and 2006 (Rens and Magee 2007, p. 8).
In conclusion, angling harvest may have significantly reduced the
abundance and distribution of the upper Missouri River DPS of Arctic
grayling during the past 50 to 100 years, but current catch-and-release
fishing regulations (or angling closures) in most waters occupied by
extant populations have likely ameliorated the past threat of
overharvest. Although we have some concerns about the potential for
cumulative mortality caused by repeated catch-and-release of individual
Arctic grayling in the Big Hole River, we have no strong evidence
indicating that repeated capture of Arctic grayling under catch-and-
release regulations is currently limiting that population or the DPS.
Moreover, fishing is restricted in the Big Hole River, an important
recreational fishing destination in southwestern Montana, when
streamflow and temperature conditions are likely to increase stress to
captured grayling. Anglers can still capture and keep Arctic grayling
in Miner and Mussigbrod Lakes in accordance with State fishing
regulations, but we have no evidence that current levels of angling are
affecting these populations. We thus have no evidence that recreational
angling represents a current threat to the DPS. If we assume that
future fishing regulations would be at least as conservative as current
regulations, and that the current levels of angling pressure will
continue, then recreational angling does not represent a threat in the
foreseeable future.
Monitoring and Scientific Study
The MFWP consistently monitors the Arctic grayling population in
the Big Hole River and its tributaries, and to a lesser extent those
populations in the Madison River and Red Rock Lakes system (Rens and
Magee 20007, entire). Electrofishing (use of electrical current to
temporarily and non-lethally immobilize a fish for capture) is a
primary sampling method to monitor Arctic grayling in the Big Hole
River, Madison River, and Red Rock Lakes (Rens and Magee 2007, pp. 13,
17, 20). A number of studies have investigated the effects of
electrofishing on various life stages of Arctic grayling. Dwyer and
White (1997, p. 174) found that electrofishing reduced the growth of
juvenile Arctic grayling and concluded that long-term, sublethal
effects of electrofishing were possible. Hughes (1998, pp. 1072, 1074-
1075) found evidence that electrofishing and tagging affected the
growth rate and movement behavior of Arctic grayling in the Chena
River, Alaska. Roach (1999, p. 923) studied the effects of
electrofishing on fertilized Arctic grayling eggs and found that while
electrofishing could result in egg mortality, the population-level
effects of such mortality were not likely to be significant. Lamothe
and Magee (2003, pp. 16, 18-19) noted mortality of Arctic grayling in
the Big Hole River during a radio-telemetry study, and concluded that
handling stress or predation were possible causes of mortality.
Population monitoring activities in the Big Hole River are curtailed
when environmental conditions become unsuitable (Big Hole Watershed
Committee 1997, entire), and recent monitoring reports (Magee and
Lamothe 2004, entire; Magee et al. 2005, entire; Rens and Magee 2007,
entire) provide no evidence that electrofishing is harming the Arctic
grayling population in the Big Hole River.
A study in the Big Hole River is investigating the availability and
use of coldwater thermal refugia for Arctic grayling and other resident
fishes (Vatland and Gressewell 2009, entire).
[[Page 54732]]
The study uses fish tagged with passive integrated transponder (PIT)
tag technology to record movement past receiving antennas. The PIT tags
are small (23 mm or less than 1 in. long) and implanted into the body
cavity of the fish during a quick surgical procedure. During 2007-2008,
a total of 81 Arctic grayling from the Big Hole River and its
tributaries were implanted with these PIT tags (Vatland and Gressewell
2009, p. 12). A short-term study on the potential effects of PIT tag
implantation on Arctic grayling found 100 percent retention of tags and
100 percent survival of tagged individuals during a 4-day trial
(Montana State University 2008, p. 7). Based on the results of the
controlled trials, we have no evidence to indicate that PIT tagging the
wild Arctic grayling in the Big Hole River constitutes a significant
threat to the population.
Traps, electrofishing, and radio telemetry have been used to
monitor and study Arctic graying in the Red Rock Lakes system (Gangloff
1996, pp. 13-14; Mogen 1996, pp. 10-13, 15; Kaeding and Boltz 1999, p.
4; Rens and Magee 2007, p. 17); however, there is no data to indicate
these monitoring activities reduce the growth and survival of
individual Arctic grayling or otherwise constitute a current or future
threat to the population.
The Arctic grayling population in the Madison River-Ennis Reservoir
is not monitored as intensively as the Big Hole River population (Rens
and Magee 2007, pp. 20-21). When electrofishing surveys targeting
Arctic grayling in the Madison River do occur, they are conducted
during the spawning run for that population (Clancey 1996, p. 6).
Capture and handling during spawning migrations or during actual
spawning could affect the reproductive success of individual Arctic
grayling. However, under recent monitoring frequencies, any population-
level effect of these activities is likely negligible, and we have no
data to indicate these monitoring activities reduce the growth and
survival of individual Arctic grayling or otherwise constitute a
current or future threat to the Madison River population.
The Miner Lakes and Mussigbrod Lake populations of Arctic grayling
are infrequently monitored (Olsen 2010, pers. comm.). Since monitoring
of these populations has been minimal, we do not believe that
monitoring or scientific study constitutes a current or foreseeable
threat to these particular populations.
The intensity of monitoring and scientific investigation varies
among the different populations in the DPS, but we have no evidence
suggesting that monitoring or scientific study has influenced the
decline of Arctic grayling in the Missouri River basin. We also have no
evidence indicating these activities constitute a current threat to the
DPS that would result in measurable, population-level effects. We
expect similar levels of population monitoring and scientific study in
the future, and we have no basis to conclude that these activities
represent a threat in the foreseeable future.
Reintroduction Efforts
Attempts to restore or re-establish native populations of both
fluvial and adfluvial Arctic grayling may result in the mortality of
embryos and young fish. The MFWP attempted to restore fluvial Arctic
graying to historic waters in the upper Missouri River using a
combination of stocking and embryo incubating devices (remote site
incubators) placed in target streams (Rens and Magee 2007, pp. 24-38).
Currently, gametes (eggs and sperm) used to re-establish the fluvial
ecotype come from captive brood reserves of Big Hole River grayling
maintained in Axolotl and Green Hollow II Lakes (Rens and Magee 2007,
pp. 22-24). Removal of gametes from the wild Big Hole River population
was necessary to establish this brood reserve (Leary 1991, entire). The
previous removal of gametes for conservation purposes may have reduced
temporarily the abundance of the wild population if the population was
unable to compensate for this effective mortality by increased survival
of remaining individuals. However, the establishment of a brood reserve
provides a conservation benefit from the standpoint that gametes from
the reserve can be harvested to use for translocation efforts to
benefit the species. Unfortunately, these translocations have not yet
resulted in establishment of any fluvial populations. Ultimately, we do
not have any data to indicate that past gamete collection from the Big
Hole River population harmed the wild population. Consequently, we have
no basis to conclude that gamete collection from the wild Big Hole
River Arctic grayling population constitutes a current or future threat
to the population.
Efforts to re-establish native, genetically pure populations of
adfluvial Arctic grayling in the Red Rock Lakes system and to maintain
a brood reserve for that population have resulted in the direct
collection of eggs from Arctic grayling spawning runs in Red Rock
Creek. During 2000-2002, an estimated 315,000 Arctic grayling eggs were
collected from females captured in Red Rock Creek (Boltz and Kaeding
2002, pp. v, 8). The Service placed over 180,000 of these eggs in
remote site incubators in streams within the Red Rock Lakes NWR that
historically supported Arctic grayling spawning runs (Boltz and Kaeding
2002, pp. v, 10). Despite preliminary observations of grayling spawning
in historically occupied waters within the Red Rock Lakes NWR following
the use of remote site incubators (Kaeding and Boltz 2004, pp. 1036),
spawning runs at these locations have apparently not become established
(Boltz 2006, pers. comm.). Attempts to establish a brood reserve of
adfluvial Arctic grayling within the NWR's boundaries (MacDonald Pond)
were not successful (Boltz and Kaeding 2002, pp. 21-22). Red Rock Lakes
NWR plans to re-establish Arctic grayling in Elk Springs and Picnic
Creeks and establish a brood stock in Widgeon Pond as part of its CCP
(USFWS 2009, pp. 72, 75). The MFWP and the Service are currently
collaborating on an effort to re-establish an Arctic grayling spawning
run in Elk Springs Creek and to establish a genetically pure brood
reserve of Red Rock Lakes grayling in Elk Lake as no such population
exists for use in conservation and recovery (Jordan 2010, pers. comm.).
These actions will require the collection of gametes (approximately
360,000 eggs) from Arctic grayling captured in Red Rock Creek (Jordan
2010, pers. comm.). Approximately 10 percent of these eggs will be
returned to Red Rock Creek and incubated in that stream (using a remote
site incubation method that results in high survivorship of embryos)
(Kaeding and Boltz 2004, entire) to mitigate for collection of gametes
from the wild spawning population (Jordan 2010, pers. comm.). We
presume these ongoing actions may necessitate the collection of gametes
from wild Arctic grayling in Red Rock Creek, so the potential effect of
such collections on the extant wild population should be evaluated and
mitigation for the use of these gametes (e.g., using remote site
incubators at the collection source or another method) should continue.
Overall, we have no evidence to indicate that collection of gametes
from the wild populations in the Big Hole River and Red Rock Lakes
systems have contributed to population-level declines in those
populations, or that the previous collections represent
overexploitation. Future plans to collect gametes from Arctic grayling
in the Big Hole River and Red Rock Lakes should be carefully evaluated
in light of the status of those populations at the anticipated time of
the collections. We
[[Page 54733]]
encourage the agencies involved to coordinate their efforts and develop
a strategy for broodstock development and recovery efforts that
minimizes any potential impacts to wild native populations. However, at
present, we do not have any data indicating collection of gametes for
conservation purposes represents a current threat to the Big Hole River
and Red Rock Lakes populations. We have no evidence to indicate that
gamete collection will increase in the future, so we have no basis to
conclude that this represents a threat in the foreseeable future.
Summary of Factor B
Based on the information available at this time, we conclude that
overexploitation by angling may have contributed to the historical
decline of the upper Missouri River DPS of Arctic grayling, but we have
no evidence to indicate that current levels of recreational angling,
population monitoring, scientific study, or conservation actions
constitute overexploitation; therefore, we do not consider them a
threat. We expect similar levels of these activities to continue in the
future, and we do not believe they represent a threat in the
foreseeable future.
C. Disease or Predation
Disease
Arctic grayling are resistant to whirling disease, which is
responsible for population-level declines of other stream salmonids
(Hedrick et al. 1999, pp. 330, 333). However, Arctic grayling are
susceptible to bacterial kidney disease (BKD). Some wild populations in
pristine habitats test positive for BKD (Meyers et al. 1993, pp. 186-
187), but clinical effects of the disease are more likely to be evident
in captive populations (Meyers et al. 1993, entire; Peterson 1997,
entire). To preclude transmission of BKD between grayling during brood
reserve, hatchery, and wild grayling translocation efforts, MFWP tests
kidney tissue and ovarian fluid for the causative agent for BKD as well
as other pathogens in brood populations (Rens and Magee 2007, pp. 22-
24).
Information on the prevalence of the BKD or other diseases in
native Arctic grayling populations in Montana is generally lacking. One
reason is that some disease assays are invasive or require the
sacrifice of individual fish (e.g., removal of kidney tissue to test
for BKD pathogen.) Therefore, such testing is typically avoided in
native populations of Missouri River Arctic grayling that are low in
abundance. Arctic grayling in captive brood reserves (e.g., Axolotl
Lake, Green Hollow Lake) and introduced populations (e.g., Sunnyslope
Canal, Rogers Lake) have all tested negative for infectious
hematopoietic necrosis virus (IHNV), infectious pancreatic necrosis
virus (IPNV), Myxobolus cerebralis (the pathogen that causes whirling
disease), Renibacterium salmoninarum (the pathogen that causes BKD),
and Aeromonas salmonicida (the pathogen that causes furunculosis)
(USFWS 2010a). Consequently, we have no evidence at this time that
disease threatens native Arctic grayling of the upper Missouri River.
We have no basis to conclude that disease will become a future threat,
so we conclude that disease does not constitute a threat in the
foreseeable future.
Predation By and Competition With Nonnative Trout
Brook trout (Salvelinus fontinalis), brown trout (Salmo trutta),
and rainbow trout have been introduced across the United States to
provide recreational fishing opportunities, and are now widely
distributed and abundant in the western United States, including the
upper Missouri River system (Schade and Bonar 2005, p. 1386). One or
more of these nonnative trout species co-occur with every native Arctic
grayling population in the basin. Ecological interactions (predation
and competition) with the brook trout, brown trout, and rainbow trout
are among the long-standing hypotheses to explain decline of Arctic
grayling in the upper Missouri River system and the extirpation of
populations from specific waters (Nelson 1954, p. 327; Vincent 1962,
pp. 81-96; Kaya 1992, pp. 55-56).
The potential for interspecific interactions should be greatest
among species with similar life histories and ecologies that did not
co-evolve (Fausch and White 1986, p. 364). Arctic grayling in the
Missouri River basin have similar ecologies to brook trout, rainbow
trout, and brown trout, yet they do not share a recent evolutionary
history. The evidence for predation and competition by nonnative trout
on Arctic grayling in the upper Missouri River basin is largely
circumstantial, and inferred from the reduced abundance and
distribution of Arctic grayling following encroachment by nonnative
trout (Kaya 1990, pp. 52-54; Kaya 1992, p. 56; Magee and Byorth 1995,
p. 54), as well as the difficulty in establishing Arctic grayling
populations in waters already occupied by nonnative trout, especially
brown trout (Kaya 2000, pp. 14-15). Presumably, competition with
ecologically-similar species for food, shelter, and spawning locations
can lead to reduced growth, reproduction, and survival of Arctic
grayling (i.e., where they are outcompeted by nonnative trout). The
strength of competition is very difficult to measure in wild trout
populations (Fausch 1988, pp. 2238, 2243; 1998, pp. 220, 227). Few
studies have evaluated competition between Arctic grayling and these
nonnative species. Brook trout do not appear to negatively affect
habitat use or growth of juvenile, hatchery-reared Arctic grayling
(Byorth and Magee 1998, p. 921), but further studies are necessary to
determine whether competition or predation occur at other life stages
or with brown or rainbow trout (Byorth and Magee 1998, p. 929).
Predation represents direct mortality that can limit populations,
and YOY Arctic grayling may be particularly susceptible to predation by
other fishes because they are smaller and weaker swimmers than trout
fry (Kaya 1990, pp. 52-53).
The incidence of competition and predation between nonnative trout
and Arctic grayling likely depends on environmental context (e.g.,
habitat type and quality, environmental conditions such as temperature,
and so forth). Nonetheless, it is widely accepted that biotic
interactions with nonnative species are to some extent responsible for
the decline of many native fishes in the western United States (Dunham
et al. 2002, pp. 373-374 and references therein; Fausch et al. 2006,
pp. 9-11 and references therein).
In the Big Hole River, brook trout, rainbow trout, and brown trout
have been established for some time (Kaya 1992, pp. 50-51) and are much
more abundant than Arctic grayling (Rens and Magee 2007, p. 42). In
general, brook trout is the most abundant nonnative trout species in
the Big Hole River upstream from Wisdom, Montana (Rens and Magee 2007,
pp. 7, 42; Lamothe et al. 2007, pp. 35-38), whereas rainbow trout and
brown trout are comparatively more abundant in the reaches immediately
above and downstream from the Divide Dam (Kaya 1992, p. 56; Oswald
2005b, pp. 22-29; Lamothe et al. 2007, pp. 35-38; Rens and Magee 2007,
p. 10). Rainbow trout are apparently more abundant than brown trout
above the Divide Dam (Olsen 2010, pers. comm.), but brown trout are
more abundant than rainbow trout below the dam (Oswald 2005b, pp. 22-
33). Recent observations of increased brown trout abundance and
distribution in the upper Big Hole River indicate that the species may
be encroaching further upstream (AGW 2008, p. 1). Overall, at least one
nonnative species occurs in the
[[Page 54734]]
mainstem Big Hole River and tributary locations where Arctic grayling
are present (Lamothe et al. 2007, p. 37; Rens and Magee 2007, p. 42).
The Big Hole Grayling CCAA recognizes that the potential for
competition with and predation by nonnative trout may limit the
effectiveness of its conservation actions (MFWP et al. 2006, pp. 54-
55).
The MFWP is the lead agency implementing the Big Hole Grayling CCAA
under an agreement with the Service, and MFWP establishes fishing
regulations for most waters in Montana. Different regulations may apply
on NWR lands administered by the Service. The MFWP has agreed to
continue catch-and-release regulations for Arctic grayling in the Big
Hole River, to increase daily possession limits for nonnative brook
trout (MFWP et al. 2006, p. 55; MFWP 2010, p. 52), and to consider
whether additional management actions are necessary to address threats
from nonnative trout based on recommendations of a technical committee
of the AGW (MFWP et al. 2006, p. 55). However, we are not aware of data
that shows angling regulations currently, or are expected to, reduce
threats from brook trout. We also are not aware of any evaluations
provided by the technical committee or of any additional management
actions taken by MFWP to address potential threats from nonnative
trout. Nonnative trout are widely distributed and abundant in the Big
Hole River, and eradication may be impossible. The Big Hole Grayling
CCAA focuses primarily on habitat-related threats (not nonnative
trout), so we presume that nonnative trout will remain a threat to
Arctic grayling for the foreseeable future.
Arctic grayling in Miner and Mussigbrod Lakes co-occur with one or
more species of nonnative trout, but we have no quantitative
information on the relative abundance of the introduced species. Brook
trout and rainbow trout are both characterized as ``common'' in lower
Miner Lakes (MFISH 2010), and brook trout in Mussigbrod Lake are
similarly categorized as ``common'' (MFISH 2010). Brook trout have been
present in the Big Hole River for at least 60 years (Liknes 1981, p.
34). The date when brook trout were introduced into Miner and Mussibrod
Lakes is unknown (Liknes 1981, p. 33), but the co-occurrence of the
brook trout with Arctic grayling in these habitats suggests that
displacement of Arctic grayling by brook trout is not inevitable.
In the Madison River in and near Ennis Reservoir, brown trout and
rainbow trout are abundant and are the foundation of an important
recreational fishery (e.g., Byorth and Shepard 1990, p. 1). Nonnative
rainbow trout and brown trout substantially outnumber Arctic grayling
in the Madison River near Ennis Reservoir (Clancey and Lohrenz 2005,
pp. 26, 29-31; 2009, pp. 91, 93).
In the Red Rock Lakes system, brook trout and hybrid cutthroat
trout (Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri)
rainbow trout; Mogen 1996, p. 42) have well-established populations and
dominate the abundance and biomass of the salmonid community (Katzman
1998, pp. 2-3; Boltz 2010, pp. 2-3). Competition and predation risk for
the Arctic grayling may be particularly acute in the shallow Upper Red
Rock Lake when all fish species are forced to congregate in a few
discrete deeper sites in response to environmental conditions, such as
ice formation in winter (Boltz 2010, pers. comm.). Removal of nonnative
trout from certain waters on the Red Rock Lakes NWR is part of the CCP
(USFWS 2009, pp. 72, 75), so the frequency of predation of and
competition with Arctic grayling by these species may be reduced at a
limited spatial scale during the 15-year timeframe of the CCP.
Studies attempting to specifically measure the strength of
competition with and magnitude of predation by nonnative trout on
Arctic grayling in Montana have yielded mixed results. Only one study
attempted to measure competition between brook trout and Arctic
grayling (Byorth and Magee 1998, entire), and their study did not find
strong evidence for presumed effects of competition, such as
differences in microhabitat use or growth rate (Byorth and Magee 1998,
p. 1998). However, the authors cautioned that further studies were
needed to determine whether or not competition may be occurring between
fish of different sizes or ages (other than those tested) or whether
competition with or predation by rainbow trout or brown trout is
occurring (Byorth and Magee, 1998, p. 929). Measuring the strength of
competition and determining the relevant mechanisms (e.g., competition
for food vs. space) is difficult to measure in fish populations (Fausch
1998, pp. 220, 227), so the lack of definitive evidence for the
mechanisms of competition may simply be due to the inherent
difficulties in measuring these effects and determining their influence
on the population. Similarly, predation by brook trout on Arctic
grayling eggs and fry has been observed in both the Big Hole River and
Red Rock Lakes systems (Nelson 1954, entire; Streu 1990, p. 17; Katzman
1998, pp. 35, 47, 114), but such observations have not been
definitively linked with a population decline of Arctic grayling. To
our knowledge, no studies have investigated or attempted to measure
predation by brown trout or rainbow trout on Arctic grayling in
Montana.
Experimental evidence notwithstanding, the decline of Arctic
grayling concurrent with encroachment by nonnative trout, combined with
the difficulty in establishing grayling populations where nonnatives
trout are present (Kaya 1992, pp. 55-56, 61; Kaya 2000, pp. 14-16),
provides strong circumstantial evidence that a combination of predation
and competition by nonnative trout has negatively affected Arctic
grayling populations in the upper Missouri River. The lack of direct
evidence for competition (e.g., with brook trout) or predation (e.g.,
by brown trout) most likely indicates that these mechanisms can be
difficult to detect and measure in wild populations and that additional
scientific investigation is needed. We recognize that displacement of
Arctic grayling is not a certain outcome where the species comes into
contact with brook trout (e.g., Big Hole River), but the circumstances
that facilitate long-term co-existence vs. transitory co-existence are
unknown. Ultimately, circumstantial evidence from Montana and the
western United States suggests that the presence of nonnative trout
species represents a substantial threat to native fishes including
Arctic grayling. At least one species of nonnative trout is present in
all waters occupied by native Arctic grayling populations in the upper
Missouri River, so the threat is widespread and imminent, and we expect
that nonnative trout will remain a part of the biological community.
Thus, we expect that nonnative trout are a threat to Missouri River
Arctic grayling in the foreseeable future.
Predation by Birds and Mammals
In general, the incidence and effect of predation by birds and
mammals on Arctic grayling is not well understood because few detailed
studies have been completed (Northcote 1995, p. 163). Black bear (Ursus
americanus), mink (Neovison vison), and river otter (Lontra canadensis)
are present in southwestern Montana, but direct evidence of predatory
activity by these species is often lacking (Kruse 1959, p. 348). Osprey
(Pandion halaietus) can capture Arctic grayling during the summer
(Kruse 1959, p. 348). In the Big Hole River, Byorth and Magee (1998, p.
926) attributed the loss of Arctic grayling from artificial enclosures
used in a competition experiment to predation by minks, belted
kingfisher (Ceryl alcyon),
[[Page 54735]]
osprey, and great blue heron (Ardea herodia). In addition, American
white pelican (Pelecanus erythrorhynchos) are seasonally present in the
Big Hole River, and they also may feed on grayling. The aforementioned
mammals and birds can be effective fish predators, but we have no data
demonstrating any of these species historically or currently consume
Arctic grayling at levels sufficient to exert a measureable,
population-level impact on native Arctic grayling in the upper Missouri
River system. We expect the current situation to continue, so we
conclude that predation by birds and mammals does not constitute a
substantial threat to Missouri River Arctic grayling in the foreseeable
future.
Summary of Factor C
Based on the information available at this time, we conclude
disease does not represent a past or current threat to the Missouri
River DPS of Arctic grayling. We have no factual basis for concluding
that disease may become a future threat, but anticipate that the
likelihood of disease in native populations will depend on and interact
with other factors (e.g., habitat condition, climate change) that may
cumulatively stress individual fish and reduce their ability to
withstand infection by disease-causing pathogens.
Circumstantial evidence indicates that ecological interactions with
nonnative trout species have led to the displacement of Arctic grayling
from portions of its historic range in the upper Missouri River basin.
Nonnative trout species, such as brook trout, brown trout, and rainbow
trout, remain widely distributed and abundant in habitats currently
occupied by native Arctic grayling populations. Consequently, we
determined that the presence of nonnative trout represents a
substantial current and foreseeable threat to native Arctic grayling of
the upper Missouri River.
Little is known about the effect of predation on Arctic grayling by
birds and mammals. Such predation likely does occur, but in contrast to
the pattern of displacement observed concurrent with encroachment by
nonnative trout, we are not aware of any situation where an increase in
fish-eating birds or mammals has coincided with the decline of Arctic
grayling. Consequently, the available information does not support a
conclusion that predation by birds or mammals represents a substantial
past, present, or foreseeable threat to native Arctic grayling in the
upper Missouri River.
D. Inadequacy of Existing Regulatory Mechanisms
The ESA requires us to examine the adequacy of existing regulatory
mechanisms with respect to those extant threats that place the species
in danger of becoming either endangered or threatened. Thus, the scope
of this analysis generally focuses on the extant native populations of
Arctic grayling and potential current and foreseeable threats based on
the inadequacy of existing regulatory mechanisms.
Federal Laws and Regulations
Native Arctic grayling are present in or adjacent to land managed
by the U.S. Forest Service (USFS) (Big Hole River, Miner, and
Mussigbrod Lakes: Beaverhead-Deerlodge National Forest), National Park
Service (NPS) (Big Hole River: Big Hole National Battlefield), Bureau
of Land Management (BLM) (Big Hole River: Dillon Resource Area), USFWS
(Red Rock Lakes NWR); and the Federal Energy Regulatory Commission
(Madison River-Ennis Reservoir: Ennis Dam, operated under Project 2188
license).
National Environmental Policy Act
All Federal agencies are required to adhere to the National
Environmental Policy Act (NEPA) of 1970 (42 U.S.C. 4321 et seq.) for
projects they fund, authorize, or carry out. The Council on
Environmental Quality's regulations for implementing NEPA (40 CFR 1500-
1518) state that, when preparing environmental impact statements,
agencies shall include a discussion on the environmental impacts of the
various project alternatives, any adverse environmental effects which
cannot be avoided, and any irreversible or irretrievable commitments of
resources involved (40 CFR 1502). The NEPA itself is a disclosure law,
and does not require subsequent minimization or mitigation measures by
the Federal agency involved. Although Federal agencies may include
conservation measures for Arctic grayling as a result of the NEPA
process, any such measures are typically voluntary in nature and are
not required by NEPA.
Federal Land Policy and Management Act
The BLM's Federal Land Policy and Management Act (FLPMA) of 1976
(43 U.S.C. 1701 et seq.), as amended, states that the public lands
shall be managed in a manner that will protect the quality of
scientific, scenic, historical, ecological, environmental, air and
atmospheric, water resource, and archeological values.
The BLM considers the fluvial Arctic grayling a sensitive species
requiring special management consideration for planning and
environmental analysis (BLM 2009b, entire). The BLM has recently
developed a Resource Management Plan (RMP) for the Dillon Field Office
Area that provides guidance for the management of over 900,000 acres of
public land administered by BLM in southwest Montana (BLM 2006a, p. 2).
The Dillon RMP area thus includes the geographic area that contains the
Big Hole, Miner, Mussigbrod, Madison River, and Red Rock populations of
Arctic grayling. A RMP planning area encompasses all private, State,
and Federal lands within a designated geographic area (BLM 2006a, p.
2), but the actual implementation of the RMP focuses on lands
administered by the BLM that typically represent only a fraction of the
total land area within that planning area (BLM 2006b, entire).
Restoring Arctic grayling habitat and ensuring the long-term
persistence of both fluvial and adfluvial ecotypes are among the RMP's
goals (BLM 2006a, pp. 30-31). However, there is little actual overlap
between the specific parcels of BLM land managed by the Dillon RMP and
the current distribution of Arctic grayling (BLM 2006b, entire).
The BLM also has a RMP for the Butte Field Office Area, which
includes more than 300,000 acres in south-central Montana (BLM 2008,
entire), including portions of the Big Hole River in Deerlodge and
Silver Bow counties (BLM 2008, p. 8; 2009c, entire). The Butte RMP
considers conservation and management strategies and agreements for
Arctic grayling in its planning process and includes a goal to
opportunistically enhance or restore habitat for Arctic grayling (BLM
2008, pp. 10, 30, 36). However, the Butte RMP does not mandate specific
actions to improve habitat for Arctic grayling in the Big Hole River.
National Forest Management Act
Under the USFS' National Forest Management Act (NFMA) of 1976, as
amended (16 U.S.C. 1600-1614), the USFS shall strive to provide for a
diversity of plant and animal communities when managing national forest
lands. Individual national forests may identify species of concern that
are significant to each forest's biodiversity. The USFS Northern Rocky
Mountain Region (R1) considers fluvial Arctic grayling a sensitive
species (USFS 2004, entire) for which population viability is a
concern, as evidenced by a significant downward trend in population or
a
[[Page 54736]]
significant downward trend in habitat capacity.
Much of the headwaters of the Big Hole River drainage are within
the boundary of the Beaverhead-Deerlodge National Forest. The Miner and
Mussigbrod Lakes Arctic grayling populations are entirely within Forest
boundaries. The Beaverhead-Deerlodge National Forest is currently
revising its forest plan. The USFS does not propose to designate key
fish watersheds solely to benefit grayling, but fluvial Arctic grayling
will remain a sensitive species with Forest-wide standards and
objectives to meet the species' habitat requirements (USFS 2009a, p.
19). With respect to fluvial Arctic grayling, the USFS is proposing a
Controlled Surface Use (CSU) stipulation in the Ruby River (an ongoing
reintroduction site) and certain tributaries of the Big Hole River
(USFS 2009b, pp. 29, B-13) to avoid impacts from mineral, gas, and oil
extraction (USFS 2009b, pp. 27-28). These CSU stipulations define the
minimum extent of buffer areas adjacent to streams. In general, the
preferred forest plan alternative (Alternative 6, USFS 2009a, p. 6) is
deemed by the USFS to provide management direction designed to ensure
the persistence of grayling populations Forest-wide, and to meet
viability requirements of this species (USFS 2009a, p. 146). The forest
plan revision has not yet been finalized through a record of decision
(ROD), so we are unable to specifically evaluate its potential effect
on native Arctic grayling populations.
National Park Service Organic Act
The NPS Organic Act of 1916 (16 U.S.C. 1 et seq.), as amended,
states that the NPS ``shall promote and regulate the use of the Federal
areas known as national parks, monuments, and reservations ... to
conserve the scenery and the national and historic objects and the wild
life therein and to provide for the enjoyment of the same in such
manner and by such means as will leave them unimpaired for the
enjoyment of future generations.'' Native populations of Arctic
grayling have been extirpated from Yellowstone National Park, but the
Big Hole National Battlefield is adjacent to the North Fork of the Big
Hole River (NPS 2006, entire), and Arctic grayling are occasionally
encountered downstream from the Battlefield (Rens and Magee 2007, pp.
7, 13). Consequently, a very small amount of currently occupied
grayling habitat is in the vicinity of lands managed by the NPS;
therefore, the NPS Organic Act is not thought to have any significant
effect on native Arctic grayling populations.
National Wildlife Refuge System Improvement Act of 1997
The National Wildlife Refuge Systems Improvement Act (NWRSIA) of
1997 (Pub. L. 105-57) amends the National Wildlife Refuge System
Administration Act of 1966 (16 U.S.C. 668dd et seq.). The NWRSIA
directs the Service to manage the Refuge System's lands and waters for
conservation. The NWRSIA also requires monitoring of the status and
trends of refuge fish, wildlife, and plants. The NWRSIA requires
development of a Comprehensive Conservation Plan (CCP) for each refuge
and management of each refuge consistent with its plan.
The Service has developed a final CCP to provide a foundation for
the management and use of Red Rock Lakes NWR (USFWS 2009, entire). Red
Rocks NWR is 2,033-2,865 m (6,670-9,400 ft) above sea level, comprises
48,955 ac, and lies east of the Continental Divide near the uppermost
reach of the Missouri drainage (USFWS 2009, pp. v, 2). The Red Rocks
NWR encompasses Lower and Upper Red Rock Lakes, which contain native
grayling. The Red Rocks NWR CCP outlines a set of broad goals and
specific objectives or strategies with respect to conservation of
Arctic grayling that focuses on habitat improvements, reestablishment
of populations, and removal of nonnative trout where necessary (USFWS
2009, pp. 67, 75-76). We expect that implementation of the CCP during
the next 15 years will address a number of significant resource issues
that affect grayling (e.g., riparian habitat condition, entrainment in
irrigation ditches, increasing the extent of occupancy in the system).
Nonetheless, actions similar to those planned inside the NWR will be
needed on adjacent properties to reduce threats to the existing
population of grayling in the Red Rock Lakes system.
Federal Power Act
The Federal Power Act of 1920 (16 U.S.C. 791-828c, as amended)
provides the legal authority for the Federal Energy Regulatory
Commission (FERC), as an independent agency, to regulate hydropower
projects. In deciding whether to issue a license, FERC is required to
give equal consideration to mitigation of damage to, and enhancement
of, fish and wildlife (16 U.S.C. 797(e)). A number of FERC-licensed
dams exist in the Missouri River basin in current (i.e., Ennis Dam on
the Madison River) and historical Arctic grayling habitat (e.g., Hebgen
Dam on the Madison River; Hauser, Holter, and Toston dams on the
mainstem Missouri River; and Clark Canyon Dam on the Beaverhead River).
The FERC license expiration dates for these dams range from 2024
(Toston) to 2059 (Clark Canyon) (FERC 2010, entire). None of these
structures provide upstream passage of fish, and such dams are believed
to be one of the primary factors leading to the decline of Arctic
grayling in the Missouri River basin (see discussion under Factor A,
above). Consequently, we conclude that historically the Federal Power
Act has not adequately protected Arctic grayling or its habitat. We
anticipate this will remain a threat it in the foreseeable future
because of future expiration dates of the FERC-licensed dams in the
upper Missouri River basin.
Clean Water Act
The Clean Water Act (CWA) of 1972 (33 U.S.C. 1251 et seq.)
establishes the basic structure for regulating discharges of pollutants
into the waters of the United States and regulating quality standards
for surface waters. The CWA's general goal is to ``restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters'' (33 U.S.C. 1251 (a)). The CWA requires States to adopt
standards for the protection of surface water quality and establishment
of Total Maximum Daily Load (TMDL) guidelines for rivers. The Big Hole
River has approved TMDL plans for its various reaches (MDEQ 2009a,
entire; 2009b, entire); thus, complete implementation of this plan
should improve water quality (by reducing water temperatures, and
reducing sediment and nutrient inputs) in the Big Hole River in the
foreseeable future. As of November 2009, the Red Rocks watershed was in
the pre-TMDL planning and assessment phase, but there was no
significant TMDL plan development activity in the Madison River (see
MDEQ 2010). Consequently, implementation of the CWA through an EPA-
approved TMDL plan began in 2009 for the Big Hole River watershed, but
has yet to begin in other waters occupied by native Arctic grayling in
the upper Missouri River. The CWA does not appear to be adequate to
protect the Missouri River DPS of Arctic grayling, but implementation
of TMDL plans should improve habitat conditions for Big Hole River
grayling in the foreseeable future.
Montana State Laws and Regulations
Arctic grayling is considered a species of special concern by
Montana, but this is not a statutory or regulatory classification
(Montana Natural Heritage Program 2010).
[[Page 54737]]
State Comprehensive Wildlife Conservation Strategies
These strategies, while not State or national legislation, can help
prioritize conservation actions within each State. Species and habitats
named within each Comprehensive Wildlife Conservation Strategy (CWCS)
may receive focused attention. The MFWP considers Arctic grayling as a
Tier I conservation species under its CWCS and the Big Hole River also
is a Tier I Aquatic Conservation Focus Area (Montana's Comprehensive
Fish and Wildlife Conservation Strategy (MCFWCS) 2005, pp. 75-76).
Montana Environmental Policy Act
The legislature of Montana enacted the Montana Environmental Policy
Act (MEPA) as a policy statement to encourage productive and enjoyable
harmony between humans and their environment, to protect the right to
use and enjoy private property free of undue government regulation, to
promote efforts that will prevent or eliminate damage to the
environment and biosphere and stimulate the health and welfare of
humans, to enrich the understanding of the ecological systems and
natural resources important to the State, and to establish an
environmental quality council (MCA 75-1-102). Part 1 of the MEPA
establishes and declares Montana's environmental policy. Part 1 has no
legal requirements, but the policy and purpose provide guidance in
interpreting and applying statutes. Part 2 requires State agencies to
carry out the policies in Part 1 through the use of systematic,
interdisciplinary analysis of State actions that have an impact on the
human environment. This is accomplished through the use of a
deliberative, written environmental review. In practice, MEPA provides
a basis for the adequate review of State actions in order to ensure
that environmental concerns are fully considered (MCA 75-1-102).
Similar to NEPA, the MEPA is largely a disclosure law and a decision-
making tool that does not specifically require subsequent minimization
or mitigation measures.
Laws Affecting Physical Aquatic Habitats
A number of Montana State laws have a permitting process applicable
to projects that may affect stream beds, river banks, or floodplains.
These include the Montana Stream Protection Act (SPA), the Streamside
Management Zone Law (SMZL), and the Montana Natural Streambed and Land
Preservation Act (Montana Department of Natural Resources (MDNRC) 2001,
pp. 7.1-7.2). The SPA requires that a permit be obtained for any
project that may affect the natural and existing shape and form of any
stream or its banks or tributaries (MDNRC 2001, p. 7.1). The Montana
Natural Streambed and Land Preservation Act (i.e., MNSLPA or 310
permit) requires private, nongovernmental entities to obtain a permit
for any activity that physically alters or modifies the bed or banks of
a perennially-flowing stream (MDNRC 2001, p. 7.1). The SPA and MNSLPA
laws do not mandate any special recognition for species of concern, but
in practice, biologists that review projects permitted under these laws
usually stipulate restrictions to avoid harming such species (Horton
2010, pers. comm.). The SMZL regulates forest practices near streams
(MDNRC 2001, p. 7.2). The Montana Pollutant Discharge Elimination
System (MPDES) Stormwater Permit applies to all discharges to surface
water or groundwater, including those related to construction,
dewatering, suction dredges, and placer mining, as well as to
construction that will disturb more than 1 acre within 100 ft (30.5 m)
of streams, rivers, or lakes (MDNRC 2001, p. 7.2).
Review of applications by MFWP, MTDEQ, or MDNRC is required prior
to issuance of permits under the above regulatory mechanisms (MDNRC
2001, pp. 7.1-7.2). Although these regulatory mechanisms would be
expected to limit impacts to aquatic habitats in general, the decline
of Arctic grayling in the Big Hole River, Madison River, and certain
waters in the Red Rock Lakes system does not provide evidence that past
implementation of these laws, regulations, and permitting processes has
effectively limited impacts to Arctic grayling habitat. Thus, we have
no basis for concluding that these same regulatory mechanisms are
adequate to protect the Arctic grayling and its habitat now or in the
foreseeable future.
Montana Water Use Act
The implementation of Montana Water Use Act (Title 85: Chapter 2,
Montana Codes Annotated) may not adequately address threats to Arctic
grayling in basins where the allocation of water rights exceeds the
available water (overallocation) and the water rights holders fully
execute their rights (i.e., use all water legally available for
diversion). The Missouri River system is generally believed to be
overappropriated, and water for additional consumptive uses is only
available for a few months during very wet years (MDNRC 1997, p. 12).
The Upper Missouri River basin and Madison River basin have been closed
to new water appropriations because of water availability problems,
overappropriation, and a concern for protecting existing water rights
(MDNRC 2009, p. 45). In addition, recent compacts (a legal agreement
between Montana, a Federal agency, or an Indian tribe determining the
quantification of federally or tribally claimed water rights) have been
signed that close appropriations in specific waters in or adjacent to
Arctic grayling habitats. For example, the USFWS-Red Rock Lakes-Montana
Compact includes a closure of appropriations for consumptive use in the
drainage basins upstream of the most downstream point on the Red Rock
Lakes NWR and the Red Rock Lakes Wilderness Area (MDNRC 2009, pp. 18,
47). The NPS-Montana Compact specifies that certain waters will be
closed to new appropriations when the total appropriations reach a
specified level, and it applies to Big Hole National Battlefield and
adjacent waters (North Fork of the Big Hole River and its tributaries
including Ruby and Trail Creeks), and the portion of Yellowstone
National Park that is in Montana (MDNRC 2009, p. 48).
The State of Montana is currently engaged in a state-wide effort to
adjudicate (finalize) water rights claimed before July 1, 1973. The
final product of adjudication in a river basin is a final decree. To
reach completion, a decree progresses through several stages: (1)
Examination, (2) temporary preliminary decree, (3) preliminary decree,
(4) public notice, (5) hearings, and (6) final decree (MDNRC 2009, pp.
9-14). As of February 2010, the Red Rock River system is currently
being examined, and the Big Hole and Madison Rivers have temporary
decrees (MDNRC 2010, entire). We anticipate the final adjudication of
all the river basins in Montana that currently contain native Arctic
grayling will be completed in the foreseeable future, but we do not
know if this process will eliminate the overallocation of water rights.
Fishing Regulations
Arctic grayling is considered a game fish (MFWP 2010, p. 16), but
is subject to special catch-and-release regulations in streams and
rivers within its native range (MFWP 2010, p. 52). Catch-and-release
regulations also are in effect for Ennis Reservoir on the Madison River
(MFWP 2010, p. 61). Arctic grayling in Miner and Mussigbrod Lakes are
subject to more liberal regulations; anglers can keep up to 5 per day
and have up to 10 in possession in accordance with standard daily and
possession limits for that angling management district
[[Page 54738]]
(MFWP 2010, p. 52). We have no evidence to indicate that current
fishing regulations are inadequate to protect native Arctic grayling in
the Missouri River basin (see discussion under Factor B, above).
Summary of Factor D
We infer that current Federal and State regulatory mechanisms are
inadequate to protect native Arctic grayling of the upper Missouri
River. We conclude this because the regulatory mechanisms may only
apply to specific populations (or parts of populations) depending on
land ownership and jurisdiction, they have no track record of
addressing significant threats to habitat, and they do not address the
threat posed by nonnative trout.
Regulatory mechanisms on Federal lands may be adequate to protect
certain fragments of Arctic grayling habitat or isolated populations
(e.g., Miner and Mussigbrod Lakes). However, the extirpation of more
than one lake population within the Beaverhead-Deerlodge National
Forest (e.g., Elk Lake - Oswald 2000, p. 10; Hamby Lake - Oswald 2005a,
pers. comm.) suggests the existing regulatory mechanisms may not be
sufficient. Difficulties in coordinating land and water use across
jurisdictional boundaries (State, Federal, private) within a watershed
also present challenges for coordinated management of Arctic grayling.
In the Big Hole River, fluvial Arctic grayling generally occupy waters
adjacent to private lands (MFWP et al. 2006, p. 13; Lamothe et al.
2007, p. 4), so Federal regulations may have limited scope to protect
the species.
Conceivably, application of existing regulations concerning
occupied Arctic grayling habitat in the upper Missouri River basin
(e.g., CWA, FLPMA, NFMA, SMZL, SPA) should promote and ensure the
persistence of Arctic grayling because these regulations were
promulgated, to some extent, to limit impacts of human activity on the
environment. However, based on the current status of the DPS and the
degradation of habitat and declines in populations observed in the past
20 to 30 years, during which time many of the above regulatory
mechanisms have been in place, we have no basis to conclude that they
have adequately protected grayling up to this time. In other words,
existing regulations theoretically limit threats to Arctic grayling,
but in practice have not done so. We suspect that incomplete or
inconsistent application of these regulatory mechanisms and
jurisdictional difficulties (State vs. Federal regulations, private vs.
public lands) relative to the distribution of Arctic grayling may be
partially responsible. Other regulatory mechanisms simply require
disclosure (e.g., NEPA) and do not necessarily mandate protection for a
species or its habitat. Consequently, we believe that existing
regulatory mechanisms that deal with land and water management have not
demonstrably reduced threats to Arctic grayling in the past, and we
have no basis to conclude that they are adequate now or will be in the
future.
Existing regulatory mechanisms do not directly address threats
posed by nonnative brook trout, brown trout, or rainbow trout (see
Factor C discussion, above). One exception is that the Red Rock Lakes
NWR CCP does consider removal of nonnative trout to be a possible
action to benefit Arctic grayling, but this may not apply to occupied
habitat outside the NWR, so the CCP is likely to only address this
threat for a portion of the population.
For the reasons described above, we conclude that the inadequacy of
existing regulatory mechanisms poses a current threat to native Arctic
grayling of the upper Missouri River. We do not anticipate any changes
to the existing regulatory mechanisms, thus we conclude that the
inadequacy of existing regulatory mechanisms is a threat in the
foreseeable future.
E. Other Natural or Manmade Factors Affecting Its Continued Existence
Drought
Drought appears to be a significant natural factor that threatens
Arctic grayling populations in streams and rivers in the upper Missouri
River basin. Drought can affect fish populations by reducing stream
flow volumes. This leads to dewatering and high temperatures that can
limit connectivity among spawning, rearing, and sheltering habitats; to
a reduced volume of thermally suitable habitat; and to an increased
frequency of water temperatures above the physiological limits for
optimum growth and survival in Arctic grayling. Drought is a natural
occurrence in the interior western United States (see National Drought
Mitigation Center 2010). The duration and severity of drought in
Montana appears to have increased during the last 50 years, and
precipitation has tended to be lower than average in the last 20 years
(National Climatic Data Center 2010). In addition, drought can interact
with human-caused stressors (e.g., irrigation withdrawals, riparian
habitat degradation) to further reduce stream flows and increase water
temperatures.
Reduced stream flows and elevated water temperatures during drought
have been most apparent in the Big Hole River system (Magee and Lamothe
2003, pp. 10-14; Magee et al. 2005, pp. 23-25; Rens and Magee 2007, pp.
11-12, 14). Although the response of stream and river habitats to
drought is expected to be most pronounced because of the strong
seasonality of flows in those habitats, effects in lake environments do
occur. For example, both the Upper and Lower Red Rock Lakes are very
shallow (Mogen 1996, p. 7). Reduced water availability during drought
would result in further shallowing (loss of habitat volume) that can
lead to increased temperatures in summer and the likelihood of complete
freezing or anoxia (lack of oxygen) in winter.
In the Big Hole River, evidence for the detrimental effects of
drought on Arctic grayling populations is primarily inferential;
observed declines in fluvial Arctic grayling and nonnative trout
abundances in the Big Hole River coincide with periods of drought
(Magee and Lamothe 2003, pp. 22-23, 28) and fish kills (Byorth 1995,
pp. 10-11, 31). Similarly, lack of success with fluvial Arctic grayling
restoration efforts elsewhere in the upper Missouri River basin also
has been attributed, in part, to drought (Lamothe and Magee 2004a, p.
28).
Given the climate of the intermountain West, we conclude that
drought has been and will continue to be a natural occurrence. We
assume that negative effects of drought on Arctic grayling populations,
such as reduced connectivity among habitats or increased water
temperatures at or above physiological thresholds for growth and
survival, are more frequent in stream and river environments and in
very shallow lakes relative to larger, deeper lakes. Therefore, we
expect the threat of drought to be most pronounced for Arctic grayling
populations in the Big Hole River, Madison River-Ennis Reservoir, and
Red Rock Lakes. We do not know whether drought has or is currently
limiting Arctic grayling populations in Miner and Mussigbrod Lakes, as
there are few monitoring data for these populations. Arctic grayling in
Miner and Mussigbrod Lakes presumably use inlet or outlet streams for
spawning; thus, if severe drought occurs during spawning and before
subsequent emigration of YOY grayling to the rearing lakes, then
population-level effects are possible. Overall, we conclude that
drought has been a past threat, is a current threat, and will continue
to be a threat to Arctic grayling of the upper Missouri River basin,
especially for those populations in the
[[Page 54739]]
Big Hole River, Madison River-Ennis Reservoir, and Red Rock Lakes.
Successful implementation of the Big Hole Grayling CCAA may partially
ameliorate the effects of drought in the Big Hole River, by reducing
the likelihood that human-influenced actions or outcomes (irrigation
withdrawals, destruction of riparian habitats, and fish passage
barriers) will interact with the natural effects of drought (reduced
stream flows and increased water temperatures) to negatively affect
suitable habitat for Arctic grayling. We expect the magnitude of the
threat from drought to increase in the foreseeable future under the
anticipated air temperature and precipitation trends projected by
climate change models (discussed in detail below).
Climate Change
Climate is influenced primarily by long-term patterns in air
temperature and precipitation. The Intergovernmental Panel on Climate
Change (IPCC) has concluded that climate warming is unequivocal, and is
now evident from observed increases in global average air and ocean
temperatures, widespread melting of snow and ice, and rising global
mean sea level (IPCC 2007, pp. 30-31). Continued greenhouse gas
emissions at or above current rates are expected to cause further
warming (IPCC 2007, p. 30). Eleven of the 12 years from 1995 through
2006 rank among the 12 warmest years in the instrumental record of
global average near-surface temperature since 1850 (ISAB 2007, p.7;
IPCC 2007, p. 30). During the last century, mean annual air temperature
increased by approximately 0.6 [deg]C (1.1 [deg]F) (IPCC 2007, p. 30).
Warming appears to be accelerating in recent decades, as the linear
warming trend over the 50 years from 1956 to 2005 (average 0.13 [deg]C
or 0.24 [deg]F per decade) is nearly twice that for the 100 years from
1906 to 2005 (IPCC 2007, p. 30). Climate change scenarios estimate that
the mean air temperature could increase by over 3 [deg]C (5.4 [deg]F)
by 2100 (IPCC 2007, pp. 45-46). The IPCC also projects that there will
likely be regional increases in the frequency of hot extremes, heat
waves, and heavy precipitation, as well as greater warming in high
northern latitudes (IPCC 2007, p. 46). We recognize that there are
scientific differences of opinion on many aspects of climate change,
including the role of natural variability in climate. In our analysis,
we rely primarily on synthesis documents (IPCC 2007; ISAB 2007; Karl et
al. 2009) that present the consensus view of a large number of experts
on climate change from around the world. We 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. Where possible, we used
empirical data or projections specific to the western United States,
which includes the range of Arctic grayling in the Missouri River
basin, and focused on observed or expected effects on aquatic systems.
Water temperature and hydrology (stream flow) are sensitive to
climate change, and influence many of the basic physical and biological
processes in aquatic systems. For ectothermic organisms like fish,
temperature sets basic constraints on species' distribution and
physiological performance, such as activity and growth (Coutant 1999,
pp. 32-52). Stream hydrology not only affects the structure of aquatic
systems across space and time, but influences the life-history and
phenology (timing of life-cycle events) of aquatic organisms, such as
fishes. For example, the timing of snowmelt runoff can be an
environmental cue that triggers spawning migrations in salmonid fishes
(Brenkman et al. 2001, pp. 981, 984), and the timing of floods relative
to spawning and emergence can strongly affect population establishment
and persistence (Fausch et al. 2001, pp. 1438, 1450). Significant
trends in water temperature and stream flow have been observed in the
western United States (Stewart et al. 2005, entire; Kaushal et al.
2010, entire), and climatic forcing caused by increased air
temperatures and changes in precipitation are partially responsible.
Warming patterns in the western United States are not limited to
streams. In California and Nevada, water surface temperatures have
increased by an average of 0.11 [deg]C (0.2 [deg]F) per year since 1992
and at a rate twice that of the average minimum air surface temperature
(Schneider et al. 2009, p. L22402). In the western United States,
runoff from snowmelt occurs 1 to 4 weeks earlier (Regonda et al. 2005,
p. 380; Stewart et al. 2005, pp. 1136, 1141; Hamlett et al. 2007, p.
1468), presumably as a result of increased temperatures (Hamlet et al.
2007, p. 1468), increased frequency of melting (Mote et al. 2005, p.
45), and decreased snowpack (Mote et al. 2005, p. 41).
Trends in decreased water availability also are apparent across the
Pacific Northwest. For example, Luce and Holden (2009, entire) found a
tendency toward more extreme droughts at 72 percent of the stream flow
gages they examined across Idaho, Montana, Oregon, and Washington.
Climate forcing may be directly or indirectly altering those
habitats. Long-term water temperature data are not available for sites
currently occupied by native Arctic grayling populations (e.g., Big
Hole River, Red Rock Creek); however, if trends in air temperature are
consistently related to increases in water temperature (Isaak et al.
2010, p. 1), then a regional pattern of increased water temperature is
likely, and it is reasonable to assume that Arctic grayling in the Big
Hole River, Red Rock Creek, and Madison River near Ennis Reservoir also
have experienced the same trend. Mean annual air temperature recorded
at Lakeview, Montana, near the Red Rock Lakes between 1948 and 2005 did
not increase significantly, although mean temperatures in March and
April did show a statistically significant increase consistent with
earlier spring warming observed elsewhere in North America during
recent decades (USFWS 2009, pp. 36-39).
The effect of such warming would be similar to that described for
increased temperatures associated with stream dewatering (see
discussion under Factor A), namely there has been an increased
frequency of high water temperatures that may be above the
physiological limits for survival or optimal growth for Arctic
grayling, which is considered a cold-water (stenothermic) species
(Selong et al. 2001, p. 1032). Changes in water temperature also may
influence the distribution of nonnative trout species (Rahel and Olden
2008, p. 524) and the outcome of competitive interactions between those
species and Arctic grayling. Brown trout are generally considered to be
more tolerant of warm water than many salmonid species common in
western North America (Coutant 1999, pp. 52-53; Selong et al. 2001, p.
1032), and higher water temperatures may favor brown trout where they
compete against salmonids with lower thermal tolerances (Rahel and
Olden 2008, p. 524). Recently observed increases in the abundance and
distribution of brown trout in the upper reaches of the Big Hole River
may be consistent with the hypothesis that stream warming is
facilitating encroachment. Further study is needed to evaluate this
hypothesis.
Observations on flow timing in the Big Hole River, upper Madison
River, and Red Rock Creek indicate a tendency toward earlier snowmelt
runoff (USFWS 2010b). These hydrologic alterations may be biologically
significant for Arctic grayling in the Missouri River basin because
they typically spawn
[[Page 54740]]
prior to the peak of snowmelt runoff (Shepard and Oswald 1989, p. 7;
Mogen 1996, pp. 22-23; Rens and Magee 2007, pp. 6-7). A trend toward
earlier snowmelt runoff could thus result in earlier average spawning
dates, with potential (and presently unknown) implications for spawning
success and growth and survival of fry. Water availability has
measurably decreased in some watersheds occupied by Arctic grayling.
For example, mean annual precipitation recorded at Lakeview, Montana,
near the Red Rock Lakes, decreased significantly between 1948 and 2005
(USFWS 2009, pp. 36-39).
The western United States appears to be warming faster than the
global average. In the Pacific Northwest, regionally averaged
temperatures have risen 0.8 [deg]C (1.5 [deg]F) over the last century
and as much as 2 [deg]C (4 [deg]F) in some areas. They are projected to
increase by another 1.5 to 5.5 [deg]C (3 to 10 [deg]F) over the next
100 years (Karl et al. 2009, p. 135). For the purposes of this finding,
we consider the foreseeable future for anticipated climate changes as
approximately 40 years, because various global climate models (GCM) and
emissions scenarios give consistent predictions within that timeframe
(Ray et al. 2010, p. 11). We used a similar foreseeable future to
consider climate change projects in other 12-month findings (see
American pika (Ochotona princeps) - 75 FR 6448, February 9, 2010).
While projected patterns of warming across North America are generally
consistent across different GCMs and emissions scenarios (Ray et al.
2010, p. 22), there tends to be less agreement among models for whether
mean annual precipitation will increase or decrease, but the models
seem to indicate an increase in precipitation in winter and a decrease
in summer (Ray et al. 2010, pp. 22-23). In the foreseeable future,
natural variation will likely confound a clear prediction for
precipitation based on current climate models (Ray et al. 2010, p. 29).
Although there is considerable uncertainty about how climate will
evolve at any specific location, statistically downscaled climate
projection models (models that predict climate at finer spatial
resolution than GCMs) for the Pacific Northwest also support widespread
warming, with warmer temperature zones shifting to the north and upward
in elevation (Ray et al. 2010, pp. 23-24).
The land area of the upper Missouri River basin also is predicted
to warm (Ray et al. 2010, p. 23), although currently occupied Arctic
grayling habitat tends be in colder areas of moderate-to-high
elevation. Four out of five populations are at approximately 1,775 to
2,125 m (5,860 to 7,012 ft) (Peterson and Ardren 2009, p. 1761).
Presumably, any existing trends in water temperature increase and
earlier snowmelt runoff in streams and rivers that is being forced by
increases in air temperature should continue. To the extent that these
trends in water temperature and hydrology already exist in habitats
occupied by native Arctic grayling, they should continue into the
foreseeable future. In general, climate change is expected to
substantially reduce the thermally suitable habitat for coldwater fish
species (Keleher and Rahel 1996, pp. 1, 6-11; Mohseni et al. 2003, pp.
389, 401; Flebbe et al. 2006, p. 1371, 1378; Rieman et al. 2007, pp.
1552, 1559). The range of native Arctic grayling in the upper Missouri
River has already contracted significantly during the past 50 to 100
years (Vincent 1962, pp. 96-121; Kaya 1992, pp. 49-51). The currently
occupied native Arctic grayling habitat tends be in colder areas of
moderate-to-high elevation that may, to some extent, be more resistant
to large or rapid changes in hydrology (Regonda et al. 2005, p. 380;
Stewart et al. 2005, p. 1142) or perhaps stream warming.
Nonetheless, we do not expect these habitats to be entirely immune
from effects of climate warming, so we expect that climate change could
lead to further range contractions of Arctic grayling of the upper
Missouri River and may increase the species' risk of extinction over
the next 30 to 40 years as climate impacts interact with existing
stressors (Karl et al. 2009, p. 81), such as habitat degradation,
stream dewatering, drought, and interactions with nonnative trout that
are already affecting the DPS. We anticipate that implementation of the
Big Hole Grayling CCAA may partially compensate for, or reduce the
severity of, likely effects of climate change on Arctic grayling in the
Big Hole River. However, if current projections are realized, climate
change is likely to exacerbate the existing primary threats to Arctic
grayling outside the Big Hole River. The IPCC projects that the changes
to the global climate system in the 21st century will likely be greater
than those observed in the 20th century (IPCC 2007, p. 45); therefore,
we anticipate that these effects will continue and likely increase into
the foreseeable future. We do not consider climate change in and of
itself to be a significant factor in our determination of whether
Arctic grayling of the upper Missouri River is warranted for listing
because of the greater imminence and magnitude of other threats (e.g.,
Factor A: habitat degradation, Factor C: nonnative trout). However, we
expect the severity and scope of key threats (habitat degradation and
fragmentation, stream dewatering, and nonnative trout) to increase in
the foreseeable future because of climate change effects that are
already measureable (i.e., increased water temperature, increased
frequency of extreme drought, changes in runoff patterns). Thus, we
consider that climate change will potentially intensify some of the
significant current threats to all Arctic grayling populations in the
DPS. After approximately 40 years, the variation in GCM projections
based on the various emissions scenarios begins to increase
dramatically (Ray et al. 2010 pp. 12-13), so 40 years represents the
foreseeable future in terms of the extent to which the effects of
climate change (a major environmental driver) can reliably be modeled
or predicted. Thus we conclude that climate change constitutes a threat
in the Missouri DPS of Arctic grayling in the foreseeable future.
Stochastic (Random) Threats
A principle of conservation biology is that the presence of larger
and more productive (resilient) populations can reduce overall
extinction risk. To minimize extinction risk due to (random) stochastic
threats, life-history diversity should be maintained, populations
should not all share common catastrophic risks, and both widespread and
spatially close populations are needed (Fausch et al. 2006, p. 23;
Allendorf et al. 1997, entire). Based on these principles, the upper
Missouri River DPS of Arctic grayling may face current and future
threats from stochastic processes that act on small, reproductively
isolated populations.
The upper Missouri River DPS of Arctic grayling exists as a
collection of small, isolated populations (Figure 2; Peterson and
Ardren 2009, entire). Patterns of dispersal among extant Arctic
grayling populations have been constrained dramatically by the presence
of dams. The inability of fish to move between populations limits
genetic exchange, the maintenance of local populations (demographic
support; Hilderbrand 2003, p. 257), and recolonization of habitat
fragments (reviewed by Fausch et al. 2006, pp. 8-9). Isolated
populations cannot offset the random loss of genetic variation (Fausch
et al. 2006, p. 8). This in turn can lead to loss of phenotypic
variation and evolutionary potential (Allendorf and Ryman 2002, p. 54).
Relative to the presumed historical condition of
[[Page 54741]]
connectivity among most of the major rivers in the upper Missouri River
basin, the extant native Arctic grayling populations face both genetic
and demographic threats from isolation, both currently and in the
foreseeable future.
Four of the five individual populations in the upper Missouri River
DPS of Arctic grayling are at low-to-moderate abundance (see Population
Status and Trends for Native Arctic Grayling of the Upper Missouri
River, above). Individually, small populations need to maintain enough
adults to minimize loss of variability through genetic drift and
inbreeding (Rieman and McIntyre 1993, pp. 10-11). The point estimates
for genetic effective population sizes observed in the Big Hole River,
Miner Lakes, Madison River, and Red Rock Lakes populations are above
the level at which inbreeding is an immediate concern, but below the
level presumed to provide the genetic variation necessary to conserve
long-term adaptive potential (Peterson and Ardren 2009, pp. 1767,
1769). Historically, effective population sizes of Arctic grayling in
the Missouri River were estimated to be 1 or 2 orders of magnitude
greater (10 to 100 times) than those currently observed (Peterson and
Ardren 2009, pp. 1767). Loss of genetic variation relative to the
historical condition thus represents a threat to Arctic grayling in the
foreseeable future.
Only the Big Hole River population expresses the migratory fluvial
ecotype that presumably dominated in the upper Missouri River basin
(Kaya 1992, pp. 47-50); therefore, the DPS lacks functional redundancy
in ecotypes. Conservation of life-history diversity is important to the
persistence of species confronted by habitat change and environmental
perturbations (Beechie et al. 2006, entire). Therefore, the lack of
additional fluvial populations represents a current threat to the upper
Missouri River DPS. Reintroduction efforts have been ongoing to reduce
this threat, but have not yet produced a self-sustaining population at
any of the reintroduction sites (Rens and Magee 2007, pp. 21-38).
Future successful reintroductions may reduce this threat, but at the
present time we consider the threat to extend into the foreseeable
future.
Populations of Arctic grayling in the upper Missouri River DPS are
for the most part widely separated from one another, particularly those
populations in the Big Hole, Madison, and Red Rock drainages (see
Figure 2). Thus, they do not appear to all share a common risk of being
extirpated by a rare, high-magnitude environmental disturbance (i.e.,
catastrophe). Three of the five populations are within the same
watershed (Big Hole River, Miner Lakes, and Mussigbrod Lake
populations), so collectively these three populations would be at
greater risk. Individually, each population appears to be at
substantial risk of extirpation by catastrophe from one or more factor,
such as restricted distribution (Miner Lakes, Mussigbrod Lake), low
population abundance (Madison Lake, Red Rocks Lakes , Big Hole River),
and concentration of spawning primarily in a single, discrete location
(Red Rock Lakes). The Big Hole River population may be at a
comparatively lower risk from catastrophe because individuals still
spawn at multiple locations within the drainage (Rens and Magee 2007,
p. 13).
The population viability analysis (PVA) demonstrates that four of
the five extant populations in the upper Missouri River DPS of Arctic
grayling are at moderate (at least 13 percent) to high risk (more than
50 percent) of extinction from random environmental variation. In this
context, random environmental variation is simply considered to be
common environmental fluctuations, such as drought, floods, debris
flows, changes in food availability, etc. that affect population size
and population growth. These PVA analyses assume that variation in
annual population growth increases as population size decreases (Rieman
and McIntyre 1993, pp. 43-46), which seems a reasonable assumption
given the large inter-annual variability in relative abundance and
recruitment observed in some Arctic grayling populations in Montana
(e.g., Big Hole River) (Magee et al. 2005, pp. 27-28). Simply stated,
smaller populations are more likely to go extinct even if they are
stable because they are already close to the extinction threshold, and
random environmental events can drive their abundance below that
threshold. Consequently, we believe that extinction risk from random
environmental variation (droughts, floods, etc.) represents a
significant threat in the foreseeable future based on the PVA.
We are unsure whether chance variation in the fates of individuals
within a given year (demographic stochasticity) is a current threat to
the upper Missouri River DPS of Arctic grayling. The magnitude of
demographic stochasticity is inversely related to population size
(Morris and Doak 2002, pp. 22-23), but we do not know whether any of
the Arctic grayling populations currently exist at or below an
abundance where demographic stochasticity is likely.
Overall, we conclude that the upper Missouri River DPS of Arctic
grayling faces threats from population isolation, loss of genetic
diversity, and small population size, which all interact to increase
the likelihood that random environmental variation or a catastrophe can
extirpate an individual population. The uncertainty of PVA predictions
increases dramatically after about 25 to 30 years, so we feel this
represents a foreseeable future in terms of stochastic threats to the
DPS. Lack of connectivity among extant populations and lack of
replicate populations for the fluvial ecotype represent current
threats. Threats from reduced genetic diversity, environmental
variation, or catastrophe are threats in the foreseeable future,
because their effects may take longer to play out (i.e., link between
genetic diversity and adaptation) and are based on probabilistic
inference concerning the magnitude of variation in population growth,
environmental fluctuation, and periodic disturbance.
Summary of Factor E
Based on the information available at this time, we conclude that
drought represents a current and future threat to native Arctic
grayling in the upper Missouri River system. Drought can affect fish
populations by reducing stream flow volumes, which leads to dewatering
and high temperatures that can limit connectivity among spawning,
rearing, and sheltering habitats; a reduced volume of thermally
suitable habitat; and an increased frequency of water temperatures
above the physiological limits for optimum growth and survival.
Climate projections suggest that the frequency and severity of
drought is expected to increase; thus the magnitude of drought-related
threats and impacts also may increase. We anticipate the effects of
drought to be most pronounced in streams, rivers, and shallow lakes;
therefore, the Big Hole River, Madison River-Ennis Reservoir, and Red
Rock Lakes populations are likely to be most threatened by drought.
There is evidence for increasing air temperatures and changing
hydrologic pattern resulting from climate change in the Pacific
Northwest and intermountain West, and we conclude that climate change
is a secondary threat that can interact with and magnify the effects of
primary threats, such as drought, stream dewatering from irrigation
withdrawals, and the outcome of interactions with nonnative trout
species that have higher thermal tolerances. We anticipate that climate
[[Page 54742]]
change will remain a threat in the foreseeable future, but that
conservation programs that increase connectivity among refuge habitats
and improve stream flows (e.g., Big Hole Grayling CCAA) will to some
extent mitigate or lessen the effects of climate change. Climate change
effects should be most pronounced in those same habitats and
populations most strongly affected by water availability (Big Hole
River, Madison River-Ennis Reservoir, Red Rock Lakes), but lake
habitats also can be affected (Schneider et al. 2009, entire), so
threats likely extend to the other populations in the DPS (Miner and
Mussigbrod Lakes).
The Missouri River DPS of Arctic grayling currently exists as a
collection of small, isolated populations that face some current and
foreseeable threats from a collection of random (stochastic) processes
characteristic of small populations, such as loss of genetic diversity
because of habitat fragmentation and isolation, and individual
populations face increased risk of extirpation from random
environmental variation (results of PVA) and catastrophe.
Finding
As defined by the DPS Policy, we determined that the native Arctic
grayling of the upper Missouri River constitutes a listable entity
under the ESA. We also considered the appropriateness of listing
separate distinct population segments based on each of the ecotypes
(fluvial and adfluvial) that occur naturally in Arctic grayling
populations in the Missouri River basin. The best scientific
information indicates these ecotypes share a recent evolutionary
history and the populations do not cluster genetically by life-history
type. Maintaining life-history diversity increases the likelihood that
a species (or DPS) will maintain both the genetic diversity and
evolutionary flexibility to deal with future environmental challenges.
Consequently we feel that preservation of both native ecotypes in their
native habitats is essential to conservation of the DPS; thus we have
determined that a single DPS that includes both ecotypes is most
appropriate from both a practical management and conservation
perspective. We refer to this DPS as the Missouri River DPS of Arctic
grayling. As discussed above, we do not include the nonnative Arctic
grayling in the DPS, based on intent of the Act, IUCN guidelines, and
NMFS policy. The Service does not currently have a specific policy
concerning nonnative species, therefore we will investigate this topic
in more detail during the proposed rulemaking process.
As required by the ESA, we considered the five factors in assessing
whether the Missouri River DPS of Arctic grayling is endangered or
threatened throughout all or a significant portion of its range. We
carefully examined the best scientific and commercial information
available regarding the past, present, and future threats faced by the
DPS. We reviewed the petition, information available in our files,
other available published and unpublished information, and we consulted
with recognized species experts and other Federal, State, and tribal
agencies. On the basis of the best scientific and commercial
information available, we find that listing the DPS as endangered or
threatened is warranted. We will make a determination on the status of
the species as endangered or threatened when we do a proposed listing
determination. However, as explained in more detail below (see
Preclusion and Expeditious Progress section), an immediate proposal of
a regulation implementing this action is precluded by higher priority
listing actions, and progress is being made to add or remove qualified
species from the Lists of Endangered and Threatened Wildlife and
Plants.
The historical range of Arctic grayling in the upper Missouri River
basin has declined dramatically in the past century. The five remaining
indigenous populations are isolated from one another by dams or other
factors. Moreover, three of these five populations (Big Hole, Madison-
Ennis, Red Rocks) appear to be at low abundance (perhaps no more than
650 to 2,000 adults per population) and have declined in abundance
during the past few decades. The Big Hole River contains the only
remaining example of the fluvial ecotype in the DPS, and the effective
number of breeding adults declined by half during the past 15 years.
Populations of Arctic grayling in two small lakes in the Big Hole River
drainage (Miner and Mussigbrod) appear to be more abundant, and perhaps
more secure than the other native populations.
This status review identified threats to the DPS related to Factors
A, C, D, and E (see Table 5). All populations face potential threats
from competition with and predation by nonnative trout (Factor C) now
and in the foreseeable future. The magnitude of this threat likely
varies by Arctic grayling population, and is greater in locations where
multiple species of nonnative trout are present, abundant, and comprise
a large proportion of the salmonid biomass (e.g., Big Hole River,
Madison River-Ennis Reservoir, Red Rock Lakes). Most populations face
threats that result from the alteration of their habitats (Factor A),
such as habitat fragmentation from large dams or smaller irrigation
diversion structures, stream dewatering, high summer water
temperatures, loss of riparian habitats, and entrainment in irrigation
ditches (see Table 5). Severe drought (Factor E) likely affects all
populations by reducing water availability and reducing the extent of
thermally suitable habitat, but we presume the effects of drought are
most pronounced for Arctic grayling that reside primarily in streams
and rivers (Big Hole River) or shallow lakes (Madison River-Ennis
Reservoir, Red Rock Lakes). We did not consider climate change (Factor
E) in and of itself to be a significant current threat, but if current
climate changes projections are realized, we expect that climate change
will influence severity and scope of key threats (habitat degradation
and fragmentation, stream dewatering, interactions with nonnative
trout, drought). As applied, existing regulatory mechanisms (Factor D)
do not appear to be adequate to address primary threats to grayling
(e.g., stream dewatering, loss of riparian habitats), as at least three
native Arctic grayling populations have continued to decline in
abundance in recent decades.
[[Page 54743]]
TABLE 5. Current and Foreseeable Threats to Individual Populations of Native Arctic Grayling in the Upper Missouri River DPS.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Madison River-Ennis
Threat Factor Big Hole River Miner Lakes Mussigbrod Lake Reservoir Red Rocks Lakes
--------------------------------------------------------------------------------------------------------------------------------------------------------
A Dams/habitat Dams/habitat Dams/habitat Dams/habitat
fragmentation\a\...... fragmentation........ fragmentation........ fragmentation
Dewatering\a\......... Thermal stress....... Dewatering
Thermal stress\a\..... Thermal stress
Entrainment\a\........ Entrainment
Riparian habitat Riparian habitat loss
loss\a\. Sediments
--------------------------------------------------------------------------------------------------------------------------------------------------------
C Predation & Predation & Predation & Predation & Predation &
competition with competition with competition with competition with competition with
nonnative trout nonnative trout nonnative trout nonnative trout nonnative trout
--------------------------------------------------------------------------------------------------------------------------------------------------------
D Inadequate Inadequate Inadequate Inadequate Inadequate
regulations\b\ regulations\b\ regulations\b\ regulations\b\ regulations\b\
(nonnative trout,..... (nonnative trout, (nonnative trout, (nonnative trout,.... (nonnative trout,
continued population extirpation of other extirpation of other federally-permitted continued population
decline). lake populations of lake populations of dam,. decline)
grayling). grayling). continued population
decline).
--------------------------------------------------------------------------------------------------------------------------------------------------------
E Reduced genetic Reduced genetic Drought Reduced genetic Reduced genetic
diversity, low........ diversity, low........ Climate change\c\.... diversity, low....... diversity, low
abundance, random abundance, random abundance, random abundance, random
events. events. events. events
Drought............... Drought............... Drought.............. Drought
Climate change\c\..... Climate change\c\..... Climate change\c\.... Climate change\c\
No replicate of
fluvial ecotype.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The magnitude of current threats to the majority of the extant population or its habitat are expected be reduced in the foreseeable future from
implementation of a formalized conservation plan (i.e., Big Hole Grayling CCAA).
\b\ Terms in parenthesis characterize the inadequacy of the regulatory mechanisms in terms of not addressing specific threats (e.g., nonnative trout,
Factor C; dams, Factor A) or having no observed record of success with protecting existing populations (continued population decline, extirpation of
other similarly situated populations).
\c\ Threats believed to be of secondary importance or that interact with primary threats.
In the Big Hole River, ongoing implementation of a formalized
conservation program (Big Hole Grayling CCAA) with substantial
participation from non-Federal landowners and State and Federal agency
partners should significantly reduce many of the habitat-related
threats to that population in the foreseeable future. In the Red Rock
Lakes NWR, implementation of a CCP should reduce many of the primary
threats to Arctic grayling that occur within the NWR's boundary, but
threats to Arctic grayling and its habitat also exist outside the
administrative boundary of the CCP.
Four of five populations appear to be at risk of extirpation in the
foreseeable future (next 20 to 30 years) from random fluctuations in
environmental conditions (e.g., precipitation, food availability,
density of competitors, etc.), simply because they are at low abundance
and cannot receive demographic support from other native populations
(Factor E). Low abundance and isolation also raises concerns that the
loss of genetic variation from chance events (genetic drift) also may
be a threat in some populations. Maintaining life-history diversity is
important for species conservation given anticipated environmental
challenges such as those anticipated under climate change, so having
only a single population of the fluvial ecotype represents a
significant threat to that ecotype's long-term persistence. A
reintroduction program designed to address this threat has been
implemented for more than a decade and has made some recent technical
advances in the production of Arctic grayling fry. Natural reproduction
by grayling has been observed at a re-introduction site in the Ruby
River. At least 5 to 10 more years of monitoring is needed for us to
establish that the reintroduced fish in the Ruby River constitute a
viable population.
We reviewed the available information to determine if the existing
and foreseeable threats render the species at risk of extinction now
such that issuing an emergency regulation temporarily listing the
species under section 4(b)(7) of the ESA is warranted. We determined
that issuing an emergency regulation temporarily listing the DPS is not
warranted at this time because there are five populations in the DPS
and the probability of simultaneous extinction of all five populations
is low, as the populations are physically discrete and isolated from
one another such that a natural or human-caused catastrophe is not
likely to extirpate all populations at once. In addition, the remaining
population that expresses the fluvial ecotype (Big Hole River) is
subject to ongoing implementation of a formalized conservation
agreement (Big Hole Grayling CCAA) with adaptive management
stipulations if Arctic grayling population goals are not being met
(MFWP et al. 2006, pp. 60-61), and provisions to rescue Arctic grayling
or address alteration to habitat in the event of a large-magnitude
disturbance such as a debris flow or flood (MFWP 2006, pp. 85-86).
Listing Priority Number
The Service adopted guidelines on September 21, 1983 (48 FR 43098),
to establish a rational system for utilizing available resources for
the highest priority species when adding species to the Lists of
Endangered or Threatened Wildlife and Plants or reclassifying species
listed as threatened to endangered status. These guidelines, titled
``Endangered and Threatened Species Listing and Recovery Priority
Guidelines'' address the immediacy and magnitude of threats, and the
level of taxonomic distinctiveness by assigning priority in descending
order to
[[Page 54744]]
monotypic genera (genus with one species), full species, and subspecies
(or equivalently, distinct population segments of vertebrates).
As a result of our analysis of the best available scientific and
commercial information, we assigned the native Arctic grayling of the
upper Missouri River a Listing Priority Number (LPN) of 3 based on our
finding that the DPS faces threats that are of high magnitude and are
imminent. These primary threats include the present or threatened
destruction, modification, or curtailment of its habitat; competition
with and predation by nonnative trout; inadequacy of existing
regulatory mechanisms to address all threats; extinction risk from
small population size and isolation; drought; and lack of replication
of the fluvial life history.
Under the Service's guidelines, the magnitude of threat is the
first criterion we look at when establishing a listing priority. The
guidance indicates that species with the highest magnitude of threat
are those species facing the greatest threats to their continued
existence. These species receive the highest listing priority. We
consider the threats that the native Arctic grayling of the upper
Missouri River faces to be high in magnitude because many of the
threats that we analyzed are present throughout the range and currently
impact the DPS to varying degrees (e.g., habitat fragmentation,
nonnative trout, inadequate regulatory mechanisms), and will continue
to impact the DPS into the future. The threats that are of high
magnitude include present or threatened destruction, modification, or
curtailment of its habitat; competition with and predation by nonnative
trout; inadequacy of existing regulatory mechanisms to address all
threats; extinction risk from small population size and isolation and
vulnerability to catastrophes; drought; and lack of replication of the
fluvial life-history. Also, the small number (five) and size and
isolation of the populations may magnify the impact of the other
threats under Factors A and C.
The DPS consists of only five populations, so loss of any
individual population would incrementally increase the risk that the
DPS will not persist. However, we presume that loss of the Big Hole
River population would create the highest risk, as this population
contains much of the genetic diversity present in the species within
the Missouri River basin (Peterson and Ardren 2009, pp. 1763, 1768,
1770) and is the only example of the fluvial ecotype. A conservation
program (Big Hole Grayling CCAA) is being implemented to address
habitat-related threats to the Big Hole River population, but the scope
of the threat posed by nonnative trout remains high. Due to the scope
and scale of the high magnitude threats and current isolation of
already small populations, we conclude that the magnitude of threats to
native Arctic grayling of the upper Missouri River is high.
Under our LPN guidelines, the second criterion we consider in
assigning a listing priority is the immediacy of threats. This
criterion is intended to ensure that the species facing actual,
identifiable threats are given priority over those for which threats
are only potential or that are intrinsically vulnerable but are not
known to be presently facing such threats. Not all the threats facing
the DPS are imminent. For example, threats from climate change and
catastrophe are reasonably certain to occur, and their effects may be
particularly acute for small, isolated populations, but the specific
nature and influence of these effects, although ongoing, are uncertain
at this point. With relative certainty, we can project that climate
change effects will exacerbate other ongoing effects throughout the
DPS. In contrast, we have factual information that some threats are
imminent because we have factual information that the threats are
identifiable and that the DPS is currently facing them in many areas of
its range. These other threats are covered in detail in the discussions
under Factors A and C of this finding and include habitat
fragmentation, stream dewatering, and riparian degradation from
agriculture and ranching; dams; and competition with and predation by
nonnative trout. Therefore, based on our LPN Policy, the threats are
imminent (ongoing).
The third criterion in our LPN guidelines is intended to devote
resources to those species representing highly distinctive or isolated
gene pools as reflected by taxonomy. We determined the native Arctic
grayling of the upper Missouri River to be a valid DPS according to our
DPS Policy. Therefore, under our LPN guidance, the native Arctic
grayling of the upper Missouri River is assigned a lower priority than
a species in a monotypic genus or a full species that faces the same
magnitude and imminence of threats. Therefore, we assigned the native
Arctic grayling of the upper Missouri River an LPN of 3 based on our
determination that the DPS faces threats that are overall of high
magnitude and are imminent. An LPN of 3 is the highest priority that
can be assigned to a distinct population segment. We will continue to
monitor the threats to the native Arctic grayling of the upper Missouri
River, and the DPS' status on an annual basis, and should the magnitude
or the imminence of the threats change, we will revisit our assessment
of LPN.
Preclusion and Expeditious Progress
Preclusion is a function of the listing priority of a species in
relation to the resources that are available and competing demands for
those resources. Thus, in any given fiscal year (FY), multiple factors
dictate whether it will be possible to undertake work on a proposed
listing regulation or whether promulgation of such a proposal is
warranted but precluded by higher priority listing actions.
The resources available for listing actions are determined through
the annual Congressional appropriations process. The appropriation for
the Listing Program is available to support work involving the
following listing actions: Proposed and final listing rules; 90-day and
12-month findings on petitions to add species to the Lists of
Endangered and Threatened Wildlife and Plants (Lists) or to change the
status of a species from threatened to endangered; annual
determinations on prior ``warranted but precluded'' petition findings
as required under section 4(b)(3)(C)(i) of the ESA; critical habitat
petition findings; proposed and final rules designating critical
habitat; and litigation-related, administrative, and program-management
functions (including preparing and allocating budgets, responding to
congressional and public inquiries, and conducting public outreach
regarding listing and critical habitat). The work involved in preparing
various listing documents can be extensive and may include, but is not
limited to: Gathering and assessing the best scientific and commercial
data available and conducting analyses used as the basis for our
decisions; writing and publishing documents; and obtaining, reviewing,
and evaluating public comments and peer review comments on proposed
rules and incorporating relevant information into final rules. The
number of listing actions that we can undertake in a given year also is
influenced by the complexity of those listing actions; that is, more
complex actions generally are more costly. For example, during the past
several years, the cost (excluding publication costs) for preparing a
12-month finding, without a proposed rule, has ranged from
approximately $11,000 for one species with a restricted range and
involving a relatively uncomplicated analysis to $305,000 for
[[Page 54745]]
another species that is wide-ranging and involving a complex analysis.
We cannot spend more than is appropriated for the Listing Program
without violating the Anti-Deficiency Act (see 31 U.S.C.
1341(a)(1)(A)). In addition, in FY 1998 and for each FY since then,
Congress has placed a statutory cap on funds which may be expended for
the Listing Program, equal to the amount expressly appropriated for
that purpose in that FY. This cap was designed to prevent funds
appropriated for other functions under the ESA (for example, recovery
funds for removing species from the Lists), or for other Service
programs, from being used for Listing Program actions (see House Report
105-163, 105\th\ Congress, 1st Session, July 1, 1997).
Recognizing that designation of critical habitat for species
already listed would consume most of the overall Listing Program
appropriation, Congress also put a critical habitat subcap in place in
FY 2002 and has retained it each subsequent year to ensure that some
funds are available for other work in the Listing Program: ``The
critical habitat designation subcap will ensure that some funding is
available to address other listing activities'' (House Report No. 107 -
103, 107\th\ Congress, 1st Session, June 19, 2001). In FY 2002 and each
year until FY 2006, the Service has had to use virtually the entire
critical habitat subcap to address court-mandated designations of
critical habitat, and consequently none of the critical habitat subcap
funds have been available for other listing activities. In FY 2007, we
were able to use some of the critical habitat subcap funds to fund
proposed listing determinations for high-priority candidate species. In
FY 2009, while we were unable to use any of the critical habitat subcap
funds to fund proposed listing determinations, we did use some of this
money to fund the critical habitat portion of some proposed listing
determinations so that the proposed listing determination and proposed
critical habitat designation could be combined into one rule, thereby
being more efficient in our work. In FY 2010, we are using some of the
critical habitat subcap funds to fund actions with statutory deadlines.
Thus, through the listing cap, the critical habitat subcap, and the
amount of funds needed to address court-mandated critical habitat
designations, Congress and the courts have in effect determined the
amount of money available for other listing activities. Therefore, the
funds in the listing cap, other than those needed to address court-
mandated critical habitat for already listed species, set the limits on
our determinations of preclusion and expeditious progress.
Congress also recognized that the availability of resources was the
key element in deciding, when making a 12-month petition finding,
whether we would prepare and issue a listing proposal or instead make a
``warranted but precluded'' finding for a given species. The Conference
Report accompanying Public Law 97-304, which established the current
statutory deadlines and the warranted-but-precluded finding, states (in
a discussion on 90-day petition findings that by its own terms also
covers 12-month findings) that the deadlines were ``not intended to
allow the Secretary to delay commencing the rulemaking process for any
reason other than that the existence of pending or imminent proposals
to list species subject to a greater degree of threat would make
allocation of resources to such a petition [that is, for a lower-
ranking species] unwise.''
In FY 2010, expeditious progress is that amount of work that can be
achieved with $10,471,000, which is the amount of money that Congress
appropriated for the Listing Program (that is, the portion of the
Listing Program funding not related to critical habitat designations
for species that are already listed). However these funds are not
enough to fully fund all our court-ordered and statutory listing
actions in FY 2010, so we are using $1,114,417 of our critical habitat
subcap funds in order to work on all of our required petition findings
and listing determinations. This brings the total amount of funds we
have for listing actions in FY 2010 to $11,585,417. Our process is to
make our determinations of preclusion on a nationwide basis to ensure
that the species most in need of listing will be addressed first and
also because we allocate our listing budget on a nationwide basis. The
$11,585,417 is being used to fund work in the following categories:
compliance with court orders and court-approved settlement agreements
requiring that petition findings or listing determinations be completed
by a specific date; section 4 (of the ESA) listing actions with
absolute statutory deadlines; essential litigation-related,
administrative, and listing program-management functions; and high-
priority listing actions for some of our candidate species. In 2009,
the responsibility for listing foreign species under the ESA was
transferred from the Division of Scientific Authority, International
Affairs Program, to the Endangered Species Program. Starting in FY
2010, a portion of our funding is being used to work on the actions
described above as they apply to listing actions for foreign species.
This has the potential to further reduce funding available for domestic
listing actions, although there are currently no foreign species issues
included in our high-priority listing actions at this time. The
allocations for each specific listing action are identified in the
Service's FY 2010 Allocation Table (part of our administrative record).
In FY 2007, we had more than 120 species with an LPN of 2, based on
our September 21, 1983, guidance for assigning an LPN for each
candidate species (48 FR 43098). Using this guidance, we assign each
candidate an LPN of 1 to 12, depending on the magnitude of threats
(high vs. moderate to low), immediacy of threats (imminent or
nonimminent), and taxonomic status of the species (in order of
priority: monotypic genus (a species that is the sole member of a
genus); species; or part of a species (subspecies, distinct population
segment, or significant portion of the range)). The lower the listing
priority number, the higher the listing priority (that is, a species
with an LPN of 1 would have the highest listing priority). Because of
the large number of high-priority species, we further ranked the
candidate species with an LPN of 2 by using the following extinction-
risk type criteria: IUCN Red list status/rank, Heritage rank (provided
by NatureServe), Heritage threat rank (provided by NatureServe), and
species currently with fewer than 50 individuals, or 4 or fewer
populations. Those species with the highest IUCN rank (critically
endangered), the highest Heritage rank (G1), the highest Heritage
threat rank (substantial, imminent threats), and currently with fewer
than 50 individuals, or fewer than 4 populations, comprised a group of
approximately 40 candidate species (``Top 40''). These 40 candidate
species have had the highest priority to receive funding to work on a
proposed listing determination. As we work on proposed and final
listing rules for these 40 candidates, we are applying the ranking
criteria to the next group of candidates with an LPN of 2 and 3 to
determine the next set of highest priority candidate species.
To be more efficient in our listing process, as we work on proposed
rules for these species in the next several years, we are preparing
multi-species proposals when appropriate, and these may include species
with lower priority if they overlap geographically or have the same
threats as a species with an LPN of 2. In addition, available staff
resources also are a factor in
[[Page 54746]]
determining high-priority species provided with funding. Finally,
proposed rules for reclassification of threatened species to endangered
are lower priority, since as listed species, they are already afforded
the protection of the ESA and implementing regulations.
We assigned the upper Missouri River DPS of Arctic grayling an LPN
of 3, based on our finding that the DPS faces immediate and high
magnitude threats from the present or threatened destruction,
modification, or curtailment of its habitat; competition with and
predation by nonnative trout; and the inadequacy of existing regulatory
mechanisms. One or more of the threats discussed above occurs in each
known population in the Missouri River basin. These threats are ongoing
and, in some cases (e.g., nonnative species), considered irreversible.
Under our 1983 Guidelines, a ``species'' facing imminent high-magnitude
threats is assigned an LPN of 1, 2, or 3, depending on its taxonomic
status. Work on a proposed listing determination for the upper Missouri
River DPS of Arctic grayling is precluded by work on higher priority
candidate species (i.e., species with LPN of 2); listing actions with
absolute statutory, court ordered, or court-approved deadlines; and
final listing determinations for those species that were proposed for
listing with funds from previous FYs. This work includes all the
actions listed in the tables below under expeditious progress.
As explained above, a determination that listing is warranted but
precluded also must demonstrate that expeditious progress is being made
to add or remove qualified species to and from the Lists of Endangered
and Threatened Wildlife and Plants. (Although we do not discuss it in
detail here, we also are making expeditious progress in removing
species from the Lists under the Recovery program, which is funded by a
separate line item in the budget of the Endangered Species Program. As
explained above in our description of the statutory cap on Listing
Program funds, the Recovery Program funds and actions supported by them
cannot be considered in determining expeditious progress made in the
Listing Program.) As with our ``precluded'' finding, expeditious
progress in adding qualified species to the Lists is a function of the
resources available and the competing demands for those funds. Given
that limitation, we find that we are making progress in FY 2010 in the
Listing Program. This progress included preparing and publishing the
determinations presented in Table 6.
TABLE 6. FY2010 Completed Listing Actions
----------------------------------------------------------------------------------------------------------------
Publication Date Title Actions FR Pages
----------------------------------------------------------------------------------------------------------------
10/08/2009 Listing Lepidium papilliferum Final Listing, 74 FR 52013-52064
(Slickspot Peppergrass) as a Threatened...........
Threatened Species Throughout
Its Range.
----------------------------------------------------------------------------------------------------------------
10/27/2009 90-day Finding on a Petition Notice of 90-day 74 FR 55177-55180
To List the American Dipper Petition Finding,
in the Black Hills of South Not Substantial
Dakota as Threatened or
Endangered
----------------------------------------------------------------------------------------------------------------
10/28/2009 Status Review of Arctic Notice of Intent to 74 FR 55524-55525
Grayling (Thymallus arcticus) Conduct Status
in the Upper Missouri River Review
System
----------------------------------------------------------------------------------------------------------------
11/03/2009 Listing the British Columbia Proposed Listing 74 FR 56757-56770
Distinct Population Segment Threatened
of the Queen Charlotte
Goshawk Under the ESA:
Proposed rule.
----------------------------------------------------------------------------------------------------------------
11/03/2009 Listing the Salmon-Crested Proposed Listing 74 FR 56770-56791
Cockatoo as Threatened Threatened
Throughout Its Range with
Special Rule
----------------------------------------------------------------------------------------------------------------
11/23/2009 Status Review of Gunnison sage- Notice of Intent to 74 FR 61100-61102
grouse (Centrocercus minimus) Conduct Status
Review
----------------------------------------------------------------------------------------------------------------
12/03/2009 12-Month Finding on a Petition Notice of 12-month 74 FR 63343-63366
to List the Black-tailed Petition Finding,
Prairie Dog as Threatened or Not warranted
Endangered
----------------------------------------------------------------------------------------------------------------
12/03/2009 90-Day Finding on a Petition Notice of 90-day 74 FR 63337-63343
to List Sprague's Pipit as Petition Finding,
Threatened or Endangered Substantial
----------------------------------------------------------------------------------------------------------------
12/15/2009 90-Day Finding on Petitions To Notice of 90-day 74 FR 66260-66271
List 9 Species of Mussels Petition Finding,
From Texas as Threatened or Substantial
Endangered With Critical
Habitat
----------------------------------------------------------------------------------------------------------------
12/16/2009 Partial 90-Day Finding on a Notice of 90-day 74 FR 66865-66905
Petition to List 475 Species Petition Finding,
in the Southwestern United Not Substantial &
States as Threatened or Substantial
Endangered With Critical
Habitat
----------------------------------------------------------------------------------------------------------------
12/17/2009 12-month Finding on a Petition Notice of 12-month 74 FR 66937-66950
To Change the Final Listing Petition Finding,
of the Distinct Population Warranted but
Segment of the Canada Lynx To Precluded
Include New Mexico
----------------------------------------------------------------------------------------------------------------
01/05/2010 Listing Foreign Bird Species Proposed Listing, 75 FR 605-649
in Peru & Bolivia as Endangered
Endangered Throughout Their
Range
----------------------------------------------------------------------------------------------------------------
[[Page 54747]]
01/05/2010 Listing Six Foreign Birds as Proposed Listing, 75 FR 286-310
Endangered Throughout Their Endangered
Range
----------------------------------------------------------------------------------------------------------------
01/05/2010 Withdrawal of Proposed Rule to Proposed rule, 75 FR 310-316
List Cook's Petrel Withdrawal
----------------------------------------------------------------------------------------------------------------
01/05/2010 Final Rule to List the Final Listing, 75 FR 235-250
Galapagos Petrel & Heinroth's Threatened
Shearwater as Threatened
Throughout Their Ranges
----------------------------------------------------------------------------------------------------------------
01/20/2010 Initiation of Status Review Notice of Intent to 75 FR 3190-3191
for Agave eggersiana & Conduct Status
Solanum conocarpum Review
----------------------------------------------------------------------------------------------------------------
02/09/2010 12-month Finding on a Petition Notice of 12-month 75 FR 6437-6471
to List the American Pika as Petition Finding,
Threatened or Endangered Not Warranted
----------------------------------------------------------------------------------------------------------------
02/25/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 8601-8621
To List the Sonoran Desert Petition Finding,
Population of the Bald Eagle Not Warranted
as a Threatened or Endangered
Distinct Population Segment.
----------------------------------------------------------------------------------------------------------------
02/25/2010 Withdrawal of Proposed Rule To Withdrawal of 75 FR 8621-8644
List the Southwestern Proposed Rule to
Washington/Columbia River List
Distinct Population Segment
of Coastal Cutthroat Trout
(Oncorhynchus clarki clarki)
as Threatened
----------------------------------------------------------------------------------------------------------------
03/18/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 13068-13071
to List the Berry Cave Petition Finding,
salamander as Endangered Substantial
----------------------------------------------------------------------------------------------------------------
03/23/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 13717-13720
to List the Southern Petition Finding,
Hickorynut Mussel (Obovaria Not Substantial
jacksoniana) as Endangered or
Threatened
----------------------------------------------------------------------------------------------------------------
03/23/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 13720-13726
to List the Striped Newt as Petition Finding,
Threatened Substantial
----------------------------------------------------------------------------------------------------------------
03/23/2010 12-Month Findings for Notice of 12-month 75 FR 13910-14014
Petitions to List the Greater Petition Finding,
Sage-Grouse (Centrocercus Warranted but
urophasianus) as Threatened Precluded
or Endangered
----------------------------------------------------------------------------------------------------------------
03/31/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 16050-16065
to List the Tucson Shovel- Petition Finding,
Nosed Snake (Chionactis Warranted but
occipitalis klauberi) as Precluded
Threatened or Endangered with
Critical Habitat
----------------------------------------------------------------------------------------------------------------
04/05/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 17062-17070
To List Thorne's Hairstreak Petition Finding,
Butterfly as or Endangered Substantial
----------------------------------------------------------------------------------------------------------------
04/06/2010 12-month Finding on a Petition Notice of 12-month 75 FR 17352-17363
To List the Mountain Petition Finding,
Whitefish in the Big Lost Not Warranted
River, Idaho, as Endangered
or Threatened
----------------------------------------------------------------------------------------------------------------
04/06/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 17363-17367
to List a Stonefly (Isoperla Petition Finding,
jewetti) & a Mayfly (Fallceon Not Substantial
eatoni) as Threatened or
Endangered with Critical
Habitat
----------------------------------------------------------------------------------------------------------------
04/07/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 17667-17680
to Reclassify the Delta Smelt Petition Finding,
From Threatened to Endangered Warranted but
Throughout Its Range Precluded
----------------------------------------------------------------------------------------------------------------
04/13/2010 Determination of Endangered Final Listing, 75 FR 18959-19165
Status for 48 Species on Endangered
Kauai & Designation of
Critical Habitat
----------------------------------------------------------------------------------------------------------------
04/15/2010 Initiation of Status Review of Notice of Initiation 75 FR 19591-19592
the North American Wolverine of Status Review
in the Contiguous United
States
----------------------------------------------------------------------------------------------------------------
[[Page 54748]]
04/15/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 19592-19607
to List the Wyoming Pocket Petition Finding,
Gopher as Endangered or Not Warranted
Threatened with Critical
Habitat
----------------------------------------------------------------------------------------------------------------
04/16/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 19925-19935
to List a Distinct Population Petition Finding,
Segment of the Fisher in Its Substantial..........
United States Northern Rocky
Mountain Range as Endangered
or Threatened with Critical
Habitat
----------------------------------------------------------------------------------------------------------------
04/20/2010 Initiation of Status Review Notice of Initiation 75 FR 20547-20548
for Sacramento splittail of Status Review
(Pogonichthys macrolepidotus)
----------------------------------------------------------------------------------------------------------------
04/26/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 21568-21571
to List the Harlequin Petition Finding,
Butterfly as Endangered Substantial..........
----------------------------------------------------------------------------------------------------------------
04/27/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 22012-22025
to List Susan's Purse-making Petition Finding,
Caddisfly (Ochrotrichia Not Warranted
susanae) as Threatened or
Endangered
----------------------------------------------------------------------------------------------------------------
04/27/2010 90-day Finding on a Petition Notice of 90-day 75 FR 22063-22070
to List the Mohave Ground Petition Finding,
Squirrel as Endangered with Substantial
Critical Habitat
----------------------------------------------------------------------------------------------------------------
05/04/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 23654-23663
to List Hermes Copper Petition Finding,
Butterfly as Threatened or Substantial
Endangered
----------------------------------------------------------------------------------------------------------------
6/1/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 30313-30318
To List Castanea pumila var. Petition Finding,
ozarkensis Substantial
----------------------------------------------------------------------------------------------------------------
6/1/2010 12-month Finding on a Petition Notice of 12-month 75 FR 30338-30363
to List the White-tailed petition finding,
Prairie Dog as Endangered or Not warranted
Threatened
----------------------------------------------------------------------------------------------------------------
6/9/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 32728-32734
To List van Rossem's Gull- Petition Finding,
billed Tern as Endangered Substantial
orThreatened.
----------------------------------------------------------------------------------------------------------------
6/16/2010 90-Day Finding on Five Notice of 90-day 75 FR 34077-34088
Petitions to List Seven Petition Finding,
Species of Hawaiian Yellow- Substantial
faced Bees as Endangered
----------------------------------------------------------------------------------------------------------------
6/22/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 35398-35424
to List the Least Chub as petition finding,
Threatened or Endangered Warranted but
precluded
----------------------------------------------------------------------------------------------------------------
6/23/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 35746-35751
to List the Honduran Emerald Petition Finding,
Hummingbird as Endangered Substantial
----------------------------------------------------------------------------------------------------------------
6/23/2010 Listing Ipomopsis polyantha Proposed Listing 75 FR 35721-35746
(Pagosa Skyrocket) as Endangered Proposed
Endangered Throughout Its Listing Threatened
Range, and Listing Penstemon
debilis (Parachute
Beardtongue) and Phacelia
submutica (DeBeque Phacelia)
as Threatened Throughout
Their Range
----------------------------------------------------------------------------------------------------------------
6/24/2010 Listing the Flying Earwig Final Listing 75 FR 35990-36012
Hawaiian Damselfly and Endangered
Pacific Hawaiian Damselfly As
Endangered Throughout Their
Ranges
----------------------------------------------------------------------------------------------------------------
6/24/2010 Listing the Cumberland Darter, Proposed Listing 75 FR 36035-36057
Rush Darter, Yellowcheek Endangered
Darter, Chucky Madtom, and
Laurel Dace as Endangered
Throughout Their Ranges
----------------------------------------------------------------------------------------------------------------
6/29/2010 Listing the Mountain Plover as Reinstatement of 75 FR 37353-37358
Threatened Proposed Listing
Threatened
----------------------------------------------------------------------------------------------------------------
7/20/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 42033-42040
to List Pinus albicaulis Petition Finding,
(Whitebark Pine) as Substantial
Endangered or Threatened with
Critical Habitat
----------------------------------------------------------------------------------------------------------------
[[Page 54749]]
7/20/2010 12-Month Finding on a Petition Notice of 12-month 75 FR 42040-42054
to List the Amargosa Toad as petition finding,
Threatened or Endangered Not warranted
----------------------------------------------------------------------------------------------------------------
7/20/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 42059-42066
to List the Giant Palouse Petition Finding,
Earthworm (Driloleirus Substantial
americanus) as Threatened or
Endangered
----------------------------------------------------------------------------------------------------------------
7/27/2010 Determination on Listing the Final Listing 75 FR 43844-43853
Black-Breasted Puffleg as Endangered
Endangered Throughout its
Range; Final Rule
----------------------------------------------------------------------------------------------------------------
7/27/2010 Final Rule to List the Medium Final Listing 75 FR 43853-43864
Tree-Finch (Camarhynchus Endangered
pauper) as Endangered
Throughout Its Range
----------------------------------------------------------------------------------------------------------------
8/3/2010 Determination of Threatened Final Listing 75 FR 45497- 45527
Status for Five Penguin Threatened
Species
----------------------------------------------------------------------------------------------------------------
8/4/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 46894- 46898
To List the Mexican Gray Wolf Petition Finding,
as an Endangered Subspecies Substantial
With Critical Habitat
----------------------------------------------------------------------------------------------------------------
8/10/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 48294-48298
to List Arctostaphylos Petition Finding,
franciscana as Endangered Substantial
with Critical Habitat
----------------------------------------------------------------------------------------------------------------
8/17/2010 Listing Three Foreign Bird Final Listing 75 FR 50813-50842
Species from Latin America Endangered
and the Caribbean as
Endangered Throughout Their
Range
----------------------------------------------------------------------------------------------------------------
8/17/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 50739-50742
to List Brian Head Petition Finding,
Mountainsnail as Endangered Not substantial
or Threatened with Critical
Habitat
----------------------------------------------------------------------------------------------------------------
8/24/2010 90-Day Finding on a Petition Notice of 90-day 75 FR 51969-51974
to List the Oklahoma Grass Petition Finding,
Pink Orchid as Endangered or Substantial
Threatened
----------------------------------------------------------------------------------------------------------------
Our expeditious progress also includes work on listing actions that
we funded in FY 2010 but have not yet been completed to date (Table 7).
These actions are listed below. Actions in the top section of the table
are being conducted under a deadline set by a court. Actions in the
middle section of the table are being conducted to meet statutory
timelines, that is, timelines required under the ESA. Actions in the
bottom section of the table are high-priority listing actions. These
actions include work primarily on species with an LPN of 2, and
selection of these species is partially based on available staff
resources, and when appropriate, include species with a lower priority
if they overlap geographically or have the same threats as the species
with the high priority. Including these species together in the same
proposed rule results in considerable savings in time and funding, as
compared to preparing separate proposed rules for each of them in the
future.
TABLE 7. Actions Funded in FY 2010 But Not Yet Completed
------------------------------------------------------------------------
Species Action
------------------------------------------------------------------------
Actions Subject to Court Order/Settlement Agreement
------------------------------------------------------------------------
6 Birds from Eurasia Final listing determination
------------------------------------------------------------------------
African penguin Final listing determination
------------------------------------------------------------------------
Flat-tailed horned lizard Final listing determination
------------------------------------------------------------------------
Mountain plover\4\ Final listing determination
------------------------------------------------------------------------
6 Birds from Peru Proposed listing
determination
------------------------------------------------------------------------
Sacramento splittail 12-month petition finding
------------------------------------------------------------------------
Pacific walrus 12-month petition finding
------------------------------------------------------------------------
Gunnison sage-grouse 12-month petition finding
------------------------------------------------------------------------
Wolverine 12-month petition finding
------------------------------------------------------------------------
[[Page 54750]]
Arctic grayling 12-month petition finding
------------------------------------------------------------------------
Agave eggergsiana 12-month petition finding
------------------------------------------------------------------------
Solanum conocarpum 12-month petition finding
------------------------------------------------------------------------
Jemez Mountains salamander 12-month petition finding
------------------------------------------------------------------------
Sprague's pipit 12-month petition finding
------------------------------------------------------------------------
Desert tortoise - Sonoran population 12-month petition finding
------------------------------------------------------------------------
Pygmy rabbit (rangewide)\1\ 12-month petition finding
------------------------------------------------------------------------
Thorne's Hairstreak butterfly\4\ 12-month petition finding
------------------------------------------------------------------------
Hermes copper butterfly\4\ 12-month petition finding
------------------------------------------------------------------------
Actions with Statutory Deadlines
------------------------------------------------------------------------
Casey's june beetle Final listing determination
------------------------------------------------------------------------
Georgia pigtoe, interrupted rocksnail, Final listing determination
and rough hornsnail
------------------------------------------------------------------------
7 Bird species from Brazil Final listing determination
------------------------------------------------------------------------
Southern rockhopper penguin - Campbell Final listing determination
Plateau population
------------------------------------------------------------------------
5 Bird species from Colombia and Ecuador Final listing determination
------------------------------------------------------------------------
Queen Charlotte goshawk Final listing determination
------------------------------------------------------------------------
5 species southeast fish (Cumberland Final listing determination
Darter, Rush Darter, Yellowcheek Darter,
Chucky Madtom, and Laurel Dace)
------------------------------------------------------------------------
Salmon crested cockatoo Proposed listing
determination
------------------------------------------------------------------------
CA golden trout 12-month petition finding
------------------------------------------------------------------------
Black-footed albatross 12-month petition finding
------------------------------------------------------------------------
Mount Charleston blue butterfly 12-month petition finding
------------------------------------------------------------------------
Mojave fringe-toed lizard\1\ 12-month petition finding
------------------------------------------------------------------------
Kokanee - Lake Sammamish population\1\ 12-month petition finding
------------------------------------------------------------------------
Cactus ferruginous pygmy-owl\1\ 12-month petition finding
------------------------------------------------------------------------
Northern leopard frog 12-month petition finding
------------------------------------------------------------------------
Tehachapi slender salamander 12-month petition finding
------------------------------------------------------------------------
Coqui Llanero 12-month petition finding
------------------------------------------------------------------------
Dusky tree vole 12-month petition finding
------------------------------------------------------------------------
3 MT invertebrates (mist forestfly(Lednia 12-month petition finding
tumana), Oreohelix sp.3, Oreohelix sp.
31) from 206 species petition
------------------------------------------------------------------------
5 UT plants (Astragalus hamiltonii, 12-month petition finding
Eriogonum soredium, Lepidium ostleri,
Penstemon flowersii, Trifolium
friscanum) from 206 species petition
------------------------------------------------------------------------
2 CO plants (Astragalus microcymbus, 12-month petition finding
Astragalus schmolliae) from 206 species
petition
------------------------------------------------------------------------
5 WY plants (Abronia ammophila, Agrostis 12-month petition finding
rossiae, Astragalus proimanthus,
Boechere (Arabis) pusilla, Penstemon
gibbensii) from 206 species petition
------------------------------------------------------------------------
Leatherside chub (from 206 species 12-month petition finding
petition)
------------------------------------------------------------------------
[[Page 54751]]
Frigid ambersnail (from 206 species 12-month petition finding
petition)
------------------------------------------------------------------------
Gopher tortoise - eastern population 12-month petition finding
------------------------------------------------------------------------
Wrights marsh thistle 12-month petition finding
------------------------------------------------------------------------
67 of 475 southwest species 12-month petition finding
------------------------------------------------------------------------
Grand Canyon scorpion (from 475 species 12-month petition finding
petition)
------------------------------------------------------------------------
Anacroneuria wipukupa (a stonefly from 12-month petition finding
475 species petition)
------------------------------------------------------------------------
Rattlesnake-master borer moth (from 475 12-month petition finding
species petition)
------------------------------------------------------------------------
3 Texas moths (Ursia furtiva, 12-month petition finding
Sphingicampa blanchardi, Agapema
galbina) (from 475 species petition)
------------------------------------------------------------------------
2 Texas shiners (Cyprinella sp., 12-month petition finding
Cyprinella lepida) (from 475 species
petition)
------------------------------------------------------------------------
3 South Arizona plants (Erigeron 12-month petition finding
piscaticus, Astragalus hypoxylus,
Amoreuxia gonzalezii) (from 475 species
petition)
------------------------------------------------------------------------
5 Central Texas mussel species (3 from 12-month petition finding
474 species petition)
------------------------------------------------------------------------
14 parrots (foreign species) 12-month petition finding
------------------------------------------------------------------------
Berry Cave salamander\1\ 12-month petition finding
------------------------------------------------------------------------
Striped Newt\1\ 12-month petition finding
------------------------------------------------------------------------
Fisher - Northern Rocky Mountain Range\1\ 12-month petition finding
------------------------------------------------------------------------
Mohave Ground Squirrel\1\ 12-month petition finding
------------------------------------------------------------------------
Puerto Rico Harlequin Butterfly 12-month petition finding
------------------------------------------------------------------------
Western gull-billed tern 12-month petition finding
------------------------------------------------------------------------
Ozark chinquapin (Castanea pumila var. 12-month petition finding
ozarkensis)
------------------------------------------------------------------------
HI yellow-faced bees 12-month petition finding
------------------------------------------------------------------------
Giant Palouse earthworm 12-month petition finding
------------------------------------------------------------------------
Whitebark pine 12-month petition finding
------------------------------------------------------------------------
OK grass pink (Calopogon oklahomensis)\1\ 12-month petition finding
------------------------------------------------------------------------
Southeastern pop snowy plover & wintering 90-day petition finding
pop. of piping plover\1\
------------------------------------------------------------------------
Eagle Lake trout\1\ 90-day petition finding
------------------------------------------------------------------------
Smooth-billed ani\1\ 90-day petition finding
------------------------------------------------------------------------
Bay Springs salamander\1\ 90-day petition finding
------------------------------------------------------------------------
32 species of snails and slugs\1\ 90-day petition finding
------------------------------------------------------------------------
42 snail species (Nevada & Utah) 90-day petition finding
------------------------------------------------------------------------
Red knot roselaari subspecies 90-day petition finding
------------------------------------------------------------------------
Peary caribou 90-day petition finding
------------------------------------------------------------------------
Plains bison 90-day petition finding
------------------------------------------------------------------------
Spring Mountains checkerspot butterfly 90-day petition finding
------------------------------------------------------------------------
Spring pygmy sunfish 90-day petition finding
------------------------------------------------------------------------
Bay skipper 90-day petition finding
------------------------------------------------------------------------
[[Page 54752]]
Unsilvered fritillary 90-day petition finding
------------------------------------------------------------------------
Texas kangaroo rat 90-day petition finding
------------------------------------------------------------------------
Spot-tailed earless lizard 90-day petition finding
------------------------------------------------------------------------
Eastern small-footed bat 90-day petition finding
------------------------------------------------------------------------
Northern long-eared bat 90-day petition finding
------------------------------------------------------------------------
Prairie chub 90-day petition finding
------------------------------------------------------------------------
10 species of Great Basin butterfly 90-day petition finding
------------------------------------------------------------------------
6 sand dune (scarab) beetles 90-day petition finding
------------------------------------------------------------------------
Golden-winged warbler 90-day petition finding
------------------------------------------------------------------------
Sand-verbena moth 90-day petition finding
------------------------------------------------------------------------
404 Southeast species 90-day petition finding
------------------------------------------------------------------------
High Priority Listing Actions\3\
------------------------------------------------------------------------
19 Oahu candidate species\3\ (16 plants, Proposed listing
3 damselflies) (15 with LPN = 2, 3 with
LPN = 3, 1 with LPN =9)
------------------------------------------------------------------------
19 Maui-Nui candidate species\3\ (16 Proposed listing
plants, 3 tree snails) (14 with LPN = 2,
2 with LPN = 3, 3 with LPN = 8)
------------------------------------------------------------------------
Dune sagebrush lizard (formerly Sand dune Proposed listing
lizard)\3\ (LPN = 2)
------------------------------------------------------------------------
2 Arizona springsnails\3\ (Pyrgulopsis Proposed listing
bernadina (LPN = 2), Pyrgulopsis
trivialis (LPN = 2))
------------------------------------------------------------------------
New Mexico springsnail\3\ (Pyrgulopsis Proposed listing
chupaderae (LPN = 2)
------------------------------------------------------------------------
2 mussels\3\ (rayed bean (LPN = 2), Proposed listing
snuffbox No LPN)
------------------------------------------------------------------------
2 mussels\3\ (sheepnose (LPN = 2), Proposed listing
spectaclecase (LPN = 4),)
------------------------------------------------------------------------
Ozark hellbender\2\ (LPN = 3) Proposed listing
------------------------------------------------------------------------
Altamaha spinymussel\3\ (LPN = 2) Proposed listing
------------------------------------------------------------------------
8 southeast mussels (southern kidneyshell Proposed listing
(LPN = 2), round ebonyshell (LPN = 2),
Alabama pearlshell (LPN = 2), southern
sandshell (LPN = 5), fuzzy pigtoe (LPN =
5), Choctaw bean (LPN = 5), narrow
pigtoe (LPN = 5), and tapered pigtoe
(LPN = 11))
------------------------------------------------------------------------
\1\ Funds for listing actions for these species were provided in
previous FYs.
\2\ We funded a proposed rule for this subspecies with an LPN of 3 ahead
of other species with LPN of 2, because the threats to the species
were so imminent and of a high magnitude that we considered emergency
listing if we were unable to fund work on a proposed listing rule in
FY 2008.
\3\ Although funds for these high-priority listing actions were provided
in FY 2008 or 2009, due to the complexity of these actions and
competing priorities, these actions are still being developed.
\4\Partially funded with FY 2010 funds; also will be funded with FY 2011
funds.
We have endeavored to make our listing actions as efficient and
timely as possible, given the requirements of the relevant law and
regulations, and constraints relating to workload and personnel. We are
continually considering ways to streamline processes or achieve
economies of scale, such as by batching related actions together. Given
our limited budget for implementing section 4 of the ESA, these actions
described above collectively constitute expeditious progress.
The upper Missouri River DPS of Arctic grayling will be added to
the list of candidate species upon publication of this 12-month
finding. We will continue to monitor the status of this species as new
information becomes available. This review will determine if a change
in status is warranted, including the need to make prompt use of
emergency listing procedures.
We intend that any proposed listing action for the upper Missouri
River DPS of Arctic grayling will be as accurate as possible.
Therefore, we will continue to accept additional information and
comments from all concerned governmental agencies, the scientific
community, industry, or any other interested party concerning this
finding.
References Cited
A complete list of references cited is available on the Internet at
http://
[[Page 54753]]
www.regulations.gov and upon request from the Montana Field Office (see
ADDRESSES section).
Authors
The primary authors of this notice are the staff members of the
Montana Field Office.
Authority
The authority for this action is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: August 30, 2010
Daniel M. Ashe,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2010-22038 Filed 9-7-10; 8:45 am]
BILLING CODE 4310-55-S