Fish and Aquatic Conservation

illustration of an Atlantic Salmon

Atlantic salmon

Salmo salar, (Linnaeus, 1758)

Cool Facts

During their ocean going life history stage, European and North American Atlantic salmon populations intermix and share their summer feeding grounds off the coast of Greenland. The maximum reported age for Atlantic salmon is 13 years.

SIZE: Average length for Atlantic salmon is 28 in to 30 in (70 to 75cm) and average weight for Atlantic salmon is 8 to 12 lbs. (3.5 to 5.5 kg). The maximum reported length for Atlantic salmon is 4 ft. 11 in. (150 cm) and a maximum reported weight of 103 lbs. (46.8 kg).

RANGE: There are three recognized population units of Atlantic Salmon. These population units are the North American, European and Baltic Units. Atlantic salmon reproduce in coastal rivers of North America, Iceland, Europe and northwestern Russia. Even though many populations of Atlantic salmon are depleted in Canada, significant reproducing populations still remain throughout their historic range. Atlantic salmon have also been introduced in New Zealand, Chile and southern Argentina.

HABITAT: Spawning habitat for Atlantic salmon is described as gravel or rubble in swiftly moving water. Eggs normally hatch in the spring. After emerging from the gravel in their natal streams, young juveniles concentrate in nursery habitats typically characterized as riffle areas with adequate cover, shallow water depth and moderate to fast water flow. After two to three years, they migrate through the estuary and into the ocean where they inhabit depths between 0 and 210 m (0 – 693ft.). Some landlocked populations of Atlantic salmon do exist.

DIET: Juvenile Atlantic salmon feed mainly on aquatic insects, mollusks, crustaceans and fish. Adults feed on squid, shrimp and fish.

Natural History

Atlantic salmon, an anadromous species, have a complex life history which begins when they hatch as fry in their natal streams, then rear as juveniles in fresh water streams and tributaries and finally migrate to sea for their adult life history stage. This species usually spends two to three years in freshwater habitats before migrating to the ocean. They also spend two to three years in the ocean before returning to their natal streams to spawn. There are also lacustrine (lake dwelling) populations of Atlantic salmon, where the adults inhabit lakes and then migrate from lakes into the surrounding tributaries to spawn.

Most male Atlantic salmon die after they spawn the first time, while 10% to 40% of the females may survive and return to the sea in autumn or overwinter in rivers, feed one additional summer and then migrate to the ocean again. These individuals may spawn in the year following their first reproduction or may remain at sea for 18 months before returning once more to the river. Of the returning females, about 0.3 % to 6% spawn a second time and a very few spawn a third and fourth time.


The Gulf of Maine Distinct Population Segment is currently listed as Endangered under the Endangered Species Act. In 2009, Critical Habitat was designated for this distinct population segment.

At one time, the National Fish Hatchery System (NFHS) of the U.S. Fish and Wildlife Service used to stock Atlantic salmon in the Connecticut River of New England. Unfortunately, after poor returns back into the Connecticut River and its tributaries, the NFHS discontinued rearing and stocking Atlantic salmon for placement in the Connecticut River Basin in 2012.

The Fish and Wildlife Service still continues to monitor and assess Atlantic salmon resources in the Connecticut River.

Migration Behavior

Atlantic salmon are migratory species. These fish are born in fresh water and then migrate to the ocean for their adult lives and then return to fresh water to reproduce.