Atlantic salmon
FWS Focus

Overview

Scientific Name

Salmo salar
Common Name
Atlantic salmon
FWS Category
Fishes
Kingdom

Location in Taxonomic Tree

Genus
Species

Identification Numbers

TSN:

Characteristics

Characteristic category

Physical Characteristics

Characteristics

Weight

 Atlantic salmon generally weigh 8 to 12 pounds.  

Size & Shape

Typical size

Smolt 5 – 7 in (13 – 18 cm) length

Grilse/1 year at sea (1 sea-winter) 18 – 28 in (46-71 cm) length

Adult, 2 years at sea (2 sea-winters) 28 – 30 in (71 to 76 cm) length and 7.9 to 11.9 lbs (3.6 to 5.4 kg) weight.

Adult, 3 years at sea (3 sea-winters) 30 – 36 in (76 – 91 cm) length and 10 – 20 lbs (4.5 – 9.1 kg) weight

Color & Pattern

Coloration varies with age, environment and life stage. Freshwater life stages include egg, alevin or sac-fry, fry and parr. Eggs are typically a reddish-orange color owing to carotenoids (antioxidant pigment) that salmon get from their diet. Parr are distinguished by 8 to 11 pigmented bars alternating with a single row of red spots (Danie et al., 1984). Smolts will become silvery on the sides, parr marking will disappear while maintaining green/brown/blue coloration on the back. Adults will be silvery with numerous black spots scatter along the body but concentrated more toward the head. As adult spend more time in freshwater they darken. Post-spawning, kelts, are very dark and even referred to as black salmon (Behnke 2002).

Behnke R.J. Trout and Salmon of North America. New York, Free Press, 2002

Danie, D.S., J.G. Trial and J.G. Stanley. 1984. Species profiles: life histories and environmental requirements of coastal fish and invertebrates (North Atlantic) – Atlantic salmon. U.S. Fish and Wildlife Service. FWS/OBS-82/11.22. U.S. Army Corp of Engineers, TR EL-82-4. 19 pp. 

Physical Characteristics

Migration Behavior: Atlantic salmon are migratory. They are born in fresh water and then migrate to the ocean where they spend their adult lives growing and feeding. Atlantic salmon travel thousands of miles to their North Atlantic feeding grounds, usually near western Greenland. They remain for one to three years before returning to the river where they were hatched to reproduce. They can travel over 6,000 miles before coming back to rivers to spawn. They will sometimes travel 200 miles up river to find preferred places to spawn. The landlocked Atlantic salmon will migrate into the lakes’ tributary rivers to spawn.  

Characteristic category

Lifecycle

Characteristics

Lifecycle

Atlantic salmon are an anadromous fish, meaning they migrate from the ocean to their natal rivers and streams to spawn in late October and November when water temperatures are 40 to 50o F degrees (4 to 10o C) (Stanley and Trial 1995). This upstream spawning migration occurs during the late spring through early fall with the peak occurring in June. Females will create a redd, a series of depressions or pits in the stream bed by fanning their caudal fin. The female salmon will then deposit eggs into a pit while male salmon fertilize the eggs. The female then covers the eggs with gravel as she digs the next pit upstream. Redds are usually constructed at the downstream end of riffles or in areas with upwelling ground water. An average 2-sea-winter female produces about 7,500 eggs with larger females producing over 11,000 eggs (Baum and Meister 1971; Baum 1997).

Eggs typically hatch in late March or April depending on water temperature. Hatching can occur as late as June in northern latitudes. These hatchlings are called alevin or sac-fry and are about 0.6 inch long (15 mm). After about six weeks, when their yolk sac has been absorbed, the fry emerge from the gravel to seek food. In Maine, fry emerge from their redds in mid to late May. Survival from eggs to fry is highly variable and estimated to be from 15 to 35% (Legault 2004).

Young salmon are called parr with their distinguishing lateral red and black spots and vertical bands on the sides (Baum 1997). The parr will then spend two to three years in freshwater. The amount of time spent in freshwater is dependent on the productivity and temperature of the water. The parr will need to reach a minimum size before they will make the transition to a smolt.

When the juveniles are about six inches (150 mm) long, they undergo several physical changes. The lose their parr marking and become silvery in color and begin emigrating from fresh to sea water. This is called the smolt stage during which the salmon undergo numerous physiological changes that allow it to make the transition from living in freshwater to living in saltwater. Survival from egg to the smolt stage is estimated to range from 0.5 to 3.5% (Legault 2004). The smolt will migrate along the northeast coast of Canada as they continue to grow and mature. Now termed post smolts, they will overwinter in an area of the Atlantic Ocean known as Grand Bank and the Labrador Sea. The following summer most Atlantic salmon will continue migrating northward to the summer feeding grounds off of the southwest coast of Greenland. Those Atlantic salmon will return to Grand Bank for a second winter in the ocean. The majority of adult return to their natal river after having spent two winters at sea; however, a few mature males will return after only one winter at sea (grilse) and few will return after three winters at sea. Unlike Pacific salmon that die after spawning, Atlantic salmon are capable of spawning in more than one reproductive season. This is known as iteroparity. While these repeat spawners once made up 30 to 40 percent of the spawning population, today, they represent less that 5 percent of the spawning population. The typical lifespan is 5 years; however, they can live up to 11 years.

Not all juvenile Atlantic salmon will migrate. Some males will become precocious parr, sexually mature and capable of fertilizing eggs. This adaptation mitigates the perils of the marine environment (Danie et al., 1984).

Baum, E.T. and A. L. Meister. 1971. Fecundity of Atlantic salmon (Salmo salar) from two Maine Rivers. Journal of the Fisheries Research Board of Canada 28(5): 764-767.

Baum E.T. Maine Atlantic Salmon. A National Treasure. Hermon, Maine. Atlantic Salmon Unlimited. 1997

Danie, D.S., J.G. Trial and J.G. Stanley. 1984. Species profiles: life histories and environmental requirements of coastal fish and invertebrates (North Atlantic) – Atlantic salmon. U.S. Fish and Wildlife Service. FWS/OBS-82/11.22. U.S. Army Corp of Engineers, TR EL-82-4. 19 pp.

Legault, C.M. 2004. Salmon PVA: a population analysis model of Atlantic salmon in the Maine Distinct Population Segment. Ref. Doc. 04-02. Woods Hole, MA 88 pp.

Stanley, J.G. and J.G. Trial. 1995. Habitat Suitability Index Models: Nonmigratory Freshwater Life Stages of Atlantic Salmon. Biological Science Report 3. Department of the Interior. Washington DC 

Lifespan

The typical lifespan is 5 years; however, they can live up to 11 years.

Reproduction

See Life Cycle

Characteristic category

Geography

Characteristics

Range

Atlantic salmon are indigenous to the North Atlantic Ocean from Portugal to Russia in Europe, from Housatonic River (Long Island Sound) to Northern Quebec in North America and the Baltic sea. In the United States, they were once found in almost every river north from the Housatonic River in Connecticut to the St. Croix River in Maine.  In addition to these anadromous populations of Atlantic salmon, there are non-anadromous or landlocked populations in North America and Europe. In the United States, there are four historic landlocked populations in Maine (Grand Lake, Green Lake, Sebago Lake and Sebec Lake) and populations in Lake Champlain and Lake Ontario. Citation: (Warner and Harvey 1985)

Atlantic salmon are born in freshwater and then migrate to the ocean where they spend their adult lives feeding and growing. Atlantic salmon migrate thousands of miles to their North Atlantic feeding grounds, usually near western Greenland. The migration of a typical Atlantic salmon begins in the spring as the smolt swim downstream from their natal rivers and embark on a journey to the Northwest Atlantic Ocean. Atlantic salmon from Maine have been documented in Nova Scotia, Newfoundland Labrador, West and East Greenland and even as far away as the Faroe Islands (Baum 1997). They are known to overwinter in the Labrador Sea and the Grand Banks (Baum 1997; Danie, et al. 1984). They remain in the ocean for one to three years before returning to the river where they were hatched to reproduce. This Journey can be over 6,000 miles for those Atlantic salmon migrating to the Northwest Atlantic. Even their migration upstream is no small feat. They will sometimes travel 200 miles upriver to find preferred places to spawn.

During their ocean-going life history stage, U.S. Atlantic salmon will become part of a mixed stock with other Atlantic salmon from North American rivers. This North American stock complex will intermix with stocks from Europe and Iceland and share their summer feeding grounds off the coast of Greenland (Behnke, 2002).

Baum E.T. Maine Atlantic Salmon. A National Treasure. Hermon, Maine. Atlantic Salmon Unlimited. 1997

Behnke R.J. Trout and Salmon of North America. New York, Free Press, 2002

Danie, D.S., J.G. Trial and J.G. Stanley. 1984. Species profiles: life histories and environmental requirements of coastal fish and invertebrates (North Atlantic) – Atlantic salmon. U.S. Fish and Wildlife Service. FWS/OBS-82/11.22. U.S. Army Corp of Engineers, TR EL-82-4. 19 pp.

Warner, K. and K.A. Havey. The Landlocked salmon in Maine: Life History Ecology and Management of Maine Landlocked Salmon (Salmo salar). Maine Department of Inland Fisheries and Wildlife. Augusta, ME. 1985.

Characteristic category

Overview

Characteristics

Overview

Atlantic Salmon (Salmo salar) are native to coastal river drainages of the north Atlantic Ocean.  In the northeastern United State, the historic range include coastal river in Maine south to Long Island sound. Atlantic Salmon were locally abundant historically throughout their native range in New England (~300,000 adults ascending rivers each year) until the mid-1800s when logging, land development, dams, pollution (associated with the Industrial Revolution), and commercial fisheries significantly reduced the abundance of natural populations. By the 1950s, the total adult run of Atlantic salmon to all U.S. rivers had been reduced to approximately 500 to 2,000 fish. Today, their distribution is limited to the Gulf of Maine. The Gulf of Maine Distinct Population Segment (DPS) of Atlantic salmon was listed as an endangered in December of 2000 and included eight coastal rivers to include the Sheepscot River, Ducktrap River, Narraguagus River, Pleasant River, Machias River, East Machias River, Dennys River, and Cove Brook, a tributary to the Penobscot River (65 FR 69459). In July of 2009, the Gulf of Maine DPS was expanded to include Androscoggin, Kennebec, and Penobscot River basins and revised listing also included the hatchery populations, propagated at Craig Brook National Fish Hatchery and Green Lake National Fish Hatchery (74 FR 29300; 74 FR 29344).

Adult Atlantic salmon are an anadromous fish, meaning they migrate from the ocean, beginning in the spring, up their natal rivers and streams to spawn in late October and November. The species will spend two to three years in freshwater before migrating to the sea to mature. The majority of adults return after having spent two winters in saltwater; however, a few mature males will return after only spending one winter at sea (grilse) and few will return after having spent three winters at sea. Unlike pacific salmon that die after spawning, Atlantic salmon are capable of spawning in more than one reproductive season. This is known as iteroparity. While these repeat spawners once made up 30 to 40 percent of the spawning population, today, they represent less that 5 percent of the spawning population.

74 FR 29300. (June 19, 2009). Endangered and Threatened Species; Designation of Critical Habitat for Atlantic Salmon (Salmo salar) Gulf of Maine Distinct Population Segment.

74 FR 29344. (June 19, 2009). Endangered and Threatened Species; Determination of Endangered Status for the Gulf of Maine Distinct Population Segment of Atlantic Salmon. 

Characteristic category

Food

Characteristics

Food

In freshwater, fry feed on plankton, but has they grown their diet shifts to aquatic insects such as mayflies, stoneflies, caddisflies and midges and may eat small fish like minnows, dace, and alewife (Baum, 1997). At sea, they feed on insects, squid, shrimp and fishes such as herring, sand lances and capelin (Danie et al., 1984; Baum 1997).

Baum E.T. Maine Atlantic Salmon. A National Treasure. Hermon, Maine. Atlantic Salmon Unlimited. 1997

Danie, D.S., J.G. Trial and J.G. Stanley. 1984. Species profiles: life histories and environmental requirements of coastal fish and invertebrates (North Atlantic) – Atlantic salmon. U.S. Fish and Wildlife Service. FWS/OBS-82/11.22. U.S. Army Corp of Engineers, TR EL-82-4. 19 pp. 

Characteristic category

Habitat

Characteristics

Habitat

Atlantic Salmon, like most salmonid fishes, require well oxygenated, cool-to-cold flowing water with a moderate gradient and clean gravel substrate for spawning.

Water temperature is a critical factor for all salmonids.  The water temperatures for spawning are typically between 40 and 50o F (4.4 to 10o C). Optimal water temperatures for growth are between 59 and 66o F (5 to 19o C). As water temperatures increase above 73o F (23o C), the habitat become less hospitable and Atlantic salmon will search for cooler water. Temperatures above 90o F (32o C) are lethal.

Suitable spawning substrate is consistent with the flowing currents that Atlantic salmon prefer and consist of gravel and cobble in riffles with a water depth of 4 to 16 in (10 to 40 cm). Fry are found at a verity of depths depending on river morphology gravel. In New England streams these fry nursery habitats averaged 10 in (25 cm) in depth. Parr are typically found in slightly deeper water.

Once the Atlantic salmon emigrate from fresh to salt water were, they inhabit depths between 0 and 693ft (0 - 210 m).

This information was gleaned from Danie et al., 1984; Stanley and Trial 1995; and Baum 1997.

Baum E.T. Maine Atlantic Salmon. A National Treasure. Hermon, Maine. Atlantic Salmon Unlimited. 1997

Danie, D.S., J.G. Trial and J.G. Stanley. 1984. Species profiles: life histories and environmental requirements of coastal fish and invertebrates (North Atlantic) – Atlantic salmon. U.S. Fish and Wildlife Service. FWS/OBS-82/11.22. U.S. Army Corp of Engineers, TR EL-82-4. 19 pp.

Stanley, J.G. and J.G. Trial. 1995. Habitat Suitability Index Models: Nonmigratory Freshwater Life Stages of Atlantic Salmon. Biological Science Report 3. Department of the Interior. Washington DC

Marine

Of or relating to the sea.

River or Stream

A natural body of running water.

Characteristic category

Behavior

Characteristics

Behavior

In freshwater, fry feed on plankton, but has they grown their diet shifts to aquatic insects such as mayflies, stoneflies, caddisflies and midges and may eat small fish like minnows, dace, and alewife (Baum, 1997). At sea, they feed on insects, squid, shrimp and fishes such as herring, sand lances and capelin (Danie et al., 1984; Baum 1997).

Characteristic category

Similar Species

Characteristics

Similar Species

Brown trout

Steelhead 

Geography

Launching the map view for this species to view geographical data available, including but not limited to:

  • Range information, including populations
  • Distribution information
  • Ability to filter facilities that include, manage, or interact with the species

Launch Interactive Map

Timeline

Explore the information available for this taxon's timeline. You can select an event on the timeline to view more information, or cycle through the content available in the carousel below.

27 Items