Maine Field Office - Ecological Services
Northeast Region

Gulf of Maine Distinct Population Segment of Atlantic salmon (Salmo salar) - Endangered

Adult male Atlantic salmon. Credit: Edward Steenstra, USFWS digital library

Adult male Atlantic salmon.
Photo Credit: Edward Peter Steenstra, USFWS digital library


Habitat: Rivers, streams, ponds, lakes, estuaries, and oceans

Occurs only in Maine: See the map below displaying the geographic boundary of the Gulf of Maine Distinct Population Segment of Atlantic salmon and designated critical habitat.


  • Low marine survival

  • Dams, stream crossings, and culverts that prevent or decrease access to habitat

  • Competition from and predation by non-native fish species

  • Habitat modification

The geographic boundary of the Gulf of Maine Distinct Population Segment of Atlantic salmon and designated critical habitat. Credit: U.S. Fish and Wildlife Service Gulf of Maine Coastal Program.

The geographic boundary of the Gulf of Maine Distinct Population Segment of
Atlantic salmon and designated critical habitat.
Map Credit: U.S. Fish and Wildlife Service Gulf of Maine Coastal Program.

Additional Information



The adult Atlantic salmon is a graceful fish, deepening rearward from a small pointed head to the deepest point under the dorsal fin, then tapering to a slender caudal peduncle which supports a spreading and slightly emarginate caudal fin. Atlantic salmon are distinguished from the Pacific salmon because they have fewer than 13 rays in the anal fin. Their mouth is moderately large. The shape, length of head, and depth of body vary with each stage of sexual maturity.

Color varies with age of this fish. Small "parr," older young salmon, have 8 to 11 pigmented bars, or "parr marks," along each side of their body, alternating with a single row of red spots along the lateral line. These markings are lost when the "smolt" age is reached. Salmon in the sea are silvery on the sides and belly, while the back varies with shades of brown, green, and blue. Atlantic salmon also have numerous black spots, usually "X"-shaped and scattered around the body. When spawning, both sexes take on an overall bronze-purple coloration and may acquire reddish spots on the head and body. After spawning, the "kelts" are so dark in color that these fish are also called "black salmon."

Anglers Warning

Anglers should be aware of the possible occurrence of Atlantic salmon when recreational fishing for other species.  In Maine, all fishing for anadromous Atlantic salmon is prohibited.  Be knowledgeable about fish identification and proper fish release procedures. Know the species you catch. [PDF]

Know the species you catch. Credit: DMR and art by Mark McColloughAttention Anglers sign

Know the species you catch poster (credit: DMR and art by Mark McCollough) and Maine Endangered Atlantic Salmon sign (courtesy of Native Fish Coalition)

Atlantic Salmon Jurisdiction

The Gulf of Maine Distinct Population Segment (GOM DPS) of Atlantic salmon was federally listed as endangered in 2000.  Endangered Atlantic salmon fall under the joint jurisdiction of both the U.S. Fish and Wildlife Service and the National Marine Fisheries Service.  In 2009, the geographic extent of the GOM DPS was expanded and critical habitat was designated in portions of the DPS.  Within the GOM DPS, 45 specific areas (HUC 10 watersheds) occupied by Atlantic salmon (at the time of listing) that comprise approximately 19,751 km of perennial river, stream, and estuary habitat and 799 square km of lake habitat are designated as critical habitat.

Small populations of anadromous Atlantic salmon also occur in certain watersheds in Maine outside of the range of the GOM DPS, like the Saco and Aroostook rivers; but these fish are not protected as a listed species.  Maine also supports land-locked Atlantic salmon, which occur only in freshwater habitats.  Land-locked Atlantic salmon are native to only four river basins in Maine: the St. Croix River, Union River, Penobscot River, and Presumpscot River.  Starting in the mid 1800s, many lakes in Maine have been stocked with land-locked salmon, so their distribution today is widespread.  Land-locked salmon are also not protected as a listed species.  Land-locked salmon
and endangered Atlantic salmon occur together in some watersheds.

Life History and Habitat

The endangered Atlantic salmon is an anadromous fish species that spends most of its adult life in the ocean but returns to freshwater to reproduce.  Atlantic salmon have a complex life history that includes territorial rearing of juveniles in rivers to extensive feeding migrations on the high seas.  During their life cycle, Atlantic salmon go through several distinct phases that are identified by specific changes in behavior, physiology, morphology, and habitat requirements.

Life cycle of the Atlantic salmon. Artwork by Katrina Mueller, USFWS and Project SHARE


Life cycle of the Atlantic salmon.  Artwork by Katrina Mueller, USFWS and Project SHARE

Atlantic salmon require cool, clean, well-oxygenated water in streams, rivers, ponds, and lakes and can utilize a wide variety of habitat types.  Adult salmon spawn in October and November in coarse gravel or cobbles (up to fist-size rocks) in moving water.  Salmon spawning areas are called redds.  Because adult salmon may spend several months in a river or stream before spawning, they require deep, cool, well-shaded resting pools during the summer.  Sometimes young male salmon, known as precocious parr (four to six inches long), become sexually mature and participate in spawning.  Unlike Pacific salmon species, Atlantic salmon do not die after spawning and may live to spawn several times.  After spawning, adult salmon return to the ocean to feed and regain body weight so that they are able to spawn again.  Most Atlantic salmon return to their natal river to spawn.

Atlantic salmon habitat in Downeast Maine. Credit: Wende Mahaney, USFWS

Atlantic salmon habitat in Downeast Maine. Photo Credit: USFWS, Wende Mahaney

Salmon eggs hatch in March or April and remain in the gravel redd until they have absorbed their yolk sac.  In May, salmon fry emerge from the gravel and begin to feed in the river, first on plankton (microscopic plants and animals) and later on insects.  As the young salmon grow they are called parr and can be distinguished by several vertical bands, or parr marks, on their sides.  Salmon parr are territorial and will vigorously defend a section of stream where they are feeding on insects that drift through the water.  Young salmon require cover in the form of rocks and boulders, aquatic vegetation, large woody debris, and over-hanging stream banks.  During the winter, parr may be found buried several centimeters beneath the stream bottom substrate.  As parr grow they often move considerable distances to find new habitats that offer rougher and larger substrates that provide better cover and foraging areas.

Atlantic salmon habitat in French Stream at Corinth, Maine. Credit: Wende Mahaney, USFWS

Atlantic salmon habitat in French Stream at Corinth, Maine. Photo Credit: USFWS, Wende Mahaney

After usually two or three years of stream life, the spring is a time of much change for salmon parr as they prepare for migration downstream to the ocean.  The fish become thinner, lose their parr marks, and turn very silvery. 
They also undergo drastic physiological changes to prepare them for life in salt water.  From April through June, young salmon - now called smolts - migrate downstream to the Atlantic Ocean.

After leaving the river, post-smolts tend to swim rapidly out of the coastal environment.  Post-smolts generally live near the surface of the water and form shoals, possibly of fish from the same river.  During the late summer and autumn, post-smolts from North America are concentrated in the Labrador Sea and off the west coast of Greenland.  After over-wintering at sea, Atlantic salmon adults may return to a river to spawn.  Some salmon spend another year or more at sea, foraging and growing, before becoming sexually mature and returning to freshwater to spawn.


Threats to the Atlantic salmon include habitat loss and degradation, predation and competition from non-native fish species, and degradation of water quality and quantity.  Historically, over-utilization of salmon by both recreational and commercial fisheries contributed to the decline in Atlantic salmon populations.  Today, the presence of hundreds of dams in Maine prohibits salmon from reaching large quantities of suitable aquatic habitats.  Additionally, dams change the character of river habitats by slowing flows, raising water temperatures and causing sedimentation of substrate, all of which make the impoundments above dams less suitable for salmon.  Some dams in Maine have fish ladders or other fish passage structures that allow at least some salmon and other fish to reach upstream habitats. Other threats include; habitat loss and degradation, predation and competition from non-native fish species, and degradation of water quality and quantity. 

This small dam, a remnant from the log driving era in Maine, on the West Brach Machias River, prevents Atlantic salmon from accessing upstream spawning and rearing habitat. Credit: Wende Mahaney, USFWS

This small dam, a remnant from the log driving era in Maine, on the West Branch Machias River,
prevents Atlantic salmon from accessing upstream spawning and rearing habitat. Photo Credit: Wende Mahaney, USFWS.

Road crossings over streams, including culverts, can also have a large impact on Atlantic salmon by prohibiting access to upstream habitat and by changing the character of the stream from erosion and sedimentation, loss of riparian vegetation, and raising temperatures in water impounded above under-sized culverts.

hanging outlet (left) Hanging outlet (right)

Hanging outlets, shallow water, high velocities, and lack of natural stream substrate often make culverts impassable for Atlantic salmon
and other fish species, particularly juveniles. Photo Credit: Clayton Hawkes, USFWS

The introduction of non-native fish species in Maine, such as smallmouth bass, northern pike and brown trout, has negative consequences for our native fish populations including Atlantic salmon.  Bass prey on Atlantic salmon fry and parr because they occur in similar river habitats.  Water withdrawals for irrigation and other uses can degrade Atlantic salmon habitat by reducing the amount of available instream habitat and raising summer water temperatures.


Species Range:   

The Atlantic salmon is native to the basin of the North Atlantic Ocean, from the Arctic Circle to Portugal in the eastern Atlantic, from Iceland and southern Greenland, and from the Ungava region of northern Quebec south to the Connecticut River.  In the United States, Atlantic salmon historically ranged from Maine south to Long Island Sound.  However, the Central New England DPS and Long Island Sound DPS have both been extirpated, leaving only the Gulf of Maine DPS today.  Atlantic salmon populations still persist in Canada, including in New Brunswick and Quebec.

Distribution in Maine:

The endangered Gulf of Maine Distinct Population Segment includes all anadromous Atlantic salmon whose freshwater range occurs in the watersheds from the Androscoggin River northward along the Maine coast to the Dennys River, and wherever these fish occur in the estuarine and marine environment.  The following impassable falls delimit the upstream extent of the freshwater range of Atlantic salmon: Rumford Falls in the town of Rumford on the Androscoggin River; Snow Falls in the town of West Paris on the Little Androscoggin River; Grand Falls in Township 3 Range 4 BKP WKR on the Dead River in the Kennebec Basin; the unnamed falls (impounded by Indian Pond Dam) immediately above the Kennebec River Gorge in the town of Indian Stream Township on the Kennebec River; Big Niagara Falls on Nesowadnehunk Stream in Township 3 Range 10 WELS in the Penobscot Basin; Grand Pitch on Webster Brook in Trout Brook Township in the Penobscot Basin; and Grand Falls on the Passadumkeag River in Grand Falls Township in the Penobscot Basin.  The marine range of the GOM DPS extends from the Gulf of Maine, throughout the Northwest Atlantic Ocean, to the coast of Greenland.

Included in the endangered GOM DPS are all associated conservation hatchery populations used to supplement the natural populations; currently, hatchery populations are maintained at Green Lake National Fish Hatchery and Craig Brook National Fish Hatchery, both operated by the U.S. Fish and Wildlife Service.  Salmon fry, parr, and smolts raised at these hatcheries are stocked in many rivers in the GOM DPS each year.  Excluded from the GOM DPS are landlocked Atlantic salmon and those salmon raised in commercial hatcheries for the aquaculture industry.

Examples of actions that may affect this species

The following is provided as technical assistance only and is not intended as a comprehensive list of all activities that may affect this species.

Within or near a stream, brook, or river:

  • construction of any new road crossings including culverts, bridges, and fords (including temporary road crossings)
  • replacement or repair or existing road crossings
  • bank stabilization projects including rock rip-rap, steel sheet piles, and gabions
  • removal of streamside or riparian vegetation, particularly trees and shrubs
  • construction of over-head electric transmission lines, including clearing of vegetation and temporary stream crossings for construction access
  • installation of buried utility lines, including gas pipelines, water lines, and sewer lines that involve temporary trenching across a stream and removal of riparian vegetation
  • dredging associated with marinas, boat yards, and other facilities that require access by boats
  • construction of piers, including pile driving
  • construction of new dams or removal of existing dams
  • construction of fish passage facilities at dams
  • construction activities near a stream that will disturb soil and could result in erosion and sedimentation into the stream
  • removal of water for irrigation or other uses
  • discharges of chemicals and other pollutants (including heated water) that affect water quality and can harm aquatic organisms

Within estuarine and marine habitats:

  • dredging associated with marinas, boat yards, and other facilities that require access by boats
  • disposal of dredged materials at near-shore and offshore disposal sites
  • construction of piers, including pile driving, and other waterfront usage facilities
  • construction or repair of bridges
  • coastal shoreline stabilization projects using rock rip-rap, retaining walls, and sheet piles
  • finfish aquaculture, particularly the rearing of domesticated Atlantic salmon in marine cages
  • oil spills and other discharges of chemicals and pollutants

Best Management Practices

The following Best Management Practices are examples of typical Conservation Measures frequently recommended by the Maine Field Office in the course of consultation or technical assistance.
  • Conduct instream work in freshwater habitat between July 15 and September 30 when stream flows are typically lower and the risks of erosion and sedimentation are minimized.
  • In estuarine and marine habitats, complete in-water work between November 8 and April 9 when Atlantic salmon (adults and smolts) are not likely to be present.
  • Isolate instream construction areas with cofferdams so that construction work can be completed in the dry or without flowing water, thereby minimizing erosion and sedimentation.
  • When using pumps to remove water from instream construction sites, ensure that hoses have proper intake screens to protect Atlantic salmon and other fish from impingement and entrainment.  Follow guidance from the National Marine Fisheries Service (2008) for intake screen specifications.  For more information about this guidance please contact Wende Mahaney at
  • When returning water to a water body downstream of a construction site, take precautions to ensure that the water does not cause scour of the substrate.  Discharge water onto ledge, boulders, or place geotextile fabric on the stream bottom.
  • Before beginning instream construction work, particularly when a portion of the stream will be de-watered, follow proper protocols for removing Atlantic salmon and other aquatic organisms from the work area.  Electrofishing may be necessary as the last step to ensure that juvenile Atlantic salmon are removed; juveniles can hide among coarse stream substrates and are difficult to remove with nets or other methods.
  • Electrofishing should only be conducted by experienced individuals following standard protocols to minimize risks to salmon and other fish.  Electrofishing requires special approval from the U.S. Fish and Wildlife Service to handle endangered salmon.

    Electrofishing to remove fish, including Atlantic salmon parr, from the East Machias River before beginning installation of a new water intake pipe inside a cofferdam used to control sediments.Credit: Wende Mahaney, USFWS

    Electrofishing to remove fish, including Atlantic salmon parr, from the East Machias River before beginning installation of a new water
    intake pipe inside a cofferdam used to control sediments. Photo Credit: Wende Mahaney, USFWS

  • Minimize removal of streamside vegetation, particularly trees and shrubs, during construction and revegetate only with native species.
  • Use proper erosion and sediment control devices for all construction work near streams to prevent sediment from reaching streams.
  • Develop and use a spill prevention and response plan for all hazardous materials that could be present at the construction site, including fuel, oil, and hydraulic fluid.
  • Any construction equipment that will be working in a stream should be properly cleaned before arrival at the construction site.
  • Design new and replacement stream crossings using the principles of Stream Simulation:  An Ecological Approach to Providing Passage for Aquatic Organisms at Road-Stream Crossings (USFS 2008)
  • Avoid bank stabilization projects that use “hard” structures, like rock rip-rap, which can interfere with natural stream processes, degrade salmon habitat, and deflect stream flows elsewhere thereby exacerbating bank erosion problems.
  • Maintain wooded riparian buffers along salmon streams.  Currently, there are no standard buffer size recommendations; but the wider the better!
  • Use fencing to prohibit livestock from free access to streams.  Limit livestock crossings to confined locations and allow woody vegetation to remain or revegetate streamside areas.
  • Avoid introductions of non-native species (both plants and animals) to Atlantic salmon streams and riparian corridors.

What to do if this species occurs on your property or project site

  • Contact the Service early in planning for any project or activity that may affect Atlantic salmon or their critical habitat; see the Species List and Project Reviews page for instructions. Through the technical assistance or consultation processes of the Endangered Species Act, the Service will provide project-specific recommendations to avoid or minimize adverse effects to listed species.
  • Individual property owners can also contact the Service for proactive conservation recommendations. Most land in Maine is privately owned. Voluntary conservation efforts by Maine residents are critical in the conservation and recovery of threatened and endangered species. Interested private landowners should contact the Maine Field Office's Partners for Fish and Wildlife Program.


Last updated: March 28, 2019
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