Atlantic salmon may be facing new challenges in the Gulf of Maine due to changing environmental conditions. Increasing numbers of hatchery-raised Atlantic salmon smolts are entering the ocean via the Gulf of Maine, but fewer are returning to spawn, raising questions as to what is happening to these fish at sea. A 2011 study co-authored by a NOAA Northeast Fisheries Science Center researcher suggests that changing spring wind patterns, warming sea surface temperatures, and new predators along altered migration routes are affecting the survival of Atlantic salmon.
- Ocean perch
- Sea Bass
- Turbot (Greenland)
ALSO KNOWN AS:
Sea Run Salmon, Kelts, Black Salmon
Commercial fishing for Atlantic salmon is prohibited; Atlantic salmon found in the market is farm-raised
- FISHING RATE
- HABITAT IMPACTS
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Atlantic salmon.LAUNCH GALLERY
Wild Atlantic salmon population levels are very low due to a variety of factors, including acid rain, habitat destruction, dams, and historic overfishing. Atlantic salmon once returned by the hundreds of thousands to most major rivers along the northeastern United States, but now only return in small numbers to rivers in Maine. Commercial fishing for the species currently is prohibited by law and the Gulf of Maine population is protected under the Endangered Species Act. Substantial efforts are ongoing to restore wild Atlantic salmon and their habitat. These include improving fish passage by removing or modifying dams so salmon can reach freshwater spawning and rearing areas critical to their survival, understanding and improving historically low salmon survival in the ocean, and supplementing wild populations with hatchery-raised Atlantic salmon.
With the decline of wild Atlantic salmon populations in the early 1800s, Atlantic salmon have been raised in hatcheries since 1864 in an effort to enhance the wild populations and sustain the fisheries that depend on them. In the late 1970s, commercial aquaculture ventures started rearing Atlantic salmon in Maine. See Atlantic Salmon – Farmed for more information.
LOCATION & HABITAT
The Atlantic salmon is the only salmon native to the Atlantic Ocean. There are three groups of wild Atlantic salmon: North American, European, and Baltic. The North American group, including the Canadian and U.S. populations, was historically found from northern Quebec southeast to Newfoundland and southwest to Long Island Sound. In the United States, Atlantic salmon once were native to almost every river north of the Hudson River. Due to industrial and agricultural development (including acid rain, habitat destruction, dams, and historic overfishing), most populations native to New England were eradicated. Now, the only native populations of Atlantic salmon in the United States are found in Maine.
Atlantic salmon are anadromous in that they leave the ocean to ascend freshwater streams and rivers to breed. After hatching, young Atlantic salmon, or "parr," remain in rivers or streams for the first 1-2 years of life. They spend the first year of life in shallow water with moderate to fast water flow and adequate cover. Parr are very territorial and move into habitat with larger substrate as they grow. These areas tend to have deeper, faster flowing water than their nursery habitat.
After this period, the salmon migrate to the ocean where they spend about 2-3 years feeding, then return to their natal streams or rivers to spawn during the fall. Females lay an average of 7,500 eggs in gravel nests, called redds. Eggs incubate slowly due to cold winter water temperatures. About 9 to 20 percent of these survive to the "fry" stage. Fry remain buried in the gravel for about 6 weeks. The fry emerge from the gravel about mid-May. They quickly disperse from the redds and develop camouflaging stripes along their sides, entering the “parr” stage. Parr eventually undergo a physiological transformation called smoltification that prepares them for life in a marine habitat. During smoltification, fish imprint on the chemical nature of the stream or river to enable them to find their way back to where they were born. After smoltfication is complete in the spring, smolts migrate to the ocean to grow, feed, and mature. Their growth rates are variable and depend on several factors including season, habitat quality, age, sex, and population density. They grow much faster in saltwater than in freshwater. After 2 years as sea, adult salmon can grow to an average length of 28 to 30 inches and weight of 8 to 12 pounds. Atlantic salmon do not die after spawning, and adults can repeat this cycle. They live for 4 to 6 years.
Juvenile Atlantic salmon mostly prey on invertebrates and terrestrial insects while in freshwater and on amphipods (small, shrimp-like crustaceans), euphausiids (krill), and fishes while at sea. Larger adult Atlantic salmon mainly prey on fish such as Atlantic herring, alewife, rainbow smelt, capelin, mummichogs, sand lances, flatfish, and small Atlantic mackerel. Birds, marine mammals, and fish prey on Atlantic salmon.
Atlantic salmon have a spindle-like body shape - rounded, broad in the middle, and tapered at each end. The shape is somewhat flattened toward the sides, which is typical of salmon species. The head is relatively small, about one-fifth of the body length. Their ventral (underside) paired fins are prominent, especially on juveniles.
Spawning adults darken to a bronze color after entering freshwater and darken further after they spawn. When spawning has been completed, they are often referred to as “kelts” or “black salmon.” Their silver color returns after they re-enter the sea.
The U.S. Atlantic Salmon Assessment Committee, a team of state and federal biologists, collects data on Atlantic salmon throughout New England and assesses the species’ population status. Scientists do not assess the abundance of salmon using the same methods they use for other fish, such as conducting surveys and using models to estimate the amount of fish in the ocean. Instead, they determine the population status by counting the number of adults that return to spawn, either directly at traps and weirs or indirectly using nest surveys and modeling. Because most U.S. Atlantic salmon are products of hatchery-raised fish, it’s important to consider those inputs in stock assessments as well.
Atlantic salmon stocks began a steady decline in the early 1900s due to a number of factors including habitat destruction, dams, and overfishing. Returns of adults to freshwater remain at extremely low levels today. Restoration projects developed throughout the latter half of the 20th century have focused on revitalizing salmon stocks throughout New England through hatchery production and, more recently, habitat restoration.
For salmon in Maine, most current research focuses on two priorities – the impact of dams on populations and survival of salmon in the ocean. See NOAA Fisheries Northeast Salmon Team.
Harvesting Atlantic Salmon
Atlantic salmon is a highly prized game and food fish. They were caught by Native Americans and U.S. commercial fisheries for Atlantic salmon started in Maine during the 1600s. Around the time of the American Revolution, weirs (an enclosure of stakes set in a stream as a trap for fish) became the gear of choice in U.S. Atlantic salmon commercial fisheries and were modified as more effective materials and designs became available. Catches in Maine exceeded 90 metric tons in the late 1800s and 45 metric tons in some years during the early 1900s. U.S. commercial fisheries for Atlantic salmon have remained closed since 1948.
Who’s in charge? NOAA Fisheries, the U.S. Fish and Wildlife Service, the New England Fishery Management Council, and the State of Maine
Domestic: The Fishery Management Plan for Atlantic salmon prohibits possession of Atlantic salmon, and any directed or incidental (bycatch) commercial fishery for Atlantic salmon is prohibited in federal waters. All Atlantic salmon caught incidentally in a fishery for other species must be released in a manner that ensures maximum probability of survival. This protects Atlantic salmon in U.S. marine waters and complements management in state-managed riverine and coastal waters.
In 2000, NOAA Fisheries and the U.S. Fish and Wildlife Service listed the Gulf of Maine Distinct Population Segment (DPS) of Atlantic salmon as endangered under the Endangered Species Act. The two agencies are jointly responsible for the recovery of this endangered population of Atlantic salmon. In December 2005, the agencies, in coordination with the State of Maine, finalized the Recovery Plan for the Gulf of Maine DPS. This plan identifies recovery actions needed to halt the decline of the species and lays out a process to minimize threats. In June 2009, they extended Endangered Species Act protection to more Atlantic salmon, adding fish in the Penobscot, Kennebec, and Androscoggin rivers and their tributaries to the endangered Gulf of Maine DPS. Protection also applies wherever these fish are found, including these rivers’ estuaries and marine environment. Hatchery fish used to supplement these natural populations are also included. The agencies also determined critical habitat (the area needed to support the fish population’s survival and recovery) for the endangered Atlantic salmon.
International: Because Atlantic salmon migrate all along the North American coast, as far north as Greenland, it’s important that foreign fisheries are also managed to conserve and restore salmon populations. The United States joined with other North Atlantic nations in 1984 to form the North Atlantic Salmon Conservation Organization (NASCO) to cooperatively manage Atlantic salmon stocks through conservation, restoration, and enhancement programs. The United States’ interest in NASCO stemmed from its desire to ensure that Atlantic salmon originating in U.S. waters were not harvested in foreign fisheries and that these fisheries did not compromise the long-term commitment by the states and federal government to rehabilitate and restore New England Atlantic salmon stocks. The International Council for the Exploration of the Sea (ICES) is the official research arm of NASCO. ICES provides scientific advice to NASCO members to use in formulating science-based management recommendations for the conservation of North Atlantic salmon stocks.
In 1989, all state and federal commercial salmon fisheries in New England were closed by law.
There is no commercial catch of wild Atlantic salmon in the United States.
Recreational fishermen have reportedly been angling for Atlantic salmon since 1832, when the first Atlantic salmon caught on rod and reel was captured in the Dennys River in Maine. Recreational fisheries have been closed in the United States for decades, with the exception of some unique fisheries for Atlantic salmon in New Hampshire, where fish retired from hatchery broodstock are released for angling, and in Maine, where an experimental catch-and-release fishery was opened in the Penobscot River in 2006 and 2007.