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Atlantic Salmon (Protected)
Atlantic Salmon (Protected)
Salmo salar
Also Known As
Sea run salmon, Kelts, Black salmon
Protected Status
ESA Endangered
Gulf of Maine DPS
Quick Facts
Weight
Average 8 to 12 pounds but may reach 30 pounds
Length
Average 28 to 30 inches (adults)
Lifespan
3 to 7 years
Threats
Climate change,
Dams and culverts that block or impede access to habitats,
Foreign fisheries,
Habitat degradation,
Marine survival
Region
New England/Mid-Atlantic
Atlantic salmon. Credit: NOAA Fisheries
Atlantic salmon. Credit: NOAA Fisheries
About the Species
Atlantic salmon. Credit: NOAA Fisheries
Atlantic salmon. Credit: NOAA Fisheries
Atlantic salmon, also known as the “King of Fish,” are anadromous, which means they live in both fresh and saltwater. Atlantic salmon have a complex life history that begins with spawning and juvenile rearing in rivers. They then migrate to saltwater to feed, grow, and mature before returning to freshwater to spawn.
Atlantic salmon are vulnerable to many stressors and threats, dams and culverts that block or impede the migratory movements between freshwater spawning and rearing habitats and the marine environment, habitat degradation, foreign fisheries, and poor marine survival. They are considered an indicator species or a “canary in the coal mine.” This means that the health of the species is directly affected by its ecosystem health. When a river ecosystem is clean and well-connected, its salmon population is typically healthy and robust. When a river ecosystem is not clean or well-connected, its salmon population will usually decline.
Atlantic salmon in the United States were once native to almost every coastal river northeast of the Hudson River in New York. But dams, pollution, and overfishing reduced their population size until the fisheries closed in 1948. Commercial and recreational fishing for wild sea-run Atlantic salmon is still prohibited in the United States. All Atlantic salmon in the public market is cultured and commercially grown. Currently, the only remaining wild populations of U.S. Atlantic salmon are found in a few rivers in Maine. These remaining populations comprise the Gulf of Maine distinct population segment, which is listed as endangered under the Endangered Species Act. Some populations in southern Canada and Europe are also declining significantly, creating concern about the status of this species globally. In addition, the Gulf of Maine DPS is one of eight Species in the Spotlight. This means that NOAA Fisheries has made it a priority to focus recovery efforts on research to better understand the major threats and stabilize the Gulf of Maine DPS by improving access to quality habitat and thus, preventing its extinction.
Our dedicated scientists and partners use a variety of innovative techniques to conserve Atlantic salmon and to protect and rebuild depleted endangered populations. NOAA Fisheries also works with partners to protect federally designated critical habitat for Atlantic salmon and makes every effort to engage the public in conservation efforts.
Population Status
Worldwide, Atlantic salmon populations among individual rivers can range considerably. Atlantic salmon returns to rivers in Northern Europe can exceed nearly a quarter million in some years. However, some populations are small, numbering in the low hundreds or even single individuals.
The endangered Gulf of Maine DPS of Atlantic salmon has declined significantly since the late 19th century. Historically, dams, overfishing, and pollution led to large declines in salmon abundance. Because of this, the commercial Atlantic salmon fishery closed in 1948. Improvements in water quality and stocking from hatcheries helped rebuild populations to nearly 5,000 adults by 1985. But dams continued to block access to habitats and marine survival has decreased significantly since the late 1980s, resulting in annual returns to the United States of generally less than 1,000 adults. The rapid decline and dire status of the ESA-listed Gulf of Maine DPS makes it a priority for NOAA Fisheries and partners to prevent its extinction and promote its recovery.
Appearance
While in freshwater, young Atlantic salmon—known as parr—have brown to bronze-colored bodies with dark vertical bars and red and black spots. These markings camouflage and protect them from predators. Once young salmon are ready to migrate to the ocean, their appearance changes; their vertical barring disappears and they become silvery with nearly black backs and white bellies. When adults return to freshwater to spawn, they are very bright silver. After entering the river, they will again darken to a bronze color before spawning in the fall. After spawning, adults—now called kelts—can darken further and are often referred to as black salmon. Once adults return to the ocean, they revert to their counter-shaded coloration dominated by silver.
Typically, an Atlantic salmon returning to U.S. waters will be 4 years old, having spent 2 years in freshwater and 2 years at sea. These fish are called “two sea winter fish,” or 2SW, and are usually 28 to 30 inches long and 8 to 12 pounds. The size of adults returning to freshwater from the ocean depends on how long they lived at sea. Young salmon returning to freshwater after 1 year at sea (known as “grilse” or 1SW) are smaller than 2SW adults. Adult salmon can migrate several times to spawn—a reproductive strategy known as iteroparity—though repeat spawners are becoming increasingly rare.
Behavior and Diet
Atlantic salmon are migratory. They travel long distances from the headwaters of rivers to the Atlantic Ocean before returning to their natal rivers. For example, U.S. salmon leave Maine rivers in the spring and reach the seas off Newfoundland and Labrador, Canada, by mid-summer. They spend their first winter at sea south of Greenland and their second growing season at sea off the coast of West Greenland and sometimes East Greenland. Maturing fish travel back to their native rivers in Maine to spawn after 1 to 3 years.
The diet of Atlantic salmon depends on their age. Young salmon eat insects, invertebrates, and plankton. The preferred diet of adult salmon is capelin. Capelin (similar in appearance to rainbow smelt) are elongated silvery fish that reach 8 to 10 inches in length.
Where They Live
There are three groups of Atlantic salmon: North American, European, and Baltic. These groups are found in the waters of North America, Iceland, Greenland, Europe, and Russia. Atlantic salmon spawn in the coastal rivers of northeastern North America, Iceland, Europe, and northwestern Russia. After spawning, they migrate through various portions of the North Atlantic Ocean. European and North American populations of Atlantic salmon intermix while living in the ocean, where they share summer feeding grounds off Greenland. The North American group historically ranged from northern Quebec to Newfoundland and to Long Island Sound. This group includes Canadian populations and U.S. populations. In Canada, healthy populations still exist today, however, many populations are severely depleted.
The GOM DPS at listing included the nine remnant populations in central and eastern Maine. River specific populations still persist in the Sheepscot, Penobscot (including the Ducktrap), Narraguagus, Pleasant, Machias, East Machias, and Dennys rivers. GOM salmon leave Maine rivers in the spring and reach the seas off Newfoundland and Labrador, Canada, by mid-summer. They spend their first winter at sea south of Greenland and their second growing season at sea off the coast of West Greenland and sometimes East Greenland. Maturing fish travel back to their native rivers in Maine to spawn after 1 to 3 years.
World map providing approximate representation of the Atlantic salmon's range.
Lifespan & Reproduction
Atlantic salmon have a complex life history and go through several stages that affect their behavior, appearance, and habitat needs. They are anadromous, which means that they are born in freshwater, migrate to the ocean as juveniles, and then return upriver to spawn as adults.
When spawning in the fall, the female salmon uses its tail to dig nests in the gravel where the eggs are deposited. These nests are called redds. Over winter, the eggs develop into very small salmon called alevin. In the spring, the alevin swim out of the redd and are then called fry. Fry grow into parr, which are only 2 inches long and are camouflaged to protect them from predators. For 2 to 3 years, the parr grow in freshwater before transforming into smolts in the early spring. The silvery smolts’ gills and organs change, allowing them to swim to the ocean where they spend 1 to 2 years maturing into adults.
The adult Atlantic salmon return to the river where they were born to lay eggs. After spawning in freshwater, the adults, now called kelts, swim back to the ocean to possibly return to spawn again in future years.
Females returning to spawn after two winters at sea lay an average of 7,500 eggs. Out of these eggs, only about 15 to 35 percent will survive to the fry stage.
Threats
Atlantic salmon populations are exposed to a variety of threats. The most significant threats to their survival include impediments—such as dams and culverts—that block their access to quality habitat, low freshwater productivity, ongoing fisheries off the shores of Greenland, and changing conditions at sea. Salmon also face many other threats that affect their survival, such as poor water quality, degraded freshwater habitats from land use practices, fish diseases, predation from introduced and invasive species, and interbreeding with escaped fish raised on farms for commercial aquaculture. All of these factors are compounded by climate change and Atlantic salmon are the most vulnerable finfish in this region to this overriding stressor.
NOAA Fisheries is committed to working together with our federal, state, tribal, and NGO partners in the conservation and recovery of all Atlantic salmon. We have focused our conservation efforts to help rebuild the depleted and endangered population in the Gulf of Maine. Our targeted management actions to secure protections for these fish include:
Improving connections between the ocean and freshwater habitats important for salmon recovery
Maintaining genetic diversity of Atlantic salmon populations over time
Increasing the number of reproducing adults through the conservation hatchery program
Increasing the number of reproducing adults through the freshwater production of smolts
Increasing Atlantic salmon survival by improving our understanding of marine ecosystems and the factors that affect salmon in the ocean
Collaborating with partners and involving interested parties in recovery efforts
Our research projects have discovered new aspects of Atlantic salmon biology, behavior, and ecology and helped us better understand the challenges that all Atlantic salmon face. This research is especially important in rebuilding depleted and endangered populations. Our work includes:
Performing stock assessments
Researching marine ecology in West Greenland
Tracking migration survival and ecology in estuaries and coastal oceans
Researching co-evolved fish
Modeling impacts of salmon upstream and downstream dam passage
You can contribute significantly to Atlantic salmon recovery by implementing best management and land stewardship practices.
Maintain forested areas next to rivers and streams to provide shade, nutrients, and cover to support Atlantic salmon and other fish.
Maintain native plants along waterways, which support healthy forests and keep dirt and other materials out of streams. Dirt fills in spaces between rocks that Atlantic salmon use to lay eggs and hide from predators.
Avoid removing wood from Maine waterways and their banks. Wood provides important habitat for Atlantic salmon and other fish to feed and find shelter.
Participate in programs to conserve land and water resources for Atlantic salmon habitats.
Learn About Bycatch
One of the main threats to marine animals is entanglement in fishing gear, especially gillnets. Fishermen sometimes catch and discard animals they do not want, cannot sell, or are not allowed to keep. This is collectively known as bycatch.
It is illegal to fish for, catch, or keep fish from the Gulf of Maine Atlantic salmon DPS.
Report a Violation
Call the NOAA Fisheries Enforcement Hotline at (800) 853-1964 to report a federal marine resource violation. This hotline is available 24 hours a day, 7 days a week for anyone in the United States.
Gulf of Maine Distinct Population Segment of Atlantic Salmon
The Gulf of Maine DPS of Atlantic salmon is one of NOAA Fisheries Species in the Spotlight. This initiative is a concerted, agency-wide effort launched in 2015 to spotlight and save the most highly at-risk marine species.
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Atlantic salmon are an iconic species of the Northeast. They 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 central and eastern Maine (Androscoggin to Dennys).
In the 1900s, Atlantic salmon from Maine were so highly valued that, for more than 80 years, the first one caught in the Penobscot River each spring was presented to the U.S. president. The last presidential salmon was caught in May 1992, because there are now too few adult salmon to sacrifice even one.
Atlantic salmon once supported lucrative commercial and recreational fisheries in New England. They were of great cultural and historical importance to Native American tribes in Maine, as well as a source of food. If this iconic species goes extinct, the services it once provided to the American and Native American people will be lost.
The GOM DPS of anadromous Atlantic salmon was initially listed as an endangered species in 2000. A subsequent rule issued by U.S. Fish and Wildlife Service (USFWS) and NOAA in 2009 expanded the geographic range for the GOM DPS to include the Penobscot, Kennebec, and Androscoggin Rivers.
Because of the rapid decline and dire status of the Gulf of Maine DPS, we and our partners have made it a priority to stabilize and prevent extinction of this iconic species.
Where Gulf of Maine Atlantic Salmon Live
Young salmon spend 2 to 3 years in the rivers and streams of Maine, then undergo physical changes to prepare them for life in the ocean. Once Gulf of Maine Atlantic salmon leave Maine streams and rivers, they migrate to the ocean. Some salmon return to Maine after their first winter at sea, but most spend a second year feeding in the Labrador Sea off the southwest coast of Greenland. Most Gulf of Maine salmon return to rivers in Maine after two winters at sea.
Population Status
The Gulf of Maine population of Atlantic salmon has declined significantly since the late 19th century. Historically, dams, overfishing, and pollution led to large declines in salmon abundance. Improvements in water quality and stocking from hatcheries helped rebuild populations to nearly 5,000 adults by 1985, but in the early 1990s there was a substantial decrease in marine survival that contributed to a significant population decline. As a result, the average number of salmon returning to GOM rivers annually is only around 1,200.
Habitat
Atlantic salmon habitat requirements change throughout their lives. Adult salmon spawn in rivers and lay their eggs in gravel nests. Once salmon eggs hatch into fry, the fry hide from predators in the spaces between gravel. The fry emerge from the gravel after a few months of growth and enter the parr stage. Most parr feed and develop in the river for two to three years before undergoing smoltification, the process in which parr go through physiological changes in order to transition from a freshwater environment to a saltwater marine environment.
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Atlantic salmon are endangered, with only a few runs
remaining in Maine rivers. Credit: Hillman, NOAA Fisheries
Throughout their lives, Atlantic salmon require the following habitats:
Parr habitat, often called "nursery habitat," refers to a usually shallow stream area where the water breaks over rocks or gravel and flows quickly. Parr will also congregate around the mouths of small tributaries.
Smolt habitat refers to unobstructed riverine and estuarine habitats that allow salmon to physiologically transform to a marine life stage.
Marine habitat refers to habitat that Atlantic salmon migrate to after leaving rivers, where they feed heavily and grow rapidly. Marine habitat must be disease-free, provide food resources, and have good water quality for salmon to survive.
Adult spawning habitat refers to habitat with a gravel bottom where adults can dig nests. Spawning habitats must have diverse pools, riffles, and runs because adults construct nests in locations with plenty of dissolved oxygen.
Threats
Dams limit or block salmon access to important habitats in Maine. More than 90 percent of Maine's rivers and streams are affected by dams, which directly kill or injure a significant number of Atlantic salmon on upstream and downstream migrations. Dams also harm important habitats by flooding free-flowing rivers, reducing water quality, and changing fish communities. Finally, dams worsen the effects of climate change by limiting Atlantic salmon's access to cool-water habitats in higher elevation areas in Maine. Of the more than 400 dams along rivers and streams that support wild Atlantic salmon, only 75 have fishways, a structure that allows fish to swim around dams to reach their spawning grounds.
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Coopers Mill Dam in 2016 before dam removal by Atlantic Salmon Federation. Credit: Michael Burke
Gulf of Maine DPS salmon survival in the ocean has decreased over the last 25 years. This means that an increasing number of salmon die in the ocean before they can return to Maine to spawn. Many Atlantic salmon die in the ocean due to predation, starvation, diseases and parasites, and changing ocean conditions. Marine survival is poor throughout the Atlantic Ocean and is affected by both nearshore and open ocean survival rates. This ongoing and significant threat has pushed populations of Atlantic salmon in the United States closer to extinction. The North Atlantic Salmon Conservation Organization leads international efforts to control and better manage foreign fisheries to reduce their impacts on Atlantic salmon born in the United States. Not all causes of low ocean survival are well-known. Threats like climate and ocean changes, plus shifts in predator and prey abundance and distribution, appear to affect salmon survival at sea.
Species Recovery
To work toward recovery of these fish, NOAA Fisheries and USFWS worked with scientists and stakeholders to develop a recovery plan, which was finalized in February 2019. The recovery plan (PDF, 64 pages) builds upon scientific studies and other observations and information sources to identify gaps in our knowledge and the research needed to fill those gaps. The recovery plan also identifies specific criteria that will signal the recovery of the species.
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Atlantic salmon coming out of the top of the Milford fish lift on the Penobscot River. Credit: Maine DMR
Primary threats with the potential to limit recovery of the Gulf of Maine DPS of Atlantic salmon include:
Dams and road stream crossings
Climate change
Low marine survival
Loss of genetic diversity
Additionally, the recovery plan identifies numerous secondary threats that, when combined, significantly affect the species chance of survival and recovery. They include:
Improve habitat productivity to increase the number of salmon smolts entering the ocean
Increase understanding of and ability to improve marine survival
In the first five years of Species in the Spotlight, we have taken important steps toward stabilizing this species and preventing its further decline. Our accomplishments have included activities in several areas:
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Releasing a tagged salmon off Greenland -
Credit: NOAA Fisheries/Tim Sheehan
Fish Passage
Worked with dam owners to make dams safer for migrating salmon
Five new fishways planned at hydro dams since 2015
Habitat Connections
70 aquatic connectivity projects completed in 2018–2019
Improved access to approximately 250 miles of streams and rivers
Reduce Mortality at Sea
Negotiated 15 mt catch reduction at West Greenland for 2018–2020, as well as an improved licensing and catch monitoring program
Continue work with North Atlantic Salmon Conservation Organization
Satellite Tagging to Study Migrations
Satellite tag project to better understand ocean habitat use and migratory patterns
2017 Species in the Spotlight Hero Award
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Andy Goode. Credit: NOAA Fisheries
Andy Goode, Vice President of U.S. Programs for the Atlantic Salmon Federation, has been a leader in negotiating dam removals throughout the state of Maine. He was instrumental in negotiating and implementing the Penobscot River Restoration Project. The project removed two mainstem dams on one of the last remaining Atlantic salmon rivers in the United States. Most recently, he successfully negotiated the removal of Coopers Mills Dam on the Sheepscot River.
John Banks has served as the director of the Penobscot Indian Nation's Department of Natural Resources since 1980. John developed and administers a comprehensive natural resources management program for the Tribe. His program advances an integrated management approach that recognizes the interconnectedness of all things in the natural world. He has served on numerous boards, commissions, and delegations. These include the U.S. delegation to the North Atlantic Salmon Conservation Organization (NASCO) and the board of directors for the Penobscot River Restoration Trust.
The Gulf of Maine DPS of Atlantic salmon is listed as endangered under the Endangered Species Act and is in danger of extinction.
In the United States, NOAA Fisheries works to protect all Atlantic salmon. We have specific recovery actions and management strategies for the Gulf of Maine DPS because it is endangered.
Recovery Planning and Implementation
Recovery Action
Under the ESA, NOAA Fisheries must develop and implement recovery plans for the conservation of listed species. The ultimate goal of the plan is to recover the species, with an interim goal of down-listing its status from endangered to threatened.
The plan recommends the following major actions:
Improve connections between ocean and freshwater habitats important for salmon recovery
Maintain genetic diversity of Atlantic salmon populations over time
Increase the number of reproducing adults through the conservation hatchery program
Increase the number of reproducing adults through the freshwater production of smolts
Increase Atlantic salmon survival by improving our understanding of marine ecosystems and the factors that affect salmon in the ocean
Consult with all involved tribes on a government-to-government basis
Collaborate with partners and involve interested parties in recovery efforts
The ESA authorizes NOAA Fisheries to appoint recovery teams to help develop and implement recovery plans. There is an action team for each major recovery program element. The action teams develop implementation plans, review project proposals, find and address areas of policy or scientific disagreement, and coordinate to implement and monitor recovery actions.
The NOAA Fisheries Greater Atlantic Regional Fisheries Office and the Northeast Fisheries Science Center work cooperatively with the U.S. Fish and Wildlife Service, Maine Department of Marine Resources, and Penobscot Indian Nation to recover Atlantic salmon.
In February 2019, we published a final recovery plan for the Gulf of Maine DPS. We will continue to involve stakeholders in this priority species initiative as we implement the plan's key strategies for preventing extinction over the coming years.
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The Ripple Effects of Atlantic Salmon Conservation. Atlantic salmon conservation helps to build resilient fisheries, expand recreational opportunities, and support communities.
Collaborative Management Strategy for the GoM DPS Atlantic Salmon Recovery Program
The Collaborative Management Strategy or CMS is a governance process that describes the working relationships between the two Federal agencies (U.S. Fish and Wildlife Service (USFWS) and NOAA-Fisheries), Maine’s Department of Marine Resources (MDMR), the Penobscot Indian Nation (PIN) and stakeholders.
Dan Tierney, Atlantic Salmon Recovery Coordinator, (207) 866-3755, dan.tierney@noaa.gov
Rory Saunders, Atlantic Salmon Recovery Coordinator for the Downeast SHRU, (207) 866-4049, rory.saunders@noaa.gov
Matt Buhyoff, Atlantic Salmon Recovery Coordinator for the Merrymeeting Bay SHRU, (207) 866-4238, matt.buhyoff@noaa.gov
Dan Kircheis, Atlantic Salmon Recovery Coordinator for the Penobscot SHRU, (207) 866-7320, dan.kircheis@noaa.gov
Consulting on Actions that affect salmon and their Critical Habitat
In 2009, we designated specific freshwater and estuarine areas in Maine as critical habitat for Atlantic salmon. We designated these areas because they contain features that are essential for Atlantic salmon survival. These areas provide important spawning, feeding, and migratory habitats for Atlantic salmon.
Any federal agencies conducting or permitting projects that may affect Atlantic salmon or adversely modify their critical habitat must consult with us, as required by Section 7 of the Endangered Species Act.
Atlantic salmon need a wide range of well-connected habitat types. In freshwater, dams and other barriers to migration block or impede salmon from accessing important spawning and nursery habitats. Approximately 10 percent of Atlantic salmon’s historical freshwater habitat remains unimpeded by dams.
NOAA Fisheries is working with dam owners to find solutions that will allow salmon to recover. We have provided significant resources for the oversight, funding, and monitoring of dam removals throughout the GOM DPS.
Furthermore, NOAA Fisheries staff continue to work with hydropower owners to plan for effective downstream and upstream fish passage at most major hydropower dams within the designated critical habitat area for Atlantic salmon. The goal is to restore Atlantic salmon access to important habitats so they can complete their migration.
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The Ripple Effects of Atlantic Salmon Conservation. Salmon restoration benefits the ecosystem as a whole by reconnecting rivers to the ocean, improving freshwater habitat, and building resilient ecosystems.
Captive Breeding and Stocking Programs
Hatchery programs have supported Atlantic salmon populations throughout New England and have prevented extinction in many of Maine's rivers where local populations were at critically low numbers that are needed for the species to reproduce and create the next generation. They also provided opportunities for an economically important recreational fishery to operate through the early 1990s.
The U.S. Fish and Wildlife Service currently has two hatcheries in Maine that conduct a conservation hatchery program. This is a river-specific stocking program, meaning that the program releases the offspring of individuals collected from a specific river back into that river. The program aims to increase the size of wild and captive river-specific populations and to have a reserve of captive salmon for stocking into vacant habitat or rivers in which wild salmon are not returning to their native habitats.
The hatchery program will continue to support conservation activities, including artificial breeding, stocking, and broodstock collection from several rivers throughout Maine. As part of ongoing recovery efforts, the facilities will also maintain captive brood lines for the Gulf of Maine population for as long as needed.
Producing Young Salmon
Producing more naturally reared smolts is the primary objective for the Atlantic salmon program during times when few salmon survive in the ocean. NOAA Fisheries aims to get more smolts, or young salmon, successfully out of rivers and into the ocean.
In the short term, smolt production could increase by changing hatchery and stocking practices. For example, researchers could target habitats that do not currently have any salmon. This can help offset the population decrease caused by ongoing threats, but has limited ability to fully recover imperiled salmon populations. Increasing accessibility to critical habitats is one of the many goals of the program and is part of the multifaceted Atlantic salmon recovery program currently in place.
International Cooperation
NOAA Fisheries aims to increase marine survival, which will also increase the number of healthy adults returning to U.S. rivers. We will do so by reducing the effects of human activities on migratory smolts. This will include minimizing potential effects of construction on Atlantic salmon migration success and protecting marine habitats through coastal zoning and planning.
International fisheries, such as those in Greenland, can catch salmon born in the United States. The North Atlantic Salmon Conservation Organization (NASCO) sets catch limits and licensing requirements for fisheries in Greenland. Canada, Denmark, the European Union, Norway, the Russian Federation, and the United States are members of NASCO and work together to manage Atlantic salmon throughout their range. NASCO also works to reduce the Greenland fishery's impact on U.S.-origin fish.
In 2017, NOAA Fisheries announced the initiation of a 5-year review for the Gulf of Maine Distinct Population Segment (DPS) of Atlantic Salmon (Salmo salar).
NOAA Fisheries is required by the Endangered Species Act (ESA) to conduct 5-year…
We, NOAA Fisheries, issue a final rule designating critical habitat for the Atlantic salmon (Salmo salar) Gulf of Maine Distinct Population Segment (GOM DPS). We previously determined that naturally spawned and several hatchery populations of Atlantic…
We (NOAA Fisheries and U.S. Fish and Wildlife Service, collectively referred to as the Services) have determined that naturally spawned and conservation hatchery populations of anadromous Atlantic salmon (Salmo salar) whose freshwater range occurs in…
The health of Atlantic salmon is directly affected by the health of their ecosystem, which includes the other species living in that ecosystem. Atlantic salmon co-evolved and historically shared the rivers of Maine with many other fish that provide alternative food sources for salmon predators and the salmon themselves. Co-evolved fish also influenced the amount of nutrients available and the habitat quality. Our scientists study how changes in co-evolved fish populations affect the recovery of Atlantic salmon.
Smolt Dam Passage
Salmon are famous for fighting their way upstream to spawn, but their trip downstream as young smolts is no less important. Our scientists study how passage through or around dams affects smolts. Scientists surgically implanted tags into 941 smolts in the Penobscot River between 2005 and 2013. Each tag emits a sound unique to the fish carrying it. Receivers then pick up the sound as the fish travels down the river to track its progress.
This research reveals that even if smolts make it past the dams, they might suffer injuries that make them more likely to die days or weeks later in the estuary, where the river meets the sea. And for each dam a smolt passes, researchers found that the smolt’s chance of dying in the estuary increases by 6 to 7 percent.
Genetic Diversity
NOAA Fisheries is monitoring the genetic diversity of Atlantic salmon to ensure that salmon born in hatcheries can have a good chance at surviving in the wild. We also want to make sure that wild salmon are genetically diverse and this diversity is maintained in the captive broodstock lines held at the hatchery. This information will help us monitor the overall genetic diversity within the Gulf of Maine DPS population and inform best practices for hatchery management and supplementation efforts supporting recovery.
Our scientists study the parasites, bacteria, and viruses that can affect Atlantic salmon health. Populations that are already threatened are especially vulnerable to disease outbreaks, so it is important to understand how specific pathogens could affect the Gulf of Maine DPS. Scientists have sampled several fish species for pathogens, including cod, eel, halibut, mackerel, trout, smelt, and flounder. Since 2000, scientists have sampled over 5,000 fish representing 23 species. These 23 species can all interact with Atlantic salmon in shared habitats. Collaborative efforts will help improve our understanding of diseases and our ability to prevent and manage disease outbreaks (PDF, 5 pages).
Stock Assessments
Determining the number of salmon in the Gulf of Maine DPS—and whether the population is increasing or decreasing over time—helps resource managers assess the successes and failures of enacted conservation measures and helps to guide future recovery actions. Our scientists collect information and present these data in annual stock assessment reports.
This database contains historic adult return, adult stocking, juvenile stocking, egg production, and aquaculture data for Atlantic salmon in New England Rivers.
