Atlantic Salmon - Protected
About the Species
Atlantic salmon, also known as the “King of Fish,” are anadromous, which means they can live in both fresh and saltwater. Atlantic salmon have a relatively 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, including blocked access to spawning grounds, habitat degradation caused by dams and culverts, 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 commercial fishing in Atlantic salmon fisheries 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 last wild populations of U.S. Atlantic salmon are found in at least eight rivers in Maine. These 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 critical habitat for the Gulf of Maine DPS and makes every effort to engage the public in conservation efforts.
Worldwide, Atlantic salmon populations in single rivers range from thousands to nearly a quarter million. However, some populations are small, numbering in the low hundreds or even single individuals.
The endangered Gulf of Maine DPS 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 more recently, scientists have discovered marine survival and populations have significantly decreased, 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.
- Gulf of Maine DPS
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 mouths 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 baitfish 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 throughout the historical range, but many populations are severely depleted.
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 adults, and then return upriver to spawn.
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, or kelt, returns to the river where it was born to lay eggs. After spawning in freshwater, the kelt can swim back to the ocean and possibly return to spawn again.
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.
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, ongoing subsistence 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, disease, predation from introduced and invasive species, and interbreeding with escaped fish raised on farms for commercial aquaculture.
Marine survival is the primary driver of population productivity for Atlantic salmon. During years with high marine survival, populations are expected to be robust and to increase, whereas during years of low marine survival, populations are expected to decline. Unfortunately, U.S. Atlantic salmon are currently in a period of persistent, poor marine survival. During the early 1990s, oceanographic changes in the Northwest Atlantic had major impacts on the dynamics of many marine species, including Atlantic salmon. These changes led to significant decreases in marine survival for Atlantic salmon across their North Atlantic range—from Labrador south to the United States. Although the exact reasons for the decrease are unknown, scientists hypothesize that the oceanographic changes altered dynamics up the food chain from primary production to prey fish and even Atlantic salmon. These changes were severe enough to similarly impact the productivity of other marine species (e.g., Atlantic cod, Bluefin tuna, seabirds, marine mammals).
Dams block Atlantic salmon migration paths between rivers and the ocean and can prevent salmon from reaching the habitats needed for spawning and juvenile rearing. Turbines used to generate electricity can kill or injure many salmon as they migrate through dams on their journeys to the ocean. Injuries caused by dams may result in delayed mortality or increase salmon vulnerability to other threats, such as predation by other fish or birds. Dams can also increase the amount of time salmon need to migrate, disrupting their life cycle in the process. These impediments impact river ecosystems by changing river flows, reducing water quality, and changing water temperature. Dams also destroy habitats important to other fish species that salmon have evolved to depend on (e.g., migrating alewives can buffer Atlantic salmon against predation from birds and other fish) and provide habitats for fish species that compete with or prey on Atlantic salmon.
Land use practices can degrade freshwater habitats necessary for Atlantic salmon survival. For example, forestry, agriculture, and development projects damage or destroy riparian areas that protect streams from erosion. These areas also provide habitat structure, essential nutrients, and forage that salmon depend on in the form of falling trees, leaf litter, and bugs that fall from the forest canopy.
Pollution causes poor water quality that may impact Atlantic salmon. Pollution can reduce the levels of oxygen in the water, making areas unsuitable for salmon survival, and it can deliver chemicals that are toxic to fish or that react with other chemicals to increase toxicity to fish. Pollution also adversely affects Atlantic salmon’s homing abilities and alters the water chemistry, which can impair the salmon’s ability to regulate its own body chemistry. Water quality can affect salmon differently depending on their life stage. For example, juvenile salmon may experience reduced growth, while adults may produce fewer eggs.
Atlantic salmon are threatened by gillnet fisheries, bycatch in recreational fisheries, and poaching. International commercial fishing has been highly restricted since 2002, but this issue has recently become a growing concern. In areas with recreational fishing, fishermen might accidentally or unknowingly catch Atlantic salmon. Even if salmon are released after being caught, they are particularly susceptible to post-release mortality from injury or stress.
Atlantic salmon can be affected by many pathogens (bacterial, viral, and fungal) found in the wild, which can lead to different diseases. A severe disease outbreak can potentially affect many individuals or an entire year class or life stage within an Atlantic salmon population. Atlantic salmon are also vulnerable to parasites, and there is strong evidence that commercial aquaculture facilities are a primary source of parasites for naturally occurring populations of Atlantic salmon. Best management practices and good fish husbandry have minimized the risks from disease and parasites. In addition, all commercial and federal hatcheries follow strict disease prevention practices. These practices help protect natural and hatchery environments from pathogens. If a disease does break out in a hatchery, managers also take steps to control the spread of the pathogen between hatcheries and river systems.
Aquaculture, or fish farming, refers to the breeding, rearing, and harvesting of marine plants and animals for public use. Aquaculture of Atlantic salmon provides the world with a healthy food source that would not be available through other means such as a wild fishery. However, commercial aquaculture of Atlantic salmon has well-documented genetic and ecological threats on wild salmon populations. These threats include interbreeding between wild and farmed individuals as well as pathogen and parasite transfers to the wild populations that live near commercial operations. Most fish raised for aquaculture purposes are closely related to their wild counterparts; however, through artificial selection during spawning, the genetic composition of farmed fish is different and less fit than wild populations. If they escape and breed with wild fish, the offspring produced will contain genes from the farmed origin parent and would be less fit for survival in the wild. While producers go to great lengths to make sure farmed fish never enter the environment and interact with wild fish, accidents have happened in the past and may be anticipated in the future. Recent improvements in manufactured gear (net pens and mooring systems) for rearing fish in open ocean environments has decreased the likelihood of escapes. Additional marking of these fish has helped to better understand the causes and helps to minimize these risks. But even with these changes, aquaculture fish still put wild Atlantic salmon at risk.
In the Spotlight
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 to spotlight and save the most highly at-risk marine species.
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 Maine.
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. Before this, they were of great cultural and historical importance to Native American tribes in Maine. Atlantic salmon supported important fisheries that were a main food source for the tribes. If this iconic species goes extinct, the services it once provided to the American and Native American people will be lost.
NOAA Fisheries listed the Gulf of Maine DPS as endangered under the Endangered Species Act in 2000. We then extended ESA protection in 2009 to include more Atlantic salmon in other rivers in Maine. Because of the Gulf of Maine DPS’s rapid decline and dire status, NOAA Fisheries and its 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 the freshwaters of Maine rivers, they migrate to Newfoundland and Labrador. They spend their first winter at sea south of Greenland.
After the first winter at sea, a few salmon return to Maine. However, most salmon spend a second year at sea, where they live and feed off the southwest coast of Greenland. Some Maine salmon are also found in waters along the Labrador coast. After a second winter in the Labrador Sea, most Gulf of Maine salmon return to rivers in Maine.
The Gulf of Maine population 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 many salmon started to die in the ocean, resulting in a significant population decline. Less than 1,000 fish now return to Maine’s rivers every year.
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. 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 habit must be disease-free, provide food resources, and have good water quality for salmon to survive.
Adult spawning habitat refers to habitat with an unembedded, 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.
Dams limit or block salmon’s 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.
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.
To work toward recovery of these fish, NOAA Fisheries formed a recovery team of scientists and stakeholders to help develop a recovery plan, which was finalized in March 2016. 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 these animals.
Threats with the potential to limit recovery of the Gulf of Maine DPS of Atlantic salmon include:
Dams and road crossings.
Inadequate regulation of dams.
Low survival rates in the ocean.
Loss of habitat features due to human activity.
High catch rates in international fisheries.
Reduced water quantity.
Reduced water quality.
Increased number of predators.
Decreased populations of interconnected fish species.
Competition with other fish species.
In developing the draft recovery plan, NOAA Fisheries aims to provide recovery goals and objectives toward which all stakeholders can work together. We work closely with the Penobscot Indian Nation, the U.S. Fish and Wildlife Service, and the Maine Department of Marine Resources to manage Atlantic salmon cooperatively under the Atlantic Salmon Recovery Framework.
In 2016, we completed a Species in the Spotlight 5-year action plan for the Gulf of Maine DPS that builds on the recovery plan and details the focused efforts that are needed over the next 5 years.
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
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 also work cooperatively with the U.S. Fish and Wildlife Service, Maine Department of Marine Resources, and Penobscot Indian Nation to recover Atlantic salmon.
As a result of this collaboration, we published a draft recovery plan for the Gulf of Maine DPS in March 2016. 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.
Critical Habitat Designation
Once a species is listed under the ESA, NOAA Fisheries evaluates and identifies whether any areas meet the definition of critical habitat. Those areas may be designated as critical habitat through a rulemaking process. The designation of an area as critical habitat does not create a closed area, marine protected area, refuge, wilderness reserve, preservation, or other conservation area; nor does the designation affect land ownership. Federal agencies that undertake, fund, or permit activities that may affect these designated critical habitat areas are required to consult with NOAA Fisheries to ensure that their actions do not adversely modify or destroy designated 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.
Habitat Restoration and Fish Passage
Atlantic salmon need a wide range of well-connected habitat types. In freshwater, dams and other barriers to migration block salmon from important spawning and nursery habitats. The Gulf of Maine DPS of Atlantic salmon has access to only 8 percent of its historical freshwater habitat.
NOAA Fisheries is working with dam owners to find solutions that will allow salmon to recover. We have provided significant resources ($22.5 million) for the oversight, funding, and monitoring of two dam removals on the Penobscot River. The Penobscot River is home to about 75 percent of the adult Atlantic salmon in the United States, so restoring access to this river is particularly important. We also supported 35 other fishway constructions and dam removal projects in Maine, including the removal of two major hydroelectric dams. In 2015, biologists counted 731 Atlantic salmon at the Milford Dam fish lift in Milford, Maine.
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.
In the Penobscot River basin alone, there are still more than 130 dams that block access to about 90 percent of salmon’s historical spawning and nursery habitat. There is still much work to be done.
Captive Breeding and Stocking Programs
Hatchery programs have allowed Atlantic salmon to survive during times when many of Maine’s rivers were not suitable for salmon survival. They also allowed an economically important recreational fishery to operate through the early 1990s.
Hatchery programs are now key to preserving the last wild Atlantic salmon populations in the United States. The U.S. Fish and Wildlife Service’s Lamar Fish Health Center and Lamar Fish Tech Center currently 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 in case wild salmon stop returning to their native habitats.
The hatchery program will continue to support conservation activities, including spawning, stocking, and brood collection in several rivers. It will also keep captive brood populations for the Gulf of Maine for as long as needed.
Producing Young Salmon
Producing many smolts is the main safety net for Atlantic salmon 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.
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 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 2000, the Gulf of Maine population was listed as endangered under the ESA. We released a final recovery plan in December 2005.
In 2009, we extended ESA protection to more Atlantic salmon by adding fish in the Penobscot, Kennebec, and Androscoggin Rivers to the endangered Gulf of Maine population first listed in 2000. We designated critical habitat for this population in 2009, and released a draft recovery plan in March 2016. The new recovery plan addresses the expanded range of the Gulf of Maine DPS of Atlantic salmon, which was finalized in 2009.
In January 2016, we completed a 5-year status review of the Gulf of Maine salmon population.
Regulatory Actions & Documents
- Final Rule to Expand DPS (74 FR 29344)
- Proposed Rule to Expand DPS (73 FR 51415)
- Notice of Availability of Status Review (71 FR 55431)
- Original DPS Final Rule (65 FR 69459)
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.
Atlantic salmon live in and migrate through freshwater streams and rivers, estuaries, coastal waters, and the North Atlantic Ocean. They thus need different water chemistry conditions at different stages in their life. Young salmon are especially sensitive to the amount of acid and aluminum in streams. Our scientists studied the effects of acid and aluminum levels on two juvenile life stages of Atlantic salmon. They found that increases in acidity can injure salmon and even increase the chance that they will die.
NOAA Fisheries is genetically monitoring Atlantic salmon to make sure that salmon born in hatcheries can survive in the wild. We also want to make sure that wild salmon are genetically diverse. This information will help us monitor the recovery of the Gulf of Maine DPS and create best practices for hatchery management.
Our scientists study the parasites, bacteria, and viruses that can affect Atlantic salmon health. Populations that are already threatened are especially vulnerable to disease, so it is important to understand how disease could affect the Gulf of Maine DPS. Scientists have sampled several fish species for disease, 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).
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 success of enacted conservation measures. Our scientists collect information and present these data in annual stock assessment reports.
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