The question of whether salmon are endangered has a complicated answer that depends entirely on the specific species and where it lives. Salmon are broadly divided into two groups: the singular Atlantic salmon species (Salmo salar) and the multiple species of Pacific salmon (Oncorhynchus), which include Chinook, Sockeye, and Coho. The conservation status of these fish is highly variable, reflecting a patchwork of healthy, stable populations alongside others facing immediate threat of extinction. Conservation efforts focus on small, distinct groups rather than the entire species, acknowledging that a population in one river can be struggling while another is thriving.
Conservation Status Across Global Populations
The legal and scientific framework for protecting salmon uses specific designations to capture the localized nature of their decline. In the United States, the National Oceanic and Atmospheric Administration (NOAA) Fisheries assesses risk under the Endangered Species Act (ESA). They use the terms Evolutionarily Significant Unit (ESU) for Pacific salmon and Distinct Population Segment (DPS) for Atlantic salmon. This approach allows for the listing of a genetically unique population, even if the species as a whole is not at risk.
NOAA Fisheries currently protects 28 population groups of Pacific salmon and steelhead as either threatened or endangered across the West Coast. For example, nine ESUs of Chinook salmon are protected, including the Snake River Spring/Summer-run listed as Threatened. Among the most imperiled are the Sockeye salmon from the Snake River system, which has been a focus of intensive recovery efforts.
The situation for Atlantic salmon is similarly acute within the United States, where the Gulf of Maine DPS is listed as Endangered under the ESA. These are the only remaining native wild Atlantic salmon populations in the U.S., historically present in nearly every river northeast of the Hudson River. Globally, the International Union for Conservation of Nature (IUCN) recently reclassified the wild Atlantic salmon from Least Concern to Near Threatened. Many regional populations, such as the main stock in the United Kingdom, are now specifically listed as Endangered.
Not all salmon face dire circumstances; populations in Alaska, for example, are considered robust and healthy due to pristine habitat and strong management. This stark contrast highlights why conservation status must be viewed on a run-by-run basis. The status of a population dictates the level of protective measures, ranging from fishing restrictions to major habitat restoration projects.
Environmental and Anthropogenic Drivers of Decline
The decline of vulnerable salmon populations stems from human activity and changing environmental conditions that disrupt their complex anadromous life cycle. Salmon must migrate between freshwater spawning grounds and the saltwater ocean, making them sensitive to changes in both environments. Habitat fragmentation, primarily caused by dams and culverts, is a major physical barrier preventing adult salmon from reaching historical spawning rivers. These structures not only block access but also alter natural river flow and increase water temperatures, making the freshwater less hospitable for eggs and juveniles.
Climate change adds complexity by influencing conditions in both the river and the ocean. Warmer air temperatures reduce mountain snowpack, resulting in lower stream flows during summer and fall months, which can strand migrating fish. Warmer ocean temperatures shift the distribution of prey and predators. Ocean acidification also threatens the base of the marine food web, such as the mollusks consumed by juvenile Pacific salmon.
Anthropogenic pollution and habitat destruction further degrade the freshwater environment necessary for salmon reproduction. Runoff from agriculture, logging, and urbanization introduces contaminants and sediment into streams, reducing water quality and smothering spawning beds. The expansion of commercial aquaculture also presents a threat, as escaped farmed Atlantic salmon can interbreed with wild populations. This dilutes the native gene pool and potentially transmits diseases or parasites to vulnerable wild stocks.
Strategies for Population Recovery and Management
Protecting and restoring salmon populations requires a multi-faceted approach involving regulatory action, habitat improvements, and technological solutions. Under the ESA, federal agencies establish recovery plans that mandate actions such as setting precise fishing limits to ensure sufficient adults return to spawn. This regulatory oversight is paired with international agreements, such as the U.S.-Canada Pacific Salmon Treaty, to manage shared fish stocks across boundaries.
Major efforts focus on improving access to historical spawning grounds through habitat restoration and the removal of obsolete barriers. Projects often involve the physical removal of dams, as seen in the Penobscot River system, or the installation of sophisticated fish ladders and bypass systems. Other habitat work includes restoring degraded tidal wetlands and estuaries, which serve as transition zones for juvenile salmon acclimating to saltwater.
Scientific monitoring plays a large role, with NOAA Fisheries and partners tracking population trends and marine survival rates to inform management decisions. Conservation hatchery programs are implemented in some instances to maintain genetic diversity and augment low populations, such as the Gulf of Maine Atlantic salmon. The ultimate goal is establishing self-sustaining wild runs. These strategies aim to address the root causes of decline and rebuild the natural capacity of rivers to support healthy salmon populations.