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Species Profile

Atlantic Salmon

Globally Least Concern on paper, but wild North Atlantic populations have fallen by more than half since the 1980s — a decline increasingly traced to what happens to salmon at sea, not just in their home rivers.

Least Concern IUCN status (global species)
~50%+ decline in wild North Atlantic returns since 1980s
Declining wild population trend across most of range
Published May 2026 Last reviewed July 2026 Evidence level Moderate, evolving evidence Reading time 6 min

Status & Range

Wild Atlantic salmon (Salmo salar) range across rivers on both sides of the North Atlantic, from eastern North America to Western Europe and Russia. While the IUCN lists the species globally as Least Concern, this reflects its overall range and abundance including farmed populations' genetic reservoir — wild, self-sustaining populations have declined sharply across most of their historic range.

Established fact

The North Atlantic Salmon Conservation Organization (NASCO) reports that total wild Atlantic salmon abundance has declined by more than 50% since the 1980s, with some U.S. and Canadian rivers seeing declines exceeding 90%.

Source: NASCO / ICES State of North Atlantic Salmon reports, 2023

Ecology

Atlantic salmon are anadromous: they hatch in freshwater rivers, migrate to sea to feed and grow for one to several years, then return to their natal river to spawn. This life cycle exposes them to distinct pressures at each stage — river habitat quality, ocean feeding conditions, and the return migration itself — making the species an unusually clear indicator of both freshwater and marine ecosystem health.

Pressures

Dams and river barriersDams block access to historic spawning grounds and alter river flow and temperature; dam removal projects in Maine and elsewhere have shown measurable, if partial, recovery in salmon access to habitat.
Aquaculture interactionsEscaped farmed salmon can interbreed with wild populations, reducing genetic fitness, while sea lice from open-net salmon farms have been linked to elevated mortality in wild juvenile salmon migrating past farm sites in Norway, Scotland, and Ireland.
Declining marine survivalThe proportion of salmon smolts that survive their ocean phase and return to spawn has fallen across most monitored rivers since the 1980s; the precise marine-stage causes (shifting prey, predation, ocean warming) remain only partially understood.

Trend

1970s–80sWild Atlantic salmon abundance still relatively high across most of the North Atlantic range.
1990s–2000sMarine survival rates begin a sustained decline, coinciding with the expansion of open-net salmon aquaculture.
2010s–Dam removals (e.g., Penobscot River, Maine) begin restoring freshwater access in parts of the range.
2023NASCO reports continued overall decline despite localized freshwater habitat gains.

Conservation Measures

Dam removal and fish-passage construction, restrictions and technology upgrades for open-net aquaculture (including a shift toward land-based closed containment in some markets), and international harvest management coordinated through NASCO are the primary tools currently in use, though most experts agree freshwater-focused measures alone cannot reverse the marine-survival decline.

Uncertainty & Evidence Gaps

The specific causes of declining marine survival are less well understood than freshwater pressures, since tracking individual salmon at sea is logistically difficult; current research relies heavily on acoustic tagging studies and indirect return-rate data rather than direct observation of ocean mortality causes.