Are Atlantic Salmon Endangered? Decline in Europe and the US

What is the global status of the Atlantic salmon?

The Atlantic salmon still lives in hundreds of rivers on both sides of the North Atlantic, so it is far from extinction. But the trend is clearly downward. According to the IUCN, the species is now restricted to a small part of the rivers it inhabited a century ago across northern Europe and North America.

A global category can hide very different local stories. In some northern rivers in Norway, Iceland, Russia and Canada, salmon are still fairly numerous. Near the southern edge of the range, in Spain, France, southern England, the Baltic and the northeastern United States, many runs are tiny or gone.

The endangered Gulf of Maine salmon

Atlantic salmon once ran up rivers from Maine south to Connecticut and probably the Hudson. Dams, mills, logging and pollution wiped out many of these runs as early as the 18th and 19th centuries, and attempts to restore salmon to the Connecticut River ended in 2012 after decades of stocking.

Today, the only wild sea-run Atlantic salmon left in the United States belong to the Gulf of Maine population. It was listed as endangered under the Endangered Species Act in 2000, covering a group of small coastal rivers such as the Dennys, Machias, Narraguagus and Sheepscot. In 2009, the listing was expanded to include the much larger Penobscot, Kennebec and Androscoggin rivers. NOAA Fisheries has named it one of the US species most at risk of extinction.

Adult returns to Maine are now counted in the hundreds to low thousands each year, a tiny fraction of the historical runs, and many of the returning fish started life in conservation hatcheries. Canada lists its Inner Bay of Fundy salmon as endangered too.

Why are Atlantic salmon declining?

Salmon face problems in both halves of their lives, which is why they are so hard to protect.

• Dams and barriers. Dams, weirs and road culverts cut salmon off from spawning gravel. A river can lose its salmon simply because the fish can no longer reach the headwaters.
• Poor survival at sea. Since about the 1990s, far fewer smolts have survived their time at sea. Ocean warming and changes in the food web are thought to be the main reasons, and in many rivers only a few in every 100 smolts now come back as adults.
• Salmon farming. Salmon lice (Lepeophtheirus salmonis) breed in large numbers around open-net farms and can kill wild smolts swimming past. Escaped farmed salmon breed with wild fish and pass on genes that are poorly suited to life in the wild.
• Pollution and silt. Farm runoff, sewage and soil washed off the land clog the gravel where eggs and young fish live.
• Warming rivers. Hot, low summer rivers stress salmon and can kill fish trapped in pools.
• Invasive species and disease. The parasite Gyrodactylus salaris has devastated salmon in dozens of Norwegian rivers, and pink salmon from the Pacific are now spreading along northern European coasts.

Overfishing at sea also played a big part in the past. In the 1960s to 1980s, large net fisheries off West Greenland and the Faroe Islands caught salmon from rivers all over the North Atlantic. These were later cut back sharply through international agreements.

How are salmon doing in Europe?

Britain and Ireland have seen some of the steepest falls. In England, most of the main salmon rivers are now assessed as at risk or probably at risk, and Scotland’s recent rod catches have been among the lowest since records began in 1952. Ireland ended its mixed-stock drift-net fishery at sea in 2007, and many Irish rivers are now open only for catch-and-release or closed altogether.

Norway, home to many of the world’s strongest wild salmon runs, has its own problems with sea lice, escaped farmed fish and Gyrodactylus. In 2023, it closed dozens of rivers to salmon fishing in the middle of the season because so few fish had returned.

In the Baltic Sea, many of the larger salmon rivers were dammed for hydropower in the 20th century, and many of the salmon there are now raised in hatcheries. The Torne River on the border between Sweden and Finland is among the most important remaining wild Baltic salmon rivers.

What is being done to save Atlantic salmon?

Many of the most hopeful projects focus on opening rivers. On the Penobscot River in Maine, the Great Works and Veazie dams were removed in 2012 and 2013, and a bypass was built around another dam, reopening much of the river to salmon and other sea-run fish. Large dam removals in France, including on the Sélune in Normandy, follow the same idea.

Other measures include:

• strict limits on fishing at sea through the North Atlantic Salmon Conservation Organization (NASCO), set up in 1983
• catch-and-release rules and river closures where stocks are low
• replanting riverbanks with trees to shade and cool the water
• reducing pollution and silt from farmland
• moving salmon farms to closed tanks on land or at sea, away from wild fish
• conservation hatcheries that keep the genes of rare river populations alive

Helping salmon return also depends on their remarkable homing skills, described in How do salmon find their way home?, and on clear routes upstream, covered in Why do salmon swim upstream?

A wider problem for migratory fish

Atlantic salmon are not alone. Many fish that move between rivers and the sea have declined for similar reasons, from dams to changing oceans. The most dramatic case in Europe is the European eel, which is now Critically Endangered, as explained in Why are European eels critically endangered?