Atlantic salmon

The fish that comes home to its river

A salmon is born in a river, then swims out to the ocean and grows there for years. Then it finds the very river it was born in by smell and swims upstream — even leaping over waterfalls! There it lays its eggs. Some salmon jump 3 metres high. Bears catch them right out of the air.

The Atlantic salmon (Salmo salar) is anadromous: born in fresh water, after 1–4 years it moves to the sea (smoltification — its gills and kidneys are re-tuned), feeds 1–3 years near Greenland, then returns to its birthplace with 95% accuracy using Earth's magnetic field and the chemical 'smell' of its river. It doesn't eat on the way up and leaps up to 3 m. Unlike Pacific salmon, some survive spawning and return to sea. Wild numbers have halved in 50 years due to dams, pollution and fishing (IUCN: Near Threatened). Farms in Norway and Chile raise 2 million tonnes a year.

Fun facts

• A salmon finds its home river by smell with 95% accuracy.
• On its way upriver it eats nothing at all.
• A salmon can jump 3 metres high.