Atlantic Salmon

Verified Timeline

Lore & Background

The Atlantic salmon was given its scientific binomial name by Carl Linnaeus in 1758. The name Salmo salar derives from the Latin salmo, meaning salmon, and salar, meaning leaper or 'resident of salt water'. Other names include bay salmon, black salmon, caplin-scull salmon, fiddler, sebago salmon, silver salmon, outside salmon, and winnish. At different life stages they are known as parr, smolt, grilse, grilt, kelt, slink, and spring salmon. Landlocked populations spend their entire lives in freshwater.

In Their Own Story

After several years wandering huge distances in the ocean, most Atlantic salmon return to the natal rivers where they were spawned. They swim up the rivers until they reach the very spawning ground that was their original birthplace. They use geomagnetic and chemical cues to guide them. They may be sensitive to the Earth's magnetic field, allowing them to navigate back to the estuary of their natal stream. Salmon have a strong sense of smell. In 1951, Hasler hypothesised that once near the estuary, salmon use chemical cues unique to their natal stream to home onto the entrance. In 1978, Hasler and his students found that salmon locate their home rivers because they can recognise their characteristic smell, which becomes imprinted when they transform into smolts just before migrating out to sea. Homecoming salmon can also recognise characteristic smells in tributary streams as they move up the main river. They may also be sensitive to pheromones given off by juvenile conspecifics. There is evidence they can discriminate between two populations of their own species. Tagging studies show a small number of fish stray to other nearby streams, which is important for colonizing new habitats. In 1984, Quinn hypothesized a dynamic equilibrium, controlled by genes, between homing and straying.

Reader's Guide

Atlantic salmon are the largest species in the genus Salmo. After two years at sea, they average 71 to 76 cm in length and 3.6 to 5.4 kg in weight. The heaviest recorded specimen weighed 49.44 kg, netted in 1960 in Scotland. The longest recorded was 160.65 cm, netted in 1925 in Norway. Young salmon have blue and red spots; adults have a silver-blue sheen with black spots predominantly above the lateral line. Males take on a slight green or red colour when reproducing. They have a fusiform body and well-developed teeth. All fins except the adipose fin are bordered with black.

Did You Know?

• Atlantic salmon can survive spawning and return to sea to spawn again, with 5–10% doing so.
• The heaviest Atlantic salmon on record weighed 49.44 kg, caught in Scotland in 1960.
• Some populations are landlocked, spending their entire lives in freshwater.
• The different life stages are called alevin, fry, parr, and smolt.