Atlantic salmon

Salmo salar

Order: Salmoniformes

Family: Salmonidae

Genus: Salmo

The Atlantic salmon is a sleek, silvery fish with a streamlined body built for long-distance migration. Adults average 71 to 76 centimetres in length and typically weigh 3 to 7 kilograms, although large individuals can exceed 15 kilograms. In freshwater, juveniles display a mottled brown pattern with vertical bars, while ocean-going adults take on a silver sheen with faint black spots. Males in breeding condition develop a hooked lower jaw known as a kype.

Atlantic salmon are anadromous: they hatch in freshwater, migrate to the ocean to grow, then return to their natal rivers to spawn—often after traveling thousands of kilometres.

Conservation Status: IUCN

Distribution

Native to the North Atlantic Ocean and rivers draining into it. In Canada, wild populations are found in rivers of Québec, Newfoundland and Labrador, Nova Scotia, and New Brunswick. Atlantic salmon are also widely farmed in aquaculture operations along both Atlantic and Pacific coasts.

Habitat

Freshwater: Clear, cold, well-oxygenated rivers and streams with gravelly bottoms—used for spawning and early development
Marine: Open ocean, where adults travel vast distances to feed, typically near Greenland and the Labrador Sea
Require healthy riparian zones and unobstructed river systems for migration and spawning

Diet

Juveniles: Aquatic insects, crustaceans, and plankton
Adults (at sea): Fish (such as capelin and sand lance), squid, and shrimp
Their diet at sea contributes to the energy reserves they need to complete their return migration and spawning without feeding.

Reproduction

Atlantic salmon reproduce in freshwater streams in late fall. Females dig depressions in gravel called redds and lay thousands of eggs. After fertilization, the eggs remain buried through winter and hatch in spring. Juveniles remain in freshwater for 1 to 3 years before migrating to the sea. Unlike Pacific salmon, some Atlantic salmon survive spawning and may return to the sea to repeat the cycle—these individuals are called kelts.

Adaptation

Anadromous life cycle enables access to abundant ocean food while maintaining natal spawning fidelity
Keen homing ability allows them to return to their birth river using smell and magnetic cues
Streamlined body suited for powerful swimming across long distances and upstream currents
Physiological adaptability to shift from freshwater to saltwater (and back again) through complex osmoregulatory processes

Threats to Survival

Habitat fragmentation (especially from hydroelectric dams and culverts)
Climate change impacting water temperature and ocean survival rates
Aquaculture interactions, including escapees, disease transmission, and genetic mixing
Overfishing and bycatch in marine fisheries
Water pollution and siltation from forestry and agriculture

Viewable