# Atlantic Salmon (*Salmo salar*)

> The Atlantic salmon (Salmo salar) is a powerful migratory fish of the North Atlantic, hatching in rivers, maturing at sea, and returning upstream to spawn. Adults typically weigh 3 to 15 kg (7 to 33 lb) and can swim in bursts of around 40 km/h (25 mph), leaping waterfalls on their way home. Wild salmon usually live 4 to 8 years and are listed as Least Concern, though many local populations are in serious decline.

- **Category:** Fish
- **Conservation status (IUCN):** Least Concern
- **Range:** Rivers and coastal waters of the North Atlantic, from northeastern North America to Europe.
- **Canonical page:** https://globalanimalguide.org/animals/salmon/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Actinopterygii
- **Order:** Salmoniformes
- **Family:** Salmonidae
- **Genus:** Salmo

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Salmo salar |
| Diet | Carnivore |
| Habitat | North Atlantic rivers and ocean |
| Lifespan | 4–8 years |
| Weight | 3–15 kg (7–33 lb) |
| Top speed | Around 40 km/h (25 mph) in bursts |
| Conservation status | Least Concern (IUCN) |

## The upstream migration

Atlantic salmon are famous for returning from the ocean to spawn in the very river where they hatched, often the exact stretch of gravel. To reach the spawning grounds they swim upriver against strong currents and leap over waterfalls and rapids, reaching burst speeds of around 40 km/h (25 mph). They appear to navigate using the Earth's magnetic field on the open ocean and then their sense of smell to pick out their home river.

## From freshwater to sea and back

Salmon begin life in freshwater, where young fish called parr spend one to several years before a bodily transformation, called smolting, prepares them to survive in salt water. They then migrate downstream and out into the North Atlantic to feed and grow. After one or more years at sea they return as mature adults to spawn, completing a life cycle that spans both river and ocean.

## Diet and feeding

Atlantic salmon are carnivores whose diet changes with age. Young fish in rivers eat aquatic insects, larvae, and other small invertebrates. At sea, adults feed on small fish such as herring, sand eels, and capelin, along with crustaceans that help give their flesh its pink colour. Once they enter their home river to spawn, adults largely stop feeding and live off stored reserves.

## Spawning and the next generation

On the spawning grounds, the female uses her tail to dig a gravel nest called a redd, where she lays her eggs for the male to fertilise. Unlike Pacific salmon, some Atlantic salmon survive spawning and return to the sea to breed again in later years. The buried eggs hatch into tiny alevins that live off their yolk sac before emerging as fry to begin the cycle anew.

## Size and lifespan

Adult Atlantic salmon typically weigh 3 to 15 kg (7 to 33 lb) and can reach around 0.9 m (3 ft) in length, with the largest specimens considerably bigger. Their lifespan is usually 4 to 8 years, split between their years in the river and their time feeding at sea. Fish that survive to spawn more than once tend to be among the largest and oldest individuals.

## Conservation and threats

Although the Atlantic salmon is listed as Least Concern globally by the IUCN, many wild populations have fallen sharply. Dams that block migration routes, pollution, warming waters, overfishing, and interbreeding and disease from fish farms all put pressure on wild stocks. Removing river barriers, improving water quality, and managing fisheries are key to helping these iconic migratory fish recover.

## Frequently asked questions

### Why do salmon swim upstream?

Salmon swim upstream to return to the freshwater rivers where they hatched in order to spawn. Reaching clean, oxygen-rich gravel beds gives their eggs the best chance of survival, so the fish battle currents and leap waterfalls to get there.

### How do salmon find their home river?

Salmon are thought to navigate the open ocean using the Earth's magnetic field, then switch to their acute sense of smell as they near the coast. This lets them home in on the unique scent of the river, and often the exact stream, where they were born.

### How big do Atlantic salmon get?

Adult Atlantic salmon typically weigh 3 to 15 kg (7 to 33 lb) and grow to around 0.9 m (3 ft) long. The very largest fish, which have spent longer at sea, can be considerably heavier.

### What do Atlantic salmon eat?

They are carnivores. Young salmon in rivers eat insects and small invertebrates, while adults at sea feed on small fish such as herring and sand eels, plus crustaceans. Adults largely stop eating once they enter their home river to spawn.

### How long do salmon live?

Wild Atlantic salmon usually live 4 to 8 years, divided between their early years in freshwater and their feeding years at sea. Unlike Pacific salmon, some Atlantic salmon survive spawning and return to breed again.

### Are Atlantic salmon endangered?

Globally the Atlantic salmon is listed as Least Concern, but many individual wild populations have declined severely. Dams, pollution, warming rivers, overfishing, and impacts from fish farms are the main threats to wild stocks.

## Sources

- [IUCN Red List — Salmo salar.](https://www.iucnredlist.org/search?query=Salmo%20salar&searchType=species)
- [Animal Diversity Web — Salmo salar. University of Michigan Museum of Zoology.](https://animaldiversity.org/accounts/Salmo_salar/)
- [Wikipedia — Atlantic Salmon.](https://en.wikipedia.org/wiki/Atlantic_salmon)

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Source: Global Animal Guide (https://globalanimalguide.org/animals/salmon/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.