FaunaHub

Salmon

FishMigratoryWild

A sockeye salmon (Oncorhynchus nerka) swimming.

Sockeye salmon (Oncorhynchus nerka).

Image: Milton Love, Public domain, via Wikimedia Commons.

Overview

Salmon are migratory fish in the family Salmonidae, including Atlantic salmon and several Pacific species such as sockeye, chinook, and coho. This page is a group-level overview; the sockeye salmon (Oncorhynchus nerka) is used as a familiar reference. Most salmon are famous for being anadromous — hatching in fresh water, maturing at sea, and returning to fresh water to spawn — often making remarkable journeys.

Habitat & Range

Salmon use both fresh and salt water across their lives. They hatch in cool, clean rivers and streams, migrate to the ocean to feed and grow, and return to fresh water — often to their natal river — to breed. Their ranges span the North Atlantic and North Pacific and adjoining rivers. Healthy salmon depend on connected, clean waterways, which makes them sensitive to barriers and habitat change.

Diet

Salmon diet changes through life. Young fish in rivers feed on insects and other small invertebrates, while at sea they take larger prey such as smaller fish and crustaceans. During the spawning run, many salmon stop feeding altogether. Diet varies by species and life stage; this page describes general feeding ecology.

Behavior

The salmon life cycle and migration are their most striking features. After years at sea, adults navigate back toward their home rivers, often leaping waterfalls and obstacles to reach spawning grounds. Many Pacific salmon die after spawning once, returning nutrients to the ecosystem, while Atlantic salmon may spawn more than once. Behaviour and timing of runs vary by species and population.

Human Interaction & Conservation

Salmon are economically, culturally, and ecologically important, supporting fisheries, aquaculture, and Indigenous traditions, and feeding wildlife from bears to eagles. Many wild salmon populations face pressures from dams, habitat loss, warming water, and fishing, and some are threatened or endangered while others remain abundant. Because status differs sharply by species and population, it should be verified against current IUCN and government (such as NOAA Fisheries) sources.

Appearance & Recognition

At sea, salmon are typically silvery and streamlined. As they return to fresh water to spawn, many change dramatically — sockeye salmon, for example, turn brilliant red with a green head, and males of some species develop a hooked jaw called a kype. Size varies by species, from modest to very large in the chinook. These spawning changes are a useful identification clue.

Similar Animals

Salmon belong to the family Salmonidae alongside trout, char, and grayling. They are wild migratory fish, unlike the aquarium fish covered on FaunaHub, and share their river and ocean habitats with predators such as bears, eagles, and seals, all profiled elsewhere on the site.

More photos of the salmon

Bright red sockeye salmon in a spawning bed during the breeding run.

Sockeye salmon in spawning colours.

Image: U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons (USFWS).

Frequently Asked Questions — Salmon

Why do salmon swim upstream to spawn?
Most salmon are anadromous: they hatch in fresh water, grow at sea, and return to rivers to breed, frequently to the very stream where they hatched. This upstream migration takes them to suitable gravel spawning beds, even if it means leaping obstacles along the way.
Do all salmon die after spawning?
Not all. Many Pacific salmon spawn once and then die, returning nutrients to the river ecosystem. Atlantic salmon and some others can survive and spawn more than once. The pattern depends on the species.
Are salmon endangered?
It depends on the species and population. Some salmon runs are threatened or endangered due to dams, habitat loss, and other pressures, while others remain abundant. Because status varies and is actively monitored, check current IUCN Red List and government sources rather than assuming.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.