Salmon Facts

Salmon is the common name for fish in the order Salmoniformes. They live in the northern Atlantic and Pacific oceans, and are anadromous, which means most types of salmon are born in fresh water, migrate to the sea, and return to freshwater to reproduce, or "spawn".

Salmon appearance varies greatly from species to species. Species like chum salmon are silvery-blue in color while some have black spots on their sides, like the Atlantic salmon. Still others, like the cherry salmon, have bright red stripes. Most of these species maintain one color when living in fresh water, then change color when they are in salt water.

Diet

In general, young salmon eat insects, invertebrates and plankton; adults eat other fish, squid, eels, and shrimp. Unlike all other salmon, the sockeye salmon has a diet that consists almost entirely of plankton.

Population

It is difficult to estimate population numbers due to the large number of species and wide geographic range. However, population numbers in the Atlantic Ocean and in parts of the Pacific, as well as the Colorado River, have dropped drastically from what they were historically. In the Colorado River, for instance, salmon numbers are down to 3% of what they were during the time of Lewis and Clark.

Range

Salmon can be found in both the Atlantic and Pacific oceans as well as inland lakes like the Great Lakes.

Behavior

Most salmon are anadromous fish, meaning they are born in freshwater (rivers or streams), travel to and live much of their lives in salt water and return to freshwater to spawn. After spawning, all Pacific salmon and up to 50% of other species die within a few weeks. The salmon that do not die can spawn two or three more times.

There are a few species and subspecies of salmon, like the Danube salmon and the kokanee salmon, that spend their entire lives in fresh water and never migrate to the ocean.

Reproduction

When the female reaches the place where she will lay her eggs, she makes a depression in the riverbed with her tail, and then deposits her eggs in this depression. She waits for males to fertilize the eggs, then covers the depression and moves on to make another. Females will make as many depressions as it takes to lay all their eggs (up to seven depressions).

Climate Change and Other Threats

Rising stream and river temperatures pose problems for salmon. Salmon favor cool water - the maximum temperature most can tolerate is in the range of 68 to 75 degrees fahrenheit. Recent climate models predict that stream temperatures will rise in many locations over the 21st century. As stream temperatures increase, up to 50% of existing salmon habitat in the United States will become too warm. As the fish become increasingly restricted to colder streams, their populations will be more fragmented and more isolated, since the populations will no longer be able to intermingle in the warmer water downstream. Learn more about how salmon are affected by climate change >>

Climate change also threatens to accelerate the spread of salmon diseases. Whirling disease, which is found in mountain streams, damages the brains and spinal cords of young fish. A marine disease called ichthyophoniasis, or "ick" for short, infects the heart and other vital organs. Warmer waters seem to increase both the generation of these organisms, and the damage they do when they infect a host.

Damming of rivers also poses a threat to salmon, as they swim upriver to get to spawning areas, and are unable to proceed further when they reach a dam.

Legal Status/Protection

Endangered Species Act:

• Atlantic salmon: Endangered in parts of Maine.
• Chinook salmon: Endangered in parts of Washington and California; threatened in parts of Washington, California, and Idaho.
• Coho salmon: Endangered in parts of California; threatened in parts of Oregon, California, and the Lower Columbia River.
• Sockeye salmon: Endangered in parts of Idaho; threatened in parts of Washington.
• Chum salmon: Threatened in parts of Oregon and Washington.

IUCN Red List:

• Cherry salmon: A subspecies of cherry salmon (Formosan land-locked salmon) is critically endangered; it is one of the rarest fish in the world.

• Learn more about legal status and protection of salmon >>

How You Can Help

• Help salmon and other wildlife by adopting an animal at our Wildlife Adoption Center.
• Take Action for Wildlife at our Wildlife Action Center.

For additional information

• University of Washington Libraries Salmon Pages
• Alaska Department of Fish and Game Salmon Pages