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.
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.
Did You Know?
Beaver ponds provide critical habitat for juvenile salmon.
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.
Salmon can be found in both the Atlantic and Pacific oceans as well as inland lakes like the Great Lakes.
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.
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).