Young Chinook salmon feed on terrestrial and aquatic insects, amphipods, and other crustaceans. Older Chinook primarily feed on other fish. Fish (such as whiting and mackerel) and birds eat juvenile Chinook salmon. Marine mammals, such as orcas and sea lions, and sharks eat adult salmon. When an adult Chinook salmon reaches maturity, which can be anywhere from three to seven years of age, it makes the long migratory journey back to the site of its birth stream to produce young. After so many years, some salmon can be hundreds of miles away. At their birth stream, male and female salmon pair up to breed.
Chinook salmon are an anadromous species which at diﬀerent phases of their life history, inhabit marine, brackish and freshwater habitats. They are the largest of the Paciﬁc salmon species. Adult Chinook migrate from the sea to their natal freshwater streams to spawn.