Chinook are the largest-bodied species of Oncorhynchus. Chinook are at increased risk of extinction in their southern range and in Washington, Oregon, California, and Idaho inland threats of habitat loss and water diversions have resulted in extirpations.
The least abundant of the five North American species overall, Chinook populations are more widely distributed on the eastern side of the Pacific than they are in Asia.
Chinook salmon are the largest of the Pacific salmon, measuring up to five feet (150 cm) and typically weigh 10-25 pounds (5 – 11 kg), with some weighing over 100 pounds.
Chinook live from 3 to 6 years. Their life histories vary greatly both within river basins and across the range of the species. Chinook spawn in mainstem rivers and have four seasonal spawning runs, each with different time periods rearing in freshwater and in their ocean phase. In the largest river basins, Chinook return virtually year-round, though there is usually a strong seasonal peak some time between May and September.
There are stream- and ocean-type Chinook. Most Chinook at the northern and southern extremes of their distribution are stream-type, rearing for up to two winters in freshwater before leaving for the ocean. Toward the center of their range, ocean-type Chinook predominate, leaving home rivers within weeks for marine waters, where they spend an average of 4 – 5 years. The two types generally use different rearing areas in the ocean, but when they return, their runs may overlap and they may share the same spawning grounds.
Chinook salmon are a staple of native peoples’ diets and are the species most strongly associated with First Salmon ceremonies which mark the first salmon runs of each year. Chinook salmon are also favored among sportfishers.