Oncorhyncus tshawytscha (Walbaum, 1792)
Some populations of Chinook salmon migrate more than 2,000 miles to spawn in in the upper Yukon River to spawn. Specimens of Chinook salmon have been recorded to weigh as much as 135 lbs. (61.4 kg.) Maximum reported age for Chinook salmon is 9 years.
SIZE: The average weight for chinook salmon is around 40 lbs. or 18 kg. The common length for chinook salmon is 70 cm (27.6 inches) with the maximum recorded length for Chinook salmon being 159 cm (50 inches).
RANGE: The range of Chinook salmon extends from the Arctic, northwest to northern Paciﬁc: drainages from Point Hope, Alaska down to Ventura River, California. They are also found in Honshu Japan, the Sea of Japan, the Bering Sea and the Sea of Okhotsk.
HABITAT: Chinook salmon are an anadromous species that spend their adult life in salt water and then migrate into their freshwater natal streams to spawn.
DIET: During their adult life history stage, Chinook feed on squid and ﬁsh such as the sandlance and herring. In the juvenile stages, Chinook feed on terrestrial insects and small crustaceans.
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. This is a cold water species and prefers waters with temperatures no higher than 25 degrees Celsius. Chinook salmon are semelparous or single spawners, meaning they only spawn once before they die. Chinook salmon exhibit significant variability in size and age at maturation.
Chinook salmon exhibit two distinct types of life history strategies. These two types of strategies are categorized as an ocean‐type or a stream‐type.
The ocean‐type of Chinook salmon typically migrates to the ocean within their ﬁrst three months of life. They spend their ocean life in coastal waters. Ocean‐type Chinook tend to use estuaries and coastal areas more extensively than other juvenile salmonids.
The stream‐type of Chinook salmon are common in freshwater streams of large river systems. They undergo extensive oﬀshore migration in the central North Paciﬁc natal streams and have longer stays in freshwater than their ocean type counterparts. At their time of saltwater entry, stream‐type chinook are much larger than their ocean‐type cohorts.
Currently there are two Endangered population segments of Chinook salmon, seven Threatened population segments of Chinook salmon, one Candidate population segment and one Species of Concern population segment of Chinook delineated under the Endangered Species Act.
A variety of conservation eﬀorts and initiatives have been undertaken by multiple fishery management jurisdictions to restore habitat, remove and modify dams, improve water quality, improve in-streamflow and acquire essential ﬁsh habitat for Chinook salmon.