Habitat Type: Freshwater
Comments: Chinook salmon generally spend most (often 2-4 years but up to 6 years) of their lives in the ocean. For spawning, they migrate up to several hundred kilometers upstream to their natal stream, where eggs are deposited in gravel bottoms of large streams and rivers.
Populations may differ dramatically in the timing of adult migration and, to a lesser extent, timing of spawning. There are two basic behavioral forms, stream-type and ocean-type. Stream-type chinook are typical of northern populations (i.e., Alaska and northern B.C.) and headwater (high elevation) tributaries of southern populations. These spend one full year as juveniles rearing in fresh water before migrating to sea, perform extensive offshore oceanic migrations, and typically return to their natal river in spring or summer, several months prior to spawning; occasionally males mature without ever going to sea. The ocean-type is typical of populations on the North American coast south of 56 degrees north latitude; these migrate to sea during their first year of life (normally within 3 months of emerging from spawning gravel), spend most of their ocean life in coastal waters, then return to their natal river in fall, a few weeks before spawning.