Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Salmoniformes Family: Salmonidae Genus: Oncorhynchus Species: O. tshawytscha NCBI Taxonomy Browser

Chinook salmon begin their life cycle in the freshwater system, stay less than a year (ocean-type Chinook) or one and a half years (stream-type Chinook) in the freshwater system before migrating to sea, and spend a number of years in the ocean before returning to the freshwater system to reproduce. I will focus on stream-type Chinook salmon for my Ph.D. research.

Stream-type Chinook salmon spawn in September and October, their eggs hatch about 3 to 5 months after they were deposited. Fry emerge in the spring when productivity is sufficient for survival and growth. Chinook salmon generally spend one year in freshwater as juveniles, then migrate out to sea in the spring and early summer months. Adults generally 4- and 5-year-olds, with a small portion of 6-year-olds, return to river May-August to spawn. Stream-type Chinook salmon are also called yearlings or spring-summer Chinook salmon, whereas the other race of Chinook salmon, the ocean-type Chinook salmon, is also known as subyearling or fall Chinook.