Coastwide distribution and ocean migration patterns of stream- and ocean-type chinook salmon, Oncorhynchus tshawytscha.

Abstract

Chinook salmon which spend a year or more in fresh water before migrating to sea (stream-type) have been considered to be an environmentally produced variant of those migrating to sea in their first year of life (ocean-type). Evidence, however, shows that these 2 life-history types differ in the coastal distribution of the 2 spawning populations, in their ocean distribution as immatures, and in the seasonal timing of their spawning migrations. These differences in distribution and behaviour cannot be accounted for by the fresh-water environmental conditions that might influence fresh-water residence. Rather, it appears that stream- and ocean-type chinook salmon are distinct races.-Author