Fig. 1. Generalized Chinook salmon life cycle and the associated environments of the salmon ecosystem. Salmon may complete their life cycles through a variety of alternative pathways, illustrated here by five juvenile life-history types reported in Sixes River, a small coastal watershed in southwest Oregon (Reimers 1973). Each life-history type represents a different pattern of freshwater or estuarine residency before ocean migration. Figure adapted from Nicholas and Hankin (1988).