Can late stage marine mortality explain observed shifts in age structure of Chinook salmon?

ABSTRACT: Chinook salmon (Oncorhynchus tshawytscha) populations have experienced widespread declines in abundance and abrupt shifts toward younger and smaller adults returning to spawn in rivers. The causal agents underpinning these shifts are largely unknown. Here we investigate the potential role of late-stage marine mortality, defined as occurring after the first winter at sea, in driving this species' changing age structure. Simulations using a stage-based life cycle model that included additional mortality during after the first winter at sea better reflected observed changes in the age structure of a well-studied and representative population of Chinook salmon from the Yukon River drainage, compared with a model estimating environmentally-driven variation in age-specific survival alone. Althou

SUBMITTER: Manishin KA 

PROVIDER: S-EPMC7895375 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature