CLIMATE CHANGE IMPACT
Sacramento River winter-run Chinook salmon are critically vulnerable to climate change due to their highly restricted range, dependence on cold water releases from Shasta Dam, and low tolerance for high stream temperatures. Their migration and egg hatching timing during the warmest months of the year make them particularly vulnerable to increasing stream temperatures. Climate change is also likely to make maintaining a cold water pool in Shasta Reservoir more difficult.
TOP THREE ANTHROPOGENIC THREATS
Shasta and Keswick dams prevent access to all historical spawning and most juvenile nursery areas for Sacramento River winter-run Chinook. Ironically, this run is entirely reliant on water releases from Shasta and Keswick dams.
Hatchery-raised winter-run Chinook salmon account for nearly a third of the spawning population and are likely accelerating the decline of wild Chinook salmon. NMFS considers the winter-run Chinook salmon population at a moderate risk of extinction from “excessive hatchery influence.”
Agricultural diversions along the Sacramento River can trap or delay fish in canals and irrigation ditches. Federal and state pumps in the southern Delta alter flows and reduce survival of juveniles. Levees have cut off rivers from over 95% of critical floodplain habitats in the Central Valley.
