Overview
The National Marine Fisheries Service (NMFS) recognizes five Evolutionarily Significant Units (ESUs) of Chinook Salmon in California based on genetic and life history similarities among geographically distinct and adjacent populations: Southern Oregon and California Coastal ESU, Upper Klamath and Trinity Rivers ESU, Central Valley fall-run ESU, Central Valley spring-run ESU, and Sacramento River (SR) winter-run ESU (Moyle 2002).
The SR spring-run ESU includes all naturally spawning populations of SR spring-run Chinook Salmon in the Sacramento River and its tributaries, the San Joaquin River, as well as two conservation programs maintained at the Feather River Fish Hatchery (FRFH) owned by the California Department of Water Resources, and operated by CDFW and the San Joaquin River Restoration Program (NMFS 2014(opens in new tab)).
Distribution and Habitat
Spring-run Chinook enter the Sacramento River from late March through September. Adults hold in cool water habitats through the summer, then spawn in the fall from mid-August through early October. Spring-run juveniles migrate soon after emergence as young-of-the-year, or remain in freshwater and migrate as yearlings.
Spring-run Chinook were historically the most abundant race in the Central Valley. Now only remnant runs remain in Butte, Mill, Deer, Antelope, and Beegum Creeks, tributaries to the Sacramento River. In the mainstem Sacramento River and the Feather River, early-running Chinook salmon occur, but significant hybridization with fall-run has occurred. Due to the small number of non-hybridized populations remaining and low population sizes, Central Valley spring-run were listed as threatened under both the state and federal endangered species acts in 1999.
Threats
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Conservation and Management
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Species Status
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Species Needs
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References
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More About this Species
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