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Trends in Central Valley Chinook Salmon Escapement: A Review by Charles Hanson, Ph.D.

This report by Charles Hanson, Ph.D., for State Water Contractors in October 2004 discusses the increasing trend in adult escapement of fall-run, late fall-run, spring-run, and winter-run Chinook salmon in the Central Valley. Key findings include the fall-run Chinook escapement exceeding doubling objectives over the past four years, with proposed downgrading from endangered to threatened status by NOAA. Winter-run cohort replacement rates have been greater than 1.0 in recent years, while spring-run populations are improving but have not yet met doubling goals. The late fall-run has met its goal in two out of the last six years, thanks to restoration/enhancement actions in the Delta and tributaries, favorable hydrology, and favorable ocean rearing conditions. Other contributing factors to these trends include changes in hatchery management, the Delta cross-channel VAMP, late fall/winter Sacramento River survival, and ongoing management investigations.

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Trends in Central Valley Chinook Salmon Escapement: A Review by Charles Hanson, Ph.D.

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  1. Trends in Central Valley Chinook Salmon In-River Escapement Charles Hanson, Ph.D. State Water Contractors October 2004

  2. INCREASING TREND IN ADULT ESCAPEMENT Fall-run Late fall-run Spring-run Winter-run

  3. FALL-RUN CHINOOK ESCAPEMENT EXCEEDED DOUBLING OBJECTIVE OVER PAST 4 YEARS

  4. NOAA proposal to downgrade listing from endangered to threatened • WINTER-RUN COHORT REPLACEMENT RATES GREATER THAN 1.0 IN RECENT YEARS

  5. SPRING-RUN IMPROVING BUT HAVE NOT YET MET DOUBLING GOAL LATE FALL-RUN MET GOAL IN 2 OUT OF LAST 6 YEARS

  6. Restoration/enhancement actions in Delta and tributaries Favorable hydrology Favorable ocean rearing Management changes (reduced ocean harvest) • VARIETY OF FACTORS CONTRIBUTE TO TRENDS

  7. CHANGES IN HATCHERY MANAGEMENT

  8. Delta cross-channel VAMP Late fall/winter Sacramento River survival Contributing to scientific foundation for improved protection/management • ONGOING MANAGEMENT INVESTIGATIONS

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