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Download Item 9 Hanson 2-2-12 Chuck Coalition Bass PP 1 - CAL
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Charles Hanson, Ph.D. Fisheries Biologist Hanson Environmental, Inc. The Department of Fish and Game’s Striped Bass Regulatory Proposal California Fish and Game Commission February 2, 2012 Sacramento, CA Predation Magnitude • Limited data on juvenile salmon and steelhead in the striped bass diet in Sacramento River • Anecdotal observations and bioenergetics model results show large numbers of juvenile fish eaten by striped bass each year • Acoustic tag data show evidence of high loss (predation) rates for juvenile salmon • Co-occurrence of striped bass and juvenile salmon/steelhead seasonally in rivers • Predation risk varies among listed fish and among years and hydrologic Conditions • Mounting scientific evidence that striped bass predation is an important source of mortality for juvenile salmon and steelhead and potentially other listed fish Juvenile Salmon Predation by Striped Bass Juvenile Salmon Predation by Sublegal Striped Bass Juvenile Steelhead Predation STRIPED BASS PREDATION ON SALMON IN SACRAMENTO RIVER Sacramento River Salmonids Constrained in Narrow Channel High Fish Losses Documented in Clifton Court Forebay Striped Bass Co-existed with Listed Fish for Over a Century • No evidence that striped bass predation caused the decline of listed fish • Multiple factors impact survival of listed fish (blockage to upstream habitat, water project management, habitat alteration, predation, etc.) • Striped bass predation contributes to the cumulative impacts on listed species abundance and survival Conclusions and Recommendation • Striped bass predation is a factor impacting survival and abundance of listed fish • Predation mortality at “hot spots” has been shown to be high (>75% in several studies) • Changes in striped bass recreational harvest is expected to reduce bass abundance and predation on listed fish • Changes in fishing regulations may result in beneficial and adverse impacts (e.g., reduced predation on listed fish, changes in recreational fishing, etc.) that require further analysis • CEQA provides a framework for public disclosure of potential impacts of changes in angling regulations to inform future decisions regarding management actions
