Transcript Item 9 Hanson 2-2-12 Chuck Coalition Bass PP 1 - CAL

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