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Timing and distribution of naturally produced coho salmon in the lower Columbia River. Presentation overview. Background Preliminary results Management implications Conclusions & recommendations. Background. Declines in lower Columbia River coho salmon
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Timing and distribution of naturally produced coho salmon in the lower Columbia River
Presentation overview • Background • Preliminary results • Management implications • Conclusions & recommendations
Background • Declines in lower Columbia River coho salmon • Hatchery supplementation reestablished abundance • Reduced genetic diversity and hatchery effects on population • Federally listed in 2005 as “threatened” • Critical uncertainties research needed (avoidance vs mark selective)
Conceptual condition Time
Estuary Receiver Mainstem Gate Tributary Gate
129 coho instrumented in 2011, 303 in 2012 • In 2011 16 heard in tributaries of interest, 15 over Bonneville • In 2012 39 heard in tributaries of interest, 44 detected over Bonneville • Excluding Willamette avg/trib ~ 2 fish • Only Washougal didn’t have coho detected at gates, but more had fish only hit at one or vacate
Conclusions • Multi-modal run-timing is not apparent in 2012 for CR coho salmon • Upper river fish appear to enter river earlier than lower river counterparts • Distance and speed positively correlated • Need to increase acoustic presence in estuary tributaries to greater account for fish • Need to increase transmitters out to get better presence in non-Willamette lower river tributaries