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30-Years of Monitoring Wild Snake River Spring/Summer Chinook Parr Using PIT Tags

Jesse Lamb, Benjamin Sandford, Gordon Axel

NOAA Fisheries, 3305 E. Commerce St, Pasco, WA 99301

Since 1991, NOAA fisheries has PIT tagged 335,604 wild Chinook salmon parr throughout the Salmon River basin and monitored estimated migration timing, growth, and parr-to-smolt survival of individual populations.  During July and August, fish are collected and tagged in up to 15 Idaho headwater streams.  As the fish migrate from their natal streams, detections are recorded on in-stream PIT arrays and again at Lower Granite Dam (LGR) and seven locations downstream.  Once arriving at LGR, fish passing through the juvenile bypass are recaptured using the sort-by-code (SbyC) system in order to collect growth data (length and weight).  Detection data at Lower Granite Dam and downstream along the Snake and Columbia Rivers allow for the estimation of parr-to-smolt survival.  Estimated survival has varied throughout the study by stream population and year (range of 7.9-25.4%), with an overall estimated survival of 15.2% across all years and populations. The data generated by this project provides critical information to regional fisheries managers to make informed decisions on operation of the hydropower system (FCRPS) to best aid ESA-listed fish during out-migration.