Passage and Survival of Adult Snake River Sockeye Salmon within and Upstream from the Federal Columbia River Power System

Snake River sockeye salmon Oncorhynchus nerka is among the most endangered of all evolutionarily significant units (ESUs) of Pacific salmon, with production sourced primarily from captive broodstock since 1990. The adult migration presents an especially significant challenge to recovery of this population because adults must migrate through various fisheries, pass 8 hydroelectric dams, and travel over 1,500 km to reach native spawning areas. Since 2008, survival for adult Snake River sockeye salmon from Bonneville Dam to the Sawtooth Weir has ranged from 60% in 2010 to 13% in 2013. To increase the number of spawners for natural production and hatchery broodstock, one potential management strategy under consideration is adult transportation from Lower Granite Dam. When conditions in the river are unfavorable for in-river migrant survival, fish would be collected at the dam and transported to the Sawtooth Valley. As a first step in assessing this option, we analyzed existing data from 920 fish marked with passive integrated transponder (PIT) tags and detected at Bonneville Dam from 2008 through 2013. The goal of our analysis was to determine whether we could identify the river conditions most unfavorable for migration success and to explore the implications of potential triggers for transportation. 2014 NMFS (National Marine Fisheries Service) NWFSC (Northwest Fisheries Science Center) Submitted Public Domain 1861