Survival and Movement of Adult Spring/Summer Chinook Salmon Through the Columbia River Estuary and Lower River

In an attempt to estimate survival and behavior for upriver bound Spring/Summer Chinook salmon, NOAA Fisheries conducted a two-tiered mark/recapture pilot study in the spring of 2010, wherein a portion of returning adults were implanted with passive integrated transponder (PIT) tags, and a second portion with both PIT tags and acoustic transmitters (AT).  Study fish were captured and tagged near Rice Island (Rkm 34) in the lower Columbia River, and then tracked as they migrated upstream to Bonneville Dam.  Data from PIT tags provided an overall survival estimate from the mouth of the river to Bonneville Dam.  Acoustic tracking provided essential information about fish movement/residence times within four subdivisions of the lower river.  Tissue samples collected from all study fish for genetic analyses were utilized to provide information on stock-specific movement and survival through the estuary and the lower river.  Survival to Bonneville for PIT-tagged study fish was estimated to be 0.88 (95% CI, 0.83-0.93) after accounting for potential gear‑associated mortality and mortality due to harvest.  Mean travel time from release to Bonneville Dam for PIT tagged fish was 15.4 d (range, 6.2-31.3 d).  Survival to Bonneville was comparable for fish identified as originating from either Upper or Middle Columbia River genetic stocks (0.87) compared to those originating from Snake River stocks (0.89).  Mean travel time to Bonneville was also similar between Upper and Middle Columbia River fish (15.3 d; range, 6.2-26.2 d) and those destined for the Snake River (15.4 d; range, 7.1-31.3 d).