Use of PIT Tags to Determine Upstream Migratory Timing and Survival of Columbia Basin Sockeye Salmon in 2008
A total of 1133 Sockeye Salmon, Oncorhynchus nerka, were PIT-tagged at Bonneville Dam in 2008, 824 with 12.5 mm PIT tags (model TX1411SST) and 309 with 8.5 mm PIT tags (model TXP148511B). These fish were tracked upstream using detections within fish ladders at Bonneville, McNary, Priest Rapids, Rock Island, Rocky Reach, Wells, Ice Harbor, Lower Granite, and Tumwater Dams. Results indicated that 8.5 mm PIT tags were commonly not detected by fish ladder antennas at several dams and thus excluded 8.5 mm tag data from further analysis. Based on 12.5 mm tag detections, upstream survival steadily declined as the migration progressed; Bonneville-Rock Island survival declined from as much as 90% for Sockeye Salmon passing Bonneville Dam during June to less than 80% during the first two weeks of July. There was also a significant linear relationship between decreasing survival and increasing water temperature. The estimated stock composition of Sockeye Salmon passing Bonneville Dam was 87.4% Okanogan 12.3% Wenatchee, and 0.4% Snake.
Fryer, J.K. 2009. Use of PIT tags to determine upstream migratory timing and survival of Columbia Basin Sockeye Salmon in 2008. Columbia River Inter-Tribal Fish Commission Technical Report 09-3. Portland, OR. 43p.