Juvenile Salmon Acoustic Telemetry System (JSATS) Used To Collect Route- and Reach-Specific Mortality Information in the Lower Columbia River and Estuary

摘要

The passage experience through the Federal Columbia River Power System (FCRPS) for juvenile salmonids on their seaward migration may affect their survival to Pacific Ocean entry. In an effort to increase the understanding of juvenile salmon mortality related to the FCRPS, we evaluated survival of acoustic-tagged run-of-the-river yearling Chinook salmon from over 695 km of the Snake and Columbia rivers using the Juvenile Salmon Acoustic Telemetry System (JSATS). Test fish were anesthetized and surgically implanted with the smallest available microacoustic transmitters (0.43 g in air). A total of 4,140 acoustic tagged fish were released at Lower Granite Dam (LGR) on the Snake River. Survival estimates showed an average of about 78% of JSATS-tagged yearling Chinook salmon survived through the lower 173 km of the Snake River, including passage through three hydroelectric facilities. Median travel times over this 173-km reach ranged from about 4 to 14 days and averaged about 8 days; travel time decreased later in the season as river discharge increased. Three-dimensional tracking revealed that most (58%) of the acoustic-tagged yearling Chinook salmon released at LGR passed John Day Dam through deep spill routes, while 16% of the fish passed over surface-flow spillway weirs. About 27% of the acoustic-tagged fish passed John Day Dam through the powerhouse. Tagged fish were detected on multiple autonomous acoustic receiver arrays downstream of Bonneville Dam to identify areas of greatest loss. Survival estimates showed most of the loss of yearling Chinook salmon in the Columbia River downstream of Bonneville Dam occurred in the lower 35 km of the Columbia River where the river transitions into a broad, tidally influenced estuary.