PNNL

Abstract

We are in the process of evaluating how the Priest Rapids Project (PRP, located north of the Hanford reach on the Columbia River) affects populations of wild, fall Chinook salmon that are produced. One part of this project involves using mark-recapture technique to monitor fall juvenile Chinook movement in the area. A passive integrated transponder (PIT) tag technology was used to document migration timing out of the influ-ence of the PRP, and track fish through downstream dams as they make their way to the ocean. On June 6 and 7, 2000, we tagged 1083 fall Chinook sub-yearlings above and below Wanapum Dam, subsequently detecting them as they began to pass through downstream dams. As of 9 August 2000, 122 fish had been detected in one or more of the dams downstream of the PRP. A mean migration time for tagged the fish of 5.5 km/day below the McNary dam and 4.5 km/day above the McNary Dam. The mean migration rate between McNary Dam and John Day Dam was 21.4 km/day. Back calculation, indicated the mean date of departure for juveniles tagged in the pool above Wanapum Dam was July 16, 2000, while juveniles tagged below Wanapum Dam was July 1, 2000. Because fish are still being detected at the dams only preliminary conclusions can be attempted. Since the peak of migration time for these fish seems to have passed, the time when these fish most likely left the PRP area can also be estimated. Data analysis will continue analysis, and hopefully some of the adult returns will be measured as they come through the dams throughout the duration of the project.