Evaluation of two release operations at Bonneville Dam on the smolt-to-adult survival of Spring Creek National Fish Hatchery fall Chinook salmon
Published By US Fish and Wildlife Service, Department of the Interior
Issued over 9 years ago
Summary
Description
In March 2004, two groups of coded wire tagged subyearling fall Chinook were released from Spring Creek National Fish Hatchery to directly evaluate the effects of alternative operations at Bonneville Dam on smolttoadult survival SAR. The first group, released on March 1st, passed Bonneville Dam during a fourday, 25 kcfs spill operation with the corner collector closed. The second group, released on March 10th, passed Bonneville Dam during a fourday, 5 kcfs corner collector operation with the spillways closed. Tagged adults were subsequently recaptured in ocean fisheries, Columbia River fisheries, and at the hatchery during 20052007. The overall SAR was 0.118 for the fish released during the spill operation and 0.100 for fish released during the corner collector operation. The overall SAR for fish released during the spill operation was 18 higher than the SAR for fish released during the corner collector operation, however this difference was not statistically significant. Using Bayesian statistical methods, we estimated an 80 probability that the SAR for the spill operation release was higher than the SAR for the corner collector operation release. Applying the results from the 2004 March release operations to the March releases over 20052007, we estimate that a foregone loss of 15,200 adults range 2,40038,900 may have occurred due to corner collectoronly operations during 20052007. Additional years of comparative study would be useful to quantify the degree of evidence that these results are consistent across years or not.