A study to estimate the effects of Iron Gate Dam discharge on ESA-listed juvenile coho salmon during their seaward migration to the ocean was begun in 2005. Estimates of survival through various reaches of river downstream from the dam were completed in 2006, 2007, and 2008 as part of this process. This report describes the estimates of survival during 2008, and is a complement to similar reports from 2006 and 2007. In each year, a series of models were evaluated to determine apparent survival and recapture probabilities of radio-tagged fish in several river reaches between Iron Gate Hatchery at river kilometer 309 and a site at river kilometer 33. These results indicate most trends in survival among reaches were similar to those from 2006 and 2007, but the magnitudes of the estimated survivals were lower in 2008. The differences in survivals from Iron Gate Hatchery to river kilometer 33 in 2006 (0.653 SE 0.039), 2007 (0.497 SE 0.044), and 2008 (0.406 SE 0.032) were caused primarily by differences in survival upstream from the Scott River. This report is intended as a brief description of the survivals estimated from the fish released in 2008 to be used by others interested in the data.
Additional publication details
USGS Numbered Series
Summary of Survival Data from Juvenile Coho Salmon in the Klamath River, Northern California, 2008