A study of the effects of the discharge from Iron Gate Dam on the Klamath River on juvenile coho salmon during their seaward migration began in 2005. Estimates of fish survival through various reaches of the river downstream of the dam were completed in 2006, 2007, 2008, and 2009. This report describes the estimates of survival during 2009, and is a complement to similar reports for 2006, 2007, and 2008. For each year, a series of numerical 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. The evaluations indicate that the primary differences among years are in the survivals through reaches upstream of the confluence of the Scott River with the Klamath River. Data from 2009, one of two years when fish from both hatchery and wild origins were available for analysis, indicate that survival of wild and hatchery fish are similar.
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USGS Numbered Series
Summary of survival data from juvenile coho salmon in the Klamath River, northern California, 2009