Coho Survival and Migration

During 2009, a report was finalized on the assessment of survival of hatchery-origin juvenile coho salmon (Beeman et al. 2009). The purpose of the study was to compare survival in the Trinity River to the Klamath River and provide feedback on suitability of sections of the Trinity River for migrating coho smolts. The data support differences in survival among river reaches. The probability of survival in the first 53 kilometers was lower than in the reaches farther downstream, which is similar to trends in juvenile coho salmon in the Klamath River. The lowest estimated survival in this study was in the first 10 kilometers from fish release site in the Trinity River (0.676 SE 0.036) and the highest estimated survival was in the final 20 kilometer reach in the Klamath River (0.987 SE 0.013). Estimated survivals of radio-tagged juvenile coho salmon from release to Klamath River kilometer 33 were 0.639 per 100 kilometers for Trinity River fish and 0.721 per 100 kilometers for Klamath River fish.