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|Estuarine and early-marine survival of transported and in-river migrant Snake River spring Chinook salmon smolts|
|Rechisky, E.L.; Welch, D.W.; Porter, A.D.; Jacobs-Scott, M.C.; Winchell, P.M.; McKern, J.L. (2012). Estuarine and early-marine survival of transported and in-river migrant Snake River spring Chinook salmon smolts. NPG Scientific Reports 2(448): 9 pp. dx.doi.org/10.1038/srep00448|
|In: Scientific Reports (Nature Publishing Group). Nature Publishing Group: London. ISSN 2045-2322, more|
Smolts; Survival; Marine; Brackish water
|Authors|| || Top |
Many juvenile Snake River Chinook salmon are transported downriver to avoid hydroelectric dams in the Columbia River basin. As mortality to the final dam is ~50%, transported fish should return as adults at roughly double the rate of nontransported fish; however, the benefit of transportation has not been realized consistently. “Delayed” mortality caused by transportation-induced stress is one hypothesis to explain reduced returns of transported fish. Differential timing of ocean entry is another. We used a large-scale acoustic telemetry array to test whether survival of transported juvenile spring Chinook is reduced relative to in-river migrant control groups after synchronizing ocean entry timing. During the initial 750 km, 1 month long migration after release, we found no evidence of decreased estuarine or ocean survival of transported groups; therefore, decreased survival to adulthood for transported Chinook is likely caused by factors other than delayed effects of transportation, such as earlier ocean entry.