Kintama’s latest paper has been published in Nature Publishing Group’s Scientific Reports. Dr. Erin Rechisky, Kintama’s Research Manager, is the lead author of the paper “Estuarine and early-marine survival of transported and in-river migrant Snake River spring Chinook salmon smolts” that was published today in Nature’s open access journal. The paper presents results from Kintama and Fish Passage Solutions’ 2006-2009 study on whether barging reduces survival of transported smolts in the Columbia River. The study used a large-scale marine acoustic telemetry array to experimentally test whether survival of transported spring Chinook salmon smolts was reduced relative to control groups that first migrated through eight major hydropower dams during their seaward migration. The results indicate that barging does not negatively affect survival of smolts post-release, a key issue that could not previously be resolved, and that attention should be placed on what ocean conditions the smolts may encounter as a consequence of altered timing of ocean entry due to transportation downstream.
The paper can be viewed in its entirety from Nature’s website while a full copy with the Supplementary Information section appended is also available direct from Kintama’s website.
“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.”