|Title:||Interception of yearling Chinook salmon in turbine intakes of hydroelectric dams by submersible traveling screens: evidence for smoltification effects|
|Author/Editor:||Albert E. Giorgi, George A. Swan, Waldo S. Zaugg, Teri Barila|
|Institution:||Report of the Northwest and Alaska Fisheries Center and the U.S. Army Corps of Engineers|
A number of hydroelectric dams in the Columbia-Snake River system are equipped with submersible traveling screens which project into the turbine intakes. The screens are designed to divert juvenile migrant Pacific salmon Oncorhynchus spp. and steelhead Salmo gairdneri from the intake upward into gatewells and the adjoining central bypass system. At Lower Granite Dam, the fish guidance efficiency (FGE) of the screens for yearling chinook salmon O. tshawytscha has been variable, typically increasing over the course of the juvenile migration. Observed change in FGE has not been attributable to hydraulic or structural changes associated with the dam. Assays of gill Na+-K+ ATPase from yearling chinook salmon collected during a routine FGE test revealed that Na+-K+ ATPase levels were significantly higher in fish guided into the gatewell than in those not guided. A model is proposed to explain the observation and guide future research efforts.