Effect of multiple turbine passage on juvenile Snake River salmonid survival
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Juvenile salmonids originating in the Snake River upstream of Lower Granite Dam must pass up to eight hydroelectric projects during their downstream migration to the Pacific Ocean. Fish may pass a project through a turbine or a spillbay or be screened into a bypass system that either collects fish into a barge or releases them downstream of the project. Previous reviews of studies of downstream passage for salmon at hydroelectric projects in the Columbia River basin found higher mean mortality at turbines than for spillways or bypass systems. The potential mechanisms of mortality during turbine passage may include pressure changes, cavitation, shear, turbulence, strike, or grinding. Observing those mechanisms is challenging in the field, but laboratory studies have demonstrated that a single exposure to shear or pressure changes similar to turbine passage conditions can result in injury for some individuals. Because fish pass several dams along their migration, individuals experience a series of passage events. If estimates of surviving the passage of a single project are applied to each passage event, then the underlying assumption is that the mortality at each project is independent of previous exposure. If individuals approaching a project were already sub-lethally stressed, higher than expected mortality rates might occur upon subsequent passage events. Report presents the hypothesis that fish passing more than one turbine will experience a greater than expected rate of mortality. Because measuring an incremental increase in mortality would be challenging in the field, scientists developed an approach to first assess whether such an increment has any potential to influence a fish population. This approach identified populations at risk and will help design laboratory or field experiments to address those risks.
- Research Organization:
- EERE Publication and Product Library, Washington, D.C. (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
- OSTI ID:
- 1218132
- Country of Publication:
- United States
- Language:
- English
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