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Evaluation of strobe lights to reduce turbine entrainment of juvenile steelhead (Oncorhynchus mykiss) at Cowlitz Falls Dam, Washington

January 1, 2009

We conducted a radiotelemetry evaluation to determine if strobe lights could be used to decrease turbine entrainment of juvenile steelhead (Oncorhynchus mykiss) at Cowlitz Falls Dam, Washington. We found that radio-tagged juvenile steelhead approached and entered two spillbays (one lighted, one unlighted) in equal proportions. However, the presence of strobe lights was associated with decreased spillbay residence time of juvenile steelhead and increased passage through induction slots (secondary turbine intakes located upstream of the ogee on the spillway). Mean residence time of tagged fish inside the lighted spillbay was 14 min compared to 62 min inside the unlighted spillbay. Radio-tagged steelhead passed through induction slots at a higher proportion in the lighted spillbay (55%) than in the unlighted spillbay (26%). Recent studies have suggested that strobe lights can induce torpor in juvenile salmonids. We believe that strobe light exposure affected fish in our study at a location where they were susceptible to high flows thereby reducing mean residence time and increasing the proportion of tagged fish entering induction slots in the lighted spillbay. Our results suggest that factors such as deployment location, exposure, and flow are important variables that should be considered when evaluating strobe lights as a potential fish-deterring management tool.

Citation Information

Publication Year 2009
Title Evaluation of strobe lights to reduce turbine entrainment of juvenile steelhead (<i>Oncorhynchus mykiss</i>) at Cowlitz Falls Dam, Washington
DOI 10.3955/046.083.0402
Authors Tobias J. Kock, Scott D. Evans, Theresa L. Liedtke, Dennis W. Rondorf, Mike Kohn
Publication Type Article
Publication Subtype Journal Article
Series Title Northwest Science
Series Number
Index ID 70176160
Record Source USGS Publications Warehouse
USGS Organization Western Fisheries Research Center