Diel Movement and Vertical Distribution of Juvenile Anadromous Fish in Turbine Intakes

The behavior of fingerling salmonids was measured in turbine intakes of The Dalles and McNary Dams on the Columbia River to aid in developing methods for reducing fish mortality in Kaplan turbines. At the Dalles Dam, diel movements and vertical distribution were sampled at both ends and at the middle of the section of the powerhouse that housed turbines 1 through 12. At the McNary Dam, vertical distribution was sampled in intake 12-C, located near the middle of the River channel. Comparisons of day-night occurrence at The Dalles Dam showed that most chinook salmon (Oncorhynchus tshawytscha), steelhead trout (Salmo gairdneri), and ammocoetes of the Pacific lamprey (Lampetra tridentata) were caught at night (7 p.m. to 7 a.m.). Vertical distribution studies at McNary and The Dalles Dams included catches of sockeye salmon (O. nerka) in addition to the above species. Salmonids were taken at all depths, but most were in the upper 30 percent of water in the intakes (within 4.6 m. of the ceiling). Ammocoetes at The Dalles Dam (no data for McNary Dam) were concentrated near the center and bottom of the intakes; very few were near the ceiling. To increase survival of fish by manipulating turbine loads during a 24-hour operational period appears feasible. During darkness when fish movements through turbines increase and power demands decrease, the reduction in turbine loads improves the flexibility for adjusting turbine loads to increase fish survival. The concentration of fingerling salmonids near intake ceilings probably causes most of the fish to pass the turbine runner at or near the hub; therefore, methods for eliminating lethal factors at the runner should be applied first at the hub. In addition, use of deflection and bypass techniques near intake ceiling would be advantageous because the concentration of fish is greatest there.
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