Rainbow trout (Oncorhynchus mykiss) are an important representative salmonid and are one of the most studied species with respect to the effects of hydropower and dams on fish migration.
Rainbow trout have been an important species in the development of Natel's approach for fish-safe turbine design, too. We conducted our first fish-safety tests in collaboration with Alden Laboratory, to examine the effect of blade strikes on rainbow trout ("Improving Survival: Injury and Mortality of Fish Struck by Blades with Slanted, Blunt Leading Edges"). We have continued to work with the species through a series of turbine passage studies involving different-sized trout and turbines, and different turbine speeds, both in our laboratory in Alameda, CA, and in our field installation in Madras, OR.
In this 2022 test conducted with PNNL, our test subjects were 186 large rainbow trout measuring up to 530 mm (20.9 inches) in length. The test found no meaningful difference between the fish passed through Natel's 1.9-meter (6.2 feet) in diameter turbine and the control group, indicating that the RHT allows safe passage of some of the largest fish ever successfully passed through a compact hydro turbine.