Turbine passage survival

A concern at waterpower projects is the survival of fish that pass through turbines. Extensive empirical data demonstrate that waterpower turbines usually are not ‘blenders’ or ‘bass-o-matics’ but more like a ‘revolving door’. Turbine passage survival is a probabilistic function based largely on the size of the fish relative to the size of the passage way. As fish size gets smaller and turbine size gets larger, survival increases. Some other factors that can influence turbine passage survival are the speed of revolution, the number of turbine blades or buckets, and the route the fish takes through the turbine. Year long entrainment studies have shown that a very large majority of entrained fish are small. These results coupled with reliable survival data indicate that passage survival is safe for >90% of fish in most cases; a recent study at the first commercial hydrokinetic turbine installation demonstrated that passage survival is 99% for fish up to 665 mm TL. The most significant concern should be with adult migratory fish. The survival for any size fish can be estimated through use of one or more mathematical models. Where modeled results indicate a potential problem, empirical studies can be employed to reliably estimate survival.