Turbine passage at four low-head hydroelectric facilities in northeast Michigan

Four low-head hydroelectric facilities in northeast Michigan were monitored over a 1-year period between 1991 and 1993 to determine the following characteristics of fish passingthrough the turbines: (1) species composition and size distribution, (2) diel and seasonaldistribution, and (3) acute turbine mortality (\u3c4 h). Fish were collected for 72-h periods (biweeklyfrom April to October and monthly from November to March) with nets placed over the turbinedischarge area; fish were identified to species, lengths were recorded, and fish were classified asalive or dead More than 80,000 fish were collected from all four facilities combined. Turbinepassage at each facility had different species compositions and was usually dominated by one ortwo species of similar groups of fish. Sixty-three percent of these fish were less than 10 cm longand were smaller-sized species (ie., Cyprinidae) and age-0 fish. Sixty-one percent of the fishpassed through the facilities between 1600 and 0400 hours, but diel patterns varied by species.Fish movement typically peaked in spring and early summer. Acute turbine mortality averaged8% and varied by species, size of fish, and turbine type; generally, mortality was higher forsmaller fish and more delicate species. Acute turbine mortality for the primary sport fish was 19%for bass (Micropterus spp). and 18% for walleye (Stizostedion vitreum)