Evaluation of a cooling lake fishery. Volume 3. Fish population studies

Abstract

A comparison of the fish communities of Lake Sangchris, a cooling lake, with those of Lake Shelbyville and three other Illinois reservoirs is presented. Preferred temperatures and movements of fishes were studied by radiotelemetry. Generally speaking, the populations in Lake Sangchris were similar to other reservoirs in Illinois. However, heated discharge from the power plant provided a longer growing season and different environmental conditions in part of Lake Sangchris to which several species responded favorably. Largemouth bass exhibited a greater annual growth in the heated area than elsewhere and two other species preferred the heated area during winter. Largemouth bass and carp spawned earlier in the heated area than elsewhere and white bass migrated upstream against the current produced by the power plant and spawned in the discharge canal. Mark-and-recapture estimates indicated a desirable population of largemouth bass that attracted anglers to the lake, especially in winter. There were significant biochemical genetic differences between the largemouth bass populations in Lake Shelbyville and Lake Sangchris as well as between areas of Lake Sangchris. Rate of infestation of monogenetic trematodes on bluegills in Lake Shelbyville was significantly greater than in either area of Lake Sangchris.