A Summary of Experiments in Michigan Lakes on the Elimination of Fish Populations with Rotenone, 1934–1942

During the period 1934–1942, 32 lakes in Michigan were treated with rotenone to remove or reduce unwanted fish populations, and an attempt to recover the entire fish population was made on 18 of them. The majority of these lakes were not supporting a desirable or normally growing fish population at the time they were treated. They were mostly small, all less than 22 acres, and included lakes whose waters ranged from very soft to very hard, from acid to alkaline, and from shallow to very deep. In productivity, as measured by the standing crop of fish recovered, these lakes ranged from 10.0 to 194.5 pounds per acre. The lakes averaged 58.5 pounds of fish per acre of which 18.2 pounds were legal-sized game fish. The hard-water lakes were, in general, more productive than the soft-water lakes and the warm-water lakes more productive than the trout lakes.