Michigan Department of Natural Resources
Institute for Fisheries Research Report No. 1777, 1971
Characteristics of a Population of Warm-Water Fish in a Southern Michigan Lake, 1964-1969
James C. Schneider
Abstract.-The fish populations of Mill Lake were observed during the 5-year period from October 1964 to October 1969; during this period, public fishing was not allowed. The size of the fish populations was estimated each spring by means of mark-and-recapture techniques. Data on growth and food habits were also collected. Age structure, year class strength, and natural mortality rates of the fish populations were determined. Descriptive models of "typical" year classes were developed. Large changes occurred in the size and age structures of the bluegill, pumpkinseed and yellow perch populations; smaller changes occurred in the black crappie, largemouth bass and northern pike populations. These changes were caused mainly, if not entirely, by natural fluctuations in year class strength. Fluctuations in recruitment seemed to be density independent, except perhaps at high densities of fish. Growth of pike and bass, and to a lesser extent, of perch and crappies, was density related. Natural mortality was not density dependent for most species. Evidence is presented that bluegill, perch, bass and pike populations are food limited.