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AbstractAn analysis of the total fish populations in three northern Wisconsin lakes, as revealed by the use of a derris-root treatment, designed to eradicate an undesirable carp population, is presented. The lakes were all bass lakes that had become infested with carp. A concentration of 1.25 pounds of derris root (5 per cent rotenone) was used per acre-foot of water. Preliminary, intensive netting operations were conducted to test the efficiency of 1/2-inch-mesh (stretched measure) fyke nets in estimating fish populations. From 10.4 to 15.6 per cent of the total weight of the fish present and from 6.8 to 31.1 per cent of the total number of individuals were caught. The wide variation in the percentage of individuals taken was due to a difference in species composition in the three lakes.Long Lake (27.1 acres), contained a “total standing crop” of 59,072 fish or 2,180 per surface acre. The total weight was 3,657 pounds (135 pounds per acre). East Twin Lake (13 acres) had a population of 20,159 fish (2,413.5 pounds or 186 pounds per acre). West Twin Lake (13.5 acres) gave a total population of 5,809 fish, with a total weight of 1,243.2 pounds (92 pounds per acre). The role of the various species of fish in the community is discussed.The three lakes were restocked according to a fish-management plan which was formulated in an attempt to restore each lake to its original status as a black bass lake. One lake was restocked with largemouth black bass, bluegills and fathead minnows; another with smallmouth black bass, bluegills and crayfish; and the third with largemouth black bass and bluegills. |
