Attempted Control of Bluegill Reproduction in Lakes by the Application of Copper Sulphate Crystals to Spawning Nests
George B. Beyerle and John E. Williams
Abstract.-The shorelines of eight southern Michigan lakes were seined at specific locations in the autumn of 1960 and 1961 to determine the relative abundance and size of young-of-the-year bluegills. In 1962 all observed bluegill nests on four of these lakes were treated with copper sulphate crystals every 3 or 4 days throughout the bluegill spawning season in an attempt to kill all bluegill eggs and fry. In the fall of 1962 all eight lakes were again seined, and the results compared with pre-treatment data. The variability of the seining data was so great that no significant reduction in the fingerling bluegill populations could be demonstrated for the treatments. However, the mean lengths of the young-of-the-year bluegills in 1962 were significantly greater than in 1960 and 1961 in the treated lakes following treatment. Even if the treatments had been successful, the considerable effort required precludes the adoption of this technique as a management procedure for bluegill control in lakes.