Changes in Largemouth Bass Populations at Kentucky and Barkley Lakes: Environmental or Regulatory Responses/

Abstract

Abundance of largemouth bass Micropterus salmoides increased in Kentucky and Barkley lakes after a 14-and-1 regulation was imposed in 1984. (The 14-and-1 regulation is a 14.0-in minimum-size limit with one fish under 14.0 in allowed in the anger's creel.) Standing crops of shad Dorosoma spp. and of all fishes also increased. These increases in fish populations had begun when the minimum-length limit was still 12 in, and they continued after the change to the 14and-1 regulation. The size limit change to 14 in coincided with the onset of the most severe drought in the history of the region, the worst part of which extended from December 1984 to October 1988. The depth of light penetration and water retention time in the two lakes increased significantly during the drought, as did Carlson's trophic state index for chlorophyll a. The increase in primary productivity may have contributed to the increases in fish standing crops observed over the study period. Because of these changes in water quality, the effects of the 14-and-1 regulation on largemouth bass populations could not be separated from the changes brought about by drought.