Assessing the Long-Term Reproductive Contribution of Stocked Fish to Largemouth Bass Populations

Abstract

We evaluated the reproductive contribution of stocked Largemouth Bass Micropterus salmoides relative to resident populations. The reproductive contribution of stocked fish was determined using the MDH-B2* allele as a genetic tag for fingerlings stocked into five study lakes. We first determined the relative survival of stocked fish by calculating the proportion of adults (which were clipped at stocking) in the population and compared it with initial survival the first fall after stocking. Stocked fish relative survival to adulthood varied among the five study lakes and was lower than initial survival after stocking. Once these stocked fish were mature, it was possible to assess their reproductive contribution to each population by comparing the prestocking frequencies of the MDH-B2* allele with poststocking frequencies. Reproductive contribution of stocked fish was high in small lakes but relatively low in larger ones. Neither adult Largemouth Bass density nor prey density affected reproductive contribution of stocked fish. Based on the proportion of stocked adults in the populations, reproductive contribution of stocked fish was similar to that of wild fish. Our results indicate that reproductive contribution of stocked fish will depend on survival of stocked fish to maturity. The influence of stocked fish will likely persist in successive generations, and potential genetic effects on wild populations of Largemouth Bass should be taken into account when making stocking decisions.

Received August 16, 2013; accepted December 11, 2013

FUNDING

Funding for this project was provided in part by Federal Aid in Sport Fish Restoration Project F-135-R through the Illinois Department of Natural Resources (IDNR), Division of Fisheries. S. Pallo, J. Ferencak, L. Dunham, S. Stuewe, and M. Conlin coordinated activities with the IDNR. We would also like to thank A. Brandenburg and the staff of the Little Grassy Fish Hatchery for producing and marking fish for this study. A special note of appreciation to the Illinois regional and district biologists, especially M. Mounce, M. Garthaus, S. Jenkins, K. Daine, S. Hirst, and J. Pontnack who assisted in collections, participated in project discussions, and provided advice on various portions of the project. We also appreciate the help and input of current and past staff of the Sam Parr and Kaskaskia Biological Stations, Illinois Natural History Survey.