Year Class Contribution of Genetically-marked Florida x Northern Largemouth Bass Stocked in Three Texas Reservoirs

Percent year class contribution was evaluated for genetically-marked Florida largemouth bass (Micropterus salmoides floridanus) x northern largemouth bass (A/. 5. salmoides) stocked in 3 Texas reservoirs. Electrofishing catch rate and size structure data were used to determine population characteristics of each study reservoir. Stocking rates of genetically-marked fingerlings ranged from 30 to 200 fish/ha. Post-stocking collections were made by electrofishing at permanent stations over a 4-year period. Town Reservoir, which had the highest largemouth densities and recruitment, had the lowest percent contribution by stocked fish (l%-7%). Conversely, Meredith and Braunig reservoirs, which had lower largemouth bass densities and historical recruitment and reproduction problems, respectively, had relatively high returns (41 %—45%). Year class strength at the time of stocking influenced success at Town and Braunig reservoirs. The percent contribution of stocked fish was greatest during years with relatively week year classes. In Town Reservoir, offspring of stocked bass contributed significantly to subsequent year classes (5%-13%). These fish appeared to change the genetic structure of this population by increasing age-0 hybrid bass phenotypes (F1) and Fx) and decreasing the northern bass phenotype. Results suggest supplemental largemouth bass stocking success may be influenced by the density and recruitment characteristics of the native population. However, due to sample size limitations a strict interpretation of these results would be inappropriate. Similar studies, with increased sampling effort, may better define the role of density and recruitment on stocking success.

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