The influence of disparate levels of submersed aquatic vegetation on largemouth bass population characteristics in a Georgia reservoir

摘要

Population characteristics of largemouth bass (Micropterous salmoides L.) including growth, body condition (relative weight), size structure, survival, and fecundity were examined in relation to abundance of submersed aquatic vegetation (SAV) coverage (primarily hydrilla Hydrilla verticillata L.f. Royle) in three major embayments of Lake Seminole, Georgia. Relative weight, fecundity, and growth of largemouth bass in the Spring Creek embayment (76 percent areal SAV coverage) was considerably less than measured in the Chattahoochee and Flint river arms that contained lower SAV coverages (26 percent and 32 percent). It took fish 1.8 years longer to reach 406 mm in Spring Creek compared to the Chattahoochee-Flint arms. Consequently, fish were smallerin Spring Creek than in the Chattahoochee-Flint arms. In addition, due to slower growth rates and lower fecundity-to-body weight relation, we predicted a 47 percent reduction in total potential ova production in Spring Creek compared to the other two reservoir embayments. The annual survival rate of 3 to 10 year old largemouth bass was higher in Spring Creek (84 percent) than in the Chattahoochee-Flint arms (72 percent) and suggested either lower harvest and/or lower accessibility of particularly largerfish to angling in dense vegetation. Contrary to our expectations, the fit between number-at-age and age in a catch-curve regression was weaker for fish collected in Spring Creek and suggested greater recruitment variability, has occurred over time in this highly vegetated embayment. In Lake Seminole, spatial differences in largemouth bass population characteristics were associated with disparate levels of SAV. Our data suggest that a reduction in hydrilla, but maintenance of an intermediate level of SAV in Spring Creek, should improve largemouth bass population in this arm of the reservoir.