Factors Regulating Florida Largemouth Bass Stocking Success and Hybridization with Northern Largemouth Bass in Aquilla Lake, Texas

Abstract We electrophoretically assayed four enzyme-encoding loci in, and determined the ages of, 1,534 largemouth bass Micropterus salmoides colleted from a new Texas reservoir (Aquilla Lake) over a 41-month period. We used these data to evaluate stocking success and subsequent hybridization of the Florida subspecies M. s. floridanus (1.5–6.5 cm total length and age 0 when stocked between 1983 and 1985) with the indigenous northern subspecies M. s. salmoides. After these stockings, genomic inflow into the population from Florida largemouth bass was rapid. In the 1986 year class, age-0 Florida largemouth bass, first-generation (F1) hybrids between the two subspecies, and second- or higher-generation (F x ) hybrids were numerically dominant (72%). For these individuals, the frequencies of Florida alleles at two diagnostic loci (fixed allelic differences between subspecies) were 0.51 and 0.52, respectively. Although the subspecies hybridized extensively in 1986, the population at age 0 did not conform to ex...