Genetic Analysis Reveals Dispersal of Florida Bass Haplotypes from Reservoirs to Rivers in Central Texas

We analyzed the genetic structure of putative largemouth bass Micropterus salmoides populations in nonstocked, wadeable streams of central Texas. Mitochondrial D-loop sequences were generated for 69 fish sampled for this project. In addition, 27 largemouth bass and Florida bass M. floridanus specimens provided by the Texas Parks and Wildlife Department (TPWD) were sequenced. The TPWD samples represented stock lineages as well as wild fish from outside of the sampling region. Our analyses revealed the presence of both largemouth bass and Florida bass mitochondrial haplotypes at all sampling locations. Haplotypes of the nonnative Florida bass accounted for 26% of all haplotypes. The presence of Florida bass haplotypes at the sampling locations indicates that the influence of stocking reaches far beyond managed reservoirs. The admixture of nonnative genetic material can increase genetic diversity of native populations, but outbreeding depression, competition, and other negative impacts are of concern. Although the stocking of nonnative Florida bass in reservoirs may enhance fishing opportunities, it also has the ability to alter stream systems that are directly connected to stocked reservoirs.