GENETIC-IMPLICATIONS OF INTRODUCING FLORIDA LARGEMOUTH BASS, MICROPTERUS-SALMOIDES-FLORIDANUS

Stocks of northern largemouth bass (NLMB), Micropterus salmoides salmoides, Florida largemouth bass (FLMB), M. s. floridanus, and both reciprocal F1 hybrids were produced through natural spawning; the genetic composition of each stock was confirmed electrophoretically, and experimental populations established. One set of experimental populations (P1 and P2) contained as broodstock equal numbers of adult NLMB and FLMB, whereas the other set (H1 and H2) initially contained equal numbers of adults of both reciprocal F1 hybrids and both pure subspecies. Each year-class produced experimentally were sampled and individuals analyzed genetically to determine their percentage. Initially, much of the YOY production in P1 and P2 was composed of small FI MB that did not survive winter well; once naturally produced F1 hybrids entered the breeding pool, most offspring were F(x) hybrids, and the population became heavily introgressed. In H1 and H2 introgression began with the production of the first year-class. Within each year-class NLMB produced in all ponds were significantly larger than all other genotypes, but it appears likely that after only a few generations, production of pure NLMB ceases, all individuals being F(x) hybrids. Results illustrate the potential negative impacts of introducing FLMB or hybrids between it and NLMB into waters within or contiguous to the native range of the northern subspecies.