The species largemouth bass Micropterus salmoides is comprised of two subspecies: northern largemouth bass M.s. salmoides and Florida largemouth bass M.s. floridanus. It is uncertain whether largemouth bass is native to the Atlantic slope and New drainages of Virginia. There exists a widely-held perception that Florida largemouth bass or F1 northern x Florida hybrids provide more trophy catches than northern largemouth bass, which has led to widespread stocking of Florida largemouth bass into native northern and intergrade largemouth bass populations. Twenty-four Virginia populations of largemouth bass were screened for the frequencies of allozyme markers diagnostic for the two subspecies. The relative contributions of the Florida subspecies to the respective populations ranged from 0.32 in Occoquan Reservoir to 0.68 in Lake Robertson. No geographic pattern in genetic variation was seen. This finding may support the hypothesis that largemouth bass is a non-native species in the Atlantic slope and New drainages of Virginia; that is, lack of geographic stock structure may have been caused by stocking largemouth bass from varied sources. Alternatively, native geographic genetic structuring or that caused by stocking in the late 1880s to mid-1900s may have been modified by more recent stocking of Florida largemouth bass. Key words: Largemouth bass, Micropterus salmoides, population genetics
