Taxonomic status and genetic diversity of cultured largemouth bass Micropterus salmoides in China

Genetic variation within and among four cultured populations of largemouth bass in Guangdong, China was evaluated using six microsatellite loci and directly compared to genetic variation in wild populations of largemouth bass in their native range. Numbers of alleles per locus were the same within all four cultured stocks with a mean of 2.17 (SD ± 0.00), but were significantly lower than in wild populations (5.55 ± 1.35). Observed heterozygosity exhibited a mean of 0.37 (± 0.03) among cultured populations, while that in wild populations averaged 0.51 (± 0.15). All cultured populations exhibited a modal shift in allele frequencies suggestive of a recent reduction in Ne. The dramatic depletion of allelic variation and less dramatic loss of heterozygosity, combined with significant signatures of a recent reduction of Ne within the cultured populations suggest that a genetic bottleneck occurred. All cultured stocks were determined to be derived from the northern subspecies of largemouth bass.