Identification of the Genetic Origin of the Largemouth Bass(Micropterus salmoides), an Invasive Fish Species, in South Korea

The largemouth bass (Micropterus salmoides), a carnivorous freshwater fish, is found ubiquitously worldwide and impacts the food-web structure of aquatic ecosystems. In this study, we collected largemouth bass specimens from seven study sites along the Seomjin River in southwestern Korea to identify their genetic origin and diversity. The collected fish were mostly small in size (<100 mm). We performed cytochrome oxidase subunit I (COI) gene analysis. The deduced COI DNA sequences closely matched those of the M. salmoides largemouth bass from the USA. Twenty single nucleotide polymorphisms with alternative nucleotides were observed distinguishing the M. salmoides northern and Florida subspecies. In addition, phylogenetic analysis suggested that the origin of wild largemouth bass in southwestern Korea is the M. salmoides northern subspecies, and not the Florida subspecies, M. floridanus. Based on nucleotide variations among the northern subspecies, we analyzed eight haplotypes using all M. salmoides COI sequences in NCBI GenBank. Two types of COI haplotypes were found across the seven sites of southwestern Korea. One nucleotide variant was found only in the largemouth bass population of southwestern Korea. Network analysis indicated a major haplotype among the eight haplotypes. Our results provide fundamental information regarding the genetic origin and diversity of M. salmoides largemouth bass.