Population Genetic Structure with Mitochondrial DNA of the Chub Mackerel Scomber japonicus in Korean Coastal Waters

Scomber japonicus, commonly known as chub mackerel, is a fish species of economic significance in Korea, China, and Japan, whose natural abundance has reduced dramatically due to overfishing and environmental changes. To investigate the genetic differentiation and population structure of S. japonicus, a 359 base pair segment of the mitochondrial DNA (mtDNA) control region sequence was analyzed in 96 individuals sampled from three locations in Korean waters. Sixty-six haplotypes were recognized, of which 61 (92.42%) were population specific, whereas only five haplotypes were shared by multiple populations (8%). Two clades were revealed with low support values, and no specific genealogical branches were recognized according to geographical locations. Significant genetic differentiations, however, were detected among the three populations, with FST values (p < 0.05). These results indicate that populations of S. japonicus in Korean waters are genetically subdivided. Migration patterns, spawning site fidelity, and current temperature could be the possible causes of this subdivision. Consequently, it is thought that each of the genetically unique S. japonicus stocks found in Korean waters requires a different approach to management.