Genetic homogeneity between adult and juvenile populations of <Emphasis Type="Italic">Scombrops gilberti</Emphasis> (Percoid,Scombropidae) in the Pacific Ocean off the Japanese Islands

Scombrops gilberti is a member of the percoid family Scombropidae, which includes a single genus and three to four species worldwide. Little is known about the ecology of this species. Juvenile S. gilberti have been found in the waters off northern Japan (Iwate Prefecture), whereas adults are found in the waters around the southern counterpart (Izu Islands), approximately 700 km from the northern waters. In the present study, we captured immature S. gilberti (106–248 mm standard length, SL) in the northern waters by set net at 8–80 m depth, whereas larger individuals (150–328 mm SL) were captured by trawling at 150–500 m depth. By contrast, only adult S. gilberti (422–590 mm SL) were captured in the southern waters. The genetic composition of the adult population of S. gilberti from the southern waters and of the juvenile population from the northern waters was compared using the nucleotide sequence of the mitochondrial DNA (mtDNA) cytochrome b gene. No significant differences in genetic parameters such as fixation index, neutrality test or mismatch distribution analysis were found between these geographically distinct populations of S. gilberti, showing that these populations are genetically homogeneous.