Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Kushiro, Hokkaido 085-0802, Japan
Mitochondrial DNA (mtDNA) of the Japanese sandfish, Arctoscopus japonicus, collected from ten localities around Japan and Korea was used to clarify the population structure. Two regions of mtDNA (one containing the control region and the other flanking the 12 S and 16 S rRNA genes) were amplified using the polymerase chain reaction (PCR). Restriction fragment length polymorphism (RFLP) was conducted on PCR products and the composite haplotypes were calculated. There were no area-specific fragment patterns in the two regions. However, compositions of the fragment pattern for the control region restricted by DpnII and the 12-16 S rRNA region restricted by HaeIII were significantly different between the Sea of Japan (Urutin Korea, Yamaguchi, Iwafune, and Kisakata) and Nemuro, and the Pacific coast (Konbumori, Erimo, Kojyohama, and Yakumo). Furthermore, the composite haplotype frequencies were significantly different between the Sea of Japan and Nemuro, and the others.