Inbreeding between Deep-Sea Snailfishes and in the Northwestern Pacific Ocean.

Genetic deviation between two deep-sea snailfishes, from the Pacific Ocean and from the Okhotsk Sea, of the species complex was analyzed, based on the nucleotide sequences of the mitochondrial cytochrome b () gene. Our sampling revealed the occurrence of individuals with -type genes off northeastern Japan, in the northwestern Pacific. Most of these individuals were collected from an area off Miyagi Prefecture, while few individuals were collected from areas to its north (off Iwate Prefecture) and south (off Fukushima and Ibaraki Prefectures). Phylogeographic analyses based on nucleotide sequences of the first intron region of the nuclear S7 ribosomal protein gene () and 11 microsatellite loci indicated little genetic deviation between individuals with -type and -type genes in the area off Miyagi Prefecture. Significant genetic differences between the Pacific Ocean and the Okhotsk Sea populations may be attributed to unidirectional migration due to a greater current from the latter to the former. In addition, peritoneum and stomach colors of 10 and 17 specimens collected from the Pacific Ocean and the Okhotsk Sea, respectively, were evaluated quantitatively. The colors were significantly different for the two populations; however, they appeared to overlap. Although only one Pacific individual with a -type gene was available for color evaluation, it was more similar to Pacific individuals than to Okhotsk Sea individuals. These results suggest inbreeding between and in the Pacific Ocean, off Miyagi Prefecture.