Genetic variability of masu salmon in Hokkaido, by restriction fragment length polymorphism analysis of mitochondrial DNA

Mitochondrial DNA (mtDNA) of masu sah-non among eight populations from six rivers around Hokkaido island were examined to clarify their genetic featur es and population structure. Restriction fragment length polymorphism (RFLP ) analysis using 10 restriction endonucleases (Acc I, Ava I, BamH I, Bgl I, Bgl II, EcoR I, Hinc II, Hind III, Pst I, Xba I) revealed considerable var iation. We found 20 haplotypes in 180 specimens. Restriction patterns were polymorphic for 7 enzymes examined. Nucleotide divergence among haplotypes ranged from 0.14 to 2.41%. Nucleotide divergence among populations ranged f rom 0.49 to 0.70%. Dendrogram constructed by UPGMA among 20 haplotypes show ed no clustering groups of localities. Nucleotide diversity and nucleon div ersity of each locality ranged from 0.0043 to 0.0072, and from 0.7617 to 0. 9304, respectively. These results showed masu salmon populations in Hokkaid o have a high mtDNA variability. It is important that high genetic variabil ity be highly regarded in stock enhancement of masu salmon.