Population Differences in Gene Frequency of the Japanese Scallop Patinopecten yessoensis on the Okhotsk Sea Coast of Hokkaido

Genetic variability in native and sown populations, including 10 collections, of the Japanese scallop Patinopecten yessoensis on the Okhotsk Sea coast of Hokkaido in Japan was surveyed by starch gel electrophoresis for 19 genetic loci. As a whole, the proportion of polymorphic loci averaged 0.405 ±0.008 and the average heterozygosity 0.158±0.002, and these values were remarkably higher than those estimated for fish. Any two of the 10 collections showed clear differences in gene frequencies at more than one locus except for a few combinations, indicating that they have a breeding structure independent of each other. The mean genetic distance was larger among native populations than among sown populations. The genetic distance was 0.0035 ±0.0003 on the average for all populations, the value being smaller than 0.01 that is considered as the level of local race. However, the mean genetic distance between native Notoro Lake population and the other native populations was 0.0077±0.0008, the value being the largest. These results suggest that the scallop population has a structure capable of being split into a number of local subpopulations.