Abstract
Horizontal starch gel electrophoresis was used to investigate the genetic stock structure of the Japanese mitten crab Eriocheir japonica. Twenty-two putative enzyme-coding loci were examined from 1072 crabs at 22 localities from Hokkaido to Okinawa in Japan and 69 Chinese mitten crabs E. sinensis. Nine loci (40.9%) were polymorphic, i.e., AAT-1*, AAT-2*, G3PDH*, GPI*, IDHP-1*, IDHP-2*, MDH-1*, MDH-2* and PGDN*. A geographical cline of allelic frequencies was not clearly recognized at all the loci but the alleles *b and *e at the GPI* locus might be a diagnostic character of the Okinawa populations. The average proportion of polymorphic loci and heterozygosity were 0.149 and 0.020, respectively. Nei's genetic distance was 0.0004 (0-0.0013) which was about 1/140 of the Nei's genetic distance between the Japanese mitten crab and the Chinese mitten crab. Gene diversity analysis indicated that only 1.20% of the variation was between samples. These results indicate that the genetic differentiation of the local populations is small.
