Using microsatellite markers, we analysed genetic polymorphism in four populations of Eriocheir sinensis
, sampled from Jiangsu, Anhui, Liaoning and Tianjin. Twenty-four pairs of primers were used to amplify the target fragments ranging from 80 bp to 445 bp, which included 16 pairs designed in our laboratory and eight pairs published internationally. Two to 10 alleles per locus in four populations were amplified, and there were 155 alleles in all populations. The average number of alleles per locus was 6.458. The average number of effective alleles per locus (Ne
) was 4.3491 to 4.7234; the average observed heterozygosity (Ho
) was 0.5690 to 0.6722; and the average expected heterozygosity (He
) was 0.7238 to 0.7546. Hardy-Weinberg equilibrium analysis (x2
test, P<0.05) revealed that seven loci in the four populations were in equilibrium. The genetic distances between the four populations were calculated and revealed that the Anhui, Jiangsu and Tianjin crabs belong to a Yangtse River population, while the Liaohe crabs form another branch.