is a rapidly maturing fish and an important aquaculture species in China. A comprehensive analysis of the genetic structure of a germplasm resource is an essential prerequisite for their effective protection and utilization. The genetic diversity and structure of six populations-Donggang (DG), Qingdao (QD), Qinhuangdao (QHD), Suizhong (SZ), Zhuhai (ZH), and Zhoushan (ZS), inhabiting the Chinese coast were determined using eight microsatellite DNA markers. A medium level of genetic diversity was detected among the six populations but no significant differences were observed. Population SZ had the least genetic diversity, whereas ZS had the most. Most populations, except QHD, had a significant loss of heterozygosity (<0.01), which was also revealed by the global Hardy-Weinberg equilibrium (<0.01) between the Lama18 and Lama42 markers. The analysis of molecular variance results detected a significant difference in variance between populations, between individuals, and between individuals within populations (<0.01); the pair-wise Fst between groups and genetic distance results showed that maximum genetic differentiation and genetic distance occurred between ZS and the other five populations. No significant genetic differentiation was detected among the SZ, DG, QHD, and QD populations. A cluster analysis showed that ZS, ZH, and QHD were clustered with SZ, DG, and QD. Three genetic compositions were observed in the six populations. The genetic information in ZS was intact and was not mixed. The other five populations had a similar genetic composition and were significantly mixed genetically. Approximately 40% genetic similarity was detected between QHD and ZH. These results indicate that genetic differentiation has occurred between the ZS population and the other five populations analyzed. The genetic diversity among the five populations (DG, QD, QHD, SZ, and ZH) of inhabiting the Chinese coast has decreased and has become more homogeneous due to interactions with escapees from local aquaculture operations.