is distributed in the coastal waters and estuaries of the northwest Pacific Ocean, including the Yellow Sea and East China Sea. This species is rapidly becoming one of the most important marine fishery species in China. Extensive studies have shown that the abundance of C. lucidus has recently declined significantly because of overfishing and environmental degradation. To develop conservation measures there is a need to better understand the genetic population structure of C. lucidus. Fish (n=209) were collected from seven sampling locations in the south Yellow Sea and East China Sea, including Lianyungang, Dafeng, Chongming, Zhoushan, Wenzhou, Ningde, and Xiamen. A 611 bp mitochondrial CO I sequence was amplified by PCR then used for genetic structure analysis. We detected 44 haplotypes, the haplotype diversity index ranged from (0.416±0.112) to (0.720±0.076), and then ucleotide diversity index ranged from (0.00110±0.00035) to (0.00444±0.00164). The results of an AMOVA revealed there were two groups (north and south). The shallow topology of the haplotype neighbor-joining (NJ) tree and the UPGMA tree based on genetic distance suggests there is distinct structure across the seven populations. We define south Wenzhou as part of the southern group, and north Wenzhou as part of the northern group. The estimate of gene flow between the southern and northern groups was <1, which indicates that gene exchanges between these two groups are rare. Based on the expansion parameter τ, we speculate that the separation occurred during the Pleistocene, and the migratory behaviorof C. lucidus likely explains the current lack of differentiation within the southern or northern groups. Our results can be used to inform the sustainable exploitation and conservation of wild C. lucidus populations.