基金The author would like to thank Mrs. Jindi Han, Mr. Xiaoguo Li, Mr. Guomin He, Mr. Zhenran Chen, and Dr. Jixing Zou for assistance in sampling and data collection. This work was supported by the National Natural Science Foundation of China (No. 30600456), Commission of Science and Technology of Shanghai, China (No. 08391910300), Project of Keji Xing Nong of Shanghai, China (No. 2008-7-2), open project of Key Laboratory for Sustainable Utilization of Marine Fisheries Resources Ministry of Agriculture (No. Shikai-2005-06), and special research fund for the national non-profit institutes (East China Sea Fisheries Research Institute, Project No. 2008Z02).