[Population division of Larimichthys polyactis in China Sea]
1Key and Open Laboratory of Marine and Estuary Fisheries, Ministry of Agriculture of China, East China Sea Fisheries Research Institute, Chinese Academy of Fisheries Sciences, Shanghai 200090, China. xiaomin@sh163.com
Abstract:
Previous approaches prevalently believed that there were three populations of Larimichthy spolyactis existed in China Sea. To clarify the number of the populations, an improved approach was adopted in this paper, based on the suite of methodologies including geographical isolation, population dynamics, morphology, anatomy, and molecular genetics. In our finding, there were two instead of three L. polyactis populations in the China Sea, one in Northern Yellow Sea and Bohai Sea, and the other in Southern Yellow Sea and East China Sea. Three evidences were against traditional approaches. Firstly, the traditional division was not supported by morphology, anatomy, and molecular genetics evidences. Secondly, in accordance with our study by referring the 1971-1982 fishing yield statistics from 14 major fishery companies in China, the geographical isolation for L. polvactis between Southern Yellow Sea group and East China Sea group was insignificant. In fact, the two L. polyactis groups inhabited at the same overwintering ground in offshore during winter, and the spawning fishes migrated towards to the nearshore of Zhoushan, Yushan, and Liisi fishing grounds in the following spring. At the same time, another L. polyactis group originally inhabited at the southern nearshore of mid East China Sea during winter migrated northwards and amalgamated with the fishes in the waters of Zhoushan. After spawning, these fishes aggregated into a large feeding group outside the prohibited fishing zone line from May to August. In contrast, the population from the northern Yellrw Sea and Bohai Sea had significant geographic isolation with the population from the southern Yellow Sea and East China Sea. Last but not least, no evidences could support that there were two populations existed at Southern Yellow Sea and the East China Sea, because the productivity of these two areas increased synchronously in recent years while the resource density at northern Yellow Sea and Bohai Sea was still much lower.
