Temporal changes in the fish community resulting from a summer fishing moratorium in the northern East China Sea

摘要

The summer fishing moratorium system practiced annually by the Chinese government aims to protect fishery resources and restore the marine ecosystem in the East China Sea. To evaluate the effects of the moratorium on the fish community, temporal changes in the structure and function of the fish community in the northern East China Sea were examined based on data from bottom trawl surveys from 2000 to 2007. The results revealed that the fish community has undergone a directional change, in terms of relative biomass composition, following the implementation of the moratorium, with increasing trends in Pseudosciaena polyactis and Lophius litulon and decreasing trends in Pampus argenteus and Acropoma japonicum. However, the changes in species composition have not resulted in the expected positive changes in the functioning of the fish community. The fish community in the study area was still moderately or heavily disturbed, based on abundance-biomass comparison analysis. Moreover, no positive trends were observed in the indicators related to the stability and functioning of the fish community (e.g. the biodiversity and the slope and intercept of the size spectrum). Therefore, the summer moratorium system does not clearly fulfill restorative expectations for the fish community. To protect the health of this ecosystem, a comprehensive set of further fishery restrictions must be imposed in the area.