长江春季禁渔对崇明北滩渔业群落的影响

Effects of spring closed season on fishery community of the north beach of Chongming,the Yangtze River

对1999至2005年每年的4～6月间崇明北滩渔业群落进行研究，对春季禁渔前后相关指标进行对比分析。实施长江春季禁渔前，崇明北滩渔业群落组成为11目、19科、25属、27种。实施长江春季禁渔后，该群落共出现鱼虾蟹等渔业生物30种，分别隶属于9目18科26属。群落优势种为凤鲚[Coilia mystus（Linnaeus）]、棘头梅童鱼[Collichthys lucidus（Richardson）]、红狼牙鰕虎[Odontamblyopus rubicundus（Hamilton-Bnchanan）]和狭颚绒螯蟹[Eriochier leptognathus（Rathbun）]，单位质量小于20g的小型种类占绝对优势，鱼类幼体所占比例极大。多样性特征值平均指标为：Margalef指数1．50，Wilhm改进指数1．83，Simpson指数0．24，Pielou指数0．72。实施春季禁渔后该群落组成变化显著，复杂程度有所下降，多样性特征值仍大幅度波动，企稳回升趋势不明显。结果显示，春季禁渔对该群落的保护作用尚不明显，针对该群落的保护工作应进一步加强。

Studies on fishery community on the north beach of Chongming in the Spring Closed season were carried out during 1999 - 2005, and contrast analysis of correlative indexes before and after the Spring Closed season was also done. After the Spring Closed season, fishes, shrimps and crabs, which belong to 9 orders, 18 families, 26 genera and 30 species, were collected from this area. The dominant species were Coilia mystus, Collichthys lucidus, Odontamblyopus rubicundus and Eriochier leptognathus. Small species which the mean weight was less than 20 g were more than others remarkably. Average characters of biodiversity after the Spring Closed season indicated that Margalef＇ s index was 1.50, Wilhm＇ s 1.83, Simpson＇ s 0.24 and Pielou＇s 0.72. It showed that the community composition changed evidently, and the complexity had a little drop. Characters of biodiversity fluctuated in a wide range, and didn＇ t show the uptrend sign towards stability. The effect of the spring closed season on this community was not obvious, so the protection should be further strengthen.