2015年夏季长江口及其邻近海域渔业生物群落结构分析

摘要

根据2015年6月(夏季)长江口及其邻近海域的底拖网调查数据,分析了该海域渔业生物种类组成、优势种、群落结构及其多样性特征.结果表明,调查共捕获渔业生物93种,其中底层鱼类56种、中上层鱼类7种、头足类10种和甲壳类20种,以底层鱼类和甲壳类为主.优势种包括小黄鱼(Larimichthy-spolyactis)、鳀(Engraulis japonicus)和带鱼(Trichiurus haumela).鱼山渔场及舟山渔场近岸区和长江口渔场离岸区群落多样性较高,舟山渔场离岸区和大沙渔场南部多样性较低.渔业生物群落可分为3组:20 m等深线附近的近岸区、20 ～ 50 m水深的长江口渔场外部和大沙渔场南部、以及50 ～ 75 m水深的舟山渔场和鱼山渔场中外部.渔业生物群落结构不同组间差异主要由小黄鱼、鳀、带鱼和刺鲳(Psenopsis anomala)引起.%Community structure analysis is one of the research focus topics in the Yangtze River Estuary and adjacent sea areas.The survey data in June can well valuate the fishery resources in the early stage of fishing moratorium,which is significant to assess the implementation effect from the summer moratorium for marine fishing.So the species composition,dominant species,community diversity characteristics and community structure of fishery species in the Yangtze River Estuary and adjacent sea areas were analyzed based on the data collected from the bottom trawl surveys in June,2015.The results showed that there were 93 fishery species,which were mainly demersal fish and crustaceans.The average catch weight was relatively high,with fish species occupying the largest proportion.These were dominant species:yellow croaker (Larimichthys polyactis),anchovy (Engraulis japonicus) and largehead hairtail (Trichiurus lepturus),indicating that the dominant species replacement had occurred compared with history data in the same period.The relatively high diversity of the community was found in the nearshore zone of Zhoushan and Yushan fishing ground,as well as the offshore zone of the Yangtze River Estuary fishing ground.While relatively low diversity of the community was found in the offshore zone of Zhoushan fishing ground and the southern part of Dasha fishing ground.The fishery biological communities could be divided into groups by the cluster analysis and the single factor similarity analysis:nearshore zone around the 20 m depth contour,offshore zone of the Yangtze River Estuary fishing ground and the southern part of Dasha fishing ground between 20 m and 50 m depth contour and the central and marginal parts of Zhoushan fishing ground and Yushan fishing ground between 50 m and 75 m depth contour.Similarity percentage analysis showed that the discriminating species among different groups were yellow croaker,anchovy,largehead hairtail and Japanese butterfish (Psenopsis anomala).Seasonal migration of the dominant species driven by temperature and water depth might be the major reason for changes of community structure.