长江口近海秋季鱼类资源的年变化分析

选用2002~2005年秋季长江口近海渔业资源和温盐度同步调查数据,对该水域秋季鱼类资源量指数、多样性指数、优势种组成以及水温、盐度的年间变化进行了分析,并对鱼类资源量与水温、盐度之间的关系进行了初步研究。结果表明:秋季长江口近海的鱼类资源量指数和多样性指数的年间变化均较为明显,但优势种组成较为稳定,以带鱼、小黄鱼、银鲳、刺鲳为主要优势种,且各年份基本上以带鱼和小黄鱼占有绝对的优势地位。当前长江口近海鱼类群落处于较低水平的相对稳定状态。秋季长江口近海鱼类的资源量和底层水温的变化趋势较为一致,而与表层水温的变化趋势呈现相反的趋势,同时和表底层的水温差变化呈负相关关系;鱼类资源量的变化受表层盐度的影响较为明显,它们之间呈现相同的变化趋势。

Analysis on the annual variations of fish resources in the offshore water of Yangtze Estuary in autumn

The present paper deals with the analysis on the annual variations of the fish resources in the offshore water of Yangtze Estuary in autumn over the period 2002-2005 based on the data taken from the bottom trawl surveys.The annual variations of fish resources biomass index,species diversity index,dominant species composition,water temperature and salinity in the surveying areas mentioned above have been analyzed,meanwhile,the relationships between the total biomass of fish assemblage and water temperature along with salinity were herewith discussed.The results revealed that there were rather obvious on the annual variations of biomass index and species diversity index,but the composition of dominant fish species was relatively stable,there were dominanted by Trichiurus japonicus,Larimichthys polyactis,Pampus argenteus and Psenopsis anomala,the anterior two were the most dominant species every year over the period in the surveying water.All of them indicated the fish assemblage were in the relatively stable status of lower level.It could be found that the variational trend of the fish resources biomass was consistantly with that of the bottom temperature,but contrary to that of surface temperature,and negatively interrelated with the temperature difference between the surface and bottom waters.The effects of surface salinity on the biomass were rather obvious,the variational trend of total biomass was positively related to that of surface salinity.