长江口及邻近海域春季仔、稚鱼的生态分布研究

Ecological distribution of fish larvae and juveniles in the Yangtze River estuary and its adjacent waters in spring

  • 摘要: 利用2008年春季在长江口及邻近海域调查获取的数据进行了仔、稚鱼的生态分布特征研究。结果表明,春季该水域仔、稚鱼种类丰富,出现率较高;总种类数呈现由北向南增加、优势种和重要种呈现由北向南减少的趋势;优势种的相对重要性指数(IRI)值较非优势种更加突出、分布范围更为集中;不同区域的种类数与表温变化趋势一致,平均单位捕捞努力量渔获量(CPUE)与表盐的变化趋势一致;仔、稚鱼集中出现海域的表温变化较小(17.0~19.5 ℃),而表盐变化较大(25~32);优势种空间分布的差异性表现为小黄鱼(Larimichthys polyactis)和六丝矛尾鰕虎鱼(Chaeturichthys hexanema)主要分布在吕泗和长江口近海,日本鳀(Engraulis japonicus)主要分布在舟山近海;仔、稚鱼高密度区均位于冷暖水混合水域,浮游生物较为丰富,有利于其生长后期的饵料获取,同时也与仔、稚鱼对环境的适应性有较大的关系。

     

    Abstract: We investigated the distribution, abundance and species composition of fish larvae and juveniles in the Yangtze River estuary and its adjacent waters based on the data obtained from integrated multi-disciplinary survey in mid-May of 2008. The results show that spring witnessed high species richness and occurrence frequency of fish larvae and juveniles. A southward increasing trend in the species richness and an opposing trend in the number of dominant species were detected. The spatial trend in species richness was accord with the surface temperature, and the catch per unit effort (CPUE) and surface salinity showed a similar spatial trend. The high-density zone of fish larvae and juveniles was characterized by a narrow temperature range of about 2.5 ℃ and a wide salinity range of about 7. The spatial distribution was different among dominant species. Larimichthys polyactis and Chaeturichthys hexanema were mainly distributed in the Yangtze River estuary and Lusi Fishing Ground, while Engraulis japonicas was mainly inhabited off the Zhoushan Inlands. The high-density zones of fish larvae and juveniles were located in the confluence zone of cold and warm currents,which were the most productive areas in the coastline of the East China Sea. The abundant prey items were expected to satisfy the nutrient requirements for the early development of the ichthyoplankton in the survey area.

     

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