钱塘江下游江段鱼类资源现状

Current status of fishery resources in downstream section of Qiantang River

2014年11月—2016年11月对钱塘江下游桐庐、富阳和闻堰江段的鱼类资源进行了逐季度采样调查,对该水域鱼类种类组成、优势种、群落多样性指数和捕捞情况进行分析。结果显示:共采集鱼类56种,隶属9目13科42属,其中鲤科鱼类种类最多,占总种类数的60.71%。优势种为光泽黄颡鱼、鲫、鲢和鳙。2015年春季捕获的鱼类种数最多,占总种数的57.89%;冬季鱼类捕获量最高,占总渔获量的26.94%。Margalef丰富度指数、Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数的变化范围分别为1.24~2.83、0.75~0.89、1.73~2.53和0.56~0.74。与历史记录比较,桐庐、富阳和闻堰江段鱼类群落组成已经发生了显著变化,除本地种光泽黄颡鱼和鲫外,增殖放流鱼种已成为了优势或重要种群。另外,外来种和杂交种的存在可能会对该江段渔业资源的健康发展构成潜在威胁。

In order to understand the fish resources in downstream section of Qiantang River,a quarterly survey was conducted by on drift-gill-net or fishpots combining with social investigation at Tonglu section,Fuyang section,and Wenyan section from November 2014 to December 2016. The results showed that a total of 56 species were collected,which belonged to 9 orders,13 families,42 genera,and Cyprinidae had the largest number of species,which constituted 60. 71% of the total species. The dominant species were Tachysurus nitidus,Carassius auratus,Hypophthalmichthys molitrix and Hypophthalmichthys nobilis. The species number and biomass of fish community displayed obvious variation quarterly,with the largest number in the spring of 2015,and the highest biomass in winter. The Margalef diversity index,Simpson diversity index,Shannon-Wiener diversity index and Pielou diversity index also showed obvious variations quarterly,with the range of 1. 24 to 2. 83,0. 75 to 0. 89,1. 73 to 2. 53,and 0. 56 to 0. 74,respectively. The fish community in the survey regions changed obviously compared with the historical records,and the released fish species had become dominant except the local species Tachysurus nitidus and Carassius auratus. Inaddition,the presence of exotic species and hybrids may pose a potential threat to the healthy development of fishery resources in the study sections.