长江上游珍稀特有鱼类国家级自然保护区干流段鱼类群落结构特征分析

长江上游珍稀特有鱼类国家级自然保护区位于向家坝坝下江段，随着金沙江下游梯级水电站相继蓄水运行和“十年禁渔”政策的实施，保护区干流段鱼类群落可能会发生改变。为探究“十年禁渔”前保护区干流段鱼类群落结构特征，基于该江段2017—2019年渔获物监测数据，对鱼类种类组成、生态类型、群落相似度、物种优势度、生物多样性以及群落结构稳定性等特征进行分析。结果显示，本次调查共采集到鱼类134种，隶属于7目21科83属，其中长江上游特有鱼类有27种，外来物种有12种，分别占总种类数20.15%和8.96%。鱼类群落以底层、产沉性卵、杂食性鱼类为主。等级聚类分析(Cluster)和非度量多维尺度分析(NMDS)显示，在一定的相似性水平上，保护区干流段鱼类的群落类型基本可分为3组，宜宾、泸州与合江可以聚为一组，巴南、江津分别独立成组。保护区干流优势种共有14种，其中瓦氏黄颡鱼是整个研究区域的优势种，在合江站点的优势度最高，IRI值为27.00%。Shannon-Wiener指数、Simpson指数、Margalef指数和Pielou指数变化范围分别为2.725～3.306、0.883～0.942、5.83...

Analysis on the characteristics of fish community structure in the main stream section of the National Nature Reserve for Rare and Endemic Fish in the upper reaches of the Yangtze River

The National Nature Reserve of Rare and Endemic Fish in the upper reaches of the Yangtze River is located in the lower reaches of Xiangjiaba Dam. With the impoundment of cascade hydropower stations in the lower reaches of Jinsha River and the implementation of the "ten-year fishing ban" policy, the fish community in the main stream of the reserve may change. In order to explore the characteristics of fish community structure in the main stream of the Reserve before the "ten-year fishing ban", based on the catch monitoring data from five sampling sites of this section from 2017 to 2019, the characteristics of fish species composition, ecological types, community similarity, species dominance, biodiversity and community structure stability were analyzed. The results showed that 134 fish species were collected in this investigation, belonging to 7 orders, 21 families and 83 genera, among which 27 species were endemic to the upper reaches of the Yangtze River and 12 species were exotic, accounting for 20.15% and 8.96% of the total species respectively. The fish community was dominated by demersal fish, sunken eggs and omnivorous fish. Cluster analysis and Nonmetric Multidimensional Scaling (NMDS) analysis showed that the fish community types of five sections in the main stream could be basically divided into three groups at a certain level of similarity, as Yibin, Luzhou and Hejiang sections formed one group, Jiangjin section and Banan section formed separate groups independently. There were 14 dominant species, among which Pelteobagrus vachelli was the dominant species in the whole area, with the highest dominance in Hejiang section where the IRI value was 27.00%. Shannon-Wiener index, Simpson index, Margalef index and Pielou index ranged from 2.725 to 3.306, 0.883 to 0.942, 5.833 to 8.811, 0.699 to 0.773, respectively. As a result, fish species diversity and the community distribution uniformity was high in the main stream of the reserve. The results of ABC curve analysis showed that the fish community structure in Jiangjin section was relatively stable, but moderately disturbed in the other section. This study could supplement the basic data of fish community information in the main stream of the nature reserve, and also provide theoretically scientific support for fish resource management and ecological evaluation of "ten-year fishing ban" in this section of the river.