长江流域鱼类资源现状与保护对策

为科学评价长江十年禁渔政策在金沙江下游水库的初步实施效果，实验于2020年11月和2022年5月在金沙江下游向家坝水库开展了渔获物调查和水声学调查，并分析了鱼类资源的变化情况。渔获物调查结果显示，2020年11月共采集到鱼类2科9种，其中䱗、瓦氏黄颡鱼占优势地位；2022年5月共采集到鱼类5科14种，其中蛇、瓦氏黄颡鱼占优势地位。水声学调查结果显示，不同年间、不同区域、不同水层间的鱼类目标强度分布存在显著性差异；2022年5月的鱼类密度 (0.60 尾/1 000 m³)高于2020年11月 (0.46 尾/1 000 m³)，鱼类资源在时空分布上呈现不均匀性；不同调查时期的鱼群密集区域存在一定的差异，2020年11月大部分区域之间差异不显著，2022年5月则差异显著；2022年5月的上层鱼类密度 (0.44±0.83 尾/1 000 m³)显著大于2020年11月 (0.06±0.15 尾/1 000 m³)；不同水层的鱼类分布差异显著，2次调查均表现为下层大于中、上层；估算得到向家坝水库鱼类资源尾数分别为3.22×10⁶ 尾 (2020年11月) 和3.53×10⁶ 尾 (2022年5月)。综上所述，水声学调查方法适用于金沙江下游水库的鱼类资源监测工作，十年禁渔实施后向家坝库区鱼类资源已得到一定程度的恢复。

Situations and conservation strategies of fish resources in the Yangtze River Basin

The Yangtze River is the longest river in China, with the richest fish resources in inland China. With the rapid economic development of the Yangtze River basin in recent decades, the intensity of human activities has been increasing, and the fish resources in the Yangtze River basin have declined sharply. To protect the ecological environment in the Yangtze River Basin, the Ministry of Agriculture and Rural Affairs has decided to ban fishing in key waters for 10 years. In order to scientifically evaluate the preliminary implementation effect of the ten year fishing ban policy in the reservoir at the lower reaches of the Jinsha River, the catch and hydroacoustic survey were carried out in Xiangjiaba Reservoir at the lower reaches of the Jinsha River in November 2020 and May 2022, and the changes of fish resources were analyzed. The results of catch survey showed that 9 species of fish belonging to 2 families were collected in November 2020, among which Hemiculter leucisculus and Pelteobagrus vachelli were dominant; In May 2022, 14 species of fish were found in 5 families, with Saurogobio dabryi and Pelteobagrus vachelli predominating. The results of hydroacoustic survey showed that there were significant differences in the distribution of fish target strength among different years, different regions and different water layers. The fish density in May 2022 (0.60 ind./1 000 m³) was higher than that in November 2020 (0.46 ind./1 000 m³). The spatial and temporal distribution of fish resources was not uniform. There were some differences in the densely populated areas of fish in different survey periods. In November 2020, there was no significant difference among most areas, while in May 2022, there was a significant difference. The density of upper layer fish in May 2022 (0.44±0.83 ind./1 000 m³) was significantly higher than that in November 2020 (0.06±0.15 ind./1 000 m³). The distribution of fish in different water layers was significantly different, and the lower layer density was higher than the middle and upper layers. The estimated fish resources in Xiangjiaba Reservoir were 3.22×10⁶ ind. (2020) and 3.53×10⁶ ind. (2022), respectively. The method of hydroacoustic survey is suitable for the monitoring of fish resources after the total fishing ban. In general, the method of hydroacoustic survey is suitable for the monitoring of fish resources in the reservoirs at the lower reaches of Jinsha River, and fish resources in Xiangjiaba Reservoir area have been recovered to some extent after the implementation of the ten-year fishing ban.