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    长江安庆段禁渔前后鱼类资源与分布格局的变化特征

    CHARACTERISTICS OF CHANGES IN FISH RESOURCES AND DISTRIBUTION PATTERN IN THE ANQING SECTION OF THE YANGTZE RIVER UNDER THE FISHING BAN

    • 摘要: 为评估长江安庆段的禁渔成效, 在禁渔前后采用水声学与网具调查相结合的方法, 对区域内鱼类资源开展了季节性调查。结果表明: (1)共调查到鱼类56种, 禁渔后调查物种数增加, 鱼类优势种增大, 多样性升高。(2)禁渔后鱼类密度整体上升, 各季均高于禁渔前, 但夏季差异不显著(P>0.05); 各生境鱼类密度均有不同程度增长, 冬季增幅最大, 达2.2—4.1倍。(3)禁渔后鱼类平均目标强度增大, 其中春季差异显著(P<0.05), 秋季和冬季高目标强度区间占比增加; 禁渔后渔获平均全长增加, 其中秋季差异显著(P<0.05), 鱼类全长四分位距呈扩大趋势, 表明鱼类个体组成趋于增大。(4)禁渔后鱼类密度和多样性呈A>B>D>C的格局, 历史捕捞水域清节洲洲尾和皖河口资源增长显著。鱼类多样性、丰富度及个体大小的改善, 表明长江安庆段禁渔措施已取得初步成效, 但目前仍处于资源快速恢复阶段, 未来需持续开展监测。此外, 鱼类丰富度和多样性呈现出的空间异质性, 提示对不同生境应采取差异化的管护措施: 优先保护清节洲尾和皖河口水域及其自然岸线, 对城区岸线实施生态化改造, 重点管控历史捕捞水域。

       

      Abstract: To evaluate the effectiveness of the fishing ban in the Anqing section of the Yangtze River, seasonal surveys of fish resources were conducted before and after the ban using a combination of hydroacoustic and net sampling methods. The results indicated that: (1) A total of 56 fish species were recorded, with an increase in species number, larger body size of dominant species, and higher diversity after the ban. (2) Fish density increased overall after the ban, being higher in all seasons compared to pre-ban levels, though the difference in summer was not significant (P>0.05). While all habitats experienced density increases, the most pronounced rise occurred in winter, reaching 2.2 to 4.1 times pre-ban levels. (3) The mean target strength increased after the ban, with a significant difference in spring (P<0.05); the proportion of high target strength range increased in autumn and winter. The mean total length of catches increased after the ban, with a significant difference in autumn (P<0.05), and the interquartile range of total length showed an expanding trend, indicating an increase in fish individual size. (4) After the ban, fish density and diversity followed a pattern of A>B>D>C, with significant resource increases observed in historically fished areas, such as the tail of Qingjie island and the estaury of the Wan River. The improvements in fish diversity, richness, and individual size demonstrate that the fishing ban in the Anqing section of the Yangtze River has achieved preliminary ecological effects. However, as the system is in a rapid recovery phase, continued long-term monitoring is essential. Furthermore, the spatial heterogeneity in fish richness and diversity suggests that differentiated management measures should be implemented for different habitats: priority protection should be given to the Qingjie island area and the estury of the Wan River and their natural shorelines, ecological restoration should be implemented for urbanized shorelines, and historically fished areas should be placed under strict control.

       

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