禁渔初期长江宜昌-城陵矶江段鱼类资源时空分布特征

SPATIAL-TEMPORAL DISTRIBUTION CHARACTERISTICS OF FISH RESOURCES IN YICHANG-CHENGLINGJI RIVER SECTION OF THE YANGTZE RIVER IN THE EARLY PERIOD OF FISHING BAN

  • 摘要: 研究于2022年7月(丰水期)和2023年1月(枯水期)使用SIMARD EY60回声探测仪对长江中游宜昌-城陵矶江段的鱼类资源进行了调查, 并结合网捕调查结果, 评估了长江十年禁渔初期该江段鱼类资源的时空分布特征。结果显示, 禁渔初期宜昌-城陵矶江段丰水期和枯水期的鱼类密度分别为128.69和38.43 ind./1000 m3, 目标强度(TS)均值分别为–57.54 和–60.18 dB, 转换后鱼类体长均值为5.22和3.85 cm。丰水期和枯水期鱼类密度和TS值均存在显著性差异。在水平方向上, 鱼类分布不均匀, 蜿蜒曲折处鱼类密度高于平直江段。两次调查鱼类密度最大江段分别为公安-石首和枝江-荆州江段; 在垂直方向上, 不同水层间鱼类平均密度表现为底层>中层>表层, 两时期各水层之间鱼类密度均存在极显著性差异。结合网捕数据及历年历史调查数据, 宜昌至城陵矶江段鱼类资源以鲤科、鲿科鱼类为主。禁渔初期鱼类资源有所恢复, 但仍以小个体鱼类为主。长江中游鱼类资源的时空分布与生活习性、水域生态环境等因素相关。相关成果将为后续进一步开展禁渔效果评估提供数据支撑。

     

    Abstract: In this study, we investigated fish resources in the Yichang to Chenglingji reach of the middle Yangtze River using the SIMARD EY60 echo detector in July 2022 (during the high-water season) and January 2023 (during the low-water season). Additionally, we integrated the results of net fishing surveys to assess the spatial and temporal distribution characteristics of fish resources in this reach during the initial ten-year fishing ban period. The results revealed that during the wet season and dry season of the fishing ban period, fish densities were 128.69 ind./1000 m3 and 38.43 ind./1000 m3, with mean target strengths (TS) of –57.54 and –60.18 dB, and mean fish lengths of 5.22 and 3.85 cm, respectively. Significant differences in fish density and TS values were observed between the two seasons. Horizontally, fish distribution was uneven, with higher fish densities observed in meandering and winding sections compared to straight river segments. The sections with the highest fish densities during both surveys were found in the Gongan to Shishou and Zhijiang to Jingzhou reaches. Vertically, fish densities showed a pattern of bottom layer > middle layer > surface layer, and significant differences were observed in fish densities among these layers during both seasons. Combining net fishing data and historical survey data from previous years, fish resources in the Yichang to Chenglingji reach were dominated by Cyprinidae and Bagridae, while there was some recovery of fish resources during the initial fishing ban period, small individual fish still dominated. The spatial and temporal distribution of fish resources in the middle Yangtze River was correlated with factors such as habitat preferences and aquatic ecological conditions. These findings provide valuable data support for future evaluations of the effectiveness of the fishing ban.

     

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