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    长江十年禁渔初期效果评估: 中游鱼类群落稳定性与种群结构的响应

    EVALUATION OF INITIAL EFFECT OF THE TEN-YEAR FISHING BAN IN THE YANGTZE RIVER: RESPONSE OF STABILITY AND POPULATION STRUCTURE OF MIDDLE REACHES FISH COMMUNITIES

    • 摘要: 为科学评估禁渔初期生态响应, 本研究基于2017—2019年(禁渔前)和2021—2023年(禁渔后)长江中游荆州、监利和黄石江段渔获数据, 综合运用丰度/生物量曲线(ABC曲线)及W统计值分析群落稳定性, 并通过体长比例分布(Proportional size distribution, PSD)、平均体长与性成熟个体占比系统评估16种常见鱼类的种群结构变化。结果表明: 禁渔前(2017—2018年)群落处于未受干扰区间(W值为0.051、0.093), 实为长期捕捞压力下的“胁迫型稳态”; 2019年W值降至0.017, 出现中度干扰信号。2021年全面禁渔引发“种群释放响应”, W值转负(-0.027)但仍属中度干扰区间, 群落层次小型鱼类(如贝氏䱗)(Hemiculter bleekeri)数量激增, 而种群层次部分物种(如鳜、蛇鮈)(Siniperca chuatsi、Saurogobio dabryi)的PSD值与平均体长已显著提升, 二者并行揭示了恢复初期的不同步生态过程。2022年W值异常升高至0.098, 主要受通江湖泊极端干旱压制小型鱼类种群的影响, 并非禁渔成效的线性延续; 2023年W值回落至0.036, 群落结构回归真实恢复轨迹。种群结构方面, 8种鱼类平均体长显著增加(2.4%—91.0%, P<0.05), 鳜、蛇鮈和䱗(Hemiculter leucisculus)的PSD值显著提升(14—70, P<0.05), 10种鱼类性成熟个体占比显著增长(2.6%—56.4%, P<0.05); 健康状态(50≤PSD<80)物种由禁渔前的3种增至禁渔后的4种, 结构不稳定(PSD<50)物种由5种减至2种。但鳊(Parabramis pekinensis)、团头鲂(Megalobrama amblycephala)和银鲴(Xenocypris argentea)的平均体长显著下降(2.8%—44.5%, P<0.05), 蛇鮈、䱗和团头鲂的性成熟占比显著降低(1.0%—52.9%, P<0.05), 显示恢复的物种特异性。研究表明, 长江十年禁渔已初步显现积极效应, 但其生态响应是政策驱动与水文干扰交织的复杂过程, 建议建立多指标综合评估体系, 并辅以栖息地修复等管理措施, 促进缓慢恢复物种种群修复。

       

      Abstract: A ten-year fishing ban was implemented in the Yangtze River in 2021 to restore its declining fishery resources and aquatic biodiversity. To scientifically evaluate the ecological response during the early stage of the fishing ban, this study used catch data from Jingzhou, Jianli, and Huangshi sections in the middle reaches of the Yangtze River for the periods 2017 to 2019 (before the fishing ban) and 2021 to 2023 (after the fishing ban). The abundance/biomass curve (ABC curve) and W statistical value were used to analyze community stability, while systematic evaluation of population structure changes in 16 common fish species was conducted using proportional size distribution (PSD), average body length, and proportion of sexually mature individuals. The results showed that before the fishing ban (2017—2018), the community remained within the undisturbed range (W values of 0.051 and 0.093), which was actually a stress type steady state under long-term fishing pressure. In 2019, the W value dropped to 0.017, signaling moderate interference. The comprehensive fishing ban in 2021 triggered a population release response, with W values turning negative (-0.027) but still falling within the moderate disturbance range. At the community level, the number of small fish species (eg: Hemiculter bleekeri) surged, while PSD values and average body length increased significantly for certain species (eg: Siniperca chuatsi and Saurogobio dabryi), revealing asynchronous ecological processes during the early recovery stages. The abnormal increase in the W value to 0.098 in 2022 was mainly attributed to the impact of extreme drought on small fish populations, rather than a linear continuation of the fishing ban effect. By 2023, the W value declined again to 0.036, signaling a return to the true recovery trajectory. Regarding population structure, the average body length of 8 fish species increased significantly (2.4%—91.0%, P<0.05), while PSD values for S. chuatsi, S. dabryi, and Hemiculter leucisculus rose markedly (14-70, P<0.05). The proportion of sexually mature individuals in 10 fish species also increased significantly (2.6%—56.4%, P<0.05). The number of healthy species (50≤PSD<80) increased from 3 before the fishing ban to 4 after, while the number of structurally unstable species (PSD<50) decreased from 5 to 2. However, the average body length of Parabramis pekinensis, Megalobrama amblycephala, and Xenocypris argentea significantly decreased (2.8%—44.5%, P<0.05), and the proportion of sexual maturity in S. dabryi, H. leucisculus, and M. amblycephala decreased significantly (1.0%—52.9%, P<0.05), indicating species specificity of recovery. Research demonstrates that the ten-year fishing ban has initially shown positive effects in the Yangtze River, but its ecological response is a complex process of policy driven and hydrological interference. It is recommended to establish a comprehensive evaluation system with multiple indicators, supplemented by habitat restoration and other management measures, to promote the restoration of slowly recovering species populations.

       

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