十年禁渔初期三峡库区干流鱼类分布特征及变化

CHARACTERISTICS AND CHANGES OF FISH DISTRIBUTION IN THE MAINSTEM OF THE THREE GORGES RESERVOIR AREA AT THE BEGINNING OF THE TEN-YEAR FISHING BAN

  • 摘要: 为掌握长江十年禁渔初期三峡库区干流江段鱼类分布特征, 研究于鱼类繁殖期和越冬期在库区干流江段开展了水声学探测, 同步进行渔获物调查。水声学调查结果显示, 繁殖期和越冬期鱼类平均密度分别为(5.52±10.43)和(3.26±5.60) ind./1000 m3, 无显著性差异(P>0.05); 鱼类平均目标强度为(–59.79±1.95)和(–56.51±2.88) dB, 存在极显著性差异(P<0.01)。估算得到繁殖期鱼类体长范围为1.24—156.68 cm, 均值为4.03 cm, 越冬期鱼类体长为1.25—155.96 cm, 均值为9.01cm。两次水声学所探测的鱼类密度在水平方向上无显著性差异; 在垂直方向上, 两次调查超过85%的鱼类分布在0—30 m的水深内, 鱼类目标强度呈现出随着水深的增加逐渐增大的分布规律。渔获物调查显示, 三峡库区以䱗、似鳊、蛇鮈等小个体鱼类为主, 外来鱼类短颌鲚数量占比较高。与蓄水175 m运行前相比, 此次调查的鱼类资源分布特征未发生太大变化, 平均目标强度增大, 鱼类小型化趋势得到遏制。研究初步揭示了禁渔后三峡库区干流江段鱼类资源时空分布特征及其变化, 积累了禁捕初期鱼类资源研究素材, 可为长江十年禁渔效果评估提供基础数据参考。

     

    Abstract: In order to understand the characteristics of fish distribution in the mainstem of the Three Gorges Reservoir during the initial period of the Ten-Year Fishing Ban, hydroacoustic surveys were conducted during both the breeding and overwintering seasons, along with simultaneous catch surveys. The hydroacoustic survey results showed that the mean fish density during the breeding and overwintering periods was (5.52±10.43) and (3.26±5.60) ind./1000 m3, respectively, with no significant difference (P>0.05), and the average target intensity of fish was (–59.79±1.95) and (–56.51±2.88) dB, respectively, with a very significant difference (P<0.01). It was estimated that the fish body length ranged from 1.24 to 156.68 cm with an average of 4.03 cm in the breeding period and from 1.25 to 155.96 cm with an average of 9.01 cm in the overwintering period. Fish densities detected by the two hydroacoustics were not significantly different horizontally. Vertically, over 85% of the fish in both surveys were distributed in water depths from 0 to 30 m, and the fish target intensities showed a pattern of gradual increase with increasing water depth. Catch surveys revealed that small individual fish such as Hemiculter leucisculus, Pseudobrama simoni, and Saurogobio dabryi dominated the Three Gorges Reservoir area, and the exotic species Coilia brachygnathus comprising a relatively high proportion of the catch. Compared to the 175 m impoundment, the distribution characteristics of fish resources in this survey did not change significantly, however, the average target intensity increased, and the trend of fish miniaturization was curbed. This study preliminarily reveals the spatial and temporal distribution characteristics of fish resources in the Three Gorges Reservoir area and their changes following the fishing ban. It accumulates research materials on fish resources at the early stage of the ban and provides basic data reference for evaluating the effect of the Ten-Year Fishing Ban on the Yangtze River.

     

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