长江上游保护区干流江安-重庆段禁渔初期鱼类时空分布特点

SPATIAL AND TEMPORAL DISTRIBUTION CHARACTERISTICS OF FISH IN THE MAIN STREAM OF THE UPPER YANGTZE RIVER RESERVE JIANG’AN-CHONGQING SECTION IN THE EARLY PERIOD OF FISHING BAN

  • 摘要: 为掌握“长江十年禁渔”初期长江上游保护区干流江安-重庆江段鱼类资源时空分布特征, 研究在开展鱼类资源调查的同时, 利用SIMRADEK80分裂波束科研回声探测仪于2020年12月和 2021年5月在江安-重庆江段开展水声探测。水声学探测结果表明, 江安-重庆江段2020年12月和2021年5月鱼类平均密度分别为25.31和41.23 ind./1000 m3, 鱼类目标强度均值分别为–55.81和–52.79 dB, 无显著差异, 估算鱼类平均体长分别为17.97和24.36 cm。在水平方向上, 两次调查鱼类都主要分布在重庆-江津江段, 两次水声学探测的鱼类密度在垂直方向上呈现出一定差异, 2020年12月表现为下层>中层>上层, 2021年5月表现为上层>中层>下层。此次鱼类资源调查共发现了鱼类12科62种, 其中瓦氏黄颡鱼、光泽黄颡鱼、蒙古鲌和贝氏䱗等小型鱼类的数量占比达到50.21%, 与水声学结果一致。研究初步探究了保护区内鱼类在不同时段的空间分布规律, 评估了禁捕初期长江上游鱼类分布特征, 为长江“十年禁渔”生态效果评估提供基础数据参考。

     

    Abstract: The evaluation of ecological effect before and after the implementation of major ecological restoration projects is a prerequisite for testing the effectiveness of restoration measures and optimizing adjustments. The spatio-temporal distribution of resources is one of the important indicator in this evaluation. In order to grasp the spatio-temporal distribution characteristics of fish resources in the Jiang’an Chongqing section of the main stream of the Yangtze River upstream protection zone during the initial period of the “Ten Year Fishing Ban”, we applied hydroacoustic analysis by using the SIMRAD EK80 split beam scientific echo detector for underwater acoustic detection in the December 2020 and May 2021, supplemented by fish resource surveys. The results showed that the average fish density in the Jiang’an-Chongqing section was 25.31 ind./1000 m3 during the dry season and 41.23 ind./1000 m3 during the wet season. The fish distribution in December 2020 and May 2021 was mainly concentrated in the Chongqing-Jiangjin section. The average target intensity of fish in dry season and wet season was –55.81 and –52.79 dB respectively, with no significant difference. The estimated average body length of fish was 17.97 and 24.36 cm, respectively. In the vertical direction, the density of fish detected by underwater acoustics showed a certain difference in December 2020 and May 2021. In December 2020, it was shown as lower layer > middle layer > upper layer, while in May 2021, it was shown as upper layer > middle layer > lower layer. We found 62 fish species belonging to 12 families in the fish resource survey, in which the small fish species such as Pelteobagrus vachelli, Pelteobagrus nitidus, Culter mongolicus and Hemiculteri bleekeri accounted for 50.21%. The study preliminarily explored the spatial distribution of fish in the reserve at different times, providing scientific basis for the protection of fish resources in the upper reaches of the Yangtze River. Additionally, the findings serve a valuable reference for assessing the ecological effect of the “Ten Year Fishing Ban” in the Yangtze River.

     

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