东湖放养鱼类时空分布的水声学研究

HYDROACOUSTIC SURVEYS ON TEMPORAL AND SPATIAL DISTRIBUTIONS OF STOCKED CARPS IN THE EAST LAKE

  • 摘要: 2000年,用鱼探仪逐月对东湖鱼类的空间分布进行探测的结果表明:东湖鱼类主要分布在1.5m以下的水层,1.5m以上与1.5m以下水层的鱼类密度分布存在显著差异.此外,东湖中不同区域的鱼类密度分布亦有显著性差异.统计分析显示,这种水平分布差异与水深、离岸距离等因素没有明显的相关,可能主要由群聚行为引起.由不同月份群聚程度不一致,推测水温的变化可能会影响鱼类的群聚行为.污水排放对鱼类空间分布也可能有一定的影响.

     

    Abstract: The temporal and spatial distributions of atrificial stocked carps in the East Lake were inverstigated with an echo sounder in 2000. The transducer was set horizontally and vertically to got fish echoes from surface (depth less than 1.5m) and middle bottom (depth from more than 1 5m to the bottom) water layers, respectively. Surveys both for surface and middle bottom water layers were undertaken once monthly along the same route. Statistics on fish densities were carried out separately by dividing the survey route into 114 units, which one unit was 100 meters in length. The fish preferred middle bottom to surface water layer in the East Lake. Average of density fish in middle bottom (0.0474 ind/m3) was much higher than that in surface (0.0069ind/m3), and significant difference between the two water layers was observed (T-test, P0.001). Meanwhile, significantly differences in fish densities were also observed horizontally within the 114 statistical units both in surface (F=1 62,P0.001) and middle bottom (F=2.11,P0.001). The spatial variations of horizontal distribution in fish densities in the East Lake might be caused mainly by aggregation activity of fish, water temperature, and sewage discharge. However, no significant correlation was found between the aggregation activity of fish and water depth, or distances from the sampling sites to the shores.

     

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