不同渔业方式水库鱼类资源的水声学评估

采用Biosonics DT-X回声探测仪(208 kHz)在2011年的秋末冬初对大溪、沙河、金牛山3个不同渔业方式的中等营养化水库进行了水声学调查，并构建了水库中鱼类资源分布的GIS模型.结果表明： 3个水库间鱼类平均大小无显著性差异，但鱼类目标强度(TS)分布曲线表明鱼类大小分布比例并不一致，受渔业方式影响明显.大溪水库鱼类密度(平均0.0183 ind·m^-3)与沙河水库鱼类密度(平均0.0124 ind·m^-3)差异不显著，金牛山水库鱼类密度(平均0.0085 ind·m^-3)显著小于大溪水库和沙河水库，3个水库中鱼类密度水平分布与水深没有显著的相关关系.3个水库中鱼类均成群分布，对大溪水库和沙河水库调查时还发现鱼类聚群行为.3个水库的鱼类资源量分布均在下游最高，除沙河水库受赶鱼作业影响外，其他2个水库大坝前鱼类资源量分布明显偏高.基于鱼类分布GIS建模的栅格化数据、各个栅格的水面面积，对TS>-60 dB鱼类资源总量进行估算，大溪水库约为48万尾,沙河水库约为61万尾,金牛山水库约为52万尾；对TS>-40 dB的鱼类进行统计评估，大溪水库约为5.04万尾，沙河水库约为5.29万尾，金牛山水库约为9.07万尾.

Hydroacoustic assessment of fish resources in reservoirs with different fishery management

By using Biosonics DT-X echosounder (208 kHz), a hydroacoustic investigation was conducted on the fish resources in three mesotrophic reservoirs (Daxi Reservoir, Shahe Reservoir, and Jinniushan Reservoir) with different fishery management in late autumn and early winter 2011, and a GIS model was constructed to assess the fish resource distribution in the reservoirs. No significant difference was observed in the average size of fish in the three reservoirs, but the distribution curves of fish target strength (TS) showed that the fish size distribution proportion was different, and had close correlation with fishery management. The fish density in Daxi Reservoir (averagely 0.0183 ind·m^-3) had no significant difference with that in Shahe Reservoir (averagely 0.0124 ind·m^-3),but the fish density in Jinniushan Reservoir (averagely 0.0085 ind·m^-3) was significantly lower than that in Daxi and Shahe reservoirs. There was no significant correlation between the horizontal distribution of fish density and the water depth in the three reservoirs. The fish in the three reservoirs were in group distribution, and fish aggregation was found in Daxi and Shahe reservoirs. In the three reservoirs, the fish biomass was the highest in downstream, and there was a greater biomass near the dam, except in Shahe Reservoir which was affected by fish catch activity. Based on the raster data obtained from GIS fish distribution model and the surface water area of each grid, the total amount of fish resources with the TS >-60 dB in the Daxi, Shahe and Jinniushan reservoirs was estimated as about 480000, 610000 and 520000 individuals, and that with the TS >-40 dB was about 50400, 52900 and 90700 individuals, respectively.