Survey on temporal and spatial distribution of fish in the Daning River
三峡库区大宁河鱼类的时空分布特征

To gain the biomass and distribution of the fish in Darting River, twice acoustic evaluation have been carried out by using the HTI Model241 fish detection equipment in the winter of 2006 and April of 2007. The density of fish was obvi-ous higher in winter than that in spring, which may be relate to the behavior of fish. Statistical analysis showed that differ-ence in horizontal distribution was not significantly correlated to water depth ; the variations of fish density in the Daning River might be caused mainly by aggregation activity of fish. In winter, there were very significant differences between sur-face and middle layers, and surface and bottom layers in fish distribution (p<0.01). In spring, average of fish density in middle was much higher than that in surface and bottom layers and obvious differences between middle and the other two layers were observed(p<0.05). The variations of fish density in spring were higher than that in winter, which have rela-tionship with the water temperature and recovery capability of fish.