长江东流河道整治对长江江豚种群数量的影响

长江江豚是生活在长江中下游的濒危水生哺乳动物,通常活动在江心洲和浅水缓滩附近。航道整治改变了鱼类栖息活动的水文环境,也给豚类生存带来负面影响。本文根据长江东流河道整治施工前和施工后各3 次野外考察资料,分析了3 种流态中江豚的数量与群结构。结果表明,该工程实施前江豚主要栖息活动在边滩的分离区,其次在洲头的分流区。工程实施后,整治江段的江豚种群数量年下降率达8. 9% 。江豚在分流区活动已消失,在分离区集群规模较小,且在流态之间移动增大。本文研究结果也提示长江江豚就地保护难度越来越大,从长江干流中把长江江豚迁入故道中是一件刻不容缓的工作。

Impact of river training on the population abundance of Yangtze finless porpoises in Dongliu section of the Yangtze River

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)is an endemic mammal in the middle and lower reaches of the Yangtze River,and generally appears around river bars and shallow edge beaches. The river training produces negative impacts on the cetacean because of alteration of the hydrological environment for fishes. Using three surveys in the Dongliu section of the Yangtze before the river training project and another three surveys after the project group structure and size of the porpoise in three flow patterns were compared. The results showed that the Yangtze finless porpoise were found mostly in separations near side bars,and secondly in bifurcations above a bar before river training.After implementation,the annual rate of decrease of the porpoise was about 8.9% .The Yangtze finless porpoise has vanished in the bifurcation zone,and is less dense in the separation zone while rapidly shifting among flow patterns in the regulated river.The results of this study also suggest that the Yangtze finless porpoise is exposed to more and more difficulty in the mainstream of the river.It is urgently that the Yangtze finless porpoise be translocated into an old channel from the mainstream of the Dongliu section.