事件:长江江豚濒临灭绝

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Since the white-flag dolphin was officially declared "functionally extinct" in 2007， the finless porpoise became the only remaining cetaceans in Yangtze River and two freshwater lakes―Dongting Lake and Poyang Lake. It is estimated that the number of existing wild finless porpoise is about 1，000. Having been living on Earth for 25 million years， the number of finless porpoises decreases at the rate of 6.4% per annum because of the interference of human activities. They are going extinct rapidly and their population has been less than that of giant pandas.

Fish resource in the Yangtze River is at the edge of full-blown recession. The living Chinese paddlefish has been extremely rare and the number of Chinese sturgeon and Acipenser sturgeon are less than one tenth of 10 years ago. The fry amount of the most common fish： “the four major Chinese carps”― black carp， grass carp， silver carp and bighead carp― have been substantially reduced. The natural catches in Yangtze are diminishing， which changes from 54 million tons in 1954 to about 10 million tons in recent years.

The main reason for deaths of finless porpoise at a large number and a full-blown recession of the fish resources are in the nets and boats spreading over the Yangtze River. The Chinese Academy of Sciences study shows that the main threat facing the Yangtze finless porpoise is from the rapid growth of the Yangtze River shipping， excessive and illegal fishing， dredging， large-scale water conservancy construction， water pollution and other human activities. At the same time， in recent years， due to the impact of climate change and hydropower projects in the upper reaches of the Yangtze River， Dongting Lake and Poyang Lake， as the main habitat of the Yangtze finless porpoise， are frequently at abnormal low water levels， making the survival of Yangtze finless porpoise suffered a great threat in the lake region.

自从2007年白鳍豚被正式宣告“功能性灭绝”后，江豚就成了长江和两个淡水湖――洞庭湖和鄱阳湖――仅存的鲸类动物。据估计，现存野生江豚的数量在1000头左右。已在地球上生存了2500万年的江豚，如今在人类活动的干扰下，以每年6.4%的速度递减，快速走向灭亡，种群数量已少于大熊猫。

目前长江的鱼类资源正处于全面衰退的边缘，白鲟活体已极为罕见，中华鲟、达氏鲟数量不足10年前的十分之一。最常见的青、草、鲢、鳙“四大家鱼”鱼苗发生量也大幅减少。长江的天然捕捞量在逐年递减，由1954年的54万吨，变为了近年来的10万吨左右。

造成江豚大量死亡、鱼类资源全面衰退的主要原因，是遍布在长江中的一张张网和一艘艘船。来自中科院的一项研究表明，长江江豚面临的威胁主要来自快速增长的长江航运、过度及非法渔业捕捞、挖沙以及大型水利工程建设和水污染等各种人类活动。同时，近年来由于气候变化及长江上游水电工程的影响，作为长江江豚主要栖息地的洞庭湖和鄱阳湖频繁出现异常超低水位，使得湖区长江江豚的生存遭受极大威胁。