Biodiversity crisis in the Yangtze River:The culprit was dams, followed by overfishing

长江是我国第一大河流，全长达6300 km.长江是一条生命之河，它的活力来自于干流、支流、湖泊和湿地的血脉沟通形成的独特生命系统.长江流域是世界生物多样性的热点区域，分布有鱼类400余种，其中纯淡水鱼类350种左右，特有鱼类多达156种.长江中下游是东亚季风气候下形成的洪泛平原区域，湖泊星罗棋布，并与江河相连，生活有珍稀水生哺乳动物——白鱀豚和江豚.1980s初中下游湖泊面积约有23123 km2.19501970年间，沿江大建闸节制，除鄱阳湖（2933 km2）和洞庭湖（2625 km2）等外，绝大多数湖泊失去了与长江的自然联系，江湖阻隔使支撑长江鱼类的有效湖泊面积减少了76%.1981年，长江上建成了第一个大坝——葛洲坝；2003年，三峡大坝开始蓄水.长江干流的渔业捕捞量从1954年的43万t下降到1980s的20万t，最后到2011年的8万t（降幅为81%）.与此完全不同的是，1950s以来，洞庭湖和鄱阳湖的渔产量分别在2~4万t之间徘徊.长江干流的饵料生物丰度不足两湖的1/7，因此干流对物种的承载力十分有限，以鱼为生的白鱀豚和江豚种群的衰退属于情理之中，加上酷捕误杀，白鱀豚已经灭绝，江豚也危在旦夕.葛洲坝的建设阻挡了鲟鱼和胭脂鱼等的生殖洄游通道，中华鲟和白鲟的灭绝已近在咫尺.长江上游建有1万多座水坝，大部分鱼类的生存受到威胁.根据对长江生物多样性危机成因的粗略估算，节制闸和水电站等水利工程贡献了70%，酷渔乱捕等其它因素贡献了30%.所谓的生态调度、鱼道或人工放流等也难以拯救膏肓之疾，即使在长江干流十年禁渔也难有根本改观.如果鄱阳湖和洞庭湖相继建闸，将使长江中下游的渔业资源量进一步衰退，江豚的灭绝在所难免，其它物种的灭绝将难以预料.长江在哭泣，众多的物种需要生态文明的呵护!;The Yangtze River is the largest river in China, with a total length of 6300 km. The Yangtze River is a river of life, with its vitality from a unique system unifying the main river, branches, lakes and wetlands. It is a key area for biodiversity of the world. The river has ca. 400 species of fishes, of which 156 species are endemic. The middle and lower reaches of the river are a flooding plain formed historically under monsoon climate, having numerous shallow lakes connecting to the river or its branches, with two rare mammals-the freshwater dolphins. In the early 1980s, the lakes had an area of 23123 km2, but during 1950-1970, except Lake Poyang and Lake Dongting, all lakes were isolated artificially by concrete sluices, and ca. 76% lake area supporting ecologically the river was decreased. In 1981, a large dam, Gezhouba, was built, followed by the Three Gorges Dam in 2003. Total catches in the main river was 4.3×105 t in 1954, declined to 2.0×105 t in the 1980s, and further to 8.0×104 t in 2011 (a reduction of 81%). In contrast, since the 1950s, total catches in Lakes Dongting and Poyang fluctuated between 2×104-4×104 t, respectively. Abundance of planktonic preys in the river were less than 1/7 of the adjacent lakes, indicating a week ability to support existence of a large number of species. Thus it is not surprising that Lipotes vexillifer and Neophocaena asiaeorientalis witnessed steady declines in abundance, as both species feed on fishes in the river or lakes, as well as partly by indiscriminated killing by fisherman. Since the day when the Gezhouba Dam was built, Chinese sturgeon and paddlefish doomed the fate of extinction, as their reproductive migration pathway was truncated. In the upper reaches of the Yangtze River, there have more than 10 thousand dams, and the survival of most fish is threatened. As to the causes of the biodiversity crisis in the Yangtze River, water conservancy projects such as gates and hydropower stations contributed ca. 70%, whereas other factor such as overfishing contributed ca. 30%. It is impossible to solve the fatal crisis by the so-called flow regulation, or artificial releasing of fingerlings or fishway, and it seems impossible to have a fundamental improvement on the fishery resources in the Yangtze River even fishing is forbidden for ten years. If Lakes Poyang and Dongting are isolated by dams, the fishery resources in the river will further decline, the extinction of the finless porpoise can hardly be avoided, and no prediction can be made for the extinction of other fishes. The Yangtze River is crying, and numerous species need the care of ecological civilization!