In the early 20th century, fishers on the Yangtze River regularly snared what may have been the biggest freshwater creature of modern times: the Chinese paddlefish. The behemoth once reached 23 feet in length, a third of that being a paddle-like snout that it used presumably to stir up the river bottom to flush out food. A single paddlefish could feed a village and was especially prized for its caviar. But decades of industrialisation in China’s heartland have sounded a death knell for the king of the Yangtze. The last time one was caught was in 2003, and it hasn’t been seen since.
The paddlefish is not the only Yangtze creature to have become the stuff of legend. The last confirmed sighting of the Yangtze river dolphin, or baiji, was in September 2004. The Yangtze giant soft shell turtle, perhaps the largest freshwater turtle on Earth, is apparently extinct in the wild. The last two known individuals, a male and a female, have been united in a Suzhou zoo but may be too old or too frail to mate. The Chinese alligator and the Chinese giant salamander are both critically endangered. The Chinese puffer fish and the Yangtze sturgeon are rarely spied these days. The Chinese sturgeon is on life support thanks only to hatcheries that release tens of thousands of fingerlings into the Yangtze each year.
Overfishing, pollution, and habitat fragmentation from dams - including the massive Three Gorges Dam - have brought the Yangtze to its current state. With more dams planned and Chinese officials intoxicated with unbridled economic growth, the future looks just as grim for the Yangtze’s vanishing species. Much of the river basin “will soon be a mere semblance of its natural state, offering few prospects for persistence of what remains of the river’s unique biodiversity,” says David Dudgeon, an aquatic ecologist at the University of Hong Kong.
All is not yet lost, however. Seasonal fishing bans have given some species a breather. “We can save the remaining ecology of the Yangtze,” argues Xie Songguang, an ecologist at the Institute of Hydrobiology in Wuhan. The potential saviour that he and others are counting on is a 10-year fishing moratorium. Such a ban may seem drastic, but it would have a tiny effect on fish markets, as the Yangtze supplies less than 1 per cent of China’s freshwater fish production, including aquaculture. A ban is feasible - if the political willpower can be summoned to implement it. With the Yangtze’s ecological health in obvious decline and the economic toll of a ban manageable, the prospects for a moratorium are looking better and better, experts say.
The Yangtze, the world’s third-longest river, flows 3,900 miles from its origins on the Tibetan Plateau to Shanghai, situated at the mouth of the Yangtze on the East China Sea. Around 40 per cent of China’s 1.3 billion people live in the Yangtze basin, and the region accounts for one-third of the country’s GDP. “The Yangtze is so important for China’s economic development,” says Wang Ding, a specialist on cetaceans at the Institute of Hydrology. “That makes it very difficult to protect river life.”
Indeed, cities on the Yangtze, including Chongqing, a megalopolis of 32 million people, have long treated the river as an open sewer. More than 25 billion tons of wastewater - half of China’s total - is discharged into the Yangtze each year, says Dudgeon. Fertiliser and pesticide runoff from farm fields and contaminants from ships add to the pollution.
When Wang came to the Institute of Hydrology as a young researcher in 1982, he says, “Nobody was talking about conservation”. By the end of the decade, however, the institute realised that the baiji was imperiled and scientists began searching for ways to protect the river’s ecology. According to the latest tally, the Yangtze has 378 fish species, including 162 that are unique, or endemic, to the river.
The river may have lost its baiji, but it still has Yangtze finless porpoises, the only freshwater porpoise population. To cetaceans, a big threat is ship traffic. The 770 or so miles of the Yangtze that are navigable are a highway of cargo vessels and barges. During the baiji survey in 2006, the research vessel had to crawl up the river: “There were so many ships in front of us,” Wang says. “There was no space for us, so there must be no space for animals as well.”
Like the lost baiji, finless porpoises must surface for air. They are also bothered by engine noise, which can drown out the sonar clicks the animals use to locate prey and communicate. Fish, meanwhile, fall victim to “highway maintenance”: dredging for easier navigation destroys spawning grounds.
Another threat to wildlife is the vast engineering works that have transformed the Yangtze basin. The river is connected to a dense network of tributaries, lakes, and wetlands, some of which have been severed by dams and levees from the Yangtze to protect communities from flooding when river levels rise during the summer monsoon season. “The Yangtze is a complex ecological system,” says Wang. “Animals once could move freely through it. That’s not the case anymore.”
Hydropower projects have created even more daunting barriers. The Gezhouba Dam, completed in 1981, took a heavy toll on Yangtze fish: It blocked breeding migrations, fragmented populations, and degraded spawning sites of paddlefish and sturgeon, Dudgeon reported in the April issue of the journal Aquatic Conservation. The Three Gorges Dam, finished in 2003, is an even more effective barrier to migration, he says, and has had a devastating effect on some fish populations.
“The impact has been huge. Fish resources below Three Gorges have suffered,” says Xie. The Yangtze’s four major carp species - bighead, black, grass, and silver - spawn when water levels rise during the summer rains. Three Gorges has subtly altered seasonal variations in water levels below the dam. Surveys have found a sharp decline in carp eggs and larvae downstream. “The dam has devastated spawning grounds,” says Xie.