Dams and Fish

Dolphin extinction shows river degradation

Zhan Yan, Shanghai Daily
February 5, 2007

Sand-dredging and river pollution are threatening the very existence of white fin in the Yangtze River. Chinese experts are increasingly concerned about the possible extinction of white fin since an international expedition declared that the Yangtze River dolphin, or baiji, or white fin, is “functionally extinct.” And while the baiji has received great attention, another Yangzte cetacean, the Yangtze finless porpoise or jiangzhu, literally river pig, is also on the way to extinction. The reason: Reckless industrial pollution, dumping of human waste and marathon sand dredging. Over six-weeks between November and December, scientists with high-performance optical instruments and underwater microphones covered over 3,500 kilometers of the Yangtze River. “The moment that experts disembarked from the ships, was the moment that humankind bid farewell to the 20-million-year-old baiji,’ said Wang Kexiong, an expert at the Institute of Hydrobiology in Wuhan. Called the “Goddess of the Yangtze,” the baiji was revered by the ancient peoples along the Yangtze, who believed that the white ‘fish,’ the same size as a human being, could help safeguard sailing. In the early 1980s, the Yangtze reportedly had around 400 baiji swimming its waters. A 1997 survey yielded 13 confirmed sightings. The last confirmed sighting of a baiji was in September 2004. As the most recent expedition returned to land, having failed to sight a single baiji, August Pfluger, head of the Baiji.org Foundation and co-organizer of the expedition, pronounced the species “functionally extinct.” Wang Kexiong expressed his concerns for the future of the Yangtze’s entire ecological system, saying: “Cetaceans (whales, dolphins and porpoises) live at the top of the food chain – if they are threatened by extinction, it means that their food sources are also dwindling and biodiversity in the Yangtze River is degenerating.” The water quality in the Yangtze has changed remarkably along with China’s economic growth, the increase in shipping, coupled with the dumping of waste in the river has polluted the waters. Sand dredging According to experts, however, the most obvious threat to the existence of dolphins is the rampant sand-dredging along the river. The Yangtze, its tributaries and lakes are filled with sand-dredging barges. There are about 12 sand-loaded ships for every kilometer of the Yangtze. However, a survey by the expedition estimated that the number of ships per kilometer in the lower reaches of the river could be 30 to 60. The Yangtze is being dredged to deepen its channel to accommodate heavier shipping. “The noise pollution is already a torture for humankind, let alone for sound-sensitive cetaceans underwater. It makes the baiji prone to collisions with ship propellers and prevents them from finding a mate, hunting and communicating with others,” said Wang Kexiong. Removing riverbed sand also destroys the habitats of other animal and plant that are sources of food for baiji. The Chinese government has been tightening measures to forbid sand dredging in the main channel of the Yangtze, however, local governments are continuing to issue permits for dredging in the river’s tributaries and surrounding lakes. “A ship-full of sand yields a profit of at least 100,000 yuan (US$12,500) – more than enough to drive thousands of people into the business,” Wang said. The Yangtze River basin is home to 400 million people, roughly a third of China’s total population – all of whose waste ends up being dumped into the river. According to the State Environmental Protection Administration, the amount of wastewater discharged into the Yangtze has shot up by almost two thirds – from 11.39 billion tons in 1998 to 18.42 billion tons in 2005. Weng Lida, an expert with the Yangtze Valley Water Resources Protection Bureau, commented how the pollution endangers some 500 city drinking-water sources along the river. “Many cities and towns fail to treat sewage properly – merely 15 percent of domestic sewage is treated properly before being discharged into the river,” Weng said. There are about 1,133 lakes in the middle and lower reaches of the river, said Wang Ding, deputy director of the hydrobiology institute. “All of these, except Dongting Lake, are equipped with dams, sluice gates, bridges or reinforced banks.” Wang then went on to explain how these dams and sluice gates have robbed the baiji of their normal habitat and cut off the migration routes of fish on which they feed. The expedition team collected water and sediment samples along the route of the river. “The results might be gloomy,” said Wang, “the Yangtze pollution is serious. Discharge from a thermal industrial plant could produce a steaming river section for several kilometers, while discharge from paper mills or chemical plants could cover some sections with a thick, multi-colored layer of scum.” Surveys show that in the mid-1980s, the Yangtze was home to some 126 animal species, however, by 2002 that number had fallen to just 52. Since 2003, a closed fishing season has been brought into effect to recover fish resources. Despite this, the situation has not improved. Cao Dongsheng, a fisherman from Yueyang County in Hunan Province, said: “Twenty years ago, by using traditional fishing methods, we could harvest 100kg of fish every day. “Today, there are little fish left in the river, as people are using poisons, electric fishing, and illegal fishing nets.”

The author is a senior writer at China Features of Xinhua news agency.

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