Emma Graham-Harrison, Reuters 19 Jun 09;
BEIJING (Reuters) - Rare fish squeezed by China's decades of frantic dam-building could be pushed over the brink into extinction if a hydropower project planned for a protected stretch of the Yangtze river goes ahead, experts say.
Scientists and activists have petitioned the government to veto the Xiaonanhai dam, which would block a critical stretch of China's longest river above the city of Chongqing, and create a reservoir stretching deep into a national-level reserve.
"This reserve is considered by many fish experts as the last habitat for some of the endangered and local fish species," said environmentalist Ma Jun, who signed a letter asking the government to protect rare Yangtze fish threatened by the construction of too many dams.
For fish that have evolved to migrate and breed along a free-flowing river, large reservoirs can be a death sentence.
"When a dam is built you effectively change everything from the point of view of a river fish," said David Dudgeon, professor of freshwater ecology at the University of Hong Kong.
"The water temperature and the oxygen content, movement and current speed change. You prevent them accessing breeding sites, and alter the characteristics of the river bottom."
The Yangtze, which rises in the Himalayas and is known in Chinese as "the long river," is rich with unique species including the Yangtze sturgeon, the Baiji or Yangtze river dolphin, and the Chinese paddlefish.
But cascades of dams now block large sections of the river as power-hungry China seeks to fuel its growth. One is the Three Gorges, the world's biggest hydropower project.
Yangtze fish also have to battle overfishing, pollution from breakneck industrialization, and heavy river traffic.
The Baiji is already believed to be functionally extinct, and the last chance of survival for other species may be the 400 km (250 miles) of river now threatened by the Xiaonanhai dam -- which would provide power to fast-growing Chongqing.
"My guess is that the paddlefish and the Yangtze sturgeon are on the way to extinction already but there are other species that the reserve may be critically important for," Dudgeon warned.
"The (Xiaonanhai) dam would probably finish off some of the more vulnerable species -- the last nail in the coffin."
POWER VS NATURE
A rare and endemic fish nature reserve was originally established on the Yangtze in the mid-1990s, but subsequently moved to make way for the giant Xiangjiaba and Xiluodu dams.
But the new reserve had been touted as a possible site for a dam before the reserve was moved and officials are exploiting this to push their plans, environmentalists fear.
Defenders of the dam say it will lie in an "experimental" zone where some construction is allowed. Opponents argue the reservoir will stretch into areas set aside for conservation.
"(Officials) just see it from an economic development angle ... this will be a big investment," said Guo Qiaoyu, Yangtze River Project Manager at The Nature Conservancy.
Water expert Ma said the dam will not be very economical, even if the spending boosts the local economy.
"This is not a tall dam, and so the installed capacity is limited and the number of people that need to be relocated is relatively high, with compensation due for that," he said.
Experts fear that pressure for growth means the fish they study may pay a price for strange looks and elusive habitats.
"The very fact that this dam may be going ahead in the center of a national-level reserve tells you how important people think the conservation of fish is compared to the cuddlier animals," Dudgeon said.
(Editing by Ken Wills)
