'Algae-eating fish' used to clean up Chinese lake

Yahoo News 20 Feb 09;

SHANGHAI (AFP) – Chinese authorities have again turned to algae-eating fish in a bid to clean up a pollution-linked blue green bloom on one of the country's most scenic lakes, state media reported Friday.

Taihu Lake in eastern China has seen a re-emergence of algae growth that forced authorities to cut water supplies to 2.3 million residents of the nearby city of Wuxi in 2007, the official Xinhua news agency reported.

About 10 million fish, including green carp and silver carp, will be released into the lake as part of a 7.4 million-yuan (1.1 million-dollar) effort, Lin Jianhua, head of the Taihu Lake Fishing Administration was quoted as saying.

However, it would take 10 times that amount of fish to clean up the entire 2,400 square-kilometre (900 square mile) lake, he was quoted as saying,

A silver carp could consume 50 kilogrammes (110 pounds) of algae and other plankton while gaining only one kilogramme (2.2 pounds) in weight, Lin said.

The lake in Jiangsu province, long celebrated through Chinese history as one of the country's most scenic bodies of water, has been massively polluted by the dumping of sewage and industrial and agricultural waste.

Although authorities have invested five billion yuan in pipes to prevent sewage from being dumped into the lake, the degradation of the water remains a major problem, Lin was quoted as saying.

Millions of algae-eating fish have been used to clean up Taihu and other lakes before, with previous efforts hailed as a bonanza for the local fishing industry despite the suspicions of eating fish that feasted on toxins.

The 2007 water crisis made Taihu a symbol of China's nationwide problem of deteriorating water quality, with even Premier Wen Jiabao publicly calling for the lake to be cleaned up.

Algae blooms are common on many Chinese freshwater lakes and are chiefly caused by untreated sewage containing high concentrations of nitrogen, a main ingredient in detergents and fertilisers.

Like much of China's environment, water quality has suffered severely amid the nation's breakneck economic growth over the past two decades.