Beijing, May 27 (IANS): A drought in central China, lasting for about 200 days, has lowered the water level in a nature reserve, so much so that the survival of a highly-endangered freshwater dolphin is under threat, experts have warned.

The water level in the Swan Island National Nature Reserve in Shishou in Hubei province has gone down to 27.38 metres, said Wang Ding, a dolphin expert at the Hydrobiology Institute under the Chinese Academy of Sciences.

"The level is the lowest over the past decades. Finless porpoises (dolphins) cannot survive if the level continues to drop," Wang was quoted as saying by the Shanghai Daily.

The river section that had room for some 30 dolphins has been reduced to 10 km from the earlier 21 km, Wang said.

"If the activity area is reduced, they might be stranded on the banks and will die if they cannot swim back," he said.

Finless porpoise - one of the six porpoise species and a protected mammal in China - is known locally as "jiang zhu", or "river pig".

The dolphin population is only 1,000, even less than that of the giant panda, and is decreasing at a rate of 6.4 percent annually, Wang said.

Extreme weather and human activity are the main threats to the species, he said.

"Some farmers pump water from the reserve to relieve the drought these days," he said. The local government was alerted and has since banned the pumping.