The population of an endangered subspecies of the finless porpoise has halved over the past 15 years, according to scientists who have spent the last 38 days studying the Yangtze River.
They estimate the population of the state-protected Yangtze cowfish is between 1,200 and 1,400. This is half the figure of 1991.
Scientists picked up sonar signals from 700 to 900 cowfish in a 1,750-kilometer Yangtze section from Yichang to Shanghai.
They estimate another 500 are in the adjoining Poyang and Dongting lakes, which are China's largest freshwater lakes.
"The decline of the freshwater mammal has been caused by water pollution, over-fishing and sand dredgers," said Wang Ding, vice director of the hydrobiology institute of the Chinese Academy of Sciences and head of the research team.
Scientists have urged the government to establish more natural reserves, improve water quality and strengthen breeding and research.
"If we don't double our efforts the Yangtze finless porpoise will face the same fate as the white-flag dolphin," said Wei Zhuo, another expert with the institute.
Scientists from six countries, including China and the US, began their search for white-flag dolphins on the Yangtze River on November 6 but failed to find a single one along the 3,400-km mainstream of the river. It's feared the species, also known as "baiji," could be extinct.
(Xinhua News Agency December 14, 2006)