(Xinhua)
Updated: 2008-03-27 22:11

WUHAN  -- Shards from broken ice in the Yangtze River have led to the death of four rare finless porpoises since Saturday at the Tian'ezhou Nature Reserve in Shishou city.

Scientists said that it appeared the animals sustained cuts from the ice. The wounds became infected and ultimately caused their deaths.

Among the four, two were female and one was pregnant. The 1.57-meter pregnant porpoise was found on Saturday, her body covered with scratches. The other three porpoises were found, also with abrasions and wounds, in the reserve. The four also had signs of severe frostbite, experts of the Institute of Hydrobiology of the Chinese Academy of Sciences said.

An attempt to save the animals' lives may have led to their demise. The river froze over during this past winter's severe weather. Porpoises, as mammals, must remain above water to breathe. When the river froze over, workers at the preserve broke the ice to allow the porpoises to surface.

Staff at the preserve are now searching for other injured porpoises.

Finless porpoises, like white-flag dolphins (baiji), are rare mammals native to the mainstream of the Yangtze River, China's longest, and its numerous lakes. However, the dolphin is considered "functionally extinct" and an international expedition in November and December 2006 failed to find a single specimen.

Only 1,200 to 1,400 porpoises now inhabit the Yangtze mainstream, Poyang Lake and Dongting Lake, according to Wang Ding, deputy head of the Institute of Hydrobiology of Chinese Academy of Sciences.

Tian'ezhou Nature Reserve began to feed finless porpoises in 1992 and now has more than 30 porpoises, with at least two newborns a year.