YICHANG, Hubei, July 9 -- The body of a critically endangered Chinese sturgeon has been found in a ship lock that forms part of the Three Gorges Dam in central China's Hubei Province, the dam's management bureau revealed on Thursday.

Fishing authorities are investigating the cause of the death.

Chinese sturgeons, nicknamed "aquatic pandas", are listed as a wild animal under state protection. They have existed for about 140 million years, but fewer than 300 are believed to live in the Yangtze River, which is spanned by the mighty Three Gorges Dam.

According to the bureau, the large fish was spotted at 8:45 a.m. on Wednesday in the Gezhou Dam's ship lock by a patrolling member of its staff. It was about one meter long with a green-grey back. The staff member reported the discovery to the bureau immediately.

Rapid economic development, over-exploitation of the river, pollution and illegal hunting have driven Chinese sturgeons to the verge of extinction. Many are killed by ship propellers or mortally injured after becoming tangled in fishermen's nets.