The wild Chinese sturgeon (acipenser sinensis) is among the oldest living species in the world, believed to have existed for over 140 million years. But just like China's Giant Panda, the fish, which weighs between 200 kg to 500 kg or 441 pounds to 1,100 pounds on average, has become critically endangered.

The advent of China's economic boom, which brought about the development of dams as well as increased pollution and boat traffic in the Yangtze River, where Chinese sturgeons are largely dispersed and spawn, has drastically reduced the number of the fish. It is listed under "China's Class One Protected Animals."

From around thousands in the 1980s, the numbers of Chinese sturgeons have been reduced to about 100. Scientists attribute this to overfishing, habitat loss and reduced water quality because of dam construction. Dams and pollution, in particular, are to blame for another factor that could seriously threaten the rare species to extinction.

In a new research, scientists have found that the Chinese sturgeon did not naturally reproduce last year. Wei Qiwei, from the Chinese Academy of Fishery Sciences, said that researchers did not find sturgeon eggs in the river water area downstream of Hubei Province's Gezhou Dam between Oct. 31 and Dec. 28 last year. Wild sturgeons swim from sea water to the river to lay their eggs between these periods when they become mature.

The researchers also found during a month-long research push that started in early August last year that there were no young sturgeons that swam along the Yangtze River to the sea. August is normally the time when the young fish swim downstream to the sea waters.

"It is the first time that we found no natural reproduction of the endangered sturgeons since records began 32 years ago when a dam was built," Wei said. "No natural reproduction means that the sturgeons would not expand its population and, without protection, they might run the risk of extinction."

The building of dams is seen as among the primary reasons behind the inability of the fish to reproduce as dams cut off the areas that the endangered fish used for spawning. Pollution has also left a negative impact on the sturgeons' ability to reproduce.

Chinese authorities have built numerous dams including the Three Gorges, the largest dam in the world, along the Yangtze River in recent years to increase the electrical supply of the country. A 2012 World Wildlife Fund study has found that animal populations in many of the country's ecosystem have dropped during decades of urbanization and development.

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