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Scientists caught three wild Chinese sturgeon fish from the Yangtze River yesterday, to conduct research on the reproductive habits of this precious species of aquatic life.

Research staff measure the length of a wild Chinese sturgeon for research. They caught the fish downstream of the Gezhouba Dam on the Yangtze River in Yichang, Central China's Hubei Province. [newsphoto.com.cn]

The research aims to discover how the Three Gorges Dam will influence the reproduction of the fish, and find solutions to any problems.

Having existed on earth for nearly 140 million years, Chinese sturgeon are one of the most ancient species of fish in the Yangtze River.

Chinese sturgeon have a special habit of swimming about 3,500 kilometres to the ocean, where they mature, from the Yangtze River where they are born during the seasons of propagation.

In the upper reaches of the Yangtze River, Chinese sturgeons will lay eggs each summer and autumn.

After the Gezhouba Dam was built in the middle reaches of the Yangtze River in 1988, the species usually lay eggs in the waters near Yichang, Hubei Province.

Since the Three Gorges Project dammed the river in 1997, the environment for the reproduction of Chinese sturgeon has changed.

Wei Qiwei, a researcher with Chinese Academy of Fishery Sciences, said that the technique of artificially breeding Chinese sturgeon has not been mastered so far.

The reproduction of the species still counts on Chinese sturgeon mating in the wild, he said.

At present, when flocks of wild Chinese sturgeon swim to the river to lay eggs, the academy's branch researching fish in the Yangtze River has decided to assign 31 ships to join in the task.

The project plans to catch 28 Chinese sturgeon, half of which will be propagated artificially. The rest will be released into the river with electronic trackers attached.

Experts said the electronic trackers will help them know more about the natural breeding habits of the fish.

Yesterday, researchers had taken out 10 eggs each from two female Chinese sturgeon fish, out of three caught for research. The three wild fish weighed between 280 to 340 kilograms.

Chinese sturgeon are among the oldest species of vertebrates in the world.

An adult Chinese sturgeon can be 5 metres long and weigh 1,000 kilograms. The species can also live to be 100 years old. It is listed among the first class of protected animals in China.

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