Two Chinese wild sturgeons, a rare and endangered species, left the Beijing Aquarium on Friday bound for the Yangtze River.

The sturgeons, identified as No 28 and No 32, have been in the care of the aquarium for more than a year. Their last public appearance on Friday drew a huge crowd of visitors.

Accompanied by five divers, No 28 swam to the bottom of the tank scared by the flashing cameras and lights.

A diver comforted the fish by gently patting it on the back. It was then transferred to a tank on a lorry where it was weighed and measured.

A 22-hour drive will take the sturgeons to Jingzhou, central China's Hubei Province for release into the Yangtze on Sunday, World Earth Day.

The river has been home to the species for centuries.

The Chinese wild sturgeon, dubbed "panda under the water", is a protected species.

Every June and July, shoals of matured sturgeon swim into the Yangtze River from the sea. It takes them more than a year to travel to the upper reaches of the river to spawn.

Statistics from the Ministry of Agriculture show that the number of wild sturgeons swimming to the river to reproduce has declined since the 1980s, mainly because of pollution and over-fishing.

The two sturgeons to be released on Sunday were among five injured and captured in Jingzhou between 2005 and 2006.

They were sent to the Beijing Aquarium for care, thanks to cooperation between the aquarium and the Jingzhou-based Yangtze River Fishery Research Institute under the Chinese Academy of Fishery Science.

The sturgeons were looked after in surroundings similar to their natural habitat. Special devices were installed to adjust water temperature and to ensure water quality.

"When they first arrived, they shied away from the divers and feeders and refused food," said Zhang Xiaoyan, assistant director of the Aquatic Department of the Beijing Aquarium.

"We swam with them and patted their backs. And in time, managed to establish a good relationship," Zhang said.

"Despite their size, sturgeons are really tame animals and easy to get along with," she added.

To help the sturgeons re-adapt to their natural environment, the aquarium has been training them to take food themselves, mainly crucian carp.

The sturgeons have gradually recovered their physical strength and No 28 and No 32 were found to be fit enough to be returned to the wild.

Experts hope the release of the two sturgeons will help boost the species.

The Yangtze River Fishery Research Institute will keep track of them. The three remaining sturgeons will also be set free in due time.

Hu Weiyong, the aquarium's general manager, said the facility will set up a recovery center for more captured and injured Chinese wild sturgeons.

(China Daily April 21, 2007)