日批在线视频_内射毛片内射国产夫妻_亚洲三级小视频_在线观看亚洲大片短视频_女性向h片资源在线观看_亚洲最大网

Society

Rare Chinese sturgeon under threat at Three Gorges

By Jin Zhu (China Daily)
Updated: 2010-06-02 07:41
Large Medium Small

Rare Chinese sturgeon under threat at Three Gorges
Workers from Xiamen Oceans & Fisheries Bureau of Fujian province release a Chinese sturgeon into the sea on April 22. A total of 108 sturgeon were released into the sea that day near Xiamen. [Zhang Guojun / Xinhua News Agency] 

BEIJING - Storing water at the Three Gorges reservoir has put off the reproductive period of wild Chinese sturgeon for about a month and may further reduce the number of the already rare species, a leading expert has said.

Wild Chinese sturgeon, an animal thought to have lived at the same time as dinosaurs and among the first class of protected animals in China, are now breeding during the last ten days of November.

That is about one month later than its usual reproductive period in late October, said Xiao Hui, chief engineer with the Chinese sturgeon research institute under the China Three Gorges Corporation.

Xiao observes wild Chinese sturgeon that migrate to the Yangtze River to lay eggs every year.

"Their reproductive time has gradually been delayed since the Three Gorges reservoir began to store water in May 2003," she told China Daily on Tuesday.

According to the institute's study, the reproductive period was delayed for a week after the water level in the reservoir reached 135 meters. When the water level rose to 156 meters, it became 15 days later than usual.

Last year, the reproductive period for the rare species was delayed about a month after the water level rose to 75 meters in September.

The current spawning site of wild Chinese sturgeon remains in the lower reaches of the Yangtze River. The site is 7 km away from another large hydroelectric plant, where the Gezhou Dam stopped the sturgeon from swimming to the upper reaches of the river since it was completed in 1981.

"After the Three Gorges reservoir began to store water, the water level of the lower reaches of the river has remained low. It also needs more time to reach a proper water temperature (usually between 17 and 21 C) for the sturgeon to lay eggs," Xiao said.

Every September to November, Chinese sturgeon swim against the sea to lay eggs in the Yangtze River. "Since the young fish have insufficient time to grow into adult fish, their survival rate could be cut when they swim back into the sea," she said.

At present, about 300 wild Chinese sturgeon migrate to the Yangtze River every year to lay eggs, experts said.

Although there is no evidence so far to show whether the delay in their reproductive period will lead to a decrease in the number of wild Chinese sturgeon, authorities have already started taking measures to protect them.

"The Ministry of Agriculture once allowed us to catch 10 wild Chinese sturgeon every year for study, but it has been banned since last year," Xiao said.

主站蜘蛛池模板: 国产精品77 | 香蕉视频免费在线播放 | 国产免费一区二区三区四在线播放 | 成人高清网站 | 国产一区在线视频观看 | 久久久精品蜜桃 | 国产1级片 | 日韩黄色免费视频 | 国产亚洲精品久久久久久 | 亚洲色图欧美在线 | 黄色三级三级三级三级 | 免费观看日批视频 | 什么网站可以看毛片 | 日本久久久久久久久久 | 国产一区二区在 | 五月婷六月丁香 | 久久久久久久久久久影院 | 青青操免费在线视频 | 国产不卡在线播放 | 色在线视频 | 91无套直看片红桃在线观看 | 黄色免费看| 日韩精品一区三区 | 久久中文娱乐网 | 美女av在线免费观看 | 美女狠狠干 | 国产黄色在线免费观看 | 日韩在线高清视频 | 成人欧美一区二区三区在线观看 | 成人观看| 国产精品亚洲天堂 | 中文一区二区在线观看 | 国产精品久久久久久久久久久免费看 | 亚洲一区福利视频 | 精品久久久久一区二区国产 | 日韩在线免费观看视频 | 黄色成人影视 | 中文字幕亚洲欧美日韩 | 国产精品69久久久久孕妇欧美 | 丁香六月激情综合 | 男人av网 |