Let's help Chine Sturgeons作文怎样做海参好吃又简单
New rearch reveals the imminent extinction of China’s once abundant freshwater fish
After surviving for more than 140 million years on Earth， the wild Chine sturgeon is now on the brink of extinction， according to a report relead by the Chine Academy of Fishery Sciences (CAFS) in mid September.
The report said that rearchers documented a reproduction rate of zero in the Yangtze River in 2013. “It is the first time that we found no natural reproduction of the endangered sturgeons since we started monitoring their population 32 years ago，” said Wei Qiwei， a principal investigator at the CAFS.
Wei said no eggs were found to have been laid by wild sturgeons in an area downstream of the Gezhou Dam in central China’s Hubei Province between October 31 and December 28， 2013. Wild sturgeons usually swim all the way from the a to the river area to lay eggs around mid and late November after they become mature.
Similarly， no young sturgeons were found swimming along the Yangtze River toward the a in August， the month when they typically do so， according to a month of rearch starting August 10， 2014.机器人英语>刘强东英文名
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“No natural reproduction means that the sturgeon population isn’t replenishing and without protection， they might risk in extinction，” Wei said.
An endangered species
The Chine sturgeon is one of the world’s oldest living species. It is thought to have existed for more than 140 million years， at the same time as the dinosaurs.
Chine sturgeons can grow to enormous proportions， with large specimens topping 5 meters and weighing in at 450 kg， according to the National Geographic Society. “The prehistoric-looking giants have a shark-like form， with large pectoral fins， a rounded snout， and rows of pronounced ridges running the length of their spine and flank，” the society’s website said. In the wild， the massive carnivores can live up to 60 years.
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Today， the primitive species has been clasd as “critically endangered” on the International Union for the Conrvation of Nature’s red list of threatened species， just one level ahead of “extinct in the wild.”
According to the CAFS， just 50 years ago， a healthy sturgeon fishing industry still existed on the Yangtze and nearby rivers. But pollution and the construction of dams took a heavy toll on the sturgeon. By the late 1970s， the sturgeon population had dropped to an estimated 10，000 adults.
之开头的四字成语The 1980s saw another drop as the Gezhou Dam cut off the upper Yangtze and blocked the sturgeons’ migratory route. By 1984， the population of spawning adult sturgeon had fallen to under 2，200. In 2000， there were 363 wild ones.
Today， only about 100 sturgeons remain in the wild， according to Wei with the CAFS. He said vere pollution， over-fishing and other human activities like building dams have threatened the Yangtze River’s aquatic ecosystem， which directly affected sturgeon survival rates.
“Dams have cut off areas where the fish ud to spawn and pollution has harmed their ability to reproduce，” Wei said.心理年龄小测试
In 1981， the Gezhou Dam was completed， which subquently blocked the channel for adult sturgeons migrating to their traditional spawning sites upstream.
“Before the building of the dam， there were 16 spawning sites for the wild Chine sturgeons along the 600-km-long Hejiang and Jinshajiang rivers of the upper Yangtze River. Each year， the sturgeons would embark on a round-trip journey of more than 3，500 km from the East China Sea to the spawning grounds，” Wei said.
“Wild animals must have a complete living environment and the dam has affected their living conditions. Their extinction was forecast when the Gezhou Dam was built，” said Xie Yan， a rearcher with the Institute of Zoology of the Chine Academy of Sciences.
But to their surpri and joy， rearchers discovered that sturgeons have found a ries of new sites for reproduction further downstream of the dam. But the new spawning sites，
which are alongside a rervation area， are fragile and have all suffered under new engineering projects. In 2004， an embankment was t up downstream， which directly destroyed the new spawning grounds.
In light of the vere situation， the Chine authorities have taken efforts to save the precious fish. In 1988， the Chine sturgeon was listed as under the highest level protection. Since the 1980s， fishery authorities started curtailing fishing along the Yangtze River and created conrvation areas below the Gezhou Dam.
Meanwhile， attempts are also being made to restock the fish’s shrinking numbers by breeding millions in captivity and then releasing them into the rivers that they are native to. Recently， many rearch laboratories have even started hatcheries.
