By+Yin+Pumin

After surviving for more than 140 million years on Earth， the wild Chinese sturgeon is now on the brink of extinction， according to a report released by the Chinese Academy of Fishery Sciences （CAFS） in mid September.

The report said that researchers 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 Chinas Hubei Province between October 31 and December 28， 2013. Wild sturgeons usually swim all the way from the sea 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 sea in August， the month when they typically do so， according to a month of research starting August 10， 2014.

“No natural reproduction means that the sturgeon population isnt replenishing and without protection， they might risk in extinction，”Wei said.

An endangered species

The Chinese sturgeon is one of the worlds oldest living species. It is thought to have existed for more than 140 million years， at the same time as the dinosaurs.

Chinese sturgeons can grow to enormous proportions， with large specimens topping 5 meters and weighing in at 450 kg， according to the National Geographic Society. “These 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 societys website said. In the wild， these massive carnivores can live up to 60 years.

Today， the primitive species has been classed as “critically endangered” on the International Union for the Conservation of Natures 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.

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 severe pollution， over-fishing and other human activities like building dams have threatened the yangtze Rivers aquatic ecosystem， which directly affected sturgeon survival rates.

“Dams have cut off areas where these fish used to spawn and pollution has harmed their ability to reproduce，” Wei said.

In 1981， the Gezhou Dam was completed， which subsequently 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 Chinese 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 researcher with the Institute of Zoology of the Chinese Academy of Sciences.

But to their surprise and joy， researchers discovered that sturgeons have found a series of new sites for reproduction further down- stream of the dam. But the new spawning sites， which are alongside a reservation area， are fragile and have all suffered under new engineering projects. In 2004， an embankment was set up downstream， which directly destroyed the new spawning grounds.

In light of the severe situation， the Chinese authorities have taken efforts to save the precious fish. In 1988， the Chinese sturgeon was listed as under the highest level protection. Since the 1980s， fishery authorities started curtailing fishing along the yangtze River and created conservation areas below the Gezhou Dam.

Meanwhile， attempts are also being made to restock the fishs shrinking numbers by breeding millions in captivity and then releasing them into the rivers that they are native to. Recently， many research laboratories have even started hatcheries.

In May 2014， Shanghai started building a research center in Chongming Island to study and help support the recovery of the endangered Chinese sturgeon.

The 55，900-square-meter center will include a workshop for rescuing and temporarily rearing Chinese sturgeons， a laboratory and other support facilities， according to the Shanghai Agricultural Commission. Staff will rescue， raise and breed sturgeons and other endangered species， as well as conducting studies and spreading knowledge among the public， authorities said.

An inefficient method

In April， 70 Chinese sturgeons， whose lengths were between 1.5 and 2 meters， were released into the yangtze River by research staff to increase the number of the endangered species.

Each year in April， some artificially bred sturgeons were released into the river. In 2012 and 2013， 1，200 and 8，000 sturgeons were reintroduced into the yangtze River respectively.

Over the past three decades， more than 5 million artificially bred Chinese sturgeons have been reintroduced into the wild， according to the yichang-based Chinese Sturgeon Research Institute.

Since the 1980s， scientists have started attempting artificial breeding of Chinese sturgeons and reintroduction into the wild. Chinese scientists have also cooperated closely with foreign counterparts in protecting the endangered species. The yichang-based Chinese Sturgeon Research Institute and the Wuhan-based yangtze River Fisheries Research Institute under the CAFS are leading in this area.

In 1983， the two institutes achieved breakthroughs in artificial breeding technology—collecting eggs by dissecting the live female Chinese sturgeons. “However， this way is very cruel. Most of the sturgeons did not survive，” said Gao yong， Director of the Chinese Sturgeon Research Institute.

With the technology available at the time， artificially bred baby sturgeons could only grow to 2-3 cm in the laboratory. “The fish could not survive in the laboratory， let alone in the wild，”Gao said.

In 1995， breeding technology saw another breakthrough. This time， fertilized eggs of the Chinese sturgeons could be hatched and bred into 10-cm-long baby fishes.

In 2009， 28，000 fertilized eggs were successfully collected in an experiment in artificial propagation of the sturgeon， and in 2012， some of 50，000 fertilized eggs gleaned from Chinese sturgeon hatched， declaring that the institutes have achieved the capability to breed the second-generation sturgeons.

According to yang yuanjin， Deputy Director of the Chinese Sturgeon Research Institute， the second-generation fish refer to those bred based on the first-generation ones， while the first generation are those artificially bred from the fertilized eggs of wild ones.

Despite the progress， scientists still reserve doubts to the real effects of the artificial breeding of the Chinese sturgeons. According to Wei with the CAFS， there is no obvious proof to testify the method. “The only thing I know is that a monitoring of the yangtze estuary shows that the population of artificially reproduced fish accounts for only 5 percent of the total sturgeon population，” Wei said.