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Environment/Energy
Environment/Energy
UPDATED: November 15, 2014 NO. 47 NOVEMBER 20, 2014
Saving the Sturgeon
New research reveals the imminent extinction of China's once abundant freshwater fish
By Yin Pumin
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RETURNING TO NATURE: A batch of artificially bred sturgeons are released into the Yangtze River on April 8, 2012 (XINHUA)

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 China's 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 isn't replenishing and without protection, they might risk in extinction," Wei said.

An endangered species

The Chinese 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.

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 society's 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 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.

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 River's 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.

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