Feds List Yangtze River Fish as Endangered

(CN) --- The U.S. Fish and Wildlife approved the listing of the Yangtze sturgeon under the Endangered Species Act on Friday in an effort to stave off the accelerated decline of the ancient fish species also known as Dabry’s sturgeon. 

“Loss of individuals due to overharvesting on the Yangtze River is the main factor that contributed to the historical decline of the species,” Fish and Wildlife said in a document published to the Federal Register. “Despite conservation efforts, this species is still currently in decline, due primarily to the effects of dams and bycatch.”

Dams in particular represent the more modern threat to the species. The Yangtze River is the longest in Asia, flowing 3,900 miles from the Tibetan Plateau in the west to the East China Sea near Shanghai in the east. 

Formerly a free-flowing river, in 1981 the Chinese completed the Gezhouba Dam which cut off upstream migration of adult sturgeon from their spawning grounds. 

“As a result of the construction of Gezhouba Dam, the species may have been extirpated in reaches below the dam,” the service said. 

Farther downstream of the Gezhouba Dam, the Chinese government built the Three Gorges Dam, which was controversial with international environmental groups at the time. Begun in 2003 and finished in 2009, the dam has further restricted migration of adult sturgeon between their present habitat and their ancient spawning area. 

The dam also rendered much of the rapidly flowing water upon which sturgeon depend into still water, which makes it more difficult for them to survive. 

While the Three Gorges and Gezhouba Dams are two of the main impediments to a population rebound, the government continues to build dams in the Yangtze River Basin thanks to its topography, with the river starting high in the mountains and rushing toward sea level making it a prime location to generate hydroelectric power.

“The growth of dam construction in China has accelerated during the past decades,” the service said. “From the 1970s to the 1990s, an average of 4.4 large reservoirs (capacity greater than 0.1 kilometers cubed) were constructed per year. By the 2000s, this number had increased to an average construction rate of 11.8 large reservoirs per year.”

The Chinese government has been responsive to declining fish populations, enacting a 10-year fishing ban for sturgeon on the Yangtze River and attempting to introduce sturgeon born in captivity into its ancient habitat. 

The results so far have been poor, with the introduced sturgeon lacking the ability to develop gonads and reproduce naturally in the river. 

“Restocked sturgeons suffer from low fitness; most notably, they lack the ability to survive to reproductive age,” the service said. “Capture data obtained from the releases in 2010-2013 found that 95 days after restocking, no restocked sturgeons were caught either by researchers or by fishermen in the upper Yangtze River.”

The lack of catch indicates a poor survival rate for sturgeon born in captivity. 

However, Chinese scientists are bullish on recovery, most notably because the water quality of the river has improved as the nation has taken environmental pollution more seriously in recent years. 

"We conducted the release before the spawning season with a clear goal: to speed up the restoration of the Yangtze River sturgeon population," Wei Qiwei, chief scientist at the Chinese Academy of Fishery Sciences, told China Daily. 

The scientist spoke as the academy released 80 captive-bred sturgeon into the upper reaches of the Yangtze in January.

The Yangtze sturgeon is a relatively large fish, with adults up to four feet in length and weighing as much as 35 pounds. The fish has a triangular head, a long snout and tactile barbels at the front of its mouth to help it dig in the river sediment in quest for food. On the dorsal (top) side can be dark gray to yellow-gray. The underside of the fish is an opalescent white. 

The Endangered Species Act often lists species that live outside the United States. While the federal government has no authority to manage or regulate wildlife in other countries it can outlaw the importation of such species, as is the case with the Yangtze sturgeon. 

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