Es­caped fish put old species at risk

Hy­brid stur­geon re­leased along with the flood­wa­ter

China Daily (USA) - - CHINA - By ZHENG CAIXIONG in Guangzhou and ZHOU LIHUA in­Wuhan Con­tact the writ­ers at zheng­caix­iong@ chi­nadaily.com.cn

Ex­perts are con­duct­ing a field in­ves­ti­ga­tion to as­sess flood dam­age to the ecosys­tem of the mid­dle and lower reaches of the China’s longest river— theYangtze— af­ter nearly 10,000 tons of for­eign and hy­brid stur­geon washed out of a breed­ing fa­cil­ity in heavy wa­ter flows.

Sci­en­tists worry that the hy­brid and for­eign species may now in­ter­breed with en­dan­gered pure­bred Chi­nese wild stur­geon in the river, whose num­bers have de­clined to dan­ger­ously low lev­els. Only 100 are thought to re­main in the Yangtze.

Wei Qi­wei of the Chi­nese Academy of Fishery Sciences, one of the in­ves­ti­ga­tors, said pure­bred Chi­nese stur­geon could face a height­ened threat of ex­tinc­tion as a re­sult of in­ter­breed­ing with the for­eign and hy­brid species over the com­ing months.

“Too many for­eign and hy­brid stur­geon that were once raised along the mid­dle and lower reaches of Yangtze River and its branches have es­caped to the wild af­ter flood­wa­ter dis­charges in July,” said Wei, who also serves as di­rec­tor of fresh­wa­ter bio­di­ver­sity con­ser­va­tion in the Yangtze River Fishery Su­per­vi­sion and Man­age­ment Of­fice of the Min­istry of Agri­cul­ture. “The pure­bred Chi­nese stur­geon is now fac­ing a se­ri­ous threat.”

Pure­bred Chi­nese stur­geon date to 140 mil­lion years ago. But they are now on the ra­zor’s edge of sur­vival. The pop­u­la­tion of adult pure­bred Chi­nese stur­geons was es­ti­mated at about 100 at the end of last year, com­pared with 10,000 in the 1970s, ac­cord­ing to a pro­tec­tion plan for the fish re­leased by the State Forestry Ad­min­is­tra­tion.

To pro­tect the an­cient species,fish­ing­was­bannedasearly as 1983, and a down­stream con­ser­va­tion areawas­built.

A sur­vey con­ducted by the fishery of­fice es­ti­mated that af­ter a reser­voir opened a sluice to re­lease flood­wa­ter on July 19, more than 9,800 tons of for­eign and hy­brid stur­geon in the Changyang and Yidu re­gions of cen­tral China’sHubei prov­ince were killed or es­caped to the wild in Poyang and Dongt­ing lakes, and to the mid­dle and lower reaches of theYangtze, where wild pure­bred Chi­nese stur­geons are liv­ing.

Flood­wa­ters washed away the net-pen fa­cil­i­ties used to raise the non-na­tive species, caus­ing huge eco­nomic losses.

It was the first time in 18 years that the Ge­heyan Power Sta­tion had dis­charged wa­ter over suc­ces­sive days in re­sponse to heavy rain­fall.

The Wuhan-based Changjiang Wa­ter Re­sources Com­mis­sion of the wa­ter min­istry has also launched and in­ves­ti­ga­tion and is re­view­ing the mat­ter, said Deng Yongy­ong, an of­fi­cial in the com­mis­sion’s pub­lic­ity depart­ment.

Zhang Huiyun, a woman in Baiyanao vil­lage who makes her liv­ing by fish­ing, said all her 14 net-pens were washed away, and more than 1,500 kilo­grams of fish were killed or es­caped, re­sult­ing in heavy eco­nomic losses.

Lo­cal fishery de­part­ments said fish­er­men re­ported catch­ing for­eign and hy­brid stur­geon be­tween July 26 and Aug 2.

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