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September 11, 2007

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First human-caused dolphin extinction reported

Aug. 11, 2007
World Science staff

Sci­en­tists this week re­ported the first hu­man-caused ex­tinc­tion of a dol­phin.

The fresh­wa­ter Yang­tze Riv­er dol­phin, al­so known as baiji, seems to be no more, re­search­ers said. The an­i­mal in­hab­it­ed the mid­dle and low­er Yang­tze Riv­er and neigh­bour­ing Qiantang Riv­er in east­ern Chi­na. 

The baiji dolphin. 
It “has long been rec­og­nized as one of the world’s rar­est and most threat­ened mam­mal spe­cies,” wrote Sam­u­el T. Tur­vey of the Zo­o­log­i­cal So­ci­e­ty of Lon­don and col­leagues in the Aug. 7 on­line is­sue of the re­search jour­nal Bi­ol­o­gy Let­ters.

“The sta­tus of the baiji has not been in­ves­t­i­gated since the late 1990s, when the sur­viv­ing popula­t­ion was es­ti­mat­ed to be as low as 13,” they wrote. Late last year, sci­en­tists con­ducted an in­ten­sive six-week search over the an­i­mal’s whole his­tor­i­cal range and “failed to find any ev­i­dence that the spe­cies sur­vives,” they added.

“We are forced to con­clude that the baiji is now likely to be ex­tinct, probably due to un­sus­tain­a­ble by-catch in lo­cal fish­er­ies. This rep­re­sents the first glob­al ex­tinc­tion of a large ver­te­brate for over 50 years, only the fourth dis­ap­pear­ance of an en­tire mam­mal family since AD 1500, and the first ce­ta­cean spe­cies to be driv­en to ex­tinc­tion by hu­man ac­ti­vity,” they wrote. Cetaceans are a group of aquat­ic mam­mals that in­clude whales, dol­phins, and por­poises.

The dol­phin was sci­en­tif­ic­ally known as Li­po­tes vex­il­lifer. The re­search­ers al­so warned that “im­me­di­ate and ex­treme meas­ures may be nec­es­sary” to save an­oth­er lo­cal spe­cies, the Yang­tze fin­less por­poise Neopho­caena pho­caenoides asi­ae­ori­en­talis.

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Scientists this week reported the first human-caused extinction of a dolphin. The freshwater Yangtze River dolphin, also known as baiji, seems to be no more, researchers said. The animal inhabited the middle and lower Yangtze River and neighbouring Qiantang River in eastern China. It “has long been recognized as one of the world’s rarest and most threatened mammal species,” wrote Samuel T. Turvey of the Zoological Society of London and colleagues in the Aug. 7 online issue of the research journal Biology Letters. “The status of the baiji has not been investigated since the late 1990s, when the surviving population was estimated to be as low as 13 individuals,” they wrote. Late last year, scientists conducted an intensive six-week search over the animal’s whole historical range and “failed to find any evidence that the species survives,” they added. “We are forced to conclude that the baiji is now likely to be extinct, probably due to unsustainable by-catch in local fisheries. This represents the first global extinction of a large vertebrate for over 50 years, only the fourth disappearance of an entire mammal family since AD 1500, and the first cetacean species to be driven to extinction by human activity,” they wrote. Cetaceans are a group of aquatic mammals that include whales, dolphins, and porpoises. The dolphin was scientifically known as Lipotes vexillifer. The researchers also warned that “immediate and extreme measures may be necessary” to save another local species, the Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis.