The Yangtze River dolphin has been declared officially extinct following an intensive survey of its natural habitat.
The freshwater marine mammal is the first large vertebrate forced to extinction by human activity in 50 years, and only the fourth time an entire evolutionary line of mammals has vanished from the face of the Earth since the year 1500.
The extinction was described by conservationists as a ”shocking tragedy”, caused not by active persecution but carelessly through a combination of factors.
In the 1950s, the Yangtze River and neighbouring watercourses had thousands of freshwater dolphins, but their numbers have declined dramatically since China industrialised and transformed the Yangtze into a crowded artery of mass shipping, fishing and power generation. A survey in 1999 estimated the population of river dolphins was close to 13 animals.
Historically, the species had been revered and achieved nearly demi-god status among fishermen. But in Mao’s Great Leap Forward, the overthrowing of idols saw their protection lifted and they were hunted for food and their skin.
Sam Turvey, a conservation biologist at London Zoo, worked with Chinese scientists to survey the entire 1 669km stretch of the Yangtze River downstream of the Three Gorges Dam to Shanghai. The team scoured the river four times, using high-powered binoculars to spot the dolphins. Sensitive hydrophones were towed behind to listen for their calls. The researchers hoped that if any dolphins were spotted, they could be taken to a reserve in the hope of boosting their numbers. But at the end of the survey, they had neither seen nor heard any sign of the dolphins, according to their report in Biology Letters. — Â