Chinese river dolphin first mammal to become extinct in 50 years

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White river dolphin - National GeographicChina’s white river dolphin, known as the baiji (Lipotes vexillifer) appears to now be extinct, according to a team of biologists that spent six weeks searching for it in its usual habitat of the Yangtze River. This makes it the first mammal globally to become extinct in the past 50 years, despite private attempts to preserve the animal. China’s rapid industrialization and pollution of the Yangtze River have largely been to blame, with no serious attempts by government to act to save the 25 million year old species.

The dolphin had been found only in the middle and lower reaches of the Yangtze River between two large tributary lakes Dongting and Poyang. Previously, its range extended from the mouth of the Yangtze upstream to 50 kilometers above the Gezhouba Dam. The baiji’s demise is attributed to overfishing, dam-building, environmental degradation, and ship collisions.

The large-ship traffic on the Yangtze, one of the world’s busiest waterways, confuses the sonar that the nearly blind dolphin uses to find food. Heavy pollution in the Yangtze also has been a contributing factor.

Using high-tech optical instruments and underwater microphones on two research vessels, the international team of 30 scientists and crew scoured almost 2,175 miles (3,500 kilometers) of the river, from Yichang near the Three Gorges Dam to Shanghai, for any signs of the dolphin.

When we started, we were really optimistic about finding them, but as each day went by it became increasingly clear that there are no baiji left” lead biologist August Pfluger told National Geographic.

“Globally, a pattern has emerged; these large aquatic animals are disappearing” said Zeb Hogan, a Phnom Penh, Cambodia-based researcher with the University of Nevada at Reno. “Unless concrete steps are taken soon to better protect these vulnerable species, this is the beginning of a wave of extinctions that is likely to occur over the next 20 to 30 years.”

The dolphin’s population had plummeted from about 400 in the late 1980s to less than 100 in the mid-1990s. The last search for the animal, in 1997, yielded just 13 sightings.