Woking Sea Cadets, Surrey: CHINESE RIVER DOLPHIN EXTINCT

The Sea Cadets

Woking & District

Rare river dolphin 'now extinct'

Adapted from a BBC online article and other sources: Tuesday 8 August 2007 and other sources.

A freshwater dolphin found only in China is now "likely to be extinct", a team of 30 scientists has concluded. The researchers failed to spot any Yangtze River dolphins, also known as baijis, during an extensive six-week survey of the mammals' habitat.

The team, writing in Biology Letters journal, blamed unregulated fishing as the main reason behind their demise. The scientists added that there were a number of human activities that caused baiji numbers to decline, including construction of dams and boat collisions. Another reason that has been put forward is shipping traffic, whose engines interfere with the sonar the baiji uses to navigate and feed.

The white dolphin, shy and nearly blind, dates back some 20 million years. Its disappearance is believed to be the first time in half a century that a large aquatic mammal has been driven to extinction.

A few baiji may still exist in their native Yangtze habitat in eastern China, but not in sufficient numbers to breed and ward off extinction, said August Pfluger, the co-leader of the expedition. Pfluger's team scoured a 1,000-mile heavily-trafficked stretch of the Yangtze, where the baiji once thrived. Around 400 baiji were believed to be living in the Yangtze in the 1980s.

photo of Baiji

The species (Lipotes vexillifer) was the only remaining member of the Lipotidae, an ancient mammal family that is understood to have separated from other marine mammals, including whales, dolphins and porpoises, about 40-20 million years ago.

Drawing of Baiji

The baiji dolphin had a long, narrow beak and low dorsal fin. It lived in groups of three or four and fed on fish.

Survey boats

The survey team carried out six-week visual and acoustic survey, using two research vessels, in November and December 2006.

Yangze map

Sketch of the natural range of the Baiji int the Yangtze River in China.

The Three Gorges

This shot of the Yangtze river shows part of the well-known and scenic Three Gorges region. The gorges themselves occupy about 120 km. Photo by Ian Sewell.

Qi Qi, the last captive baiji

The photo above, made available in 2006, shows Qi Qi, a rare Baiji dolphin, who was rescued from the Yangtze River in 1980 after being beached and injured. Qi Qi lived for 22 years before dying of old age in 2002. (AFP/Getty Images)

There are a few other river dolphin species around the world. They share many similar physical features that the have evolved in response to their river environment. They have very long and narrow beaks with lots of teeth, somewhat similar to alligators and crocodiles.

They also have atrophied eyes. Instead of using sight to catch prey, the nearly blind baiji relied on their advanced echo-location system. Similar to sonar, this system allowed the baiji to use sounds to locate fish, other baiji and obstacles - even in murky water.

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