The nearly blind Baiji dolphin, which inhabited the Yangtze River in China, has been declared extinct after a fruitless six-week search for the species came to an end. Fossil records indicate that the dolphin species migrated from the Pacific Ocean to the Yangtze River around 20 million years ago. The Baiji is the first large aquatic mammal driven to extinction since the Caribbean monk seal disappeared in the 1950s from hunting and overfishing. Only three other species of freshwater dolphins now remain in the world.

Sonar from busy ship traffic, snagline and electrofishing techniques, pollution, and run-ins with boat propellers are the main reasons for the Baiji’s extinction. Fishing gear alone is responsible for over half of the dolphin deaths. The impact of the massive Three Gorges Dam may have also been a factor. The world’s only Baiji held in captivity, a lone male named Qi Qi, died in 2002.

The loss of the river dolphin is the canary in the mine shaft for aquatic species. Its extinction is an indication that the ecosystem of the Yangtze is being grossly mismanaged. Randall Reeves, chairman of the World Conservation Union’s Cetacean Specialist Group, said the expedition was surprised at how fast the dolphins disappeared as conservationists were still thinking of ways to save them. “Some of us didn’t want to believe that this would really happen, especially so quickly,” he said. “This particular species is the only living representative of a whole family of mammals. This is the end of a whole branch of evolution.”

Pfluger [a Swiss naturalist who helped put together the expedition] said China’s Agriculture Ministry, which approved the expedition, had hoped the Baiji would be another panda, an animal brought back from the brink of extinction in a highly marketable effort that bolstered the country’s image.The expedition was the most professional and meticulous ever launched for the mammal, Pfluger said. The team of 30 scientists and crew from China, the United States and four other countries searched a 1,000-mile heavily trafficked stretch of the Yangtze, where the Baiji once thrived.

The expedition’s two boats, equipped with high-tech binoculars and underwater microphones, trailed each other an hour apart without radio contact so that a sighting by one vessel would not prejudice the other. When there was fog, he said, the boats waited for the mist to clear to make sure they took every opportunity to spot the mammal.

Around 400 Baiji were believed to be living in the Yangtze in the early 1980s, when China was just launching the free-market reforms that have transformed its economy. The last full-fledged search, in 1997, yielded 13 confirmed sightings, and a fisherman claimed to have seen a Baiji in 2004.

While conducting their search for the Baiji, the expedition also surveyed the Yangtze Finless Porpoise population, which has fallen below 400. “The situation of the finless porpoise is just like that of the Baiji 20 years ago,” said Wang Ding, a Chinese hydrobiologist and co-leader of the expedition. “Their numbers are declining at an alarming rate. If we do not act soon they will become a second Baiji.”

source