Photos: Extinction of the Yangtze river dolphin is confirmed
Photos: Extinction of the Yangtze river dolphin is confirmed
mongabay.com
August 8, 2007
After an extensive six-week search scientists have confirmed the probable extinction of the baiji or Yangtze river dolphin. The freshwater dolphin’s extinction had been reported late last year.
“The loss of such a unique and charismatic species is a shocking tragedy. The Yangtze River dolphin was a remarkable mammal that separated from all other species over twenty million years ago. This extinction represents the disappearance of a complete branch of the evolutionary tree of life and emphasizes that we have yet to take full responsibility in our role as guardians of the planet,” said Dr Sam Turvey of the Zoological Society of London.
Turvey, working with Chinese government scientists, surveyed the entire 1,669km stretch of the Yangtze river from the Three Gorges Dam to Shanghai, an area which has been the natural habitat for river dolphins. The team used two boats to search the river four times during the six-week survey, using hydrophones listen for their calls and spotters to look for the dolphins. None were found.
The survey followed an earlier expedition led by the Swiss-based baiji.org.
  The Baiji or Yangtze River Dolphin. Photo by Wang Ding and courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences. |
Baiji populations have steadily declined since China declared the species endangered in 1979. In 1986 official estimates placed the Baiji population around 300 but an extensive survey in 1998 found only 7 individuals. The last confirmed sighting was in 2004 and the last captive baiji, Qi Qi, died in 2002 at the Institute of Hydrobiology in Wuhan. The Chinese government had set up a reserve in a lake in Hubei province to protected any captured baiji, but the attempt came too late to save the species.
Researchers say that a few Baiji may still exist in the murky waters of the Yangtze but that the population is no longer viable and any stragglers will die out within a generation. Technically, the Baiji can’t be classified as extinct until 50 years after the last sighting according to the standards of the International Union for the Conservation of Nature / World Conservation Union (IUCN).
“We have to accept the fact, that the Baiji is functionally extinct. It is a tragedy, a loss not only for China, but for the entire world,” said August Pfluger, a noted Baiji expert and head of baiji.org.
[top] The Three Gorges Dam. NASA image created by Jesse Allen, Earth Observatory, using ASTER data made available by NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. In May the Chinese government completed structural work on the Three Gorges dam which blocks the flow of China’s mightiest river, the Yangtze, which today is but a shadow of its former self. Once known as “the Amazon of the East,” today the Yangtze’s estuary has been declared a dead zone, meaning the water doesn’t have enough oxygen in it to support fish. [bottom] VIP and media are visiting the new holding pens in the Shishou Swan Oxbow. Courtesy of baiji.org |
When the Baiji is officially declared extinct by IUCN, it will be first large aquatic mammal to disappear since the Caribbean monk seal in the 1950s. Chinese rivers still support a population of freshwater cetaceans: the endemic Yangtze Finless Porpoise. However, the Baiji survey found less than 400.
“Their numbers are declining at an alarming rate. If we do not act soon they will become a second Baiji”, said Wang Ding, deputy director of the Institute of Hydrobiology of the Chinese Academy of Science in Wuhan.
The Baiji is survived by other river dolphins, all themselves threatened: the Ganges and Indus River Dolphin from India, the Amazon River Dolphin or Boto from South America, and the La Plata Dolphin or Franciscana, also from South America.
The ultimate demise of the Baiji was caused by pollution, overfishing, boat traffic, and obstructions like dams.
Earlier this year the Chinese government said that pollution, dams and excessive boat traffic have caused an “largely irreversible” decline in the aquatic ecology of the Yangtze. The report, issued by China’s official State Environmental Protection Administration (SEPA), revealed that the more than 600 kilometers of the river are in “critical condition” and nearly 30 percent of its major tributaries, including the Minjiang, Tuojiang, Xiangjiang, and Huangpu rivers, are “seriously polluted.” The report further indicated that the river’s annual harvest of aquatic products dropped by about 77 percent between the 1950s and the 1990s, from 427,000 tons to roughly 100,000 tons.
Photo by Wang Ding and courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences. |
“The impact of human activities on the Yangtze water ecology is largely irreversible,” said Yang Guishan, a researcher of the Nanjing Institute of Geography and Limnology under the Chinese Academy of Sciences and one of the chief editors of the report. “It’s a pressing job to regulate such activities in all the Yangtze drainage areas and promote harmonious development of man and nature.”
“The baiji’s extinction also highlights the need for new conservation initiatives in China’s increasingly threatened Yangtze ecosystem, which is also home to endangered freshwater porpoises, seven-metre long fish, giant salamanders and white Siberian cranes,” concluded Dr. Turvey.
This article is based on earlier mongabay.com articles and uses quotes from a Zoological Society of London news release.
