The Baiji, a rare white dolphin regarded in China as the "goddess of the Yangtze," has been declared extinct by a team of international scientists. This represents the first extinction of a large aquatic mammal since hunting and overfishing killed off the Caribbean monk seal in the 1950s. The recent fate of the Baiji reflects a global trend--large river fish and mammals are declining worldwide, and particularly in the rapidly industrializing countries of Asia. Concrete actions to protect these threatened species will be necessary to prevent future extinctions.
Searching for the Baiji
December 13th marked the end of a six-week search expedition to determine the status of the endangered Baiji dolphin. Using high performance optical instruments and underwater microphones, a team of 30 scientists covered over 3,500 kilometers of the Yangtze, from the Three Gorges Dam to the Yangtze Delta. Although a 1997 survey yielded 13 confirmed sightings, this most recent expedition did not locate any Baiji. Scientists expressed the possibility that one or two animals could have been overlooked, but insisted that such animals would have no chance of survival.
Distribution of Freshwater Dolphins and Porpoises
Source: Baiji.org Foundation
Habitat Destruction to Blame
The decline of the Baiji--a species nearly 20 million years old--began in recent decades. The population quickly plummeted from over 400 in the late 1980's to less than 100 in the mid 1990's, reflecting China's rapid economic and population growth. Baiji's final demise is attributed to illegal fishing, collisions with ships, and general habitat destruction. Although the Yangtze River is moderately polluted, toxins were not found in concentrations lethal to the dolphin. The river is, however, one of the busiest commercial waterways in the world, and large ship traffic disrupts the dolphin's sonar. Since the Baiji is essentially blind, this sonar is vital to its ability to navigate and locate food.
River Channel Fragmentation and Flow Regulation
This map shows the extent of human impact on freshwater ecosystems.
Other Freshwater Species at Risk
Dolphins are a flagship species for freshwater ecosystems and the over 45,000 species that they support. Freshwater biodiversity is rapidly declining worldwide due to habitat loss, introduction of alien species, pollution, and over-harvesting. There are now only five species of freshwater dolphins left in the world, all of which are critically endangered and on the World Conservation Union's Red List of Threatened Species. Four of these species reside in major freshwater systems in Asia, including the finless porpoise of the Yangtze River. With fewer than 400 individuals remaining, the situation of the finless porpoise is beginning to resemble that of the Baiji.
RELATED LINKS:
World Conservation Union Species Survival Commission
World Wildlife Fund's Global Freshwater Programme
EarthTrends
Feature: Freshwater Biodiversity in Crisis
