The Yangtze River dolphin declared functionally extinct in 2006 was the baiji, also known as the Chinese river dolphin.
Its scientific name was Lipotes vexillifer, and it was found only in China’s Yangtze River system. Historical accounts describe the baiji for roughly 2,000 years, while estimates suggest that thousands remained in the river during the 1950s. By the late twentieth century, its numbers had collapsed.
A major 2006 survey searched about 3,500 kilometers of the Yangtze over 45 days but found no baiji. Scientists therefore described it as functionally extinct: even if a few animals had survived unseen, the population was considered too small to reproduce and recover. This wording does not prove that every individual had died.
Fishing bycatch, heavy ship traffic, pollution, dams, habitat degradation, and declining prey all contributed to the collapse. The baiji is often confused with the Yangtze finless porpoise, which is a different cetacean still associated with the river.