The baiji population declined drastically in decades as China industrialized and made heavy use of the river for fishing, transportation, and hydroelectricity. It has been credibly claimed, after surveys in the Yangtze River during the 1980s, that baiji could be the first dolphin species in history that humans have driven to extinction. A Conservation Action Plan for Cetaceans of the Yangtze River was approved by the Chinese Government in 2001. Efforts were made to conserve the species, but a late 2006 expedition failed to find any baiji in the river. Organizers declared the baiji functionally extinct. The baiji represents the first documented global extinction of a "megafaunal" vertebrate for over 50 years since the demise of the Japanese sea lion and the Caribbean monk seal in the 1950s. It also signified the disappearance of an entire mammal family of river dolphins (Lipotidae). The baiji's extinction would be the first recorded extinction of a well-studied cetacean species (it is unclear if some previously extinct varieties were species or subspecies) to be directly attributable to human influence.
The Yangtze river dolphin is pale blue to gray on the dorsal (back) side, white on the ventral (belly) side. It has a long and slightly-upturned beak with 31-36 conical teeth on either jaw. Its dorsal fin is low and triangular in shape, and resembles a light-colored flag when the dolphin swims just below the surface of the murky Yangtze River, hence the name "white-flag" dolphin. It has smaller eyes compared to oceanic dolphins. A mature Yangtze river dolphin is about 8 feet (2.5 m) long and weighs about 500 pounds (220 kg).
Swiss economist and CEO of the baiji.org Foundation, August Pfluger funded the expedition, in which an international team, taken in part from the National Oceanic and Atmospheric Administration and the Fisheries Research Agency in Japan, searched for six weeks for signs of the dolphin. The search took place almost a decade after the last exploration in 1997, which turned up only 13 of the cetaceans.