the baiji river dolphin became extinct 25 million years ago.
when did the baiji river dolphin become extinct?
25 million years ago
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.
baiji
as china developed economically, pressure on the baiji river dolphin grew significantly. industrial and residential waste flowed into the yangtze. the riverbed was dredged and reinforced with concrete in many locations. ship traffic multiplied, boats grew in size, and fishermen employed wider and more lethal nets. noise pollution caused the nearly blind animal to collide with propellers. stocks of the dolphin's prey declined drastically in the late 20th century, with some fish populations declining to one thousandth of their pre-industrial levels. in the 1950s, the population was estimated at 6,000 animals, but declined rapidly over the subsequent five decades. only a few hundred were left by 1970. then the number dropped down to 400 by the 1980s and then to 13 in 1997 when a full-fledged search was conducted. on december 13, 2006, the baiji ("lipotes vexillifer") was declared "functionally extinct", after a 45-day search by leading experts in the field failed to find a single specimen. the last verified sighting was in september 2004.
river dolphin