December 13 — Baiji Porpoise Declared Extinct (2006)

The Baiji porpoise (Lipotes vexillifer) was a small freshwater aquatic mammal that lived exclusively in the Yangtze River, China.  On December 13, 2006, a group of scientists who had been conducting an intensive study to locate Baiji declared that the animal was extinct.

The definitive extinction of a species, of course, can never be totally confirmed, especially an aquatic species.  Because we cannot definitively survey every part of a large water body at one instant, the possibly always exists that a survey could miss some specimens of a species.  This particular survey, however, was performed according to exacting statistical methods using modern hydro-acoustic technology.

The Baiji has been known throughout recorded history in the Yangtze River.  It was a relatively small porpoise, about the size of an adult human.  It had a stocky body, with a long narrow beak.  Baiji generally lived in small groups of fewer than five individuals.  It was a predator, feeding on fish of many species and at all locations in the river.  Individuals generally lived in areas of slower current, such as eddies and the confluence of tributaries with the main stem of the Yangtze River.  It was the only species in its genus, the name of which translates as “left behind” in Greek, denoting the restricted range of the species.

It was called the goddess of the river in earlier generations, protecting the safety of fishermen and aiding their catches.  Unfortunately, accidental catches of Baiji during fishing for other species greatly reduced its populations.  This, along with the continued development of the Yangtze River for hydropower and river transportation, continued to drive Baiji populations lower and lower in recent decades.  The last confirmed sighting of a Baiji was in 2002.  The IUCN Red List categorizes the Baiji porpoise as critically endangered, but notes that extinct has already probably occurred.

The extinction of the Baiji represents the first extinction of a cetacean (whales, dolphins, and porpoises) at the hands of humans.  It is also the first extinction of a large mammal in the last fifty years.  But it is not likely to remain the last.  Another freshwater porpoise in the Yangtaze River, the Yantze River finless porpoise, has now been declared critically endangered as its numbers have fallen below 100.  And another small dolphin—the vaquita or Gulf of California porpoise—that lives only in the upper reaches of the Gulf of California is considered the next most endangered marine mammal.

References:

Arklive.  Baiji (Lipotes vexillifer).  Available at:  http://www.arkive.org/baiji/lipotes-vexillifer/.  Accessed December 13, 2017.

IUCN.  2017.  Lipotes vexillifer.  Available at:  http://www.iucnredlist.org/details/full/12119/0.  Accessed December 13, 2017.

Lovgren, Stefan.  2006.  China’s rate river dolphin now extinct, experts announce.  Natinal Geographic News, December 14, 2006.  Available at:  http://news.nationalgeographic.com/news/2006/12/061214-dolphin-extinct.html.  Accessed December 12, 2016.

Turvey, Samuel T., et al.  2007.  First human –caused extinction of a cetacean species?  Biology Letters October 22, 2007.  Available at:  http://rsbl.royalsocietypublishing.org/content/3/5/537.short.  Accessed December 12, 2016