when did the baiji river dolphin become extinct
Baiji 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.[5] 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.[6] The baiji represents the first documented global extinction of a "megafaunal" vertebrate for over 50 years[7] 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).[7] 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.
Killer whale The killer whale or orca (Orcinus orca) is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. Killer whales have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as seals and dolphins. They have been known to attack baleen whale calves, and even adult whales. Killer whales are apex predators, as there is no animal that preys on them. Killer whales are considered a cosmopolitan species, and can be found in each of the world's oceans in a variety of marine environments, from Arctic and Antarctic regions to tropical seasâ€”killer whales are only absent from the Baltic and Black seas, and some areas of the Arctic Ocean.