Detailed Description:
Baiji
From Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Baiji
Conservation status: Critically Endangered
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Eutheria
Order: Cetace
Suborder: Odontoceti
Superfamily: Platanistoidea
Family: Lipotidae
Genus: Lipotes
Species: L. vexillifer
Binomial name: Lipotes vexillifer
The Baiji (Chinese: 白鱀豚; pinyin: báijìtún) (Lipotes vexillifer, Lipotes meaning "left behind", vexillifer "flag bearer") is a freshwater dolphin found only in the Yangtze River in China. Nicknamed "Goddess of the Yangtze" (simplified Chinese: 长江女神; traditional Chinese: 長江女神; pinyin: Cháng Jiāng nǚshén) in China, the dolphin is also called Chinese River Dolphin, Yangtze River Dolphin, Whitefin Dolphin and Yangtze Dolphin. It is not to be confused with the Chinese White Dolphin.
The Baiji population declined drastically in recent decades as China industrialized and made heavy use of the river for fishing, transportation, and hydroelectricity. 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",[3] which would make it the first aquatic mammal species to become extinct since the demise of the Japanese Sea Lion and the Caribbean Monk Seal in the 1950s. It would also 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.
In August 2007, Zeng Yujiang reportedly videotaped a large white animal swimming in the Yangtze. Although Wang Kexiong of the Institute of Hydrobiology of the Chinese Academy of Sciences has tentatively confirmed that the animal on the video is probably a baiji, the presence of only one or a few animals, particularly of advanced age, is not enough to save a functionally extinct species from true extinction. The last known living baiji was Qi Qi (淇淇) who died in 2002.
Anatomy and morphology
Baiji are thought to breed in the first half of the year, the peak calving season being from February to April. A 30% pregnancy rate was observed.[7] Gestation lasts 10-11 months, delivering one calf at a time; the interbirth interval is 2 years. Calves measure around 80-90 centimetres (32-35 in) at birth, and nursed for 8-20 months. Males reach sexual maturity at age four, females at age six. Mature males were about 2.3 metres (7.5 ft) long, females 2.5 metres (8 ft), the longest specimen 2.7 metres. The animal weighed 135-230 kilograms (300-510 lb), with a lifespan estimated at 24 years in the wild.
When escaping from danger, the Baiji can reach 60 km/h (37 mph), but usually stays within 10 to 15 km/h (6-9 mph). Because of its poor vision and hearing, the Baiji relies mainly on sonar for navigation.
Distribution
Historically the Baiji occurred along 1,700 kilometres (1,000 miles) of the middle and lower reaches of the Yangtze from Yichang in the west to the mouth of the river, near to Shanghai. This had been reduced by several hundred kilometres both upstream and downstream, and was limited to the main channel of the Yangtze, principally the middle reaches between the two large tributary lakes, Dongting and Poyang. Approximately 12% of the world’s human population lives and works within the Yangtze River catchment area, putting pressure on the river. The construction of the Three Gorges Dam, along with other smaller damming projects, also led to habitat loss.
Evolutionary history
Fossil records suggest that the dolphin first appeared 25 million years ago and migrated from the Pacific Ocean to the Yangtze River 20 million years ago. It was one of four species of dolphins known to have made fresh water their exclusive habitat. The other three species, including the Boto and the La Plata Dolphin, have survived in the Río de la Plata and Amazon rivers in South America and the Ganges and Indus rivers on the Indian subcontinent.
It is estimated that there were 5,000 Baiji when they were described in the ancient dictionary Erya circa 3rd century BC. A traditional Chinese story describes the Baiji as the reincarnation of a princess who had been drowned by her family after refusing to marry a man she did not love. Regarded as a symbol of peace and prosperity, the dolphin was nicknamed the "Goddess of the Yangtze."
Conservation
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. Now the most endangered cetacean in the world, according to the Guinness Book of World Records, the Baiji was last sighted in August 2007. It is listed as an endangered species by the U.S. government under the Endangered Species Act.