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Thursday, July 28, 2011

Baiji-Chinese River Dolphin

Beauty Of Animal | Baiji-Chinese River Dolphin| The Baiji (Chinese: pinyin: About this sound báijìtún (help·info)) (Lipotes vexillifer, Lipotes meaning "left behind", vexillifer "flag bearer") was a freshwater dolphin found only in the Yangtze River in China. Nicknamed "Goddess of the Yangtze" (simplified Chinese:  traditional Chinese: pinyin: Cháng Jiāng nǚshén) in China, the dolphin was 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",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, which died in 2002.
Anatomy and morphology
Baiji were 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. Gestation would last 10–11 months, delivering one calf at a time; the interbirth interval was 2 years. Calves measured around 80-90 centimetres (32-35 in) at birth, and nursed for 8–20 months. Males reached 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 weigh 135-230 kilograms (300-510 lb),with a lifespan estimated at 24 years in the wild.

When escaping from danger, the Baiji could reach 60 km/h (37 mph), but usually stayed within 10 to 15 km/h (6-9 mph). Because of its poor vision and hearing, the Baiji relied 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 2004, though there was a possible sighting in 2007.It is listed as an endangered species by the U.S. government under the Endangered Species Act.Causes of decline

The World Conservation Union (IUCN) has noted the following as threats to the species: a period of hunting by humans during the Great Leap Forward, entanglement in fishing gear, the illegal practice of electric fishing, collisions with boats and ships, habitat loss, and pollution. During the Great Leap Forward, when traditional veneration of the Baiji was denounced, it was hunted for its flesh and skin, and quickly became scarce.As China developed economically, pressure on the 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 recent decades as well, with some fish populations declining to one thousandth of their pre-industrial levels.In the 1970s and 1980s, an estimated half of Baiji deaths were attributed to entanglement in fishing gear. By the early 2000s, electric fishing was considered "the most important and immediate direct threat to the Baiji's survival."Though outlawed, this fishing technique is widely practiced throughout China. The building of the Three Gorges Dam further reduced the dolphin's habitat and facilitated an increase in ship traffic.

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