Chinese river dolphin

from Wikipedia, the free encyclopedia
Chinese river dolphin
illustration

illustration

Systematics
Superordinate : Laurasiatheria
Order : Whales (cetacea)
Subordination : Toothed whales (Odontoceti)
Family : Lipotidae
Genre : Lipotes
Type : Chinese river dolphin
Scientific name of the  family
Lipotidae
Zhou , Qian & Li , 1978
Scientific name of the  genus
Lipotes
Miller , 1918
Scientific name of the  species
Lipotes vexillifer
Miller, 1918

The Chinese river dolphin ( Lipotes vexillifer ), also known as the Yangtze River Dolphin or Baiji ( Chinese  白 鱀 豚 , Pinyin báijìtún ), is a river dolphin native to the middle and lower catchment area of ​​the Yangtze River . It has been considered one of the rarest mammals in the world since the 1980s and is believed to be extinct .

The name Lipotes is derived from the Greek word leipos , which can be translated as left behind or left over and refers to the very limited range of the species. Vexillifer is derived from the syllables vexillum for flag and fer for to carry , meaning flag- bearing .

features

The Chinese river dolphin grows up to 2.4 meters long and weighs up to 160 kilograms. The males are likely to remain slightly smaller than the females at around 2.2 meters and weighing 125 kilograms. It is pale gray to bluish on top and white on the underside. The whitish color of the abdomen extends far up in the cheek area and at the base of the tail. The fluke and flippers are also gray on the top and white on the underside. It has a small triangular dorsal fin with a blunt tip. The almost beak-like snout is clearly set off from the head and slightly curved upwards towards the tip. It is very narrow and has between 31 and 35 similarly shaped, conical teeth per half of the jaw . The forehead is steeply sloping and the eyes are stunted but not functionless. You sit relatively high on your head.

distribution

Distribution of the Chinese river dolphin

Originally it was believed that the Chinese river dolphin was confined to Dongting Lake , before it was recognized in the 1970s that it stretched over a length of 1,600 kilometers from the mouth of the Yangtze River up to about the level of the Yichang and in the neighboring east China river Qiantang was to be found. A river dolphin was found about every four kilometers. During floods, the animals also penetrated into tributaries of the river and lakes. It disappeared from Dongting Lake after very large amounts of sediment had accumulated in the water from agriculture. After that he was only seen in the broad, slowly flowing central part of the Yangtze River.

Way of life

The cladogram from the first description of Inia araguaiaensis shows the Chinese Flussdelfin as a sister group to a clade of the genus Inia and the La Plata Dolphin .

Little is known about the way of life. Because of their stunted eyes, Chinese river dolphins rely on echolocation to catch their prey. Their food is exclusively fish , which they catch in just 20 seconds of dives. The range of prey fish is very large, the main prey being eel-like elongated catfish species that they hunt on the bottom of the water.

The Chinese river dolphin lives solitary. It used to be found in pairs or in small groups of three to six animals, and occasionally groups of up to ten animals were seen. Most of the time, the river dolphin stays just below the surface of the water. When emerging, the head comes out first, and the animal descends again with a hump-shaped curvature. The fluke does not appear.

Almost nothing is known about the reproductive behavior of the Chinese river dolphins. The young were born less than 95 centimeters long and ten kilograms of body weight.

Only two animals were kept in captivity. These were the male Qiqi , which was injured by a fisherman and then kept in the Wuhan Institute of Hydrobiology from 1980 to 2002, as well as another animal that was kept in the Shishou Semi-natural Baiji for a year (1996 to 1997) Dolphin Sanctuary lived and then passed away. A female was also captured near Shanghai in 1998, but refused to feed and died a month later.

Systematics

The Chinese river dolphin was in 1918 by the American zoologist Gerrit Smith Miller described . According to fossil recordings, the river dolphin colonized the Yangtze River from the Pacific about 20 million years ago . He is the only representative of the genus Lipotes .

The system of river dolphins has not yet been fully clarified. While in the past all representatives of this group were considered to be convergent and not related to each other, it was later assumed that the Amazon dolphin ( Inia geoffrensis ) and the La Plata dolphin ( Pontoporia blainvillei ) are related to one another, while the Chinese river dolphin is the sister group of one common clade of these two river dolphin species with the dolphin-like (Delphinoidea) is. Recently, however, molecular genetic studies have shown that the Chinese river dolphin is more closely related to the rest of the river dolphins than to the dolphin-like. Wilson & Reeder (2005) therefore classify them in the common family Iniidae . In contrast, more modern systematics classify the Chinese river dolphin into an independent, monotypical family, the Lipotidae.

Persistence and Threat

The first description of the animals comes from the nature encyclopedia Erya from the Han dynasty (206 BC to 220 AD). Biologists estimate that around 5,000 river dolphins were still living in the Yangtze River at that time. In 1978, the Freshwater Dolphin Research Center (淡水 海豚 研究 中心) of the Chinese Academy of Sciences was established for animal research.

The river dolphin had not been seen in eastern China's Qiantang River since the 1950s. Around 1980 the population in the Yangtze River was estimated at around 400 animals. The Chinese industrialization in particular had greatly affected the population of these animals. The pollution of the Yangtze, excessive shipping traffic and frequent entanglement in fishing nets (" bycatch ") brought the species to the brink of extinction. Many documented deaths are attributed to line and hook fishing for sturgeon ( Chinese sturgeon , Yangtze sturgeon and sword sturgeon ), and there were frequent collisions with motor boats, the number of which increased massively on the Yangtze.

Although the People's Republic of China recognized the dolphin as an endangered species as early as 1979 and placed it under strict protection in 1983 and issued a hunting ban, the threatening circumstances for the animal did not change. In 1986, 300 Baijis were found at one count, in 1990 the population was around 200 animals. By 1997 this number had been reduced to an estimated 50 or less; 23 animals were actually counted. In 1998 there were only seven animals. A stranded female was found in 2001 and a live animal was last photographed in 2002.

In 2006 and 2007, several attempts were made to find live specimens of the Chinese river dolphin. However, these were unsuccessful, which is why the scientists involved assumed that the river dolphin was finally extinct. The Baiji dolphin would be the first whale species to become extinct in historical times . However, reports surfaced in the press in 2007 that the river dolphin had continued to be seen and even filmed by locals. In 2016, a team of Chinese amateur conservationists reported a sighting of a river dolphin near the city of Wuhu . Zoologists believe the recent sightings are mistaken for porpoises .

literature

  • Mark Carwardine : Whales and Dolphins. Delius Klasing, Bielefeld 1996, ISBN 3-7688-0949-8 (high quality guide)
  • Mark Carwardine: Dolphins. Biology, distribution, observation in the wild. Naturbuch, Augsburg 1996, ISBN 3-89440-226-1 (informative illustrated book)
  • Ralf Kiefner: whales and dolphins worldwide. Pacific Ocean, Indian Ocean, Red Sea, Atlantic Ocean, Caribbean, Arctic, Antarctica. Year Top Special, Hamburg 2002, ISBN 3-86132-620-5 (guide of the magazine "tauchen", very detailed)
  • RR Reeves, BS Stewart, PJ Clapham, JA Powell: Sea Mammals of the World. A Complete Guide to Whales, Dolphins, Seals, Sea Lions and Sea Cows. Black, London 2002, ISBN 0-7136-6334-0 (guide with numerous pictures).
  • Gérard Soury: The great book of the dolphins. Delius Klasing, Bielefeld 1997, ISBN 3-7688-1063-1 (detailed illustrated book)
  • Rüdiger Wandrey: The whales and seals of the world . Franckh-Kosmos Verlags GmbH, 1997, ISBN 3-440-07047-6
  • M. Würtz, N. Repetto: Underwater world. Dolphins and Whales. White Star Guides, Vercelli 2003, ISBN 88-8095-943-3 (identification book)
  • Douglas Adams , Mark Carwardine: The Last of their Kind . Heyne, Munich 1992, ISBN 3-453-06115-2
  • DE Wilson and DM Reeder: Mammal Species of the World. Johns Hopkins University Press 2005 ISBN 0-8018-8221-4

Individual evidence

  1. ↑ sueddeutsche.de: In vain search for the last of its kind
  2. ↑ a b Wandrey (1997), p. 121 u. 122.
  3. ↑ Gerrit S. Miller (1918). A new river-dolphin from China. Smithsonian Miscellaneous Collections 68 (9): 1-12.
  4. ^ Yongchen Wang: Farewell to the baiji . China Dialogue. January 10, 2007. Archived from the original on September 28, 2007. Retrieved on September 24, 2019.
  5. ↑ Insa Cassens, Saverio Vicario, Victor G. Waddell, Heather Balchowsky, Daniel Van Belle, Wang Ding§, Chen Fan, RS Lal Mohan, Paulo C. Simoes-Lopesi, Ricardo Bastida, Axel Meyer, Michael J. Stanhope & Michel C Milinkovitch: Independent adaptation to riverine habitats allowed survival of ancient cetacean lineages. PNAS , October 10, 2000, vol. 97, no.21
  6. ^ Healy Hamilton, Susana Caballero, Allen G. Collins, Robert L. Brownell: Evolution of river dolphins . Proceedings of the Royal Society, DOI: 10.1098 / rspb.2000.1385
  7. ↑ for example Laura May-Collado and Ingi Agnarsson: Cytochrome b and Bayesian inference of whale phylogeny. In: Molecular Phylogenetics and Evolution 38 (2006), pp. 344-354. PDF
  8. ↑ John Gatesy, Jonathan H. Geisler, Joseph Chang, Carl Buell, Annalisa Berta, Robert W. Meredith, Mark S. Springer, Michael R. McGowen: A phylogenetic blueprint for a modern whale , Molecular Phylogenetics and Evolution, 2012, Volume 66 , Issue 2, February 2013, Pages 479–506, doi: 10.1016 / j.ympev.2012.10.012
  9. ↑ Don E. Wilson, Russell A. Mittermeier: Handbook of the Mammals of the World - Volume 4, Sea Mammals. Lynx Edicions, July 2014, ISBN 978-84-96553-93-4
  10. ↑ In webarchive.org: The Society for Marine Mammalogy: List of Marine Mammal Species & Subspecies , January 6, 2015. Retrieved March 13, 2019
  11. ↑ Nature , Volume 440, p. 1096 (April 27, 2006)
  12. ↑ GEO.de : The first whale species to be exterminated by humans: the Chinese river dolphin . Retrieved March 13, 2019
  13. ↑ Neue Zürcher Zeitung: Filmed a Baiji in the Yangtze?
  14. ↑ The Guardian: China's 'extinct' dolphin may have returned to Yangtze river, say conservationists . Report dated October 11, 2016. Retrieved March 13, 2019

Web links

Commons : Chinese river dolphin  - Collection of images, videos and audio files
This version was added to the list of articles worth reading on November 17, 2005 .