Yangtze sturgeon
| Yangtze sturgeon | ||||||||||||
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Yangtze River sturgeon ( Acipenser dabryanus ) |
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| Scientific name | ||||||||||||
| Acipenser dabryanus | ||||||||||||
| Duméril , 1869 |
The Yangtze River sturgeon ( Acipenser dabryanus ) is a species of fish from the genus of sturgeon ( Acipenser ) that is endemic to the Yangtze River and its tributaries in China . The species is considered critically endangered and is listed in Appendix II of the Washington Convention on Endangered Species .
features
The Yangtze River sturgeon is a relatively small sturgeon that reaches an average length of 80 to 110 and a maximum of 130, according to some sources up to 250 cm, and a weight of over 16 kg. There is a breathing hole. The snout is short and roughly conical. Two pairs of barbels sit close to the mouth, the lips of which have small papillae. The body has five rows of ganoid scales , the skin between them is rough. The first of the eight to 14 back plates does not touch the head plates. The 26 to 54 side panels are wider than they are high. The body above this row of plates is dark gray, gray-brown or yellowish-gray, below it is milky white. The ventral rows have 8 to 15 plates. The arches of the gill trap carry 32 to 55 rays. The dorsal fin has 44 to 66, the anal fin 25 to 41 soft rays. There are 1 to 2 plates behind the dorsal fin, but none behind the anal fin.
Way of life
Adult Yangtze River sturgeon are diurnal. They mainly inhabit remote river areas in 8 to 10 meters water depth above sandy-silty subsoil. As omnivores , they find an abundance of detritus , benthic organisms, little bristles and small fish, as well as other invertebrates and aquatic plants. Young animals prefer sandy shallow water areas. They are predominantly nocturnal and feed on zooplankton .
Males reach sexual maturity at four to seven years of age, females only at six to eight years of age. The animals migrate upriver during the spring floods to lay their spawn. Their spawning grounds were in the city of Yibin, about 2,800 km from the estuary, on a 320 km stretch between Maoshui (Yibin) and Heijang, in the Sichuan province. The sticky eggs are laid on stones.
Danger
The Yangtze sturgeon occurred exclusively in the river system of the Yangtze and in some larger tributaries. The population declined rapidly at the end of the 20th century. The reasons for this were the increasing overfishing, the destruction of its traditional habitat by the construction of the Gezhouba dam , and the rapidly increasing water pollution. Although the population increased sharply, no sewage treatment plants were built and no garbage disposal systems were developed. Everything is disposed of via the river.
From 1988 the Yangtze sturgeon in the lower reaches of the Yangtze River was considered to be extinct. He was seen in the upper reaches between Luzhou City and Jiangjin District in Sichuan Province, as well as in the Ming, Tuo Jiang and Jialing Rivers.
In 2007 more than 5,000 farmed young fish were released in the upper reaches. It is uncertain whether these will reproduce in the wild. The Yangtze River sturgeon is listed as critically endangered (possibly extinct) on the IUCN Red List .
Web links
swell
- ↑ a b c d IUCN: Yangtze Sturgeon (Acipenser dabryanus), in the IUCN Red List of October 23, 2009. Retrieved March 6, 2019
- ^ A b Food and Agriculture Organization of the United Nations: Species Fact Sheet of the FAO . Retrieved March 6, 2019
- ^ Minister of Supply and Services Canada: CITES Identification Guide - Sturgeons and Paddlefish: Guide to the Identification of Sturgeon and Paddlefish Species Controlled under the Convention on International Trade in Endangered Species of Wild Fauna and Flora . Wildlife Enforcement and Intelligence Division, Environment Canada, 2001, ISBN 0-660-61641-6 (English, French, Spanish, full text, 181 pages as PDF . Accessed March 6, 2019).
- ↑ FishBase : Acipenser-dabryanus Yangtze sturgeon. Retrieved March 6, 2019