Chinese sturgeon
| Chinese sturgeon | ||||||||||||
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Chinese sturgeon ( Acipenser sinensis ) |
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| Acipenser sinensis | ||||||||||||
| Gray , 1835 |
The Chinese sturgeon ( Acipenser sinensis ) is a species of fish from the genus of the sturgeon ( Acipenser ). It occurs in the China Sea off China and Korea as far as the Japanese Sagami Bay . As an anadromous migratory fish , the species migrates to the Yangtze River to spawn . It used to be found in the Yellow River and the Pearl River as well. It is listed as a species to be protected in Appendix II of the Washington Convention on the Protection of Species and classified as critically endangered on the IUCN Red List .
history
The sturgeon (Acipenseridae) belong to a group of bony fish that lived in the waters of the northern hemisphere around 140 million years ago and today still counts 25 species. One of these species is the Chinese sturgeon. This was native to China, Japan, North and South Korea near the coast in the Yellow and East China Sea. To spawn, he hiked up the Yangtze River 2,500 to 3,300 km. His favorite spawning sites in the Yangtze and some of its tributaries were turbulent stretches of river between steep cliffs. On the way there are in 2019, or will be built, seven hydropower plants with insurmountable dams.
features
The Chinese sturgeon has the typical elongated body structure of the sturgeon. The snout is pointed, the forehead arched and the caudal fin asymmetrical. The dorsal fin sits far back, an adipose fin is missing. Five rows of bone plates run along the body, one along the back, one midway along the flank and one along the edge of the abdomen. The four barbels in front of the lower mouth are relatively small. The 14 to 37 bone plates along the flank are large and taller than they are long. The back row has 9 to 17 plates, the first of which touches the top plate. One or two bone plates are also found behind the dorsal and anal fin, but neither are flanked by bone plates. The ventral rows have 8 to 15 plates. The arches of the gill trap carry 14 to 28 rays. The dorsal fin has 49 to 59 soft rays, the anal fin 29 to 39. Adult animals reach an average length of 200 to 330 cm and a maximum of about six meters and weigh up to 600 kg.
Way of life
Males reach sexual maturity at 9 to 18 years of age, females at 14 to 26 years, the maximum age is 33 years. Adult fish with almost mature gonads migrate into the Yangtze from June. In September or October they reach the Gezhouba Dam after 1,600 km . Since its construction (1970 to 1988), the sturgeon migration upstream has ended here. No fish ladders were built, but special spawning grounds for the Chinese sturgeon were created after construction was completed. It was hoped that the sturgeon would adopt and use their new spawning grounds. They stayed in their traditional spawning grounds for a year, and then in October and November they deposited their spawn in regions rich in gravel and rock. The eggs stick to the ground until the young ones hatch. The newly hatched embryos swim towards the light in order to migrate downstream with the current. About a week later they retreat to the river bed, where they use up their yolk supply. After about 12 days, the larvae begin to eat and migrate further downstream into the sea. Chinese sturgeons stay close to the ground in salt water.
Danger
The Chinese sturgeon is traditionally fished for its meat and the roe used as caviar . Fishing, injuries from ships and pollution as well as the construction of the Gezhouba Dam are threatened in their population. The total spawning population was estimated at 10,000 animals in the 1970s. With the construction of the Gezhouba dam, the sturgeons were disturbed in their usual environment and could no longer reach their spawning grounds. The stocks went down rapidly. While in the 1980s around 3500 animals per year were counted at the Yangtze estuary, in 2007 it was only around 250. This corresponds to a decrease between 1970 and 2007 of 97.5%.
The Chinese government founded the "Research Institute for the Chinese Sturgeon" in Yichang in 1982 to research the rearing of the threatened fish. As of 1984, 4.44 million embryos have been released. In order to better protect the remaining stocks, the Chinese sturgeon was given a state-protected animal classification in 1988.
To draw attention to the importance of the fish and its problems, the Museum for the Chinese Sturgeon was set up in 1993 on the premises of the research institute. Since 1983 attempts have been made to increase the population again through breeding programs. By optimizing the breeding techniques it was possible to raise young animals that have been released since 1999. Despite great efforts, the population does not seem to be recovering.
The IUCN carries out regular inventories. The Chinese sturgeon was present in China in the Yellow River, Yangtze River, Pearl River, Min Jiang and Qiantang . The results of the censuses from October 2009 show that fish are considered extinct in all rivers. In the Yangtze, only small stocks could be identified in the lower reaches. The Chinese sturgeon is on the "Red List" of animals threatened with extinction which is published by the IUCN.
Web links
swell
- ↑ a b c Fischbase.de : Acipenser sinensis (English). Retrieved March 6, 2019
- ↑ Fishbase: Family: Acipenseridae Sturgeons.Retrieved March 5, 2019
- ↑ a b Cosmos Magazine: Endangered Chinese sturgeon gives up fight to survive . Report dated September 18, 2014. Accessed March 5, 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).
- ^ Robert Freer: The Three Gorges project on the Yangtze river in China , February 2001, p. 23. Retrieved March 9, 2019
- ↑ IUCN: Acipenser sinensis . Red List 2008 of Threatened Species. Retrieved March 6, 2019
- ↑ Ping Zhuanga, Boyd Kynardc, Longzhen Zhanga, Tao Zhanga, Wenxuan Cao: Ontogenetic behavior and migration of Chinese sturgeon, Acipenser sinensis . In: Environmental Biology of Fishes . tape 65 , 2002, pp. 83-97 (English).
- ^ Yangtze River Cruises: Chinese Sturgeon Museum - Yangtze River Museum . Retrieved March 5, 2019
- ↑ Chinadialog, Zhe Kan: Who is killing the Chinese sturgeon? . Collected work from September 28, 2007 (online). Retrieved March 6, 2019
- ↑ Martin Walters, Heather Angel: Chinese Wildlife: A Visitor's Guide . Bradt Travel Guides, 2008, ISBN 978-1-84162-220-0 .
- ^ IUCN Red List: Chinese Sturgeon . Retrieved March 5, 2019