|Scientific Name:||Acipenser sinensis|
|Species Authority:||Gray, 1835|
|Taxonomic Notes:||The Chinese Sturgeon Acipenser sinensis is restricted to the main channel of the Yangtze and the Pearl rivers and the East and South China Seas. Though there is still disagreement about the taxonomy of the Pearl and Yangtze River populations, Chinese scholars commonly divide Chinese Sturgeon into two populations; one is the Pearl River Chinese Sturgeon, which spawns in spring, and is close to dying out. The other is the Yangtze River Chinese Sturgeon, which spawns in autumn and still maintains a certain amount below the Gezhouba Dam.|
|Red List Category & Criteria:||Critically Endangered A2bcd; B2ab(i,ii,iii,iv,v); C2a(ii) ver 3.1|
|Reviewer/s:||Pourkazemi, M., Zhang, H., Du, H. & Smith, K.|
The Chinese Sturgeon is a large anadromous species. This species was historically recorded in southwestern Korea and in western Kyushu, Japan and in the Yellow, Yangtze, Pear, Mingjiang, and Qingtang rivers in China, but has been extirpated from all of these areas except for the mid-lower section of the Yangtze River, below the Gezhouba dam. This species was historically overfished. In the 1970s, the total spawning population of this species was estimated at 10,000 individuals, but between 2005-2007 the total spawning stock of Chinese Sturgeon was estimated to be 203-257 individuals. This data indicates a 97.5% reduction in the total spawning population over a 37 year period. The construction of the Gezhouba dam in 1981 blocked the migration routes of this species, making it impossible for it to reach spawning sites in the upper reaches of the river. Currently, there is just one remaining spawning ground (a 4 km stretch of river), which is situated below the Gezhouba dam. Furthermore, in 2003, the Three Gorges dam was constructed 40 km upstream of the Gezhouba dam. This has changed the hydrological regime (lowering the water level of the river in autumn and winter) and affected the water temperature. Between 1983 and 2007, more than 9 million juveniles (including larvae) were released into Yangtze River to increase population numbers, but the contribution to wild stocks is considered to be less than 10%. This species has therefore been assessed as Critically Endangered.
|Range Description:||The Chinese Sturgeon is the most southerly distributed of the Acipenseriformes. It was historically recorded in southwestern Korea and in western Kyushu, Japan. In China this species was historically found in the Yellow, Yangtze, Pearl, Mingjiang, and Qingtang rivers. However, it is now considered extirpated in the Yellow, Mingjiang, Qingtang and Pearl rivers (Chen 2008). This species has also recently been extirpated from the upper reaches of the Yangtze River, above the Three Gorges dam, and currently occurs in the middle and lower reaches of the Yangtze river and close to shore in the Yellow and East China Sea (The Changjiang Aquatic Resources Survey Group 1988, Chen 2008).|
Possibly extinct:China; Japan; Korea, Democratic People's Republic of; Korea, Republic of
|FAO Marine Fishing Areas:||
Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
In the 1960s, this stock supported a major commercial fishery, but catches in the late 1970s had declined to about 500 fish per year (The Changjiang Aquatic Resources Survey Group 1988).
In the 1970s, the total spawning population of this species was estimated at 10,000 individuals. In 1981, the construction of the Gezhouba dam isolated the upper reaches of the Yangtze river. In 1983 and 1984, the mean spawning stock size was estimated at 2,176 individuals (946 and 4,169 as 95% confidence intervals). Available data from acoustic surveys show that between 2005 and 2007, the total spawning stock of Chinese Sturgeon was 203-257. This data indicates a 97.5% reduction in the total spawning population over a 37 year period.
During 1996-2001, studies using tag-recapture methods, population structure analysis and sonar counting indicated that the spawning stock in the Yichang spawning area (mid-lower reaches of the Yangtze river) had decreased since the completion of the Gezhouba Dam. Annual estimates of spawning adults within the 40 km (including the 4km long spawning area) ranged from 199 to 473 (Chang 1999, Wei 2003).
Between 1983 and 2007, more than 9 million juveniles were released into Yangtze River to increase wild stocks. Prior to 1996, only the larvae were released as techniques had not been developed to cultivate fry, so survivability is expected to be very low (Wei 200, Chen 2008). After 1999, improvement in hatchery techniques allowed juveniles to be raised and the released, but the contribution to wild stocks is considered to be less than 10% (Wei 2003, Zhu 2003).
|Habitat and Ecology:||
This species is anadromous (spending at least part of its life in salt water and returning to rivers to breed). Young of this species live in estuarine and nearshore habitats. When the species becomes sexually mature, it migrates up-river. Nearly mature adults (early stage III) arrive at the mouth of the Yangtze River in June or July. The adults do not feed while in the river.
Adults reach the middle sections of the river in September or October, where they overwinter. Ripe individuals were formerly found as far inland as the Jingsha River during the following October and November, where they spawned. Prior to construction of the Gezhouba Dam, the migration distance was as long as 2,500 to 3,300 km. Spawning sites often occur in turbulent sections of the river with rocky substrate and steep cliffs on both banks.
The roe is very large and it sinks and sticks to gravel until hatching. The hatched fries descend from the river to sea near the coast where they grow. They feed mainly on zoobenthos and other bottom invertebrates.
Juvenile A. sinensis of 7 to 38 cm tail length occur in the Yangtze River estuary from the middle of April through early October. These are presumably one-year-old individuals. Juveniles weighing a few kilograms can be found in coastal waters near the river mouth. Individuals from 25 to 250 kg in weight were registered in some fishing grounds of East China Sea and Yellow Sea. This species attains a length of more than 3 metres.
This species has been historically overfished. In the 1970s, fishing was unlimited, but seasonal (occurring mostly between October and November). Gear types include gill nets (upper reach) and row hooks (middle reach). Due to its life history characteristics, once depleted, stocks of this species take a long time to recover. Fry are also captured by traditional Chinese fishing methods (drift nets in the river and set nets at the river mouth).
Habitat fragmentation, alteration, destruction and changes to hydrological conditions also significantly impacts this species. The construction of the Gezhouba dam in 1981 blocked the migration routes of this species, making it impossible for it to reach spawning sites in the upper reaches of the river. Currently, there is just one remaining spawning ground, which is situated below the Gezhouba dam.
In 2003, the Three Gorges dam was constructed 40 km upstream of the Gezhouba dam. This has changed the hydrological regime (lowering the water level of the river in autumn and winter) and affected the water temperature.
Additionally, an increase in the amount of shipping traffic in the Yangtze river could be detrimental to the Chinese Sturgeon.
New evidence shows that water pollution is a potential factor lead to the decline of Chinese Sturgeon. Synthetic chemicals in water could contribute to the population decline of this species by significantly decreasing both the quality and quantity of eggs and spawning frequency of fish (Hu 2009).
Current conservation measures in the Yangtze River include the strict limitation of harvest, the establishment of protected areas and the ongoing restocking programmes.
Commercial fishing has been closed since 1983, and now just small numbers (less than 40 individuals in recent years) are caught for scientific or propagation purposes.
In 1988, A. sinensis was listed a Class I State protected animal. In 1996, Yichang Chinese Sturgeon Nature Reserve was established, protecting the spawning population. In 2002, a Chinese Sturgeon Nature Reserve in the Yangtze River estuary was established to protect juvenile sturgeons gathering there. This species was listed on CITES Appendix II in 1998.
In 1983, the Yangtze River Fisheries Institute artificially spawned this species (Fu et al. 1985). From 1983 to 2007, more than 9 million Chinese Sturgeon (including larvae) were released into Yangtze River to increase the stock (Xiao et al. 1999, Chen 2007).
Currently, adult sturgeons are captured on spawning ground to be used for artificial breeding . Efforts are being made to rear and breed this species in captivity so that captive adults can be used for stocking in the future.
|Citation:||Qiwei, W. 2010. Acipenser sinensis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 18 May 2013.|
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