Endemic Range/ Yangtze River Basin
Acipenser dabryanus is an endangered demersal fish found in portions of the Yangtze River Basin, previously inhabitating even greater extents of the basin. The upper Yangtze basin is considered the part from the headwaters to the Three Gorges area, or a catchment area of approximately one million square kilometers; this upper basin is quite mountainous. The upper Yangtze basin consists chiefly of Paleozoic limestone and terrigenous sedimentary rock, with some granitic material. The highest elevation ecoregion of the Yangtze Basin is the uppermost reach or headwaters catchment area of the Yangtze, known as the Tibetan Plateau alpine shrub and meadows.
The most downstream element of the upper Yangtze basin is often termed the Sichuan Basin; here the Yangtze cuts through Triassic and Permian material before entering the Three Gorges. The Three Gorges area is a stretch of the Yangtze that runs approximately 660 kilometers, terminating at the site of the Three Gorges Dam. Construction of this dam without adequate biotic mitigation has resulted in considerable aquatic habitat degradation and decline of native fish populations.
The demersal fish Silurus meridionalis also is found as a middle reach Yangtze River endemic species. Some of the notably large native demersal fish occurring in the Yangtze Basin are the 120 centimeter (cm) long Chinese sturgeon (Acipenser sinensis), the 200 cm Giant mottled eel (Anguilla marmorata), the 122 cm black carp (Mylopharyngodon piceus) and the 300 cm Chinese paddlefish (Psephurus gladius), and the 100 cm Silurus meridionalis.
A. dabryanus has recently (possibly since 1995) been extirpated from the lower river and is restricted to the upper main stream of the Yangtze River in the Sichuan Province. It also enters major tributaries, including the Ming, Tuo, and Jialing rivers. (Zhuang et al. 1997).
Yangtze River Demersal Habitat
This taxon is one of a number of demersal species in the Yangtze River system. Demersal river fish are found at the river bottom, feeding on benthos and zooplankton.
The upper Yangtze basin consists chiefly of Paleozoic limestone and terrigenous sedimentary rock, with some granitic material. The most downstream element of the upper Yangtze basin is often termed the Sichuan Basin; here the Yangtze cuts through Triassic and Permian material before entering the Three Gorges. The Three Gorges area is a stretch of the Yangtze that runs approximately 660 kilometers, terminating at the site of the Three Gorges Dam. Prior to construction of the dam, the Three Gorges area was a site of exceptional natural beauty; after dam construction the gorge areas were filled with approximately 100 meters in depth of Yangtze water, and considerable amounts of the watershed were graded.
The lower Yangtze basin consists of anabranching river structures and Pleistocene coastal terraces. Prior to development of the Three Gorges Dam, the Yangtze Delta was replenished with a copious sediment load reaching the river mouth; however, the dam has now severely limited the natural flow and deposition of sediment to the delta region. Consequently, the integrity of the delta is been compromised, with scouring exceeding deposition, and the very stability of the delta is endangered.
Lower and middle basins of the Yangtze carry heavy pollutant loads. In the lower Yangtze basin nitrate levels are high, measuring at about 1000 tons per day at Datong; these levels accrue from high applications of chemical fertilizer applied and also considerable loadings of untreated sewage due to the large human population of the basin, with correspondingly little infrastructure for sewage treatment.
Heavy metal concentrations are also high in the lower Yangtze, with measurements of dissolved lead at 0.078 microgram/liter; cadmium (0.024 microgram/liter), chromium (0.57 microgram/liter), copper (1.9 microgram/liter), and nickel (0.50 microgram/liter). Levels of dissolved arsenic have been measured at 3.3 microgram/liter) and zinc at 1.5 microgram/liter), both notably higher by factors of 5.5 and 2.5 respectively than other typical large world rivers. In Yangtze River suspended sediment, arsenic comprises 31 microgram/gram, lead comprises 83 microgram/gram, and nickel comprises 52 micrograms/gram of sediment content
There are several large native demersal fish found in the Yangtze River, chiefly the 250 centimeter (cm) long endangered Yangtze sturgeon (Acipenser dabryanus), the 120 cm Chinese sturgeon (Acipenser sinensis), the 200 cm Giant mottled eel (Anguilla marmorata), the 122 cm black carp (Mylopharyngodon piceus), the 300 cm Chinese paddlefish (Psephurus gladius), and the 100 cm Silurus meridionalis. Furthermore, there are a few exceptionally large native benthopelagic fishes found in the Yangtze, namely, the 105 cm Silver carp (Hypophthalmichthys molitrix), the 200 cm Wuchang bream (Megalobrama amblycephala), the 200 cm yellowcheek (Elopichthys bambusa), the 145 cm common carp (Cyprinus carpio carpio), the 122 cm Mongolian redfin (Chanodichthys mongolicus), the 102 cm predatory carp (Chanodichthys erythropterus) and the 100 cm snakehead (Channa argus argus).. The demersal fish Silurus meridionalis also is found as a Yangtze River endemic species.
Habitat and Ecology
This species spawns in upper reaches of the Yangtze River, in the spring (March-April) and the autumn (October-December). Its key spawning reach is between Maoshui and Heijang, a stretch of 321.7 km (The Chanjiang Aquatic Resources Survey Group 1988).
Molecular Biology and Genetics
Barcode data: Acipenser dabryanus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Acipenser dabryanus
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Critically Endangered
Fishing effort and intensity has also increased in the past, for example in the Neijiang reach of the Tuo River there were only 500 fishing boats in 1950s, but this number increased to about 2000 by 1985. In the Leshan Reach of the Ming River, drift gill nets are crowded together from day to night.
The primary traditional fishing season in the main stream of Yangzte River is between March and August, with more than 30% of the catch processed between April and May. However, this is also spawning season of A. dabryanus, therefore spawning stock are particularly vulnerable to capture.
Furthermore, the construction of the Gezhouba Dam in 1981 and the Three Gorges Dam in 2003 have caused major adverse effects to the habitat of this species and have resulted in a reduction in the area of occurrence of this species, which is now restricted to the upstream river, above the dams. More recently, the construction of the Xiangjiaba Dam in 2008 is situated in the middle of this species spawning reach and therefore is expected to adversely affect the population through habitat fragmentation and associated habitat degradation.
Additionally pollution from increasing human development affects the entire Yangtze basin. Much untreated waste water discharges into the river each year. Water quality is also affected by run-off caused by deforestation of the the upper Yangtze Valley (Zhuang et al. 1997).
This species has been listed as a First Class Protected Animal of the State since 1988, and has received the same effective protection as Acipenser sinensis. This species was also listed on CITES Appendix II in 1998.
Artificial propagation was first carried out in 1976. Since 2007 more than 5000 juveniles have been released into the upper Yangtze River for stock rehabilitation, but these species are not thought to be breeding in the wild and no larvae have been seen in recent years.
It is considered that the survival of this species is entirely reliant on restocking efforts, without which this species would possibly become extinct (Zhang et al. 2009).
Since the 1970s, the Institute of Aquatic Products of Sichuan Province have increased efforts regarding raising and breeding of A. dabryanus. For example young A. dabryanus from the Yangtze River have been introduced into the Changshou City reservoir for culturing (The Changjiang Aquatic Resources Survey Group 1988).
In 2000 the first national nature reserve was created in the upper Yangzte river. The area of this reserve was extended in 2005 to mitigate the conflict between hydroelectric projects and the maintenance of the functionality of the ecosystem. The reserve is now the largest aquatic reserve in China, which has a total length of 1162.6 km (including 436.5 km of the main river) (Zhang et al. 2009).
Relevance to Humans and Ecosystems
Dabry's sturgeon (Acipenser dabryanus) is a species of fish in the sturgeon family, Acipenseridae. Other common names include Yangtze sturgeon, Chiangjiang sturgeon, and river sturgeon. It is endemic to the Yangtze River Basin in China. It was a food fish of commercial importance. Its populations declined drastically, and in the early 1980s, it was designated an endangered species and commercial harvest was banned. It has been listed as a critically endangered species by the IUCN since 1996 and since 2010 (possibly extinct) has been added to its status.
This sturgeon has been known to reach 2.5 m in length, but it is usually much smaller. Its body is blue-gray above and yellowish white on the belly, with five rows of scutes. The head is triangular and the snout is long with the mouth located on the underside. There are two pairs of barbels.
The fish lives in slow-moving river waters over substrates of sand and mud. It feeds on aquatic plants, invertebrates, and small fish. This species is potamodromous, taking part in a migration, but never leaving fresh water. It spawns in the upper Yangtze, mainly during March and April, and sometimes around November and December. Males spawn each year, but most females do not. The female produces 57,000 to 102,000 eggs.
This was once a common fish in the Yangtze system. It was known from the main river and some of its larger tributaries, as well as some lakes attached to the system. By the late 20th century, it was extirpated from the lower river and limited to the upper reaches in Sichuan. The main causes of its drastic decline include overfishing, including the overharvesting of juveniles. The construction of dams, such as the Three Gorges Dam, blocked the movement of the fish along the river, restricting it to the upper reaches. It also caused habitat fragmentation and degradation. Increased development and deforestation on land near the river has increased pollution from wastewater and runoff.
The fish has been bred in captivity since the 1970s. Thousands of individuals have been released into the river, but are apparently not breeding. Nevertheless, this restocking may be the only effort preventing the extinction of the species.
- Qiwei, W. 2010. Acipenser dabryanus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. Downloaded on 15 October 2013.
- Zhuang, P., et al. (1997). Biology and life history of Dabry's sturgeon, Acipenser dabryanus, in the Yangtze River. Environmental Biology of Fishes 48(1-4), 257-64.
- Froese, R. and D. Pauly. (Eds.) Acipenser dabryanus. FishBase. 2011.
- Gao, X., et al. (2009). Threatened fishes of the world: Acipenser dabryanus Duméril, 1869. Environmental Biology of Fishes 85(2), 117-18.
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