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Hemimyzon confluens

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII CYPRINIFORMES BALITORIDAE

Scientific Name: Hemimyzon confluens
Species Authority: Kottelat, 2000

Assessment Information [top]

Red List Category & Criteria: Vulnerable B1ab(i,ii,iii) ver 3.1
Year Published: 2012
Date Assessed: 2011-01-19
Assessor(s): Kottelat, M.
Reviewer(s): Rainboth, W., Parenti, L. & Brooks, E.
Justification:
The species is known from a single location in the Nam Ngum drainage, Lao PDR, where it was discovered during sampling in 1999. No further research has been carried out and therefore the species has not been observed again. The species habitat is impacted by logging, deforestation and agriculture, through soil erosion, sedimentation and agricultural pollution expected. Recent survey work within the Nam Ngum drainage has shown that there are extensive mining activities with consequential downstream pollution impacts (M. Kottelat pers. comm. 2012), and some planned hydropower dams are now either operational or under construction.

The species has an Extent of Occurrence of less than 20,000 km2, and a restricted number of locations. The species is considered Vulnerable at present as it has a restricted Extent of Occurrence that is inferred to be declining as a result of dam development and mining activities, which probably has also negatively impacted the species' Area of Occupancy. Further research is required to confirm the species' distribution. It is possible that the species would qualify for a higher threatened category, and the species should be reassessed when further information becomes available.

Geographic Range [top]

Range Description: The species is known from a single location in the Nam Ngum drainage, Lao PDR (Kottelat 2000) and has not been recorded elsewhere.
Countries:
Native:
Lao People's Democratic Republic
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The species is only known from two surveys, conducted in 1998 and 1999 (W. Rainboth pers. comm. 2011 and Kottelat 2000, respectively). It has not been observed again as no additional research has been carried out in the area (Kottelat 2000). Populations are inferred to be declining due to mining operations and dams (both under construction and in operation) in the Nam Ngum drainage in 2012 (M. Kottelat pers. comm. 2011).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Found under stones in fast flowing hillstreams (Kottelat 2000) and rivers.
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is utilised as part of local subsistence fisheries (M. Kottelat pers. comm. 2011).

Threats [top]

Major Threat(s): The surrounding habitat has been deforested and agriculture occurs in the area. Associated impacts such as soil erosion, sedimentation and agricultural pollution are expected to impact the aquatic environment (M. Kottelat pers. comm. 2011). Additional survey work in the area in 2012 found extensive small-scale gold mining excavations in the area, which impact several kilometres of stream downstream, and a there is a large-scale Australian-owned company (Phu Bia Mining Ltd.), and it is possible that iron ore extraction may occur.

The Nam Ngum 1 dam was completed in 1971. Further dams and flow control developments are proposed within the Nam Ngum basin (the "Nam Ngum hydropower cascade"), ; the Nam Ngum 2, north of the Nam Ngum 1 dam, is now in operation (M. Kottelat pers. comm. 2012), and there are at least six further proposed projects: Nam Ngum 3 (construction to start in 2012; M. Kottelat pers. comm. 2012), Nam Ngum 5 (under construction; M. Kottelat pers. comm. 2012), Nam Lik 1 and 2 and Nam Bak 1 and 2 (International Rivers 2011, Vattenfall 2011). The scale and nature of the impacts arising from these subsequent dams is not clear and further information on the distribution of the species is required before the nature of the threat from dams can be determined.

Conservation Actions [top]

Conservation Actions: No conservation actions are known. More research is needed for this species.

Citation: Kottelat, M. 2012. Hemimyzon confluens. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 21 October 2014.
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