SANBI

Rationale (Changed due to Same category and criteria)

Although there is no reliable information about population trends of Enteromius hospes, it has been suggested that river regulation in the Orange River System may have benefited this species. The species is found throughout the lower Orange River, from the Augrabies Falls to near the mouth, a distance of excess of 500 km, and is also present in the lower reaches of the Fish River, which is a tributary of the lower Orange River. The Orange River is characterized by good habitat and water quality. Given the extensive extent of occurrence and area of occupancy and possible population increase due to river regulation, E. hospes is assessed as Least Concern.

Distribution

Enteromius hospes is endemic to the lower Orange River, and has been recorded from below the Augrabies falls to the estuary, including the lower Fish River in Namibia, where its upstream movement is curtailed by a waterfall at Witputs (Hey et al. 1997, Skelton 2001, Naesje et al. 2007).

Habitat View more ecological information

Population trend

Trend

According to Hay et al. (2007), this species is considered abundant in the lower Orange and Fish rivers. This was confirmed during fish surveys of the lower Orange river between 1995 and 2001 where 1305 Enteromius hospes were caught (representing 10% of the total fish catch) at eight of the 10 sampling stations used by Naesje et al (2007). Hay et al. (1997) noted that although the species was common in the lower Fish River, it is probably not optimal for the species because of the lentic nature of this river, which is characterized by extended droughts interspersed with flood events. Preliminary seine net data kindly provided by Dr S. Lamberth suggest that catches of E. hospes are lower than those of Naesje et al. (2007). However the species is still widespread and decline in population numbers are not likely, but further studies are needed.

Threats

There are few current threats to this small species which inhabits a large long river which has varied habitat and overall good water quality. There appear to be adequate flows in this regulated river. Flows are regulated by several very large instream dams (e.g. Gariep, van der Kloof) which release water for downstream irrigation use and to generate hydro-electricity. The water quality in the Vaal River, the mains tributary of the Orange River, is of increasing concern, due to impacts of mines, industry and waste water treatment plants which discharge waste water into the river.

Conservation

The Ai-Ais/Richtersveld Transfrontier National Park and Augrabies National Park were primarily proclaimed for terrestrial fauna and flora and scenery. These parks include and protect a substantial length of riverine habitat, especially the former. However, the riverine reaches in the parks are not secure against upstream impacts above the parks.
Regular surveys (every 3-5 years) of the lower Orange River, within the distribution range of Enteromius hospes, should be undertaken to inform the conservation status of this range restricted species. Where possible the sampling sites of Naesje et al. (2007) should be used for comparative purposes.

References

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 author = {Skelton, P.H.},
 title = {A Complete Guide to the Freshwater Fishes of Southern Africa},
 year = {2001}
}
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,@book{2426,
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,@electronic{2426,
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 title = {The IUCN Red List of Threatened Species. Version 2017-3},
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,@article{2428,
 author = {Cambray, J.A.},
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,@article{2428,
 author = {Skelton, P.H. and Cambray, J.A.},
 title = {Freshwater fishes of the middle and lower Orange River},
 year = {1981}
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,@techreport{2428,
 address = {Trondheim},
 author = {Naesje, T.F., Hay, C.J., Nickanor, N., Koekemoer, J. , Strand, R and C.B. Thorstad},
 title = {Fish populations, gill net catches and gill net selectivity in the lower Orange River, Namibia, from 1995 to 2001},
 year = {2007}
}
,@article{2566,
 author = {Skelton, P.H.},
 title = {South African Red Data Book - Fishes},
 year = {1987}
}
,@article{2566,
 author = {Cambridge, UK. Hay, C.J., van der Bank, F.H and J.T. Ferreira},
 journal = {Madoqua},
 number = {2},
 pages = {95--97},
 title = {Aspects of the ecology of Barbus hospes from the Fish River, Namibia},
 volume = {19},
 year = {1997}
}
,]

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