SANBI

Rationale (Changed due to Same category and criteria)

Incomati Chiselmouth (Labeobarbus nelspruitensis) is endemic to the escarpment streams of the Inkomati and Pongolo River systems. This species does not qualify under the IUCN (version 3.1) criteria B as Vulnerable as the extent of occurrence (EOO) is 25,414 km², while the area of occupancy (AOO) has been calculated as 180 km², this is known to be an underestimate and the real AOO is much larger as not all known localities within the distribution area are supported by specimen data at present. It is known from more than 10 locations and has six subpopulations. Some of these subpopulations are small and impacted upon by sedimentation, reduced water quality, forestry, agriculture, alien fish invasions and illegal gill netting (especially in the Sabie River). Due to all of these impacts this species needs to be closely monitored and conservation action is required as as any further loss will result in the uplisting of this species. This taxon qualifies as Near Threatened under criterion B1b(iii,v).

Distribution

Incomati Chiselmouth occurs in the headwaters of tributaries of the Inkomati River System where four isolated subpopulations occur. The stronghold of this species is the Sabie River and its tributaries, Mac-Mac, Mariti and Ngwaritsana rivers. In the Pongolo River System there are two isolated subpopulations, one in the Usuthu River and its tributaries and the other subpopulation in the upper Pongola River tributaries (Kleynhans 1982, 1984). It was historically recorded in the upper Komati in the Boesmanspruit area but following acid mine drainage this habitat is no longer viable.

Habitat View more ecological information

Population trend

Trend

Restricted within its distribution, but where present, they are usually abundant and adults occur in deeper water in schools of up to 50 to 100 fishes (Kleynhans 1984). More frequent in the Inkomati River System tributaries (population density of 27.4% with a CPUE of 1.22) than the Pongolo River System tributaries (population density of 8.3% with a CPUE of 0.61) (Kleynhans 1984). Weeks et al. (1996) reported that L. nelspruitensis made up 10% of the species assemblage in foothills streams of the Sabie-Sand rivers.

Threats

This taxon has experienced degradation of upper catchments within its range due to poor farming activities, reduced water quality, forestry activities and the introduction of cool-water alien fish species for example trout. Illegal gill netting on the Sabie River (stronghold of the species) is causing ongoing decline to the population. Since 2010 there has been increased pressure from gill netting within both deep pools and rocky rapid areas (the spawning areas). In the Usuthu Catchment area there has been an increase in coal mining since 2008. Water transfer schemes are resulting in interbasin transfers with large amounts of water being abstracted from this catchment.

Uses and trade

Targeted for subsistence fishing. There has been an increase in the use of gill netting since 2010.

Conservation

Management of alien fish stocking and habitat improvement is needed for key populations.

References

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 address = {Lydenburg},
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 year = {1982}
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,@phdthesis{2572,
 author = {Kleynhans, C.J. },
 school = {University of Pretoria},
 title = {Die verspreiding en status van sekere seldsame vissoorte van die Transvaal en die ekologie van sommige spesies.},
 year = {1984}
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,@techreport{63301,
 author = {Weeks, D.C., O’Keefe, J.H., Fourie, A. and Davies, B.R. },
 title = {A Pre-impoundment study of the Sabie-Sand River system, Mpumalanga with Special reference to predicted impacts on the Kruger National Park: Volume 1 -The ecological status of the Sabie-Sand River system. },
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,@article{63301,
 author = {Vreven, E.J., Musschoot, T., Snoeks, J. and Schliewen, U.K.},
 journal = {Zoological Journal of the Linnean Society},
 pages = {231--305},
 title = {The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history},
 volume = {177},
 year = {2016}
}
,]

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