|Scientific Name:||Labeobarbus capensis|
|Species Authority:||(Smith, 1841)|
Barbus capensis Smith, 1841
|Red List Category & Criteria:||Vulnerable B2ab(iii,v) ver 3.1|
|Assessor(s):||Impson, D. & Swartz, E.|
|Reviewer(s):||Snoeks, J. (Freshwater Fish Red List Authority) & Darwall, W. (Freshwater Biodiversity Assessment Unit)|
Criterion A does not apply as the greatest populations declines occurred between 1940 and 1970 following the introduction of smallmouth bass into the system in the 1940s. The current population is, however, still likely to be suffering a continued slow decline because of declining habitat quality and range expansions of invasive alien fishes. Criterion B applies because of the small actual areas of occupancy and the limited number of locations (seven). Locations have been identified as the subpopulations protected by barriers to aliens, namely the Ratels, Boskloof, Rondegat, Biedou and Driehoeks Rivers and then "open" rivers that are treated as one location namely the Upper Olifants-Thee-Noordhoeks-Jan Dissels-Kobee-Doring-Groot-lower Twee (indigenous range). Very few Clanwilliam yellowfish have been recorded in the Clanwilliam and Bulshoek dams because of very high bass numbers, so these areas cannot be included in the analysis. Most fishes are in the upper Olifants River, in tributary streams and in the Doring River where they are present in low numbers because of bass invasion. Therefore it qualifies as Vulnerable under B2ab(iii,v).
|Range Description:||Endemic to the Olifants River System on the West Coast of South Africa (Skelton 2001). Seems to have gone extinct or is very rare in the mainstream areas of the Upper Olifants River above Clanwilliam Dam and below the Olifants Gorge where they were previously plentiful (Harrison 1938). They are still widespread in the Doring River (Paxton et al. 2002) and occurs in several tributaries of the Cederberg Mountains.|
Native:South Africa (Western Cape)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Anecdotal reports indicated very large numbers of Labeobarbus capensis were present in suitable habitat before the introduction of Micropterus dolomieu into the system in the 1940’s (Harrison 1938, Wells 1949). Currently, healthy numbers of Labeobarbus capensis are found only in areas free of alien fishes. These areas probably represent less than 10% of its original distribution range. However, as the system is large, the 10% still equates to a population size that could be large.|
|Habitat and Ecology:||They are found in rivers of variable size, including mountain streams. Adults prefer relatively fast flowing water of variable depth (Gore et al. 1991). Sub-adults are frequently found in riffles, with juveniles smaller than 4 cm in backwaters and slow flowing shallow riffles. Deep permanent pools with good cover provided by rocky reefs or palmiet (Prionium serratum) beds are important refuges for the species in seasonal rivers during the hot dry summers. Adults are light brown, males becoming golden yellow during the breeding season. Juveniles are silvery with irregular dark blotches or vertical bars on the sides (Jubb 1965). Adults are omnivorous, feeding on aquatic macro-invertebrates and algae (van Rensburg 1966). Juveniles feed on zooplankton and small aquatic invertebrates. Breeds in late spring to summer when water temperatures exceed 20°C; then small schools of adults migrate to riffles and glides that are 0.2 to 0.5 m deep to spawn (King et al. 1998). It is a multiple spawner during the breeding season, laying non-adhesive eggs that develop into photophobic embryos (Cambray 1999). Like Barbus andrewi, it can spawn successfully in impoundments in shallow rocky bays.|
|Major Threat(s):||The major threat to the species has been the predatory impact of invasive alien fish species, especially Micropterus dolomieu (van Rensburg 1966, Gaigher 1973, Bills 1999) and to a lesser extent Lepomis macrochirus, Micropterus salmoides and Micropterus punctalatus. Juvenile Labeobarbus capensis also compete with Tilapia sparrmanii, Lepomis macrochirus and Micropterus dolomieu for food. Habitat degradation is another substantial threat as the Olifants catchment and some tributaries are the focus for intensive citrus, deciduous fruit and vineyard development. Two large instream dams (Clanwilliam and Bulshoek) act as barriers to fish migration, and rivers are over-abstracted to fill hundreds of smaller farm dams. The lower reaches of many tributaries have been bulldozed and canalised for flood protection purposes. The excess use of fertilisers and pesticides (many copper based) also poses a substantial threat to indigenous fishes (Bills 1999).|
Labeobarbus capensis has been listed as endangered by the provincial Nature Conservation Ordinance making catch and release compulsory. The upper reaches of several tributaries (e.g., Rondegat and Driehoeks Rivers) with good Labeobarbus capensis populations are situated in the Cederberg Wilderness Area. The Greater Cederberg Biodiversity Corridor (GCBC), which encompasses the majority of the Olifants-Doring catchment, was established in 2004 to enable authorities and private land-owners to jointly manage valuable conservation areas.
The most important tributaries and mainstem areas for indigenous fish conservation in the Olifants River system have been identified (Impson et al. 1999). The Clanwilliam Yellowfish Station was established in 1976 by the then Cape Department of Nature Conservation to culture Labeobarbus capensis, then regarded as the most threatened Cederberg fish species, for re-stocking purposes (CDNC 1978/79). The station was never effective because of water quality problems that contributed to regular losses of fish. The station was however instrumental in distributing thousands of Labeobarbus capensis to farm dams and to tributaries (CDNC 1981/82), some of which were outside the natural range of yellowfish. For example, in the mid 1980’s Labeobarbus capensis was introduced above waterfall barriers on the Twee River, home to the Critically Endangered Barbus erubescens, in a misguided attempt to conserve the species. The station stopped producing fishes in the late 1990’s.
The advent of the Cape Action for People and the Environment (CAPE) in 1999, a collaborative programme to more effectively conserve the Cape Floristic Region, has culminated in a dedicated project to eradicate invasive alien fishes from its priority rivers. Included in the project are two rivers in the GCBC that have Clanwilliam yellowfishes (the Krom and Rondegat rivers). The national yellowfish working group, established in 1997, includes in its aims promoting awareness of threatened yellowfishes and increasing research and monitoring effort on such fishes.
|Citation:||Impson, D. & Swartz, E. 2007. Labeobarbus capensis. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 03 September 2015.|
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