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Barbus andrewi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII CYPRINIFORMES CYPRINIDAE

Scientific Name: Barbus andrewi
Species Authority: Barnard, 1937
Common Name(s):
English Berg-breede River Whitefish

Assessment Information [top]

Red List Category & Criteria: Endangered B2ab(iii,v) ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Assessor(s): Impson, D. & Swartz, E.
Reviewer(s): Snoeks, J. (Freshwater Fish Red List Authority) & Darwall, W. (Freshwater Biodiversity Assessment Unit)
Justification:
Most the major decline happened in the mid-20th century because of the introduction of alien fishes, mainly smallmouth bass. Current decline is occurring at a much slower rate than previously experienced. Therefore criterion A does not apply. Actual area of occupancy (AOO) has been calculated as 189 km² meeting the criterion B2 threshold for Endangered. Apart from occasional unconfirmed reports from some sections of the Breede River system, existing populations are severely fragmented with probably no migration between the major populations that remain. Only three locations remain (Heks River, Brandvlei Dam and Sanddrift Dam). Some introductions have been made into farm dams but there is no evidence yet that the introductions are successful. A dam in Porterville was stocked with this species, but recently bass was introduced stopping recruitment. The only remaining riverine population of this species has been invaded by smallmouth bass recently. The general quality of the riverine habitats is continually declining because of the intensive nature of expanding agricultural activities in the region, which include the use of pesticides, river channelisation and over-abstraction of water. The Brandvlei Dam population has been a stronghold for this species over the years, but is vulnerable to invasion by alien fishes. There are already unconfirmed reports of sharptooth catfish (Clarias gariepinus) in the dam. Brandvlei Dam is known to have a substantial viable population and Sanddrif Dam is suspected to also have many recruiting individuals. The riverine populations, however, have very low numbers of adult fish (probably less than 1,000) and are probably decreasing due to further invasion by smallmouth bass. This loss, however, only affects a small proportion of the overall population therefore criterion C does not apply. Overall population size is expected to be large, therefore criterion D does not apply. No quantitative analysis has been conducted, therefore, criterion E is not applicable. The resulting assessment classifies the species as Endangered under B2a(ii) and B2b(iii,v).
History:
1996 Vulnerable
1994 Vulnerable (Groombridge 1994)
1990 Vulnerable (IUCN 1990)
1988 Vulnerable (IUCN Conservation Monitoring Centre 1988)

Geographic Range [top]

Range Description: Endemic to the Berg and Breede River Systems of the Western Cape Province, South Africa (Skelton 2001). Originally widespread in both systems, it is now common in less than 5% of its original range and it seems to have gone extinct in the Berg River system.
Countries:
Native:
South Africa (Western Cape)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Barbus andrewi was originally abundant in both the Berg and Breede river systems (Harrison 1952). The introduction of Microterus dolomieu in the 1940s into both systems led to a slow collapse of recruitment of this long lived species. CapeNature, the provincial conservation agency for the Western Cape Province, considered the species extinct in the Berg System by 2000 (Impson 2003). The Breede system is characterised by very low numbers of whitefish in lotic environments, due to bass (Micropterus) invasion and habitat degradation. The Hex River is the only known lotic population that has good recruitment. Brandvlei and Sandrif dams in the Breede catchment have very large Barbus andrewi populations. Six farm dams have been stocked with this species, but not enough time has passed to evaluate whether these transplantations have been successful.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Habitat has not been studied well. Adults prefer deep pools of larger rivers, where rock or overhanging vegetation cover is present. Juveniles are common in riffles. They also thrive in impoundments (Impson 2001). Biology is also poorly studied. Adults are omnivorous, feeding on bottom dwelling invertebrates and algae (Skelton 2001). Juveniles feed on zooplankton and small aquatic invertebrates. Breeds in late spring, when water temperatures exceed 20°C, and schools of adults migrate to deep (1 to 1.5 m) riffles and spawn. Spawning was observed in late morning. Fecundity is high with 2.5 kg captive females yielding about 100,000 eggs (Smith 1987). Spawns successfully in impoundments, with spawning occurring over gravel and rocky beds in shallow water (Impson 2001). A genetic study based on mitochondrial DNA cytochrome b of the Berg and Breede populations indicated little variation between these two river systems (Impson and Bloomer 1999).
Systems: Freshwater

Threats [top]

Major Threat(s): Major threats are invasive alien fishes and habitat degradation, with experts agreeing that the predatory impacts of smallmouth bass (Micropterus dolomieu) are the most significant factor driving this species to extinction. Bass (Micropterus) species dominate preferred Barbus andrewi habitat and now halt their recruitment. The Berg and Breede catchments are characterised by intensive agricultural development, culminating in over-abstracted and polluted rivers that have become a haven for other alien fish species such as Cyprinus carpio and Oreochromis mossambicus. These two species are competitors to Barbus andrewi.

Conservation Actions [top]

Conservation Actions: The species is listed as “endangered” by the provincial Nature Conservation Ordinance making capture and kill illegal. Unfortunately, less than 1% of its preferred habitat is inside protected areas. B. andrewi has been successfully cultured (Smith 1987, Bok and Immelman 1989) for re-stocking purposes and to stock suitable impoundments. CapeNature, the provincial conservation agency, has established a dedicated whitefish fund to capacitate recovery efforts. These efforts involve angler awareness, riparian land-owner education and promoting this species as an angling alternative to bass (Micropterus) and trout (Oncorhynchus mykiss and Salmo trutta) within its distribution range. Barbus andrewi have been stocked into several farm dams to create “safe” populations for later recovery efforts. Such efforts will involve the eradication of alien fish species from rivers with suitable Barbus andrewi habitat.

Citation: Impson, D. & Swartz, E. 2007. Barbus andrewi. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 26 October 2014.
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