|Scientific Name:||Pseudobarbus serra Peters, 1864|
Barbus serra Peters, 1864
|Taxonomic Source(s):||Yang, L., Sado, T., Hirt, M.V., Pasco-Viel, E., Arunachalam, N., Li, J., Wang, X., Freyhof, J., Saitoh, K., Simons, A.M., Miya, M., He, S. and Mayden, R.L. 2015. Phylogeny and polyploidy: Resolving the classification of cyprinine fishes (Teleostei: Cypriniformes). Molecular Phylogenetics and Evolution 85: 97-116.|
It must be noted that Pseudobarbus serra formerly belonged to the genus Barbus, but following the work of Yang et al. (2015), the genus Pseudobarbus was expanded to include additional species resulting in the renaming of the Clanwilliam Sawfin to ‘Pseudobarbus’ serra (Skelton 2016).
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Impson, D., Van der Walt, R. & Jordaan, M.|
|Reviewer(s):||Raimondo, D. & Harrison, I.J.|
|Facilitator/Compiler(s):||Van Der Colff, D.|
Anecdotal reports indicate that major declines of Clanwilliam Sawfin (Pseudobarbus serra) occurred between 1930 and 1970, after the introduction of Smallmouth Bass (Micropterus dolomieu) into the Olifants-Doring River System (ODRS). The current extent of occurrence (EOO) is estimated at 5,188 km2 (based on the total area within a minimum convex polygon around all known occurrences) whilst the area of occupancy (AOO), is estimated at 128 km2 (based on a 2x2 km2 grid overlay on the range map). From the subpopulations present, 13 locations have been determined. There are large subpopulations in Beaverlac Dam, an offstream impoundment in the Ratels Catchment, and in an instream dam on the Boontjies River within Bushmanskloof Nature Reserve above a waterfall barrier. The latter is extra-limital, but within the greater ODRS. The species is continuously experiencing threats from predation and competition from invasive alien fish. It is also impacted by habitat degradation due to unsustainable agricultural development caused mainly by over-abstraction during the dry season; reducing water quality and habitat availability. This species is known from more than 10 locations therefore cannot qualify as threatened but is listed as Near Threatened B1b(iii,v)+2b(iii,v). It is a borderline threatened species and needs to be monitored.
|Previously published Red List assessments:|
|Range Description:||Clanwilliam Sawfin is endemic to the Olifants-Doring River System (ODRS), Western Cape Province, South Africa (Skelton 2001). The species was originally widespread in the system, inhabiting both mainstream and tributary areas (van Rensburg 1966, Gaigher 1973, Paxton et al. 2002). The introduction of Smallmouth Bass into the ODRS in the 1940s (De Moor and Bruton 1988), and its subsequent invasion and establishment in mainstream environments, caused recruitment collapse of the species. This resulted in localized extirpation of this species from the middle and lower Olifants River and from several tributaries prior to the 1970s. |
Recent surveys have revealed new subpopulations in the Dwars, Boschkloof, Eselbank and Langkloof rivers (van der Walt et al. 2014) and Beaverlac Dam (translocated population) on the Ratels Catchment. There are at least 13 subpopulations present, five in the Olifants Catchment area (Olifants Gorge - Boschkloof River, Dwars River, Ratels River, Beaverlac Dam in Ratels Catchment and Jan Dissels River) and eight in the Doring Catchment Area (Gif, Oorlogskloof, Biedouw, Tra-tra, Eselbank, Driehoek-Matjies, Langkloof) and an extra-limital one in an artificial impoundment at Bushmanskloof Nature Reserve.
Native:South Africa (Northern Cape Province, Western Cape)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Recent fish surveys by the provincial conservation agency CapeNature indicate that the following rivers have healthy subpopulations (good recruitment and large numbers of fish); Biedouw, Driehoeks, Gif, Jan Dissels, Matjies, Olifants (gorge area), Oorlogskloof-Kobee and Ratels. New subpopulations have been recorded in the upper Boschkloof, Dwars, Eselbank and Langkloof rivers, but these are small populations with very restricted distributions because of bass invasion. There are thriving subpopulations in two off-stream dams: Beaverlac Dam in the Ratels Catchment and the main dam at Bushmanskloof Nature Reserve, on the Boontjies River in the Brandewyn Catchment. The latter dam population is extra-limital in that the dam is above a large waterfall which use to be a barrier to fish (Impson and Tharme 1998). There are thus 11 riverine subpopulations and two dam subpopulations. Where alien fish, especially bass (Micropterus spp.) predominate in the ODRS, the adult fish of this species is present in very low numbers (for example Doring River), or is locally extirpated (for example middle and lower reaches of Olifants River). Surveys of the Doring River indicate that numbers are declining (Paxton 2008).|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Common in rivers of variable size with good habitat and an absence of alien fishes. Juveniles are primarily pool dwellers (Gore et al. 1991) of foothill river zones whereas adults prefer larger, deeper pools in transitional zones of rivers. It is omnivorous, feeding primarily on aquatic insects (van Rensburg 1966). It is a relatively large cyprinid attaining 3.04 kg (Skelton 2001) but is a slow growing species with 1, 3 and 10 year old fish attaining 90, 200 and 390 mm standard length (SL) respectively (van Rensburg 1966). Breeds from late spring (October) to summer (December), with small schools of adults gathering over cobble beds in shallow riffles. It is a repeat spawner and also a multiple spawner (Paxton 2008). It is likely that the species also breeds in dams with rocky shoreline habitat as a recruiting subpopulation is present in Beaverlac Dam which lacks a suitable in-flowing river. Usually co-occurs with other large cyprinids such as Clanwilliam Yellowfish (Labeobarbus seeberi) and Clanwilliam Sandfish (Labeo seeberi), but also small cyprinids such as Redfins (Pseudobarbus spp.) and Rock Catfishes (Austroglanis spp.).|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Use and Trade:||It is listed as an endangered Wild Animal under Schedule 1 of the Provincial Nature Conservation Ordinance for the Western Cape, thereby preventing the collection and trade of the species without a permit. It is also listed nationally as a Threatened or Protected Species under South Africa’s National Environmental Management: Biodiversity Act of 2004. It is occasionally caught by anglers, especially fly fishermen, who generally target the species on a catch and release basis. It is also occasionally caught for subsistence, but not regularly enough to consider it as a use. Translocations of this species are controlled by CapeNature’s Indigenous Fish Utilisation policy (Jordaan et al. 2016). It is sometimes kept in public aquaria for awareness and education purposes.|
|Major Threat(s):||This species usually co-exists with Clanwilliam Yellowfish and faces the same threats, namely predation by and competition with invasive alien fishes and habitat degradation by ecologically unsustainable agricultural development. The main agricultural threat is over-abstraction of many tributaries in the dry season (summer) which limits habitat availability and reduces water quality when recruitment is taking place. Smallmouth Bass are regarded as the most serious invader, but there is a growing concern about the recent spread of Sharptooth Catfish (Clarias gariepinus) in the system due to illegal introductions for angling purposes.|
|Conservation Actions:||There are viable populations in several rivers, including those in Protected Areas such as the Cederberg Wilderness Area, and Matjies River and Oorlogskloof Nature reserves as well as in private nature reserves such as Grootwinterhoek Protected Environment and Bushmanskloof Nature Reserve (the latter is an extra-limital subpopulation). Despite occurring in formally protected areas, many rivers in protected areas are invaded by alien fishes, including Smallmouth Bass. The species is listed as endangered by the provincial Nature Conservation Ordinance making catch and release compulsory for anglers. Species conservation is now focused on the conservation of its habitat, especially the “Fish Sanctuary Areas” that have been identified as National Freshwater Ecosystem Priority Areas (Nel et al. 2011). CapeNature, the provincial conservation agency, has embarked on a programme of river rehabilitation projects that involve localised eradication of alien fishes from “Fish Sanctuary Areas”. The Krom, Biedouw and Breekkrans rivers have been identified for rehabilitation between 2016 and 2020. CapeNature has also recently published a report on the priority rivers for fish conservation in the ODRS, which is targeted at stakeholders involved in management of catchment areas and rivers (Impson et al. 2016).|
|Citation:||Impson, D., Van der Walt, R. & Jordaan, M. 2017. Pseudobarbus serra. The IUCN Red List of Threatened Species 2017: e.T2569A100148283.Downloaded on 21 February 2018.|
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