S. Afr. J. Zool. 1995, 30(3) 71 Patterns of distribution and conservation status of freshwater fishes in South Africa P.H. Skelton' J.L.B. Smith Institute of Ichthyology, Private Bag 1015, Grahamstown, 6140 Republic of South Africa J.A. Cam bray Albany Museum, Somerset Street, Grahamstown, 6140 A. Lombard and G.A. Benn FitzPatrick Institute of African Ornithology, University of Cape Town, Private Bag, Rondebosch, 7700 Received 15 February 1995; accepted 4 May 1995 The combined fish collection databases of the Albany Museum and the J.l.B. Smith Institute of Ichthyology are used to identify hotspots of endemism and threatened fish distributions in South Africa. Hotspots of fish species richness occur in the north-eastern lowveld sectors of South Africa and along the ecotone between the tropical/ subtropical and temperate faunal zones. Hotspots of endemic fish richness occur within both the tropical and temperate faunal regions, notably in the Olifants River system, Western Cape and in areas of high relief such as the Cape Fold Mountains, the Amatola-Winterberg (Eastern Cape), and the Drakensberg Escarpment (Kwazulu/ Natal-Eastern Transvaal). Threatened taxa are concentrated in the hotspots of endemic species richness which coincide largely with areas of major river conservation concern. There is limited scope for fish conservation within the ambit of formal (or informal) declared reserves, and the survival of the fauna depends on the success of river catchment conservation management. The value 01 museum collections in identifying areas of conserva· tion concern for freshwater fishes is emphasized, and highlights the importance of well-preserved voucher spec­ imens for biodiversity conservation. Die gekombineerde visversamelingsdatabasisse van die Albany Museum en die J.l.B. Smith-Instituut vir Viskunde is gebruik om brandpunte van endemisme en die verspreidings van bedreigde vissoorte in Suid-Afrika te identifiseer. Brandpunte van visspesierykheid kom voor in die noord-oostelike laeveldstreek van Suid-Afrika asook in die ekosone tussen die tropiese/subtropiese en gematigde streke. Brandpunte van inheemse vis­ soortverspreiding kom voor in be ide die tropiese en gematigde streke, veral in die Olifantsrivierstelsel (Weskaap) en in hooggelee streke soos die Kaapse Plooiberge, die Amatola-Winterberge (Ooskaap), en die Drakensberg (Kwazulu/Natal-Oos Transvaal). Bedreigde spesies is hoofsaaklik gekonsentreer in die gebiede van endemiese visrykheid wat grootliks ooreenkom met die belangrikste riviertJewaringsgebiede. Daar is . ) beperkte ruimte vir visbewaring binne die formele (01 informele) verklaarde natuurreservate, en die oorlewing 9 0 van die vislewe hang a1 van die suksesvolle bestuur van die rivieropvanggebiede. Die waarde van museumver­ 0 samelings om bewaringsgebiede vir varswatervisse te identifiseer word hierdeur beklemtoon, asook die bel an­ 2 d grikheid van goed gepreserveerde bewyseksemplare vir die bewaring van die biodiversiteit. e t a To whom correspondence should be addressed. d * ( r e h s i The natural distribution of many animals and plants in South is extensive. Furthermore rivers arc dynamic longitudinal sys­ l b Africa is governed largely by the complexity of climate tems so that impacts at one place are transmitted downstream u P (Stuckenberg 1969). In the case of freshwater fishes, hydro­ for distances proportional to the scale and nature of the e graphic and geomorphological history are equally important h impact. This includes introduced aquatic organisms that often t factors determining distribution patterns (Skelton 1994). y disperse widely throughout aquatic systems unless prevented b Stuckenberg's (1969) Effective Temperature map (Figure 1) by barriers from doing so. These are all vital considerations to d e provides a measure of the influence of climate on distribution. t the conservation of freshwater fishes. n The 16" ET isotherm is particularly useful for describing a a The restriction of fishes to rivers and lakes both facilitates r g reasonably good division between the distribution of the and complicates the monitoring of fish status and distribution. e Zambezian and the southern temperate freshwater fish faunas c Rivers are discrete linear entities so that distribution records n e (Skelton 1994). Freshwater dispersant fishes are entirely c can be traced to particular points more easily than in open ter­ i l dependent on freshwater habitats for their existence and sur­ restrial systems. Most fishes are uncommon and need to be r e vival, and connections between freshwater bodies therefore d identified by trained biologists or taxonomists, and reliable are the only reliable means of natural dispersal. n distribution records require voucher specimens for scientific u The dependence of fishes on the aquatic environment y verification. Museum collections are therefore essential and a renders them extremely vulnerable to human demands, uses w usuall y the best means for determining distribution and con­ e and abuses of freshwater resources. South Africa is a predom­ t a servation status of fishes. inantly dry country and its rivers and lakes are heavily used G The present objectives are to analyse fish distributions in t and impacted on as sources of frc'shwater for human needs e South Africa, Lesotho and Swaziland, based on actual records n (DWA 1986). As key integrals of landscape processes rivers i b and lakes are affected by practically every activity within the in museum collections, in order to identify patterns of species a S landscape (Davies, O'Keeffe & Snaddon 1993), and in South richness and endemism that might focus and optimize efforts y b Africa. as elsewhere. anthropogenic impact on the landscape lo conserve these organisms. d e c u d o r p e R 72 S. Afr. Tydskr. Dierk. 1995,30(3) considered. The geographical scopc of the study is restricted to the Repuhlic of South Africa and the Kingdoms of Lcsotho and Swaziland. For convenience the area encompassed by the three countries will be referred to as 'South Africa'. Refer­ ence to endemicity within this area is taken within a liberal framework of river basin catchments, i.e. a species is consid­ ered to he endemic to 'South Africa' if it occurs only within the horders of South Africa or is restricted to the river systems that partly or entirely occur within the borders of South Africa. In South Africa freshwater fish collections are now concen­ trated in two Grahamstown museums, the J.L.B. Smith Insti­ tute of Ichthyology and the Alhany Museum. For this study the freshwater fish collection records for South Africa of both museums have been combined to construct a GIS (Arciinfo) 500 km distribution database of records covering 727 quarter degree squares (QDS) (Figure 2). The scale of data analysis and map Figure 1 Effective Temperature isotherms in southern Africa (after production was a quarter degree square (15' by IS') [see Stuckenberg, 1969). Right slant shading indicates tropical area, left detailed methodology in Lombard (1995)]. slant shading indicates temperate area. The status of threatened species is based on the assessment given by Groombridge (1993) in the lUeN Red List of Materials and methods Threatened Animals. Non-endemic threatened species are taken from Skelton (1987). This study is restricted to indigenous freshwater dispersant fishes, i.e. primary and secondary freshwater fishes which are defined according to their tolerance (secondary) or intoler­ Freshwater fishes in South Africa ance (primary) of hrackish water (Myers 1949). Excluded There are 15 families, 29 genera and 94 indigenous freshwa­ therefore are species of marine origin or affinity, and diadro­ ter fishes in South Africa (Table I) and a further 18 alien spe­ mous species such as anguillid eels. Alien species also are not cies have been introduced and are estahlished in the country's . ) 9 0 0 2 d e t a [J 1 d 8 ( r e h 9 16 " s i l b u • 17 - 24 P ') e h t • 25 - 32 y b d e • t n a r g ~- e c n \ e c i l r e d n u y a w e t a G t e n i b a S Figure 2 Indigcnous fish species richness plotted from records in the fish collections of the lL.B. Smith Institute of Ichthyology and the y b Albany Museum, Grahamstown. d e c u d o r p e R S. Afr. J. Zoo!. 1995, 30(3) 73 Table 1 Indigenous freshwater fishes of South Africa, Table 1 Indigenous freshwater fishes of South Africa, indicating faunal status, endemicity, conservation sta­ indicating faunal status, endemicity, conservation sta­ tus. Abbreviations: Z = Zambezian; ST = southern tem­ tus. Abbreviations: Z = Zambezian; ST = southern tem­ perate; E = endemic to South Africa; • = endemic to a perate; E = endemic to South Africa; • = endemic to a single drainage basin, .. = endemic to less than three single drainage basin, •• = endemic to less than three drainage basins; .., = endemic to several drainage drainage basins; ... = endemic to several drainage basins; En = endangered; V = vulnerable; R = rare; S = basins; En = endangered; V = vulnerable; R = rare; S = safe; K = status not known sufficiently; SA = South safe; K = status not known sufficiently; SA = South Africa Africa (Continued) Species Fauna Endemicity ConselVation Species Fauna Endemicity Conservation Pro/(}pteru<~ anna'lens z VISA O[J.mridium perinrueyi Z VISA Marcuseniu.{ macrolepidotus z Pseudobarbus afer ST R PetrocephaiuJ catustoma z Pseudobarbus asper ST E" R Kneria auriculata Z RlSA Pseudobarbus burchelli ST R-S'] Barbus aeneus ST Pseudobarbus burgi ST E" En Barbus almhamiltoni Z Pseudobarbus phlegethon ST E' En Barbus amato/ieus ST E" Pseudobarbus lenui.{ ST E" V Barbu.f andrewi ST E" En Pseud(!barbus quathlambae ST E' En Barbu.f annectens Z Varlcorhinus neispruitens;,{ Z E" Barbus anopfus ST E*** Brycinus imberi Z Barbus aTKenteuJ Z Brycinus lateralis Z RISA Barbus bifrenatus Z Hydrocynus vitw!uJ Z Barbus brevipinnis Z E" R Micralestes acutidens Z Barbus ea/idus ST E' R Auslro):lanis barnardi ST En Barbus capen.~is ST E' R AUJlTORlani.f Nilli ST E' R Barbus erube.H.:ens ST E' E AUJlroglani.f .Kiater; ST E' KJV Barbus euraenia Z Sellithe intermediu.f Z Bm'bus gurney; ST E*** Amphiliu.f nata{ensis Z Barbu.f IlOspe.f ST E' R Amphilius uranoscopus Z .