P.P. Ramollo, M. SchumannOur aNaturend W.A.J. (201Pretorius2) 10: 8-1/ 6Our Nature (2012) 10: 8-16 Freshwater Fish of the Oorlogskloof River, Northern Cape Province,

P.P. Ramollo1*, M. Schumann2 and W.A.J. Pretorius3

1Northern Cape Department of Environment & Nature Conservation (DENC) Private BagX6102, Kimberley, 8100, South Africa 2Northern Cape Department of Environment & NatureConservation (DENC), Oorlogskloof Nature Reserve P.Box142, Nieuwoudtville 8180, South Africa 3Northern Cape, Department of Environment & Nature Oorlogskloof Nature Reserve P. Box 142 Nieuwoudtville 8180,South Africa *Email: [email protected]

Abstract The freshwater fish of Oorlogskloof River were sampled in March 2010. The study aimed to determine the distribution and relative abundance of freshwater fish in the Oorlogskloof River. A total of 4643individuals represented by five fish species belonging to two families were sampled. The Barbus anoplus was only sampled in the upper reaches of the Oorlogskloof River gorge while endangered Labeobarbus capensis appeared downstream in the Oorlogskloof River. Barbus serra dominated the fish species in the system. The invasion of Tilapia sparmanni in this system was confirmed during the survey andthe species appeared to be widespread throughout the system. At this stage it does not appear to be posing a serious threat to the endangered fish species. The Oorlogskloof River can be considered as a potential refuge site for the conservation of some endemic and threatened freshwater fishes of South Africa.

Key words: Abundance, conservation, distribution, endemic, Oorlogskloof River

Introduction The Oorlogskloof River plays a pertinent Reserve, is of unparallel importance in the role as a spawning and nursery site for Olifants-Doring system as a fish sanctuary endemic and endangered fish species. The (Impson, 1995).On the southern side of the sound conservation management of the Oorlogskloof Nature Reserve, the Oorlogskloof River within the 5 000 hectare Oorlogskloof River becomes known as the Oorlogskloof Nature Reserve commenced in Kobee River where the Klein Kobee River 1987. The relative inaccessibility of the joins it. The Kobee is a tributary of the Oorlogskloof River, where it flows through which runs into the Olifants the Oorlogskloof gorge south of River at Melkboom in the Nieuwoudtville, has prevented Province. The Kobee River probably forms destruction and other impacts prevalent an important link for the clanwilliam along its upper catchment and other yellowfish (Labeobarbus capensis), tributaries of the Olifants-Doring system. (Barbus serra) and clanwilliam sandfish This has ensured that the Oorlogskloof (Labeo seeberi) on their migration from the River, within the Oorlogskloof Nature Doring River to the spawning and nursery

8 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 grounds in the Oorlogskloof River gorge catchment of the Oorlogskloof River north (Abrahams and Pretorius, 2000). of the Oorlogskloof Nature Reserve. These The Oorlogskloof River has a relatively were subsequently netted using a seine net low diversity of indigenous fish species and and proved to be banded tilapia (Tilapia is dominated by cyprinids. Abrahams and sparmanni). In March 2010 a survey was Pretorius (2000) recorded a total of six fish conducted in the Oorlogskloof River by a species in the Oorlogskloof-Kobee River, team of officials from the Northern Cape with two alien species namely the Department of Environment and Nature (Micropterus dolomieu) Conservation and CapeNature. The aim was and bluegill sunfish (Lepomis macrochirus) to investigate the distribution and recorded in the lower reaches of the abundance of the indigenous species known Oorlogskloof River. A natural barrier of to occur in this river, as well as investigate huge boulders is located in the lower whether the T. sparmannihad invaded the reaches of the Oorlogskloof River (south of Oorlogskloof River from the the Oorlogskloof Nature Reserve) and Nieuwoudtville municipal dam. The appears to be preventing these two species Nieuwoudtville area was flooded in July from migrating further upstream and 2007 making this a distinct possibility. reaching the Oorlogskloof Nature Reserve. Both the endangered sawfin (B. serra) and Materials and methods clanwilliam sandfish (L. seeberi) are endemic and successfully within the Site description Oorlogskloof River. The value of the The Oorlogskloof River originates in the reserve for indigenous fish conservation is Roggeveld Mountains near Calvinia in the further enhanced, as Barbus anoplus also Northern Cape Province, South Africa. It occurs in the Oorlogskloof River system. can be regarded as naturally seasonal, with According to Impson (1995) B. anoplus in flows in summer ceasing until the first the Oorlogskloof Rivermay be a subspecies, major rains in the catchment in winter. as it is genetically distinct from other However, the flow regime is highly variable populations of the Olifants River and and unpredictable (Abrahams and Pretorius, Orange-Vaal River system. The clanwilliam 2000). In its upper catchment, it flows yellowfish (L.capensis), classified as through livestock farms and arable fields. vulnerable, has also been recorded in the Fields are often overgrazed and much of the Oorlogskloof and Kobee rivers. The last riparian vegetation is disturbed with alien time it was recorded in the Oorlogskloof terrestrial plants such as mesquite (Prosopis Nature Reserve was in 1982 and the cause glandulosa). An area approximately six for its decline in the reserve is unknown and kilometres upstream of the northern need further investigation (Abrahams and boundary of Oorlogskloof Nature Reserve Pretorius, 2000). has been invaded by mesquite and blue gum In 2009 reports were received that (Eucalyptus camaldulensis). The there were numerous small fish in the Oorlogskloof Nature Reserve, where most Nieuwoudtville municipal dam (pers. of the survey took place, is situated on the comm. Pretorius), which lies within the Bokkeveld Plateau in the Nieuwoudtville 9 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 area and falls within an area marked by N = total number of individuals in sharp climatic, geomorphological and all species, biological transition (Abrahams and ln = natural log, = sum of the values Pretorius, 2000). South of Nieuwoudtville for each species. Therefore the Oorlogskloof River drops into a deep percentage (%Pi) = the number of ravine which forms the eastern boundary of individuals within a species (ni) Oorlogskloof Nature Reserve. The terrain divided by the total number of bordering the river is rocky and almost individuals (N) present in the entire inaccessible and has prevented habitat sample x 100.The relative destruction and other adverse anthropogenic abundance gave comparisons of impacts prevalent along its upper catchment. diversity at all the sampled sites.

Study area Results The same 32 sites sampled in 2000 by M. dolomieu and L. macrochirus have Abrahams and Pretorius were sampled again previously been recorded in the lower in March 2010. These sites were all located reaches of the Oorlogskloof River, below a in the Oorlogskloof River gorge above the natural barrier. This study showed that Klein Kobee River and Oorlogskloof River these alien fish were still not present above junction. In addition the Nieuwoudtville the natural barrier. The fish species recorded municipal dam was also sampled. Fish were in the Oorlogskloof river gorge above the collected using a seine net (6m x 1m) at natural barriers were namely: B. serra, B. each sampling site. Gill nets were not used anoplus, L. seeberi, L. capensis and due to the high numbers of endemic and translocated T. sparmanni. Of the endangered fish species in the study area. A indigenous fish caught in the Oorlogskloof subsample of 50 specimens was measured River B. serra comprised the largest for the standard length and total length and proportion of 80.4% (n = 3735), followed the remaining were counted for total by L. seeberi 8.01%(n=372), B. anoplus numbers. 8.00% (n = 371), L. capensis0.60% (n=28) and T. sparmanni 3.00% (n = 137) occurred Data Analysis throughout the range sampled with the small Fish data collected was analyzed using species B. anoplus largely restricted to the Shannon-Wiener Index (H) to evaluate Oorlogskloof River (Tab. 1). species diversity. The index is determined by both the number of species and the even a) B. anoplus distribution of individuals among those During this study the indigenous B. anoplus species (relative dominance). It was was distributed in low numbers and calculated using the following equation: contributed a relative abundance of 8.0% (Tab. 1). The population appeared to be H = - Pi (lnPi), more abundant in upstream than in where Pi (relative abundance) = ni/N, downstream. All the sites where it was ni = the number of individuals recorded comprised predominantly of within a species, juveniles of 2-4 years of age and ranged in 10 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 length from 29 mm to 95 mm. Most 145mm were also present. Very small individuals were recorded at site 2 (n=183) juveniles ranging from 30mm were found and site 3 (n=110) (Tab. 1). Most more frequently at other sites. individuals appeared to be embedded with digenean cysts. Discussion Generally in aquatic ecosystem there are b) L. seeberi factors that affect fish species composition, During this study L. seeberi(endangered) distribution and abundance. The variation in was found to be substantially distributed in individual growth in fish populations occur the Oorlogskloof River system. It because growth is strongly dependent on contributed a relative abundance of 8.01% food availability, flow dynamics and water (Tab. 1). Total length ranged from 22mm to temperature (Persson and De Roos, 2001; 270mm with a good distribution of DeAngelis Roseet al., 1993; Cincotta and juveniles, sub-adults and adults. Staffeur, 1984). However in natural populations there is a trend of species size c) B. serra dissimilarity amongst individuals born at the The endangered B. serra was the most same time in the same environment, abundant species in the system and it affected and influenced by biotic and abiotic exceptionally comprised of80.4%of the total factors (Persson and De Roos, 2001; Husset catch (Tab. 1). The bigger the pools the more al., 2007). Depending on size reached at fish were recorded during this study. Its certain times of the season, variability in life populations were dominated by juvenile fish history among individuals can be crucial for and subadults. It’s standard-lengths varied whether a total recruitment failure will take between 16mm and 270 mm. place or whether some larger individuals can survive (Huss et al., 2007). When d) L. capensis favourable conditions are attained, the The numbers of endemic L. capensis were survival improves and the dominant group relatively low, contributing to a relative begins to grow. abundance of0.60% (Tab. 1). They were During this survey, only a hand drawn recorded at only six of the sampled sites. seine net was used to sample the fish Total length ranged from 75mm to 125mm. populations. This net may have been biased Its populations were dominated by sub in that only fairly shallow pools, or shallow adults fish. areas in large pools, could be netted and therefore larger individuals may be absent e) T. sparmanni from the sample. However, despite a During this study T. sparmanni comprised possible bias towards smaller size, the fish 3.00% of total catch (Tab. 1).It appeared results manifested that the Oorlogskloof remarkably widespread in the system with River contains healthy endemic fish site 14 comprising the highest recorded populations with juveniles of sawfin and number of (n=45).Most of the T. sparmanni sandfish in particular, occurring in multiple juveniles at the sampled sites were between pools netted. The Oorlogskloof-Kobee 30mm and 80mm, but sub adults of up to Rivers also provide connectivity for the 11 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 Table 1. Species composition recorded during the sampling surveys 2010

L. T. Locality B. anoplus B. serra capensis L. seeberi sparmanni Total Site A1 4 17 20 41 Site 1 53 49 4 106 Site 2 183 27 75 3 288 Site 3 110 15 83 208 Site 4 4 18 3 25 Site 5 7 50 3 60 Site 6 141 1 9 151 Site 7 Site 8 442 33 1 476 Site 9 11 11 Site 10 1 1 Site 11 1 1 Site 12 120 5 125 Site 13 58 2 1 61 Site 14 2 1 45 48 Site 15 5 402 23 2 432 Site 16 120 1 12 133 Site 17 72 24 96 Site 18 5 88 14 5 112 Site 19 63 3 66 Site 20 49 3 3 55 Site 21 46 6 52 Site 22 80 1 81 Site 23 219 6 225 Site 24 20 1 1 9 31 Site 25 181 3 5 189 Site 26 124 14 7 3 148 Site 27 51 8 26 11 96 Site 28 353 3 1 357 Site 29 40 2 42 Site 30 49 3 52 Site 31 687 1 11 5 704 Site 32 152 3 15 170 Total 371 3735 28 372 137 4643 % pi 8.00% 80.4% 0.60% 8.01% 3.00% 100%

182 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 upstream migration of these fish and the individuals may die as the shallow, deep and dispersal of sub adult fish from their nursery remnant pools dry out. grounds to the main stem Doring River (Impson, 1997). b) L. seeberi L. seeberi prefers pool waters and deep runs a) B. anoplus of the river (Skelton, 2001).It is distributed This species prefers cold waters and occurs in the Olifants-Doring river system but in a wide range of varying from seems to be absent in the Upper Olifants shallow streams to the shorelines of large river. The invasive alien fish species such as impoundments (Cambray et al., 1978; M. dolomieu, M. salmoides, and L. Skelton, 2001). It breeds in the summer macrochirus coupled with agricultural when rivers are filledwith water. It is activities have made a significant population omnivorous and is preyed upon by larger decline of L.seeberi (Impson 1997). The fish and birds. Unlike other fish species that results of this study concurred with the migrates upstream in order to spawn, study conducted by Abrahams and Pretorius spawning migration of B. anoplusis not (2000) who reported high numbers at most necessary because they can spawn locally if of the sampled sites. The abundance of L. there is an increase in the water flows and seeberi in the river can probably be inundation of the marginal vegetation attributed to successful spawning due to (Cambray et al., 1978). intact habitat, and the lack of the more During this study the indigenous B. aggressive predatory alien fish, as well as anoplus was distributed in low numbers and the presence of unlimited food availability contributed a relative abundance of 8.00% from the decomposed vegetation. This in (Tab. 1). The high numbers of B. anoplus turn encourages the rapid increase of occurring upstream in the Oorlogskloof freshwater invertebrates, a diet for several Nature Reserve can probably be attributed other fish species. Results of fish to bigger size of the pools with associated measurements showed that the Oorlogskloof diversity of marginal vegetation. The river populations have a good distribution of number of juveniles versus adults could be juveniles, sub-adults and adults. What was due to a bias in the seine netting, with adults encouraging was that juveniles with <50mm possibly preferring the deeper vegetated total length occurred at the sites occupied by areas of the pools. According to Cambray the translocated species T. sparmanni. and Bruton (1985), size of 73mm fork Indications are therefore that the T. length females reflects age of 3-4 and size sparmanni may not pose a threat to 60mm of males reflects 2-3 years. Most of abundance and distribution of L. seeberiat the individuals recorded during this study this stage. According to Skelton (2001) the appeared to be within the aforementioned decline in the recruitment of L. seeberi is range. B. anoplus can survive harsh caused by poor water quality, habitat environmental conditions but if the area is modification and dam construction which affected by climate change many cause significant changes in the annual flow

193 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 patterns. The damming of the Oorlogskloof sparmanni is low and therefore not affecting River and habitat destruction should be the distribution and abundance of fish at this discouraged in order to ensure the juncture. The increase in the numbers of B. conservation of this species. Climate change serra at some of the sites may have been the predictions should also be taken into result of a variety of substrate, appearance account during any conservation planning, of submerged vegetation and woody debris as an increase in extreme events such as which are an important refuge for small fish. droughts, could cause a crowding effect on Another factor may have been changes in fish resulting in massive fish kills due to the water velocity and depth at certain sites, lack of oxygen. Due to the relative which favours the establishment of these abundance of L. seeberi and good age species. distributions recorded, this population is of huge importance and due to its conservation d) L. capensis status; it should be monitored regularly to L. capensis is endemic to the Olifants- determine population decrease. Doring River system and it prefers deep pool waters (Skelton, 2001). It is c) B. serra widespread in the Doring River but the This fish favours deep pools(Skelton, numbers appear to be declining due to bass 2001).It used to be widespread and invasion/predation (Paxton et al., 2002). substantially abundant in the Olifants River The numbers recorded during this study but the number have decline due to invasive supported previous findings of Abrahams alien fish and habitat degradation and and Pretorius (2001) which recorded low fragmentation (Impson, 1999).In late spring numbers of fish. Results showed a poor and summer the school of adults migrate reproductive success or perhaps high upstream to shallow riffles and cobbles to mortality of juveniles, which likely will lead spawn (Kinget al., 1998; Skelton, 2001). to long-term population decline. According to Paxtonet al. (2002) the Causes for the poor success of L. Oorlogskloof-Kobee River system is the capensis in this system could possibly be most important in terms of B. serra habitat ascribed to environmental flows, habitat and recruiting populations are known to integrity and competition of food or perhaps occur in the Oorlogskloof Nature Reserve. invasion by T. sparmanni. The mature The high numbers and good age distribution individuals of L. capensis migrate upstream of B. serra recorded during this survey to spawn in summer in response to the indicateda healthy population status and that increased water flows (King et al., 1998; there is still significant recruitment of this Skelton, 2001).There are indications that species in the system. Relatively high they might not spawn every year due to numbers of fish were collected and showed environmental factors, which may be why distinct cohorts and thus supported the juvenile fish numbers were so low. findings of Abrahams and Pretorius However, L. capensis is a multiple spawner (2000)and Paxton et al.(2002).The size during the breeding season (Cambray, variations showed that the predation by T. 1999), so if there were spawning events

194 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 over the last few years, more sub adults and and nursery area for endangered L. seeberi, juveniles should have been recorded. The B. serra and B. anoplus, despite the invasion bias of the seine net also needs to be taken of T. sparmanni. The Oorlogskloof River into account, but as healthy numbers of supports a healthy fish species composition juvenile and sub adults of the other fish and provides good breeding and nursery sampled were recorded, one would have ground for endangered fish species. It is one expected a fairly good representation of of a few potential statutory conservation juvenile and sub adult numbers of L. areas and a natural riverine sanctuary on the capensis as well. Olifants-Doring River system. Accordingly it is of immense importance to the survival e) T. sparmanni of at least two (possibly three, including L. T. sparmanni is tolerant of a wide range of capensis) threatened fish species and the habitats, preferring slow moving or standing genetically-unique B. anoplus. L. seeberi waters with submerged or emergent was widespread throughout in the system vegetation (Skelton, 2001). It is omnivorous while B. serra was the most dominant and feeds on algae, soft plants, small species. Interestingly no B. anoplus were invertebrates such as and small fish recorded at the sites where L. capensis were (Skelton, 2001).It presence in the system is recorded and this apparent association needs likely attributed to the flooding of further investigation, as well as why L. Municipal dam in 2007. Individuals were capensis does not appear to be recruiting or also netted in this dam during this study and surviving well in this system. Regular in 2009 (pers. comm. Pretorius). It was monitoring and more research are urgently considered common along the entire length required in the Oorlogskloof Kobee river of the Oorlogskloof River gorge surveyed, system in order to ensure the conservation but were more abundant downstream than of these important fish species and their upstream probably due to habitat habitat. requirements. According to Skelton (2001) it attains a standard length of about 230mm Acknowledgements but none were recorded, perhaps due to We would like to thank the Oorlogskloof seine net bias or due to habitat limitations. Nature Reserve field rangers,Mr Johannes Large numbers of juvenile and sub adult T. Afrika, Mr Leon Koopman, Mr Esau sparmanni were recorded indicating Andrews, Mr Nathan Kotze and Mr Koos successful recruitment in the system, further Koopman, Ms Wilma Smith (Oorlogskloof signifying its distribution in the system. Nature Reserve intern), as well as the volunteers from the Nieuwoudtville Conclusion community who assistedwith the survey; The Oorlogskloof River has a relatively low CapeNature officials, in particular Mr Dean diversity of indigenous fish species and is Impson,Dr Martine Jordaanand Ms Jean dominated by cyprinids. This survey re- Gouws for assisting with the survey and on- affirmed the importance of the Oorlogskloof going support, DENC supervisors Ms Nature Reserve as an important breeding Elsabe Swart and Mr Julius Koen for creative inputs provided and for editing the 1105 P.P. Ramollo, M. Schumann and W.A.J. Pretorius / Our Nature (2012) 10: 8-16 document and Department of Environment structured models–from versatile technique to and Nature Conservation for financial ecological theory.Oikos94: 51-71. Huss, M., P., Bystrom and L. Persson 2007. The support and use of equipments. Special origin and development of individual size thanks to Dr Bruce Paxton of University of variation in early pelagic stages of Cape Town, Freshwater Consulting for fish.Oecol.153(1):57-67. guidance in writing this manuscript. Impson, N.D. 1995. Distribution of fishes in the Oorlogskloof and Kobee Rivers. Unpublished Report. Cape Nature Conservation, Jonkershoek. References Impson, N.D. 1997. Threatened fishes of the world: Abrahams, A.A.M. and W.A.J. Pretorius. 2000. The Labeo seeberi Gilchrist & Thompson, freshwater fish fauna of Oorlogskloof Nature 1911().Environ. Biol. Fishes 49 (4): Reserve, Northern Cape, South Africa. 480. Unpublished Report. Northern Cape Nature Impson, N.D. 1999. Threatened fishes of the world: Conservation Service, Kimberley. Barbus serra Peters, (Cyprinidae).Environ. Biol. Cambray, J.A., S., Hahndiek and Q. Hahndiek 1978. Fishes 54: 44. The juvenile fish population in the marginal areas King, J.M., J.A., Cambray and D.Impson 1998. of the Hendrik Verwoerd Linked effects of dam-released floods and water Dam.J.Limnol.Soc.S.Afr.44(1): 21-30. temperatures on spawning of the Clanwilliam Cambray, J.A. and M.N. Bruton. 1985. Age and yellowfish Barbus capensis.Hydrobiol.384: 245- growth of a colonizing minnow, Barbusanoplus, 265. in a man-made lake in South Africa. Environ. Paxton, B.R., B.M., Clarke and C.A. Brown 2002. An Biol. Fishes12(2): 131-141. assessment of the effects of habitat degradation Cambray, J.A. 1999. Threatened Fishes of the world: and exotic fish species invasions on the Barbus capensis A. Smith, 1841 distribution of three endemic cyprinids: Barbus (Cyprinidae).Environ. Biol. Fishes54: 150. capensis, Barbus serra and Labeo seeberi in the Cincotta, D.A. and J.R Staffeur. 1984. Temperature Olifants and Doring Rivers, Western Cape. preference and avoidance studies of six North Department of Water Affairs and Forestry, Report American freshwater fish No. PB E000-00-1302. species.Hydrobiol.109:173 -177. Persson, L. and A.M. De Roos. 2006. Food-dependent DeAngelis, D.L., K.A., Rose, L. B., Crowder,E. A., individual growth and population dynamics in Marschall and D. Lika 1993. Fish Cohorts fishes.J. Fish Biol.69 (3): 1-20. Dynamics. Application of Complimentary Skelton, P.H. 2001.A complete guide to the freshwater Modelling approaches.The Am. Nat. 140 (4): 604- fishes of southern Africa. Southern Book 622. Publishers, Halfway House. pp. 117-291. De Roos, A.M. and L. Persson.2001. Physiologically

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