Originally published in Environmental Biology of Fishes,1996, Volume 46: 308. Reproduced here with permission of the author and publisher.

Threatened fishes of the world: Pseudobarbus quathlambae (Barnard, 1938)(Cyprinidae)

Jim A. Cambray - Albany Museum, Somerset Street, Grahamstown, 6139 South Africa

Common names: Drakensberg minnow (redfin), Maluti minnow (E), Drakensberg-rooivlerkie, Maluti-rooivlerkie (Afrikaans).

Conservation status: Endangered (South African Red Data Book-Fishes Skelton 1987,IUCN 1990)

Identification: A redfin minnow adapted to a high altitude mountainous habitat, with small scales, high vertebral count and a flattened ventral profile. D III + 7, A III + 5, LL 60-72. The body is slender, the mouth is sub-termina l with a single pair of short barbels, the scales are radiately striated and the pectoral fins are large and horizontally inserted. Pigmentation depends on the habitat as well as physiological state. The bases of the fins are scarlet in adults, the body v arying from dirty olive brown to bluish olive in breeding males with ventral surface silvery white with a scaleless chest. Different populations have distinct patterns of dark spots or wavy lines dorsally and there is a dark lateral band on the trunk. Sex ual dimorphism is expressed in reproductively active males through variations in pigmentation and degree of tubercle development on the head and body as well as the shape and size of the pelvic and pectoral fins. The Maluti minnow is most closely related to the slender redfin (P. tenuis) which occurs in th e southern Cape. Reaches 130 mm SL.

Photograph by R.A. Jubb, Albany Museum records

Remarks: One of only seven species in the genus Pseudobarbus, the flexible-rayed redfin minnows. This is a distinct group of barbine minnows from the Cape Fold and the Drakensberg Mountains which appear to be descendants of an ancient lineage in southern Africa. Three of the seven species are endangered.

Distribution: Headwater streams of the Orange River (approximately 1900 - 3000 masl) within the mountain Kingdom of Lesotho (called Senqu River in Lesotho)(2855' to 2958'S; 2800' to 2918E). Extinct in its type locality, the Umkoma zana River in Natal, possibly due to the introduction of trout (Pike & Karssing, 1995). Some scientists suggest that it never occurred in Natal and was first collected in Lesotho. Recent collections have extended its range within Lesotho.

Abundance: Relatively abundant in the Senqunyane, Jordane and Bokoaneng Rivers with an estimated population of 3300 (Rall et al., 1993). Several of these populations are threatened by the Lesotho Highlands Water Project.

Habitat and ecology: The Drakensberg redfin is an ecological specialist confined to the uppermost streams of the Orange River system above 1935 masl. Occurs in pools and sheltered parts of rocky streams in clear, low to moderate gradient streams. During their life cycle most of the riverine habitat types available are used except for deep, silt laden pools (Rall et al., 1993). Larval fish occur in backwater pools (Cambray & Meyer, 1988). P. quathlambae has a high mortality rate (Z=2.47) with a recruit survival of 8% at the end of the first year, a maximum age of 4 years with a sex ratio of 1:1.7 (Rall et al., 1993). The minnows feed on stream invertebrates, mainly aquatic nymphs and adults of Ephemeroptera and Diptera, and simuliid larvae.

Reproduction: P. quathlambae breeds in late spring and summer (late October to February) which coincides with the rainy season and spawns several times per season. The males have tubercles during the breeding season and their fins become a darker red. The eggs are scattered, non-adhesive, d emersal and are spawned midchannel in riffles above pools after an increase in flow. Fecundity is high with up to 53 000 oocytes at different stages of development. They may be fractional spawners, with few ova being shed per spawning. The number of mature ova in individuals between 66 to 108 mm FL was 225 to 2875. This multiple spawning habit is also confirmed by the wide range of developmental stages of free embryonic and larval fish found in the riffles and downstream pools (Cambray & Meyer, 1988). After hatching there is a swim-up stage and the larval fish are transported to food-rich backwaters.

Threats: The species is threatened by loss of habitat due to anthropogenic pressure, damming and invasive alien fish. Alien trout prey on the minnow and compete for the same niche. Early life-history stages are very vulnerable to predation by introduced trout. Ecotourism (using trout angling to entice people to visit Lesotho) is a threat.

Conservation action: Sehlabathebe National Park, on the Tsoelikana River, has been created for this species. Unfortunately a lodge and trout ponds were built in the upper catchment area. The dams were poorly constructed and this h as resulted in siltation in this prime Maluti minnow habitat. Good survey work has recently been conducted in areas which will be impacted by the Lesotho Highlands Water Scheme. The development and enforcement of a conservation strategy was recommended. < P>

Conservation recommendations: All further trout stockings should at first be assessed for their potential impact on the remaining populations of the Maluti minnow. Good sanctuary areas should be located high up in the rivers where the fish naturally occurs to avoid many of the negative impacts which occur lower in the mountain streams. The Jordane, Bokoaneng, Bokong and Senqunyane Rivers above the Semongkoaneng waterfall (1935 masl) have been identified as good potential sanctuary sites as the waterfall is a barrier to alien species. However, the Mohale reservoir will flood 77% and 99% of the existing habitat of the minnow in the Jordane and Bokoaneng Rivers respectively. The habitat of the population of Maluti minnows within the Sehlabathebe National Park should be protected against any further man-made disturbances. Captive breeding, gamete preservation and resettlement have been recommended to ensure the survival of P. quathlambae populations threatened by the Mohale Da m (Rall et al., 1993).

Literature

Barnard, K.H. 1938. Description of a new species of fresh-water fish from Natal. Ann. Natal Mus. 8: 525-528.

Cambray, J.A. & K. Meyer. 1988. Early ontogeny of an endangered, relict, cold-water cyprinid from Lesotho, Oreodaimon quathlambae (Barnard, 1938). Rev. Hydrobiol. trop. 21(4): 309-333.

Gephard, S.R. 1978. Observations on the three allopatric populations of the Maluti minnow, Oreodaimon quathlambae (Barnard) with notes on its evolution, ecology, spawning and conservation. J. Limnol. Soc. sth. Afr. 4(2): 105-111.

Greenwood, P.H. & R.A. Jubb. 1967. The generic identity of Labeo quathlambae Barnard (Pisces, Cyprinidae). Ann. Cape Prov. Mus. (Nat. Hist.) 6(2): 17-37.

IUCN 1990. 1990 IUCN red list of threatened animals. IUCN, Gland, Switzerland. 192 pp.

Jubb, R.A. 1966. Labeo (?) quathlambae, a rare freshwater fish now feared extinct. Piscator 67: 78-80.

Pike, T. & R.J. Karssing. 1995. Investigation of the presence of Maluti minnows, Pseudobarbus quathlambae, in the Umkomozana River. Lammergeyer 43: 64.

Pike, T. & A.J. Tedder. 1973. Rediscovery of Oreodaimon quathlambae. The Lammergeyer 19: 9-15.

Rall, J.L., G.J. Steyn, H.H. du Preez & M. Maema. 1993. An ecological study on the Maloti minnow (Pseudobarbus quathlambae) in the catchment area of Phase 1B of the Lesotho Highland Water Scheme. Report, Dept of Zoology, Rand Afrikaans Univers ity, Aucklandpark. 99 pp.

Rondorf, D.W. 1976. New locations of Oreodaimon quathlambae (Barnard, 1938)(Pisces, Cyprinidae) populations. S. Afr. J. Sci. 72:150-151.

Skelton, P.H. 1987. South African Red Data Book - Fishes. S. Afr. Nat. Sci. prog., Report no. 137. 199 pp.

Skelton, P.H. 1988. A taxonomic revision of the redfin minnows (Pisces, Cyprinidae)from southern Africa. Ann. Cape Prov. Mus. (Nat. Hist.) 16: 201-307.

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