Fish species diversity of Kyoga basin lakes (past status)

Item Type monograph

Authors Namulemo, Gertrude

Publisher National Fisheries Resource Research Institute

Download date 26/09/2021 08:45:24

Link to Item http://hdl.handle.net/1834/34481

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Fish species diversity of Kyoga ~

Namulemo Gert "" el "

_ ~"'\""-"-.v ,.....'V"/ ~·Introduction ~->=--.:'_~_.-:'/' Kyoga basin lakes are a very important natural resource for' the communities within the lake basin and beyond. Fisheries of the Kyoga basin lakes enable millions of poor fishers, processors and traders to diversify their livelihood strategies on the basin of income while at the same time supplying vast numbers of poor consumers with essential nutrition. Fish is particularly important for the poor as it is often the most readily available and affordable source of protein and other micronutrients crucial to a healthy diet. The lakes also generate substantial revenue to the local governments within their catchment's area. Thus the fisheries of Kyoga basin lakes are a key instrument in poverty eradication and ."food security. .

In addition to employing people around the lakes directly as fishers and fish traders, the fishery of these lakes also indirectly employs a range of other skilled workers such as boat builders, fishing gear fabricators, makers of crafts such as baskets and mats, etc. The lakes also have a great potential as a source of water and are also used as transport routes.

Some of the Kyoga small lakes harbour species which have disappeared from the main lakes Victoria and Kyoga and are therefore important for .conservation. The native tilapiines esculentus and fl· plus several species of that are threatened with extinction still occur in some of the small Kyoga basin lakes. Based on a survey funded by the USAID Consortium (Ogutu-Ohwayo et al 1999), it was recommended that some of the lakes, especially Nawampasa, Gigati, Kawi, Agu and Nyaguo, be designated as conservation areas for species threatened in the main lakes.

However, there is concern that the fish stocks of Kyoga basin lakes are declining

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-' .. and may not be enough to meet the ever increasing demand. Even in lakes where perch was introduced in the 1950s, its biomass has greatly declined and in some lakes, especially , the species is rarely caught by the fishers. Stock enhancement of some of the Kyoga basin lakes has therefore been proposed as one of the solutions to ensure sustainability of the fishery resources of these lakes. This paper therefore provides a review of the past status of fish species diversity of the Kyoga basin lakes in order to establish which lakes require stock enhancement and with what fish species.

Background Fish faunal surveys have been carried out in various small lakes in the Kyoga basin since 1998. Some of these lakes were not stocked with and are spatially separated from the main lakes in which Nile perch was introduced by, which provide. The extensive papyrus swamps that surround the lakes act as barrier to Nile perch invasion and other human impacts. Results have indicated "'that some of the indigenous species, especially Oreochromis escu/enfus and Oreochromis variabilis, depleted from the main lakes due to Nile perch predation pressure and destructive fishing methods are still present in these small lakes (Ogutu-Ohwayo, ef a/1999).

Some Kyoga small lakes have a high fish species diversity especially of the haplochromine cichlids. Most of the haplochromine species that have disappeared from lakes Victoria and Kyoga were found to occur in most of the Kyoga small lakes. This may be due to habitat diversity since most are characterized by dense mats of water lilies and other submerged waterweeds "that provide refuge to endangered fish species especially the haplochromine cichlids. Some small lakes are therefore suitable for conservation of native fish species since, due to their small size, they can be easily monitored. Many of these lakes can also be closed to fishing since they are close to the main Lake Kyoga which can provide alternative sources of fish protein.

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The major threat to Kyoga basin lakes is over-exploitation and use of destructive fishing gears leading to decline in fish stocks. In Lake Kyoga, the decline in catches was noted in the 1980s. By 1985 the contribution of Nile perch to the total commercial output was less than 20% compared with about 50% in 1980 (ADP/Fishery Survey 1992). The decline in the species was attributed to 1 extensive use of seine nets. Other threats include drainage of surrounding wetlands for agriculture, collection of ornamental fish for aquarium trade and 'invasion by water hyacinth. Fish species diversity, especially of Lake Kyoga, has also declined from 43 species recorded in the late 1920s (Worthington 1929) to 32 species recorded in the recent past (ARTP 11, 2005)

Study Area, The review was based on 13 lakes of the Kyoga basin namely lakes Kyoga, Nawampasa, Kimira, Nakuwa, Gigate, Bisina, Kawi, Lemwa, Nyaguo, Agu, Kwania, Opeta and Nabisojjo. Some of the lakes sampled are shown in Figure 1. The area and average depth of some of the lakes so far sampled is shown in

Table 1

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Figure 1. Map of Lake Kyoga small lakes, with an inset map of ,

showing some of the lakes sampled ~1

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.....; Table1. Area and average depth of lakes sampled

2 Lake Area (km ) Average depth (m) Kyoga 2032 3.5 Lemwa 10.4 3.1 Kawi 5.0 3.2 Agu 2.2 2.2 Gigati 6.7 2.4 Nakuwa 73 3.3 Nawampasa 7.0 2.6 Bisina 141 3.5 Opeta 11.0 Kwania 400 3.5 Kimira ? Nyaguo 24 2.4 Nabisojjo 6 2.0

Fish Species Composition, relative abundance and Distribution Overall, twenty-seven fish taxa were recorded from all the 13 lakes sampled, including haplochromine cichlids as a single species group as shown in Table 2 (FIRRI, 2000; NaFIRRl, 2005, LVEMP in prep). The highest number of fish taxa was recorded from Lake Nyaguo (19) followed by lakes Bisina, Agu and Kyoga at 17 each, Opeta (15),Nakuwa and Kwania (12 each),Nawampasa (11), Lemwa and Gigati (10 each). Lakes Nabisojjo, Kimira and Kawi had the lowest number of fish taxa (8 each). Protopterus aethiopicus, haplochromine cichlids, Clarias gariepinus, and were recorded from all the lakes sampled. Haplochromine cichlids were the most dominant fish taxa in all the lakes except lakes Nakuwa and Nyaquo where the catch was dominated by Synodontis afrofischeri and Brycinus sadleri respectively. Lates niloticus was ,'. only recorded from Lake Nakuwa whereas Oreochromis niloticus was recorded from all lakes except lakes Nyaguo and Agu, although it was most dominant in Lake Nakuwa. O. esculentus was recorded from lakes Nawampasa, Nyaguo,

5 Bisina, Gigati, Lemwa, Kimira and Nabisojjo while O. variabilis was recorded from lakes Opeta, Nawampasa, Bisina, Gigati and Agu. Although S. afrofischeri was recorded from most of the lakes sampled, its contribution to the catches was significantly higher in lakes Bisina and Nakuwa. The contribution of Synodontis victoriae was significantly higher in Lake Nakuwa although it was recorded from several lakes. Bagrus docmac was only recorded from Lake Bisina.

Among the haplochromine cichlids 43 species were recorded from all the Kyoga basin lakes as shown in Table 3. The highest number of species was recorded from Lake Nawampasa (27) followed by lakes Gigati (23), Kawi (20), Agu and Bisina (17 each), Nyaguo (16), Kyoga (15), Opeta (12), Kimira (9), Kwania (8) and Nakuwa (4). Haplochromine cichlids from Lake Nabisojjo were not identified to species level

Gaps • Information on the current status of the fish species diversity in the Kyoga basin is lacking • Information on some of the Kyoga small lakes is not available Recommendations • Lakes that contain the endangered fish species, especially O. esculentus, '" O. variabilis and several that are considered extinct in the main lakes Kyoga and Victoria, should be designated as conservation areas, • Some of the lakes without endangered native fish species should be considered for stock enhancement • Baseline surveys should be carried out in the lakes where information is lacking. • Information on the current status of the fish species diversity in the Kyoga basin lakes should be collected through surveys in order to identify the most suitable species to be used in stock enhancement for each of the

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6 Reviewed literature ADP/Fishery Survey 1992. Fishery Survey of Kyoga lakes. Agricultural Development Project report for the period April 1990 to November 1991.

FIRRI 2000. Workshop report on the Fisheries research on Lake Nabisojjo ­ Luwero district. 40 pp

LVEMP (in prep). Aquatic Biodiversity of Basin. Its Conservation and sustainable use

NaFIRRI. 2005. Report on the fishery of Lake Kimira. October 2005. 4 pp

Ogutu-Ohwayo, R.; S. B. Wandera; G. Namulemo & D. Mbabazi, 1999: The role of satellite lakes in conservation of fish species diversity in the Lake Kyoga Basin. Final report of the Biodiversity Support Program funded by USAID Consortium. 20 pp

Worthington E. B. 1929. A report on the fishing survey of Lakes Albert and Kyoga. Cambridge. 1929. 136 pp

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7 t Table 2. The overall percentage composition of fish species from cflfferent lakes in the Kyoga Lake Basin . Species Kyoga Opeta Nawampasa Nabisojjo Kimira Bisina Nakuwa Kwania Lemwa Kawi Gigate Nyaguo Agu L.n 65.9 0 0 0 0 0 12.8 58.2 0 0 0 0 0 Hap 8.5 33.9 26.9 1.3 13.3 24.2 11.0 13.9 89.3 69.4 53.9 44.2 19.4 O.e 0 0 10.7 40.2 10.1 0.1 0 0 0.3 0.2 0 2.2 0 0.1 0.2 0.5 3.5 1.7 0.4 0.8 1.8 0 2.3 0.4 4.5 0.9 2.9 O. n 3.4 16.6 11.9 1.6 2.9 10.7 3.7 2.2 0.3 0.1 0.3 5.1 0.6 O.v 0 20.6 13.7 0 0 2.6 0 0 0 0 1.5 0 2.9 T.z 0.1 4.7 1.5 0 0 4.9 0 2.2 0 0 0.2 0 7.5 G.I 0 1.9 0 0 0 0 0 0 0 0 0 0.5 12.6 G.v 0.01 1.2 0 12.0 0 0.2 1.8 0 0 0 0 1.1 4.5 M.g 0.1 1.6 0 0 0 0 0 1.6 0 0 0 0.4 7.4 M.n 0 0.9 0 0 0 0 0 0 0 0 0 0.1 0.2 M.m 0.1 1.1 0 0 0 0 0 0 0 0 6.9 4.1 M.k 0.02 0 0 0 0 0 0 0 0 0 0 7.1 0 P.c 0 0 0 0 0 0 0 0 0 0 0 3.9 2.1 C.I 0 0.9 0 0 0.4 0 4.6 0 0 0 0 0 0.4 C.g 0.4 7.6 17.9 30.7 65.6 18.1 0.9 0.6 2.9 0.4 0.3 9.5 6.9 B.s 1.4 5.9 3.6 0 0 10.5 0 15.5 0 0 28.2 1.2 0 B.d. 0 0 0 0 0 3.5 0 0.3 0 0 0 0 0 B.a 4.4 0 0 0 0 0 12.8 1.3 0 0 0 0 0 B.p 0 0 0 0 0 0.1 0 0 0.3 0 0 0.7 0 B k. 0 1.9 0 0.03 + 1.1 0 0 2.3 0.1 0.1 0.1 0.2 Pa 0.8 0 6.2 12.2 7.3 2.7 2.7 0 + 29.3 10.2 0.1 14.9 S.a 6.3 0.4 2.9 0 0 14.6 32.1 3.2 0.3 0.2 0.5 2.4 9.7 S.v 7.9 0 1.3 0 0 4.1 14.7 0.3 1.0 0 0 2.8 3.5 S.i 0.5 0 0 0 0 1.7 3.7 0.6 0 0 0 0 0 C.m 0 0 0 0 0 0.1 0 0 1.0 0 0 0 7.1 A.f 0.1 0 0 0 0 0 0 0 0 0 0 0.4 0 No. of 17 15 11 8 8 17 12 12 10 8 10 19 17 species

Note: Lakes Nakuwa, Bisina and Kwania were stocked with Nile perch in the 1950s

9 Key L.n = Lates niloticus" Hap. = Haplochromines" O.e = , 0.1 = Oreochromis leucostictus, O.n = Oreochromis niloticus, O. v = Oreochromis varia bilis, T.z = zillii, G. I =Gnathonemus longibarbis, G. v =Gnathonemus victoriae, M. g = Marcusenius grahami, M. n = Marcusenius nigricans, M.k =Mormyrus kannume, M. m =Mormyrus macrocephalus, P.C = Petrocephalus catastoma, C. I = C/arias liocephalus, C.g = C/arias gariepinus, B.s =Brycinus sadIe ri, B.d =Bagrus docmac, B.a =Barbus altianalis, B.p = Barbus palludinosus, B.k =Barbus kestern, P.a =Protopterus aethiopicus, S.a =Synodontis afrofischeri, S. v =Synodontis victoriae, S. i =Schilbe intermedius,

C. m =Ctenopoma murieri, A.f =Afromastacembelus frenatus 'J~

9 ..., Table 3 The overall percentage co'fnposition of haplochromines by number frof;'1 Kyoga lake basin. Lakes Species Kyoga Lemwa Opeta Kwania Kawi Agu Nyaguo Gigati Nawampasa Nakuwa Kimira Bisina Astatoreochromis alluaudi 0.3 0.7 0.7 0 1.2 3.2 0.5 0.9 0.2 0 0 0.5 Astatoti/apia latifasciata 0 0 2.7 0 0 0.6 0 0.6 1.4 0 0 2.6 Astatotilapia martini 0 0.1 0 0 0 0 0.7 0.1 0 0 0.2 0 Astatotilapia nubila 25.9 22.9 0 0 8.7 3.2 25.8 0.4 0.3 2.2 0 0.1 Astatotilapia "miniblack" 0 0.1 0.7 0 0 7.9 0 0.7 5.9 0 0 0.8 Astatotilapia "fattoth" 0 54.7 2.7 0 64.4 17.6 49.1 26.2 39.1 0 1.1 0 Astatoti/apia "macrops" 0 0 0 0 0.2 0 1.5 0.3 0.1 0 0 0 Astatotilapia "thicklipped" 0 0 0 2.3 0 0 0 0.1 0.1 0 0 0 Astastotilapia "kyogaastato" 6.9 0 0.7 72.7 0 0 0 0 0.2 72.5 0.1 0 Gaurochromis sp 0.1 0 0 0 0 0 0 0 0.2 0 0 0 Haplochromis lividus 0.1 13.0 6.8 6.8 0.6 43.1 0.5 43.7 32.3 0 18.0 57.5 Lipochromis "blackcryptodon" 0.1 0.2 0 0 3.5 0.6 0.7 0.4 0.8 0 0 0 Lipochromis cryptodon 0 0 0 0 0.4 0 0.5 0.1 0 0 0 0.3 Lipochromis microdon 0 0 0 0 0.2 0.6 0 0.4 0.4 3.3 0 0 Lipochromis obesus 0 0 0.7 0 2.7 4.8 0.5 0.9 0.6 0 0 0.1 Lipochromis paNidens 0.1 0 0 0 0.2 1.9 0 1.2 0.9 0 0 0.4 Lipochromis "white" 0 0 0 0 0.2 0 0 0 0 0 0 0 Lipochromis maxil/aris 0 0 0 0 0.3 0.6 0 0.1 0.5 0 0 0.4 Harpagochromis michaelli 0 0 1.4 0 0 0 0 0 0 0 0 0 Paralabidochromis "blackpara" 40.7 6.8 0 4.5 1.4 0 0 0.1 0 21.9 0.4 0 Paralabidochromis"redfin" 0 0.1 0 0 0.6 0 0 0.3 0.6 0 0 0 Paralabidochromis "deep body" 0 0 0 0 0 0 0 0.1 0 0 0 0 Prognathochromis argentus 0 0.6 2.7 0 2.4 5.1 0 0.5 4.8 0 0.3 5.5 Prognathochromis "long lower jaw piscivore" 0 0 0 0 0 0 0.5 0.1 0 0 0 0 Prognathochromis pellegrini 0 0 0 0 0 2.6 0 0 3.8 0 0 1.8 Prognathochromis "silvermale" 0 0 0 0 0 0 1.9 0 0 0 0 0 Prognathochromis "black red tail piscivore" 0 0 0 0 0 0 0.7 0 0.1 0 0 0

11 ., t, Prognathochromis "stilleto" " 0 0 2.7 2.3 "0.1 0.3 0 0 1.9 0 0 1.6 Prognathochromis "shove/mouth" 19.3 0 5.5 2.3 8.3 2.2 13.9 1.6 2.9 0 0 2.3 Pfyochromis "gigatisheller" 0 0 0 0 0 0 0.3 0.1 0.1 0 0 0 Pfyochromis sauvagei 0 0 0 4.5 0 0 0 0 0 0 0 0 Pyxichromis orthostoma 0.3 0.4 0 4.5 4.4 0 1.9 0.3 0.4 0 1.2 0.4 Para/abidochromis "victoriae" 0 0 0 0 0 0.3 0.7 0 0 0 0 0.4 Xystichromis phytophangus 0.3 0 64.4 0 0.2 5.1 0 20.8 2.3 0 0.4 2.4 Yssichromis "/emwa zoop/anktivore" 0 0.2 0 0 0.2 0 0 00 0 0 0 0 Yssichromis "kyoga zoop/anktivore" 0.4 0 0 0 0 0 0 0 0 0 0 0 Para/abidochromis "earthquake" 2.3 0 0 0 0 0 0 0 0 0 0 0 Prognathochromis guiarti 0.7 0 0 0 0 0 0 0 0 0 16.0 0 Xystichromis "flame back" 2.4 0 0 0 0 0 0 0 0 0 0 0 Para/abidochromis "si/verpara" 0 0 0 0 0 0 0 0.1 0 0 0 0.6 Hap/ochromis "unicuspid" 0 0 0 0 0 0 0 0 0.1 0 0 0 Astatoti/apia "redtailfattooth" 0 0 0 0 0 0 0 0 0.1 0 0 0 Astatoti/apia "pseudomartini" 0 0 0 0 0 0 0 0 0.2 0 0 0 Grand total 15 9 12 8 20 17 16 23 27 4 9 17

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