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|The aquaculture potential of indigenous catfish (Clarias gariepinus) in the Lake Victoria Basin, Uganda
|Isyagi, Ajangale Nelly
|University of Stirling
|Local and international demand for Lake Victoria’s fish has begun to outstrip supply. Production from the fishery has attained its sustainable limits, the diversity of catch has declined and subsequently employment and levels of earnings among fishers have become less secure. Under prevailing conditions, aquaculture offers the most immediate solution to augmenting fish production and sustaining earnings from the sector. It may also provide an avenue through which the diversity of aquatic resources can be increased through for example, the culture of indigenous species; in this case the African catfish (Clarias gariepinus), particularly as a polyculture species with conventional tilapia (Oreochromis) culture.. To ensure that benefits be derived from the culture of C. gariepinus, an assessment of its potential as a candidate species and of appropriate production options was done within the context of fish farmers’ local socio-economic, environmental and biotechnical constraints. This was especially necessary because of the persistent poor performance of aquaculture as a farm enterprise among Ugandan farmers and the need to improve their livelihoods. Hence also, a systems approach was chosen as the basic research framework. The study was conducted in 3 of the 5 agro-ecological zones in the Lake Victoria basin, namely: the Banana Millet Cotton (BMC), Intensive Banana Coffee Lake Shore (IBC) and Western Banana Coffee Cattle (WBC) farming systems. Rapid Rural Appraisals (RRAs) were used to obtain data from a total of 104 fish farming units out of an estimated 212 in the study area. The tools used included semi-structured interviews, ranks and scores, discussions with key informants. Wealth rankings were conducted in 50 villages from which a total of 238 fish farmers were ranked. Quantitative data on farmers’ management and production was obtained from a subset of 54 fish farming units. 69 ponds were sampled. Data on the marketability of C. gariepinus for table fish was obtained from a total of 25 markets where 65 fish-sellers and 97 fish consumers were interviewed. Information on market potential of C. gariepinus as bait was obtained from 14 landing sites where 118 line fishermen and 38 dealers were interviewed. The information obtained from the RRAs provided an insight into the social, financial and human capital farmers had invested into aquaculture. It also provided information on the environmental constraints in terms of the ability to generate natural physical capital for aquaculture. The effect of the interaction of these factors on farmer’s production was analysed using Principal Component Analysis (PCA). Impact on yield was analysed with the PCA in relation to state (inputs), rate (management) and intrinsic (farmers and farm characteristics plus location) variables within the context of fish species currently farmed. The potential entry points for C. gariepinus were subsequently derived based on key constraints and marketability. Poor performance of enterprises was noted by the fact that over 50% of farmers had had no returns, either in cash or food from their ponds. In general, farmer’s management practices were adaptive rather than strategic. Key variables causing greatest variance and unstable production in current systems were found to be: (i) se d - notably stocking density, size at stocking, stocking ratios and cost (ii) frequency and regularity with which feed and fertiliser were applied (iii) pond size (iv) location within the agro-ecological zones. Though there was variance between zones, maize bran and cow dung were t e most widely used feed and fertiliser inputs in all zones respectively. It was also found that in a typical polyculture context, O. niloticus was the most marketable fish Two experiments were designed to test comparative economic returns for monoculture and polyculture based on the above findings (i) the effect of stocking density on pond yield and economic returns of O. niloticus fed maize bran in earthen ponds fertilised with cow dung (ii) the effect of varying cow dung and maize bran input levels on pond yield and economic returns in O. niloticus – C. gariepinus polyculture. The potential of farming C. gariepinus as bait was also assessed from secondary C. gariepinus hatchery information. The financial returns were assessed based on farmers’ actual local costs of production and prevailing local market prices. Results indicated that (i) farming C. gariepinus as either a table fish or bait resulted in higher yields, better returns, improved productivity and utilisation of inputs, better technical and economic efficiency compared to O. niloticus monoculture. (ii) C. gariepinus in the farming system has the potential to reduce the risk of aquaculture as a livelihood option. (iii) The farming potential and constraints were significantly agro-ecological zone-specific and also influenced by farmers’ profiles: therefore different options may be appropriate (iv) It is more important for farmers if yields were defined in shillings based on local costs rather than tonnes, as the units of exchange affecting investment and operating decisions were numbers and size.
|Thesis or Dissertation
|School of Natural Sciences
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