Fish
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All Fish research conducted over the years for both capture and aquaculture can be accessed in this collection
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Item Fisheries and SDGs at Namasagali Fishing Village, Kamuli Disrtict, Uganda(European Journal of Theoretical and Applied Sciences, 2023-09-11)Attainment of SDGs has been derailed mainly by conflicts, pandemics and climate change. In Uganda, limited quantification of the value Riverine fisheries provide to communities is a major driver to unsustainable harvesting and destruction fisheries resources. This study was conducted to determine the monetary value contributed to households by fisheries activities at Namasagali fishing Village, one of the spots along Victoria Nile, major challenges faced and possible strategies to be adopted to enhance community ownership and sustainable management. A cross sectional survey was conducted using questionnaires and data on major activities conducted around the fishery and the corresponding income recorded and as analyzed using SPSS statistical package. Results showed that fisheries activities aprovided the highest amount of daily household income of between (5000 - 100,000 Shillings; USD $1.35-2.70) to 45% of households in the community. This income was higher than the established World Bank poverty line of US $1.25/1.9 per day in the year 2005. Major challenge to sustainability of the fishery were use of illegal fishing gears and methods. Sensitization of the fisherfolk i and enforcement of fisheries regulations was recommended as the main strategy to advance sustainable fisheries resources at Namasagali Fishing Village.Item Introgressive hybridization levels of Tilapiine species in Lake Victoria basin, Kenya inferred from microsatellite and mitochondrial DNA genotyping based on next-generation sequencing(Conservation Genetics, 2023-09-27) Gerald Kwikiriza; Thapasya Vijayan; Papius Dias Tibihika; Manuel Curto; Gerold Winkler; Juliet Kigongo Nattabi; John Kariuki; Harald MeimbergDespite their high abundance and species richness, tilapiines have been compromised by various factors especially over fishing, climate change, and uncontrolled sh transfers and introductions. Fish introductions have negatively impacted native tilapiine populations through competition, predation, hybridization, and introgression compromising their genetic integrity. The hybridization levels of different tilapiines in the Lake Victoria basin remain relatively understudied. The study utilized nuclear microsatellite and mitochondrial DNA (mtDNA) genetic markers to investigate hybridization signals and compare the genetic diversity of different tilapiines in Lake Victoria, Kenya, using next-generation sequencing. Low levels of hybridization from Oreochromis niloticus into other Oreochromis species were detected by Bayesian clustering analysis and principal coordinate analysis (PCoA). The results contribute to the need for conservation measures for these sh species.Item A decline in Fish catches and the size of Oreochromis niloticus in Lake Wamala (Uganda) following human exploitation(Afr. J. Trop. Hydrobiol. Fish., 1995-04-07) JOHN OBBO OKARONONThe fishery of Lake Wamala has declined since the lake was stocked in 1956 and opened to fishing during the 1960s. Surveys were conducted on the lake during 1975/78 and 1988/92 to investigate the causes of declining fish catches. The lake produced an average of 4000 - 6000 tonnes of fish annually from 1960s through 1970s. Total fish catches decreased from a maximum of 7100 tonnes in 1967 to less than 500 tonnes by 1990s. Catch rates decreased from about 8 kg in the I960s to less than 1 kg per net per night by 1975. During the 1970s the catch was dominated by Oreochromis niloticus (67%) followed by Clarias gariepinus (17%), and Protopterus aethiopicus (15.1 %). By 1990s the proportion of O. niloti- cus had decreased to 45.1 % while that of P. aethiopicus had increased to 37.6%. These changes seem to have been caused by overfishing resulting from increased fishing effort from the recommended 250 to about 1000 boats and the additional increase in effort through driving fish into the nets by beating water. The maximum size of O. niloticus in the fishery decreased from 32 cm total length in 1975/78 to 22 cm in 1988/92 while the size at first maturity decreased from about 21 cm to 14 cm during the period. This has been concurrent with a shift in the mesh size of gillnet used from 127 mm (5") in 1960s to 64 mm by 1990s. Environmental changes, especially in lake level in 1980, may also have affected the fishery.Item Morphometric Variations of Nile Tilapia (Oreochromis niloticus) (Linnaeus, 1758) Local Strains Collected from Different Fish Farms in South Western Highland Agro-Ecological Zone (SWHAEZ), Uganda: Screening Strains for Aquaculture(Fishes, 2023-04-20) Gerald Kwikiriza; Mourine J. Yegon; Nelson Byamugisha; Apulnal Beingana; Faith Atukwatse; Alex Barekye; Juliet K. Nattabi; Harald MeimbergDespite the global contribution of aquaculture as an important pillar for food and nutritional security, its rapid growth has been hampered by inadequate and poor-quality seed due to inbreeding, hybridization of related stocks, and poor-quality broodstock. Phenotypic and genotypic characterization of Nile tilapia in natural water bodies of Uganda has been studied but research gaps remain on the morphometric characterization of farmed O. niloticus in Uganda, which hinders selective breeding initiatives. This study characterized O. niloticus from various farmers in Uganda’s Southwestern Highland Agro-Ecological Zone using their morphometric traits. In this study, 8 morphometric traits were taken on each of the 258 fish samples collected with at least 30 samples sampled from each pond system in the zone. The morphometric data generated were analyzed using multivariate analysis. In order to delineate the populations from the different ponds, Discriminant Function analysis (DFA) was performed on the dataset and distribution plots generated to test on the purity of the strains. There were significant differences in the morphometric traits among the populations with the Victoria fish population having the highest standard length while the Kyoga population had the highest weight. Morphometric characterization grouped the fish into three clusters, indicative that fish farms in the zone possibly had different sources of fish seed. The condition factor, which is a measure of wellbeing of the fish, showed that all the populations displayed an isometric growth which is indicative of the fish growing in length as it is in weight. The results of this study provide evidence that local O. niloticus from different farms display differences in body shape as a result of using fish seed from different sources. This aspect can be applied in selective breeding programs after establishing the genetic structure of the farmed Nile tilapia stock.Item Dietary inclusion of pine pollen alters sex ratio and promotes growth of Nile tilapia (Oreochromis niloticus, L. 1758)(Aquaculture Reports, 2022-11-14) Ivan Abaho; Peter Akoll; Clifford L.W. Jones; Charles MasembeThe potential of pine pollen (PP) to masculinize sexually undifferentiated Nile tilapia was evaluated by feeding graded levels of PP (0.08–3.20 g kg-1 basal diet) to triplicate groups of three-day-old Nile tilapia for 28 days. Masculinization and associated differences in growth were compared to sh individuals fed the same basal diet with no PP (CT; negative control) and with 0.06 g 17α-methyltestosterone (MT) kg-1 basal diet (positive control). Both PP and MT treatments significantly skewed the expected 50:50 (male: female) ratio towards more male individuals. Notably, MT and 1.28 g PP kg-1 of diet produced a significantly high proportion of males (89.2 ± 2.2% and 80.0 ± 2.9% respectively), compared to 50.8 ± 2.2% in the CT treatment (P < 0.001). Except for 0.08 g PP kg-1 of diet, the final body weight and specific growth rate of individuals fed PP and MT-supplemented feeds were signi-ficantly higher than sh from the CT group. Although 1.28 g PP kg-1 diet produced the highest masculinization, the sh fed 3.20 g PP kg-1 diet had the highest final weight (14.73 ± 0.54 g), suggesting the presence of growth enhancers in PP. Similarly, a superior feed conversion ratio was recorded in both PP and MT- treated groups compared to the CT treatment (P = 0.024). However, the condition factor and survival rate of sh in all groups did not differ significantly. Overall, 1.28 g PP kg-1 diet was potent in sex inversion and promoted the growth of Nile tilapia, making PP a promising alternative to MT in the production of all-male stock.Item Exploring the morphological dynamics of Nile tilapia (Oreochromis niloticus Linn. 1758) in Victoria Nile as depicted from geometric morphometrics(BMC Zoology, 2023-11-23) Papius Dias Tibihika; Manuel Curto; Harald Meimberg; Cassius Aruho; George Muganga; Jerome Sebadduka Lugumira; Victoria Tibenda Namulawa; Margaret Aanyu; Richard Ddungu; Constantine Chobet Ondhoro; Tom OkurutBackground Various anthropogenic activities continue to threaten the fish biodiversity of the East African water bodies such as the Victoria Nile. Although the Victoria Nile is a significant source of livelihood for human populations, the biology and ecology of Nile tilapia in this ecosystem remain understudied with little or no information on the morphology of the fish given varying and immense anthropogenic activities. Here, we use geometric morphometrics to examine the morphology/shape variations of Nile tilapia populations in Victoria Nile to gain insights into their current ecological state. Results Our results indicate unexpectedly smaller Nile tilapia body weights in Victoria Nile than in L. Victoria. Despite this, nearly all the populations displayed a relative condition factor (Kn) of greater ≥1 suggesting a healthy stock. How- ever, two populations, LMF and VN_Bukeeka demonstrated Kn values of less than one (< 1). We also report that some Upper and Lower Victoria Nile populations display morphological similarities. Apart from L. Albert, Nile tilapia populations from Lakes Victoria and Kyoga are morphologically divergent from the riverine ones. We note that Nile tilapia from Nalubale Dam Reservoir is morphologically distinct from the close neighbouring Victoria Nile populations which are likely allied to the influence of the Nalubale Hydroelectric power dam as a barrier. Conclusion Nile tilapia’s morphological variation appears to be influenced by various anthropogenic disturbances notably, over fishing, hydroelectric power dams, and fish translocational history in Uganda. Management should enforce regulatory frameworks to avert human-mediated activities as these are likely to compromise the sustainability of the sheries. Further studies are required to follow these populations with molecular genetics and environmental data to gain a deeper understanding of the sh species for informed sustainable management and conservation options.Item Growth and Economic Evaluation of Different Fish Species for Culture in Uganda’s Mid Altitude Areas Using Local Feeds(Journal of Applied Sciences, 2023-03-02) Constantine Chobet Ondhoro; Ismail Kagolola; Gerald Osipa; Robinson Odong; Godfrey Kawooya Kubiriza; Lawrence OwereBackground and Objective: The East African high-altitude areas remain ecologically challenging to tropical native farmed fish species, the Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) yet the potential for cold-water fish culture is as well unexploited. This study describes the effects of environmental quality and local feed on the growth and economic performance of selected fish species for 5 months along the slopes of Mountain Elgon Uganda. Materials and Methods: Three earthen ponds each 200 m3 by volume were conditioned with hydrated lime at 0.1 kg mG3 for a week. The ponds were stocked with juveniles of Rainbow trout (Oncorhynchus mykiss), Nile tilapia and Mirror carp, averaging 1.5±0.1, 17.9±2.2 and 2.0±0.2 g (±SE), respectively. The fish were fed to satiation daily on 35% C.P local feed for 5 months. Water quality and growth data were collected daily and monthly, respectively. Performance parameters were computed and analyzed using univariate ANOVA and regression analysis in SPSS20. Results: There was a highly significant difference (p<0.001) in mean body weight gain (g/day) between Rainbow trout and the Nile tilapia (mean diff 0.0788, p<0.001) and Mirror carp (mean diff 0.087, p<0.001) and between Rainbow trout and the two species combined (mean diff 0.016, p = 0.006). The highest weight gain (4.8 g/day) overall was demonstrated by Mirror carp in the 4th month of growth. The mean relative condition (Kn) for respective species (p<0.05) were all <1. The Mirror carp was the most profitable, at Ugshs 4, 130, 463 (44.9%) of total revenue, while trout incurred over 92.1% (Ugshs -3, 974, 994.5) losses. Mirror carp demonstrated better economic viability with the experimental feed in the area, however, this can be much better with improved management. Conclusion: The observed growth patterns were consistent with temperature variation and feed quality, thus, Nile tilapia performed poorly due to low water temperature and Rainbow trout was worse due to poor feed quality that negatively influenced visibility and feed intake.Item Characterization of Potential Threats from Cyanobacterial Toxins in Lake Victoria Embayments and during Water Treatment(Toxins, 2022-09-23) Mark Olokotum; Jean-François Humbert; Catherine Quiblier; William Okello; Ronald Semyalo; Marc Troussellier; Benjamin Marie; Kathrin Baumann; Rainer Kurmayer; Cécile BernardAfrica’s water needs are often supported by eutrophic water bodies dominated by cyanobacteria posing health threats to riparian populations from cyanotoxins, and Lake Victoria is no exception. In two embayments of the lake (Murchison Bay and Napoleon Gulf), cyanobacterial surveys were conducted to characterize the dynamics of cyanotoxins in lake water and water treatment plants. Forty-six cyanobacterial taxa were recorded, and out of these, fourteen were considered potentially toxigenic (i.e., from the genera Dolichospermum, Microcystis, Oscillatoria, Pseudanabaena and Raphidiopsis). A higher concentration (ranging from 5 to 10 μg MC-LR equiv. L−1) of microcystins (MC) was detected in Murchison Bay compared to Napoleon Gulf, with a declining gradient from the inshore (max. 15 μg MC-LR equiv. L−1) to the open lake. In Murchison Bay, an increase in Microcystis sp. biovolume and MC was observed over the last two decades. Despite high cell densities of toxigenic Microcystis and high MC concentrations, the water treatment plant in Murchison Bay efficiently removed the cyanobacterial biomass, intracellular and dissolved MC to below the lifetime guideline value for exposure via drinking water (<1.0 μg MC-LR equiv. L−1). Thus, the potential health threats stem from the consumption of untreated water and recreational activities along the shores of the lake embayments. MC concentrations were predicted from Microcystis cell numbers regulated by environmental factors, such as solar radiation, wind speed in the N–S direction and turbidity. Thus, an early warning through microscopical counting of Microcystis cell numbers is proposed to better manage health risks from toxigenic cyanobacteria in Lake Victoria.Item Impacts of the Victoria Nile Bujagali hydropower dam on fisheries and livelihoods(River Res Applic., 2023-01-08) Everest Nduwayesu; Anthony Basooma; Stephen Kabali Sekiranda; John Stephen Balirwa; Samuel Bassa; Elias Muhumuza; Bairon Mugeni; Alex Mulowoza; Moses Musobya; Herbert NakiyendeThe Upper Victoria Nile (UVN) flows from Lake Victoria into Lake Kyoga, spanning 117 km and supports a diverse aquatic fauna that sustains livelihoods of riverside communities. The UVN is habitat to critically endangered (Labeo victorianus), near threatened (Oreochromis variabilis and Oreochromis esculentus), and rare species (Neochromis simotes). Four hydropower dams were built on the UVN to provide energy for industrial and socioeconomic development, notwithstanding consequential environmental and socioeconomic impacts. The impacts of Bujagali hydropower (BHP) dam on fisheries and livelihoods were assessed biannually (April and September) from 2006 to 2019, using fishing effort, species abundance, catch composition, and eco- nomic beach revenue at upstream, mid-reservoir, and downstream transects. The fishing boats increased from 31 in 2009 to 293 in 2019 and fishers from 83 to 500 over the monitoring period. Maximum annual catch of 461.4 t was recorded in 2014 and lowest of 54.2 t in 2009. In all transects, Protopterus aethiopicus and Labeo victorianus were least in the commercial catches and the use of Mormyrus kannume juveniles as bait for Nile perch fishery corresponded with increased catches from 3.3 t in 2009 to 148.2 t in 2019. Women were mostly engaged in post-harvest activities such as fish drying, smoking, and food vending. These observations suggest coupling effects of the hydropower dam and ineffective fisheries management. The harvest of M. kannume wild stocks for bait should be banned and research in possible domestication of the species undertaken. There is a need to strengthen fisheries enforcement to curb illegal effort and overexploitation and to implement conservation actions to mitigate potential biodiversity impacts from the hydropower dam operations.Item Dietary Fishmeal Substitution by Peanut-Based Meals in Nile Tilapia (Oreochromis Niloticus L.): Effect of Pond Water Quality on Biomass Production(Uganda Journal of Agricultural Sciences, 2022-06-10) Musita A. A.; Ogello E. O.; Balirwa J. S.; Bassa S.A 16 week experiment was conducted in earthen ponds in Iganga District of Eastern Uganda to investigate the effect of water quality on biomass production in Nile tilapia (Oreochromis niloticus L.) fed on peanut-based meals as alternative dietary fishmeal. Iso-nitrogenous diets containing 30% and 25% Crude Protein were applied for the first 12 weeks and last four weeks while the control was a local diet for Nile tilapia of 25% Crude Protein throughout the experiment. Treatments included the fishmeal-based diet and two peanut-based diets; peanut meal-based diet and mixed meal-based diet. Each of the 16 pond units measuring 3.0 x 4.0 x 1.0 were stocked with 48 fish fingerlings of 21.7 grams mean weight. Significant differences (p≤0.05) in mean values occurred among targeted parameters; pH, Dissolved Oxygen, nitrite nitrogen and unionized ammonia with exception to temperature. Apart from the unionized ammonia, the significant variations (p≤0.05) in water quality parameters did not significantly affect (p≥0.05) biomass production because they were maintained in suitable ranges for Nile tilapia.Item Effects of hydrocarbon extraction on freshwaters(encyclopedia of Inland Waters, 2022-05-11) Esterhuyse, S.; Redelinghuys, N.; Charvet, P.; Fearnside, P.; Daga, V.; Braga, R.; Okello, W; Vitule, J.; Verheyen, E.; Van Steenberge, M.Aim: This chapter explains hydrocarbon extraction and discusses its effects on inland water resources. Main concepts covered: Section 1 provides an overview of the history of hydrocarbon extraction, the occurrence, and formation of hydrocarbon resources, and explains the conventional and unconventional hydrocarbon extraction techniques. Section 2 discusses the main impacts associated with conventional and unconventional oil and gas extraction on freshwaters. This discussion covers distinct water resource impacts associated with hydrocarbon extraction, acute, ecological, and legacy impacts on surface water and groundwater resources, and water-related socio-economic impacts. Section 3 covers management tools to minimize negative impacts. Throughout, case studies that mostly stem from Africa and South America are used to illustrate impacts and related management options. A detailed glossary explains technical concepts. Conclusion: The discussion of impacts clearly illustrates that oil and gas extraction imperils water resources next to fuelling climate change. Considering the Paris agreement of limiting global temperature increases to 1.5 °C, governments should therefore limit fossil fuel extraction and pursue sustainable development to ensure a liveable planet for current and future generations.Item Drying fish (Rastrineobola argentea) on the bank of Lake Victoria in a prototype solar-heated enclosure: Using renewable energy to reduce drying-time and improve product quality and value(African Journal of Food Science, 2022-11-09) Andrew Whiston; Andreas W. Rost; Richard S. Mangeni; Cayleigh Bruce; Andrew S. BrierleySilver cyprinids (Rastrineobola argentea) are small pelagic fish endemic to Lake Victoria. High-quality dried fish are an important protein-rich human food. This study was carried out to determine if it would be practical to use renewable energy to dry silver cyprinid. Drying is presently achieved by laying fish out in the sun on the ground or on racks. In the wet seasons, however, drying is compromised and much of the catch becomes fit only for animal consumption, or spoils. Lake Victoria’s surface waters are c. 25°C year-round. Its enormous volume of tropical water offers a source of thermal energy that could be used to dry fish. As a proof of concept, we used solar-generated electricity to drive a heat pump to harvest heat energy from water in a 10,000-L rainwater tank beside Lake Victoria, used the energy to heat air, and blew the air over fish in a tent-like enclosure. Fish in the enclosure dried in about 4 h versus about 7 h outside, were free from insects, and not at risk of theft by or defecation upon by birds. The drying processes inside and outside the enclosure were modelled. The model correctly reproduced observed drying times, and enabled exploration of options to improve drying performance. Up-scaling the prototype could provide year-round sustainable fish-drying capability, reduce waste, boost food security, and add value to the catch.Item Scaling aquaculture for food security and employment in Africa: Insights from Egypt, Kenya and Nigeria(Center for Development Research, University of Bonn, 2023-06-07) John K. Walakira; Etienne Hinrichsen; Victoria Tarus; Sandra Langi; Nabil Ahmad Ibrahim; Olanrewaju Badmus; Andrew Aziz; Heike BaumüllerAquaculture is the fastest growing food sector in the world and now accounts for more than half of the fish consumed globally. However, the sector in Africa remains in its infancy, with the notable exception of Egypt, one of the world’s largest producers. This paper provides a thorough analysis of the sector in the selected countries of Egypt, Kenya and Nigeria to help identify investment and policy priorities that can sustainably advance aquaculture across Africa to boost income and employment, rural development and food security. The analysis focuses on nine themes to ensure a comprehensive overview of the sector and to better understand the relative strengths and weaknesses in each country: sector trends, national policy frameworks, government institutions, natural resources to support aquaculture, sector-specific innovation, feed and seed, market access, public-private partnerships, and sectoral impacts. With these in mind, the paper provides a series of recommendations for African policymakers and investors aimed at improving sectoral development across the continent. Among other factors, the recommendations highlight the need to not only increase productive capacity but also linkages to markets and consumers, adopt national policies that provide targeted support to high-potential areas, increase local research capacities and scaling of research results, decentralize seed and feed production for improved access, and promote sustainably produced fish as a promising source of animal-derived protein.Item Integration of probiotics in aquaponic systems: an emerging alternative approach(Aquaculture International, 2023-08-28) Nasser Kasozi; Gerald Degu Iwe; John Walakira; Sandra LangiThe increasing demand on water resources, reduced land for agriculture, and concerns over food and nutrition security have prompted the evolution of innovative and complex food production systems. In this context, e cient and sustainable food production systems such as aquaponics are viewed as an important and environmentally friendly technology for adaptation under resource-limited environments. Producing food in soilless systems is a promising strategy, as this method utilizes signi cantly less water than traditional agricul- ture. However, optimizing growing conditions to enhance crop and sh yields in aquapon- ics is frequently ambiguous and is often not economically feasible. One of the strategies to improve plant yields and supply of nutrients in aquaponics is the application of probiotics. With this strategy, the crop yields in aquaponics are improved via a variety of mechanisms, including nitrogen xation, solubilization of mineral nutrients, organic matter mineraliza- tion, plant hormone modulation, and biocontrol. As a result, incorporating probiotics in aquaponic systems is a strategy for mitigating environmental e ects and advancing sustain- able agriculture. This review paper provides the current knowledge of the use of probiot- ics in aquaponics. Suggestions for further studies on the e ects of probiotics in aquaponic systems are proposed. Through literature review, integrating probiotics into aquaponic systems has the potential to improve nutrient supply, modulation of water quality param- eters, and microbial communities, which are key processes in enhancing the productivity of aquaponic systems.Item Histological features of the gastrointestinal tract of elongate tiger fish, Hydrocynus forskahlii (Cuvier, 1819), from Lake Albert(The Journal of Basic and Applied Zoology, 2024-05-10) Nasser Kasozi; Gerald D. Iwe; Sandra Langi; Victoria T. Namulawa; John WalakiraThe tiger fish (Hydrocynus forskahlii) is an important food fish in different regions of Africa. As such, interest in its performance and nutritional requirements as a potential candidate for aquaculture is increasing. Char- acterization of the morpho-histological features and functions of the gut provides valuable insights into the feeding physiology and digestive system of fish species.Item Potential Impacts of Oil and Grease on Algae, Invertebrates and Fish in the Bujagali Hydropower Project Area(National Agricultural Research Organisation, 2021-09-01) Wanda F. M.; Moureen Matuha; Godfrey Magezi; Racheal Nabwire; Brenda AmonditoThis study determined the concentration of oil and grease and inferred its impacts on algae, invertebrates and fish. Water samples were collected in April and September from 2012 to 2018 at the upstream and downstream transects and in the reservoir, and analysed for oil and grease following standard procedures. Environmental compliance was compared to NEMA’s discharge standard of 10 mg/l, and its PAH effluent discharge standard of ≤ 0.1 mg/l. At all sites, average concentrations of oil and grease were below 10 mg/l throughout the sampling period. Out of the 14 data sets for each transect, only 3 along the upstream transect, and 2 at each of the downstream transect and the reservoir were compliant with the effluent discharge standard. Although impacts of oil and grease on aquatic biota were not assessed, their relatively high concentration compared to total Polycyclic Aromatic Hydrocarbon (> 0.1 μg/l) is considered hazardous to most aquatic organisms. The diverse activities around the project area implied that sources of oil and grease were proportionately diverse. Hence, the observed trends may not solely be attributed to the hydropower project. Accordingly, assessment of the various sources of oil and grease and their impact on aquatic biota in the area is recommended.Item Profit Indices in Nile tilapia (Oreochromis Niloticus L.) Fed on Peanut-Based Meals as Alternatives to Dietary Fishmeal in Grow- Out Earthen Ponds(National Agricultural Research Organisation, 2021-09-01) Musita A. A.; Ogello E. O.; Balirwa J. S.; Bassa S.Persistence of dietary fishmeal probably accounts for the low profitability in farmed Nile tilapia in Uganda. A 24 week field study was conducted in Busoga sub-region of Eastern Uganda to compare profit indices in pond cultured Nile tilapia fed on peanut-based meals as alternatives to dietary fishmeal. It consisted of an experiment and sample survey that targeted fish biomass production and input-output valuation respectively. Each of the 12 earthen ponds measuring 12 cubic meters were stocked with 48 ‘all male’ Nile tilapia (Oreochromis niloticus L.) fingerlings of mean initial weight of 21.7 grams. Iso-nitrogenous diets containing 30% and 25% Crude Protein were applied for the first eight and last four respectively. Dietary treatments included fishmeal-based diet and two peanut-based diets; peanut meal-based diet and mixed plant-based diet. Profit indices for the fishmeal and mixed plant-based- diets were not significantly different (p0.05). On the contrary, the Profit index characteristic to the PNM-based diet was significantly lower (p≤0.05) than the other test diets. Accordingly, the mixed plant meal should be used for complete substitution of dietary fishmeal in pond cultured Nile tilapia.Item Increasing Farmers’ Access to Aquaculture Extension Services: Lessons from Central and Northern Uganda(National Agricultural Research Organisation, 2021-06-15) Gertrude Atukunda; Peter Atekyereza; John K. Walakira; Andrew E. StateThis paper focuses on examining the modalities of extension service provision, and determining feasible approaches for increasing accessibility among fish farmers in Uganda. The paper draws on a cross-sectional study involving fish farming households and extension workers to determine access to extension services for improved farming practices. Quantitative data were collected from 246 households using a semi-structured questionnaire. Qualitative data were generated from Key Informant interviews with selected extension workers, officials in charge of extension planning District Fisheries Officers and Fish Farmer Group leaders. Focus Group Discussions were also conducted with fish farmers. The results indicated a significant association between socio- economic characteristics of fish farmers and access to extension services. Size of land owned, income from pond fish and membership to fish-farmer groups were the significant factors (P<0.05). All the respondents reported pressing needs which required extension intervention. The respondents expressed the need to form effective farmer groups for the purpose of sharing knowledge, arriving at mutual agreement on scheduling extension activities and providing feedback to the extension workers. Specifically for the northern region, there is a need for the Fisheries Extension Officer to identify and respond to the extension needs of fish farmers through various means including ICTs. Identifying solutions to social, technical and institutional constraints in extension can increase access to services through constructive social interactions between farmers and extension agents. The article provides important lessons for practice and policy, and proposes a farmer-centred model, capable of facilitating increased access to aquaculture extension services in Uganda.Item Dietary Fishmeal Substitution by Peanut-Based Meals in Nile Tilapia (Oreochromis Niloticus L.): Effect of Pond Water Quality on Biomass Production(National Agricultural Research Organisation, 2022-03-01) Musita A. A.; Ogello E. O.; Balirwa J. S.; Bassa S.A 16 week experiment was conducted in earthen ponds in Iganga District of Eastern Uganda to investigate the effect of water quality on biomass production in Nile tilapia (Oreochromis niloticus L.) fed on peanut-based meals as alternative dietary fishmeal. Iso-nitrogenous diets containing 30% and 25% Crude Protein were applied for the first 12 weeks and last four weeks while the control was a local diet for Nile tilapia of 25% Crude Protein throughout the experiment. Treatments included the fishmeal-based diet and two peanut-based diets; peanut meal-based diet and mixed meal-based diet. Each of the 16 pond units measuring 3.0 x 4.0 x 1.0 were stocked with 48 fish fingerlings of 21.7 grams mean weight. Significant differences (p≤0.05) in mean values occurred among targeted parameters; pH, Dissolved Oxygen, nitrite nitrogen and unionized ammonia with exception to temperature. Apart from the unionized ammonia, the significant variations (p≤0.05) in water quality parameters did not significantly affect (p≥0.05) biomass production because they were maintained in suitable ranges for Nile tilapia.