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Exploitation of Brycinus nurse (Rüppell, 1832) and Engraulicypris bredoi (Poll, 1945) in lake albert, Uganda: implications for management

(Makerere University, 2026) Nakiyende, Herbert

Lake Albert supports a diverse artisanal fishery characterized by multi-species exploitation using a wide range of fishing gears. The fishery is increasingly dominated by two small pelagic fish species (SPS), Brycinus nurse and Engraulicypris bredoi, which are primarily harvested using vertically stacked small seine nets operated in conjunction with artificial light attraction. Despite their growing importance, the ecosystem-level impacts of these fishing techniques on both target and non-target fish stocks remain poorly understood. The use of these light assisted gears has also generated conflicts with fishers targeting large-bodied species, particularly Nile perch (Lates niloticus), due to perceptions that these gears negatively affect the recruitment and availability of larger species stocks. This study was conducted on the Uganda portion of Lake Albert between September 2019 and July 2022, with the aim of evaluating the socio-ecological effects of light-attraction fishing techniques as a basis for informing sustainable fisheries management. A mixed-method approach was adopted, integrating literature reviews, experimental fishing, catch assessment surveys, hydroacoustic assessments, and stakeholder consultations. These methods were used to quantify catch rates, species abundance and distribution, life-history traits, exploitation patterns, and biological reference points relevant to the management of the lake’s artisanal fisheries. Results indicated a substatial light-attraction fishing effort on Lake Albert, accounting for approximately 40% of the lake’s active fishing vessels. Fishing activity peaked during moonless nights and was significantly (P<0.05) associated with higher SPS catch rates. High bycatch, unregulated expansion of light-fishing effort, excessive net stacking, and the increasing use of solar-powered fishing lights emerged as the principal drivers of user conflict within the fishery. Marked spatial variation in SPS abundance was observed across the lake. Engraulicypris bredoi dominated catches in the central region (F (2, 15240) = 172.45, p<0.001), whereas B. nurse was more abundant in the southern region (F (2, 4447) = 41.166, p<0.001). Hydroacoustic survey and artisanal catch statistics consistently demonstrated the dominance of SPS, which constituted approximately 82% and 70% of total biological scatter and catch volume, respectively, indicating a high standing biomass of small pelagic species stocks in Lake Albert. Analysis of life history traits revealed pronounced sexual dimorphism in length at 50% maturity (Lm50) for both species. Male E. bredoi matured at a larger size (31.6 mm) than females (23.9 mm), whereas female B. nurse matured earlier and at a larger size (60.9 mm) than males (56.8 mm). Both species exhibited positive allometric growth and high condition factor: B. nurse (b = 3.21, K = 2.08) and E. bredoi (b = 3.06, K = 1.27), suggesting favourable physiological condition and relatively healthy stock status. Experimental fishing trials demonstrated that light attraction significantly enhanced SPS catch rates (p<0.05), with near-zero catches recorded under control treatments without light. This finding corroborates observed fishing patterns characterized by intensified effort during dark nights and confrims the functional necessity of artificial light in SPS exploitation. Bycatch, particularly of Lates niloticus, Oreochromis niloticus, Hydrocynus forskahlii, and Distichodus niloticus, was predominantly recorded in shallow inshore waters (< 20 m depth). These habitats serve as critical zones for biodiversity conservation, recruitment, and stock replenishment, underscoring the need for their protection from intensive fishing pressure. Net stacking was found to significantly increase both SPS catch rates and bycatch. Optimal SPS yields with comparatively minimal bycatch were achived at a net depth of approximately 16 meters (eight panels), suggesting a a potential management threshold for regulating fishing effort. Estimates of maximum sustainable yield (MSY) and fishing effort at MSY indicated that current exploitation levels for both E. bredoi (~90,000 t; 2500 boats) and B. nurse (~37,000 t; 2000 boats) remained below 2022 observed thresholds, implying that SPS were not yet fully exploited. These findings have important implications for sustainable management of Lake Albert’s SPS fisheries. The study recommends revising existing fishing regulations to incorporate SPS-specific management measures, including species-specific licensing, protection of inshore breeding and nursery habitats, regulation of net stacking, and promotion of standardized solar fishing lights. In addition, strengthening regional collaboration for comprehensive stock assessments and harmonized fisheries management frameworks is essential. These measures, when implemented could contribute to reduction in bycatch, mitigate fishing conflicts, and promote the long-term coexistence of multi-species fisheries within the Lake Albert ecosystem.
The status and distribution of carnivores in Bwindi Impenetrable National Park (BINP), South-Western Uganda

(Makerere University, 2000) Andama, Edward

This study was conducted between December 1997 and July 1998 in Bwindi Impenetrable National Park (BINP), South Western Uganda. The aims were to determine the occurrence, population status, distribution, food habits, and to investigate human factors likely to affect the survival of carnivores. Seven sites were selected on the basis of altitude, vegetation type, and extent of forest disturbance for in-forest assessment. Population status was assessed using both direct (night survey) and indirect (scent station visitation rates) methods along transects in the forest. Geographical Positioning System (GPS) was used to map the distribution of carnivores from sightings and signs of spoors and scats. Food habits were assessed from scat analysis. And a questionnaire was administered to 107 respondents from eight parishes neighbouring the park to assess anthropogenic factors likely to affect carnivore status. Sixteen carnivore species were recorded by this study, forming 42.1 percent of the species that occur in Uganda. The Clawless Otter, Aonyx capensis Schinz, Spotted necked Otter, Lutra maculicollis Lichtenstein, Honey Badger, Mellivora capensis Schreber, and African wild Cat, Felis sylivestris Schreber were recorded for the park for the first time. The results indicate that human disturbance and percentage ground vegetation cover (GVC) are important factors affecting abundance and distribution of carnivores. The carnivore species, especially side-striped jackal, Canis adustus Sundevall and African Civet, Viverra civetta Schreber that mostly depend on scavenging and crop raiding as alternative ways of obtaining food items were more common in the periphery of the park, at sites with high human activity. On the other hand, Golden Cat, Profelis aura/a Temminck, M capensis and A. capensis, which are not scavengers, were mostly restricted to sites with minimum human presence. High GVC appeared to attract the species that are more dependent on rodents as main food items. The distribution of aquatic carnivore species, such as Water Mongoose, Atilax paludinosus G. Cuvier, L. maculicollis and A. capensis was associated with the presence of swamps and rivers, while Banded Mongoose Mungos mungo Gmelin was restricted to the low altitude parts of the park (northern sector), with predominantly grassland vegetation. Among the carnivore species recorded, there was no completely speciali sed feeder. The wild prey items featured most prominently, with rodents and insects being the most common food items. Canis adustus and V civetta had opportunistic feeding habit, complimenting their diets with village refuse, local food crops and wild plants fruits, while the Golden Cat, P. aurata was the only carnivore species whose diet mainly consisted of medium sized herbivores especially Duikers. The Local people had substantial knowledge of carnivore species: more than 80 percent of the carnivore species were known to most of them. The most important factor determining the attitude of the local residents towards carnivore conservation appeared to be the perceived economic loss resulting from livestock/poultry raiding by the wildlife. Raiding on domestic animals was reported to be on the increase (67.79 percent of the respondents), as a result of better protection accorded to the wildlife. The use and trade in skins and other products obtained from carnivores are currently minimal and mostly limited to medicinal purposes. Genets were the only culturally revered species in the area. The status of carnivore species is most insecure outside the park as a result of habitat loss and persecution. Efforts to change negative attitude of people residing in sites close to the park periphery will probably take more time. However, this could be achieved through introduction of modem poultry farming methods and extensive conservation education programs.
Assessment of mosquito repellent efficacy of different formulations from tithonia diversifolia, cymbopogon citratus, and eucalyptus globulus

(Makerere University, 2026) Aheebwa, Scovia

Mosquito-borne diseases remain a major public health concern, particularly in sub-Saharan Africa. Growing limitations of synthetic repellents including resistance, environmental concerns, and safety issues have increased interest in plant-based alternatives. This study evaluated the repellent efficacy of essential oil formulations from T. diversifolia, C. citratus, and E. globulus against anopheles gambiae mosquitoes. Plant essential oils extracted via hydro-distillation, were characterized using FTIR and GC–MS for 1,8-cineole in E. globulus citral in C. citratus, and d-limonene in T. diversifolia. Individual essential oils were tested at 12% ,15% and 18%v/v test concentrations of the main active repellent compounds. Three Polyherbal blend formulations; Blend A (12%), Blend B (15%), and Blend C (18%) were prepared using the minimum effective concentrations of T. diversifolia (15%), C. citratus (12%), and E. globulus (12%). Repellency efficacy of the individual oils versus the blended formulations against Anopheles gambiae was assessed following the Surface Landing method with Odomos and methanol as the positive control and negative control respectively. At 12%, Blend A maintained 89.0 ± 2.0% repellency at 4 h and 15.0 ± 0.2% at 8 h, compared with 01EO (59.0 ± 1.4%, 1.0 ± 0.0%), 02EO (88.7 ± 1.6%, 11.0 ± 0.0%), and 03EO (83.1 ± 1.7%, 10.0 ± 1.5%), with significant differences for 01EO at all time points and with 02EO and 03EO at later hours (p < 0.05). At 15%, Blend B retained 82.4 ± 1.5% and 78.0 ± 2.0% repellency at 5–6 h and 20.2 ± 0.5% at 8 h, exceeding 01EO (86.6 ± 1.8%, 73.3 ± 0.0%, 10.0 ± 0.0%), 02EO (85.0 ± 1.6%, 72.8 ± 1.5%, 15.0 ± 1.7%), and 03EO with significant differences for all individual oils at later hours (p < 0.01-0.001). At 18%, Blend C maintained 96.4 ± 2.5%, 86.0 ± 1.0%, and 60.0 ± 0.5% repellency at 5, 6, and 8 h, respectively, compared with 01EO (68.0 ± 1.6%, 36.0 ± 1.6%, 10.0 ± 1.4%), 02EO (90.0 ± 0.0%, 83.3 ± 1.7%, 30.0 ± 0.0%), and 03EO (89.0 ± 1.7%, 80.2 ± 1.7%, 40.0 ± 1.9%), with Blend C significantly outperforming all oils at most time points (p < 0.05-0.001). Findings from this study indicate that blends are more effective than individual oils and show that potential synergistic blending significantly improves both potency and duration.
Development and evaluation of loop-mediated isothermal amplification assays for diagnosis of malaria and sickle cell anaemia

(Makerere University, 2026) Balinda, Charles

Malaria and sickle cell anaemia (SCA) are co-endemic and are among the leading cause of child morbidity and mortality in Uganda. Misdiagnosis of malaria and delayed diagnosis of SCA due to low parasite density and lack of diagnostic facilities at the point of care leads to poor case management. This study developed Loop-mediated isothermal amplification (LAMP) assays for diagnosis of malaria and SCA with the aim of improving the diagnosis of both malaria and SCA at the point of care. The LAMP assay primer sets targeting the Plasmodium falciparum plasmoredoxin (Plrx) gene and the SCA rs334 mutation were designed. The LAMP assays were optimized and their diagnostic performance were evaluated in terms of sensitivity and specificity using blood samples from consented participants. The Plrx based LAMP assay for diagnosis of malaria had a limit of detection of 7 parasites/µL, analytical specificity of 100% and a turnaround time of 30 minutes when DNA is available. The Plrx based LAMP assay had a diagnostic sensitivity of 100% and specificity of 95%, with an almost perfect agreement (κ = 0.929) compared to nested Polymerase chain reaction when performed on 127 blood samples. The SCA rs334 mutation based LAMP assay for diagnosis of SCA had analytical sensitivity of 0.2 ng/µL and failed to accurately differentiate all the rs334 mutations and wild type alleles. The SCA LAMP assay had a turnaround time of 60 minutes, diagnostic sensitivity and specificity of 100% and 64.3% respectively. The Plrx LAMP assay and SCA LAMP assay developed in this study are simple, rapid and require less sophisticated dry heat block and are therefore, good options to be applied at the point of care.
Larvicidal potency of plectranthus barbatus, Andr. Labiatae on some culicine and anopheline mosquitoes

(Makerere University, 1998) Asiimwe, Caroline Twesigye

For a long time, plectranthus barbatus Andr. (Labiatae), a dicotyledonous shrub has been used successfully by the Luo people in Eastern Uganda as a mosquito repellent by placing it’s branches in windows. This act, implies that P. barbatus has mosquitocidal properties, which were investigated in this study with a major objective of finding out whether or not this plan contained bioactive compounds against mosquitoes. Samples of the plant were collected from Tororo District and separated into floral, leaf and stem portions. Following methods described by Odyek et al. (1989), cold extraction was carried out using ether, methanol and water. Crude extracts obtained, were tested for their toxicity against shrimp, mosquito larvae and adults, using bench to bioassay guided screenings, recommended for dose-effect experiments. Results obtained were analysed using Finney’s subprogram and three factor Analysis of Variance which was recommended in reviews cited by Simpson et al (1960). Examination of results obtained from the shrimp assay indicated significant bioactivity within the leaf and stem methanolic crude extracts. However, only ether crude extracts were found significantly bioactive against mosquito larvae. Floral and leaf ether crude extracts exhibited the highest activity against all mosquito larvae (LSD value 12.73; 10.75, p=0.05, 2df) unlike the stem extract (LSD value 6.78, p=0.05, 2df). Larval response varied among species with higher mortalities in Anopheles and Culex (LSD values respectively = 11.87; 11.22, p=0.05, 2df) unlike Aedes (LSD value 7.159, p=0.05, 2df). LD50 values obtained also agreed with the above results confirming that floral and leaf crude extracts of P.borbatus are significantly toxic to Culex, Aedes and Anopheles mosquito larvae unlike the stem extracts. All the ether crude extracts obtained did not exhibit toxic or repellent properties to Culex, Aedes and Anopheles adult mosquitoes. This contradicated with the indigenous knowledge and use of the plant by the Luo people in Eat Uganda, as a mosquito repellent. It was thus deduced that P.barbatus contains useful larvicidal coumpounds which could be isolated and identified.

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