Businge, Anatori2026-05-152026-05-152025Businge, Anatori.(2025). An assessment of the impacts of sand mining and increased silting levels on the fish species composition and abundance along the river nile, Namasagali catchment area, Kamuli Districthttps://bdears.busitema.ac.ug/handle/123456789/2769Sand mining is a widespread practice in Uganda, posing significant environmental challenges to freshwater ecosystems, including habitat destruction, water pollution, and a loss of biodiversity. The Namasagali catchment area, a sub-basin of the Victoria Nile River, is one of the affected regions, with sand mining activities threatening the livelihoods of local communities dependent on fishing. This study investigated the impacts of sand mining on fish species composition,abundance, and catch rates within this area. Specific objectives included: (1) to determine the changes in riverbed substrate composition due to sand mining; (2) to assess the impacts of sand mining on fish species composition and abundance; and (3) to evaluate the effects of sand miningon fish catches and catch rates from the perspective of local fishers. A retrospective experimental approach with control sites was employed, combining quantitative and qualitative data. Riverbed grab samples were visually analyzed, and fish populati ons were assessed using standard gill nets and longlines. Demographic and catch-rate data were collected through a questionnaire administered to local fishers. The results showed that sand mining has fundamentally altered the physical composition of the riverbed, creating a new, coarse-grained substrate of sand and gravel with a notable absence of shells, in contrast to the natural fine and silty offshore sediments. Fish species diversity across the sites was composed of six species, with the Lake Victoria squeaker (Synodontis victoriae) being the most dominant. A one-way ANOVA analysis revealed significant inter-site variability in fish catches (F (3,10) =7.92, p<0.05), with the active mining site, Kalama, exhibiting the highest total catch. This counterintuitive finding is attributed to the temporary exposure of food particles caused by the mining process, which acts as a localized fish attractant. However, a paired -samples t-test on fisher-reported data indicated a highly significant decline in average dai ly catches from a historical average of 19.0 to a current average of 9.7 individuals (t (29) x =9.00, p<0.0001). While sand mining can create temporary, localized feeding grounds for fish, its broader impact is a significant alteration of the riverbed ecosystem and a substantial adverse effect on the overall catch rates and livelihoods of the fishing community. The findings underscore the need for effective management strategies to mitigate these impacts.enThesis