Abstract:
Sand mining is a widespread practice in Uganda, posing significant environmental challenges to
freshwater ecosystems, including habitat destruction, water pollution, and 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 and agriculture. This study aimed to investigate the impacts of sand mining and
increased siltation on fish species composition and abundance within the Namasagali catchment
area of the Nile Kamuli district. 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 mining on fish
catches and catch rates.
A retrospective experimental approach with control sites was employed, combining quantitative
and qualitative data collection methods. Line transects, grab samples, scoop nets and standard gill
nets were used to assess riverbed substrate composition and fish populations
The results showed significant differences in sand and cobbles percentages among the four study
sites, with Kabeto A having significantly higher sand percentage (53.2%) compared to
Nsangabiire (46.1%). Fish catches varied among sites, with Nsangabiire having the highest
number of fish caught (19 fish) and Kabeto A having the lowest (8 fish). Local fishers reported
significant variations in average number of individuals per species among the sites, with Nile
tilapia (Oreochromis niloticus) being the most abundant species (4.2 kg per site).
The study found that sand mining has significant impacts on freshwater ecosystems, including
alterations to riverbed substrate composition and fish populations. The findings highlight the need
for sustainable management strategies. Recommendations include: (1) enforcing environmental
regulations to prevent sand mining in sensitive habitats; (2) promoting alternative livelihoods for
sand miners, such as agriculture and tourism; and (3) conducting further research on the long-term
impacts of sand mining on freshwater ecosystems.
