Cage‐Cultured Nile Tilapia (Oreochromis niloticus) Farming: A Third Generation of Pollution in Lake Victoria, Tanzania
2025
Richard S. Komba | Chacha J. Mwita | Esther G. Kimaro
ABSTRACT This study was carried out along the Mwanza Gulf, Lake Victoria, Tanzania, where water samples for the determination of physico‐chemical parameters were collected from March to October 2023. NH4+‐N, NO3−‐N, NO2−‐N, and PO4+‐P were analyzed using standard methods. Temperature (°C), electrical conductivity (µS/cm), dissolved oxygen (mg/L), pH, and turbidity were measured in situ. Water temperature ranged from 27.9°C at Misungwi to 29.1°C at Nyamagana. Dissolved oxygen (DO) was high at Ilemela (6.70 mg/L) and declined (5.78 mg/L) at Nyamagana. Electrical conductivity and water turbidity increased as the number of cages sampled increased. Nitrate increased from 0.09 mg/L (90 µg/L) at Ilemela to 0.15 mg/L (150 µg/L) at Nyamagana, ammonia concentration from 0.26 mg/L (260 µg/L) to 0.45 mg/L (450 µg/L) at Nyamagana, and phosphate increased from 0.26 mg/L (260 µg/L) to 1.41 mg/L (1410 µg/L). When the results of this study were compared to those reported before 2015, the variations were significant at all levels. We conclude that inputs from cage fish farming are contributing immensely to nutrients loading and thus pollution in the lake. The riparian governments around the lake are urged to take measures that will ensure sustainable cage fish farming without jeopardizing the environmental quality of Lake Victoria with the consequential collapse of the existing fishery.
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