The possibility of using fallowing as an ecosystem management measure to restore ecosystem functions in disturbed aquatic environments under cage culture was evaluated in this study. The cage aquaculture site in the Southeast arm of Lake Malawi was studied following the abandonment of cage aquaculture activities in 2022 after 18 years of producing fish. The study found that physical-chemical parameters of water such as temperature, pH, ammonia, turbidity and dissolved oxygen were not significantly different (p>0.05) across the cage and non-cage sites and between seasons.
However, ammonia levels recorded in this study were lower than the values reported by studies done when cage culture operations were in progress, an indication that some recovery processes are happening at the site. Chl-a levels were found to be insignificantly different between cage and non-cage sites (p>0.0.5) but were found to be significantly influenced by season (p<0.05). The Chl-a levels in this study were higher than those of previous researchers suggesting that the increase is independent of cage aquaculture but rather a response to external inputs that may be linked to agriculture run off considering that high levels were recorded in the wet season. Chl-a was found to be significantly and highly correlated positively with temperature, followed by total suspended solids and pH. Overall, the site is undergoing recovery with respect to the abandonment, but the effect is masked by external inputs of nutrients into the Lake. Although the study found that Lake Malawi is still an oligotrophic lake, the increasing levels of Chl-a are alarming and calls for inclusion of watershed management in agriculture and environmental management programming to sustainably safeguard the health of the Lake.