Physical characterization of the cage culture of Oreochromis niloticus L. 1758, in the Bukavu sub-basin on Lake Kivu, Democratic Republic of the Congo

Abstract

This work consisted in physically characterizing the floating cages used for farming Tilapia Nile in four bays of the sub-basin of Bukavu on Lake Kivu. The measurement of several parameters such as the depth of the water column and the distance of the cage taken by D-173 Bricodis decameter. The result shows that there are 218 cages of which 156 are exploited and 62 non-exploited. 76 cages are installed at 50 m and 58 cages are located at 6–49 m of the coast. The fact that the water of Lake Kivu is essentially pelagic pushes the fish farmers to place the cages on the littoral. Local cages are more abundant than those offered by FPI/IITA. 54% of the Oreochromis niloticus fry came from the D.R. Congo and 46% from Rwanda. Anthropogenic activities on a catchment scale cause benthic modification and reduce site characteristics. The diverse origin of fry should be discouraged to avoid new exotic species. Environmental impact studies of this culture on the biology and physicochemical parameters in the bays would help to address the environmental challenges of this culture in the Lake Kivu ecosystem.