Large scale fish deaths on Lake Victoria not linked to poisoning
Communities living in and around the shores of Lake Victoria have recently been concerned by the growing number of dead fish, especially Nile Perch, being wash They are worried that the Lake is contaminated by poisonous chemicals. The dead fish are not only an eyesore but also emit an offensive odor as the decomposition occurs.
However, preliminary investigations have ruled out the possibility of poison as the cause of the deaths of the fish.
The occurrence has been attributed to a drop in oxygen levels. Nile perch is species of fish known to be sensitive to low oxygen levels- (below 2mgl).
As a result of the recent flooding and rising water levels, large masses of weeds were submerged and sunk into the lake bed. These weeds use up oxygen as they rot from within the lake hence a drop in the oxygen levels.
Also, the recent strong winds around the lake Victoria basin have heightened lake overturn; a phenomenon that causes water from the bottom of the lake that is low in oxygen, to come up and mix with upper layers, where fish live; leading to a reduction in oxygen, hence the death of fish.
This is not the first time large scale fish deaths are occurring on Lake Victoria; Fishing communities have always referred to this situation as “Kaliro” and it occurs periodically.
Communities living around the lake are advised to bury the dead fish to contain the pungent smell; as further research and studies are undertaken by all stakeholders including, NEMA, MAAIF, Communities, developers etc