Kampala, Uganda | THE INDEPENDENT | Hundreds of dead fish are floating on Lake Victoria.
Although the cause is not yet established, with many fearing poisoning or pollution, the Ministry of Agriculture, Animal Industry and Fishery (MAAIF) together with the environmental authority in Uganda have raised the possibility that the cause could be increasing algae, which they say tends to suffocate the fish by using up the oxygen in the water.
The ministry’s conclusion came after investigation teams picked sample collection from Kasenyi landing site and surrounding areas, Gguda landing site (greenfields), Bugonga landing site and Kigungu Landing site and Wagagi Flower Farm and Lido beach all in Wakiso.
“As we await the comprehensive laboratory findings report due on Monday January 11th, 2020, preliminary investigations have ruled out fish poisoning. As only the Nile Perch specie has been affected by this phenomenon,” MAAIF Permanent Secretary Pius Wakabi Kasajja said in a statement.
National Environment Management Authority (NEMA) also issued a statement on Sunday stating that, “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).”
NEMA added that, “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.”
A lot of the dead fish can be seen floating over Bugonga Bay in Entebbe and curiously, it is only one type dying – the Nile Perch (Empuuta).
NEMA said the recent strong winds around the lake Victoria basin have heightened lake overturn, a phenomenon they say 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. This, NEMA says, leads 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.”
Baguma says besides poison, the fish could be struggling from the effects of rotting weeds which affect water quality. He said the water hyacinth is a main suspect, because it uses oxygen in the process of decaying.
Experts say the best way to determine what could be happening to the dead fish is subjecting them to laboratory tests.
The National Fisheries Resources Research Institute (NaFIRRI) has embarked on testing and research on the main cause of the deaths and results will be communicated.
“Dead fish is floating in many parts of the lake especially at Bugonga bay and surrounding areas,” Baguma says. “Incidentally we have not experienced it yet in Kalangala. However, anything can happen any time since we share the same water body.”
Fishermen on Lake Victoria have been seen picking the dead floating fish for sauce in their homes without first determining the route cause of their death.
Baguma said they should wait until NaFFIRI identifies whether it is poison or rising temperatures in Lake Victoria waters, before they pick the fish.
NEMA advised that communities living around the lake should bury the dead fish to contain the pungent smell as further research and studies are undertaken by all stakeholders including, NEMA and MAAIF.