THE mysterious death of fish in Lake Victoria reported since last month has been caused by low oxygen levels in the lake, the government has disclosed.
"The recent strong winds around Lake Victoria basin have heightened the lake causing water from the bottom, which is low in oxygen, to come up and mix with upper layers, where fish live; this leads to reduction in oxygen, hence the death of fish," the Permanent Secretary in the Ministry of Livestock and Fisheries Dr Rashid Tamatamah said at stakeholders meeting.
He said few weeks ago samples from Bukoba, Rorya, Musoma, Mwanza, Sengerema, Chato and Geita were taken to the Government Chemist Laboratory Agency (GCLA) and the results came out on Wednesday showing that the fishes did not die from poison.
Dr Tamatamah assured fishermen that the fishes are not harmful; however, he cautioned them to be careful as some fishes may not be good for consumption.
A month ago stocks of dead fish were reported floating on waters of Lake Victoria. He said the lake has layers where the level of oxygen differs. There is more oxygen on the top than the bottom.
"Sometimes water from the top layer is mixed with the one in the bottom which affects the level of oxygen concentration in water. This happens when rivers flow very fast into the lake causing water to stir up," he explained.
He said in any lake, there is always stratification; there is normally a layer of cold water underneath warm water that is lighter. The colder water in most circumstances does not have enough oxygen because of pollution.
"Nile perch requires large amounts of oxygen, so the process deprives the water of oxygen making the water environment completely inhabitable for fish," noted Dr Tamatamah.
The three-day meeting attracted more than 315 participants from all institutions under the ministry and other stakeholders in the fisheries sector.
The meeting’s objective was to jointly evaluate the implementation of various policies and programmes implemented in the fisheries sector so that it could contribute more to individual income and the Gross Domestic Product (GDP) in general, increase employment, food security and poverty reduction.
Since December, communities living in and around the shores of Lake Victoria have been complaining over the growing number of dead fish, especially Nile Perch, being washed ashore.
In May 2020, Lake Victoria levels recorded 13.42 metres, surpassing the highest recorded level at 13. 41 metres in May 1964. The occurrence caused massive flooding as the lake waters broke their banks, displacing hundreds of families and businesses near the shores.