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KMFRI introducing prototype fish cages to monitor oxygen levels

The loss of fish worth Sh1 billion in Lake Victoria has prompted the introduction of a prototype in fish cages to monitor oxygen levels to guard against further losses.

This comes as a relief to the fisher folk practicing cage fish farming on the lake after having incurred the heavy losses attributed to upwelling, a natural phenomenon that involves drastic temperature changes and oxygen depletion.

Kenya Marine & Fisheries Research Institute (KMFRI) experts said upwelling usually takes about an hour but during the process, fish contained in cages are deprived of adequate oxygen culminating in the huge amounts of fish killed on the shared water mass.

Chief Executive Officer (CEO) KMFRI Prof. James Njiru said global warming enhances land to sea temperature gradients that in turn increase upwelling favourable winds resulting in evaporation, lack of precipitation and changes of the earth tilting on its axis.

Prof. Njiru said it means that Lake Victoria is now at the risk of disappearing, quoting a 2020 study analysis on historical and geological data over the past 100, 000 years that established that the entire water body could disappear in the next 500 years.

Even so, KMFRI also apportioned blame on heavy polluters like industries and the discharge of raw sewer directly into Lake Victoria, which caused the fast increase of the algae bloom and the ferocious waterweed hyacinth to grow since they relied on the effluent, he stated.

Algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems.

The other major concern is the phosphorus fertilizers used by farmers uphill that have on a limited scale also contributed to the fish kills or death.

The don said industries treated the lake as a dustbin where they could discharge raw sewer and other effluent at any time they deemed fit without any deterrent measures being instituted against them.

In this light, Prof. Njiru argued that the fish was already caged and so the fisher community have been advised to ensure the fish cages are located in strategic positions and levels not haphazardly and deep down the lake.

He said the enforcement arm of the government should also move with speed to confirm that the fishers have conformed to the directive, while the fish farmers were also advised to stop investing in the wrong places since the returns would not be satisfactory.

“The fisher folk should get free expert advice from the KMFRI offices in Kisumu. We will also ensure consistent monitoring and assistance to farmers working closely with Gatsbi and other partners,” he explained.

Prof. Njiru also reassured the public that fish in Lake Victoria is 100 percent clean as the huge fish kills was not in any way associated with chemical poisoning except lack of adequate oxygen.

“This is why we have introduced a prototype into the cages to warn the fish farmers whenever the oxygen levels drop drastically,” he added.

While calling on the relevant agencies to ensure the fish safety guidelines are followed to the letter and in line with the East African Community (EAC) protocols, the don pointed out that similar fish kills also happened in the sister states of Tanzania and Uganda.

He stated that the fisher folk should refrain from locating the fish cages near the fish landing beaches which were the first point the raw sewer, fertilizers from agricultural activities uphill and other effluent from heavy polluters ended up in.

By Joseph Ouma

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