Researchers warn of toxic metals in Lake Nakuru fish as business flourishes

Researchers have warned of presence of toxic heavy metals found in fish within Lake Nakuru as residents swarm the lake with fishing nets and boats to fish following swelling of the lake.

Lake Nakuru, according to a recent study, currently has three newly introduced tilapia fish species that previously never existed.

Until the recent rise in water levels in the lake researchers say only one species which was introduced in 1953 existed within the soda lake. The new fish species, has attracted locals and has seen makeshift eateries spring up on the boundaries of lake shores.

Danger, is however lurking as locals continue to eat fish that consume toxic heavy metals as revealed by a research that was done in April this year.

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 “Toxic heavy metals were detected in all the fish samples.  The levels of Chromium exceed the FAO limit of 0.14mg/l. The other toxic metals are of concern,” researchers noted.

The detection of heavy metals in the fish even in small concentrations, researchers say, may not have immediate health threat on consumers of fish and fish products from L. Nakuru, but will likely have adverse effects if there is prolonged consumption of the fish species since heavy metals accumulate.

The researchers further blame pollution of Lake Nakuru noting that over 65 percent of human waste ends up in the lake untreated, due to inefficient transport and treatment. Solid waste and storm water and drainage management is also limited. 

“This is the reason that the lake is completely anoxic and cannot support life, particularly in the mid-lake and at depths below one meter from the surface,” the report on research noted.

The research was conducted following a mass fish kill that was reported at Lake Nakuru in January this year. According to the researches drawn from Kenya Wildlife service and Kenya Marine Fisheries Institute the first sighting of fish deaths was recorded in January. On February and March, locals reported capturing mature Nile tilapia on 13th January at a bridge adjacent to the lake.

The research was part of the investigations on fish die-offs at Lake Nakuru as well as provide the state of the lake’s water quality as well as presence of heavy metals.

Metals including Arsenic, Cadmium, Chromium, Lead, Nickel, Mercury, Selenium, Cobalt, Copper and Zinc were reported as the most frequently occurring heavy metals in Lake Nakuru water with Molybdenum metal reported as exceeding the recommended standards.  

“Chromium (Cr), Copper (Cu), Lead (Pb), and Zinc have accumulated in the sediments as a result of unregulated discharges and because this alkaline lake has no outlet,” the researchers noted.

Fishing within the farms where water from Lake Nakuru has spilled in to, according to the locals, is a rare chance that has given them opportunities to fish and supply commodity to eateries in towns.

“Now that the water has displaced us, we have to fish and sell to survive. We are fishing within our own farms and the fish tastes good,” Lucy Muthoni, one of the residents said.

The booming business within Mwariki has further attracted fishermen from Lakes Naivasha and Victoria to explore the new ground, which they say, is fertile for fish.

“I moved from Naivasha with my boat to come and help owners of these farms maximise on their profits. We have agreed to share profits from the fish I get from their farms,”Kerio Edonga, a fisherman said.

For Peter Wanjala, a fisherman who moved from Lake Victoria, he said the size of the fish ‘is not bad’ and farmers can now get good revenue.

“It is just the normal fish, only that we are not allowed to venture deeper past the face separating residential areas and the park,” Wanjala said.

But according to Lake Nakuru senior warden Collins Ochieng, the fishing activities within the eastern side of the lake spoils for human-wildlife conflicts. He said the park hosts endangered species that needs to be protected and the swelling lake has made the fence porous.

“The locals want to fish on their farms but then again these farms borders protected area and we do not allow fishing. Animals like snakes and hippopotamuses often does not like to be disturbed and can be dangerous. Those fishing are exposing themselves to danger,” Mr Ochieng’ said.

He added that surveillance has however been increased to boost protection of endangered species like rhinos.

Since 2012 the lake level has been rising from an average level of 3 meters to the highest level of approximately 8.5 meters recorded in April 2020. This has resulted in a significant increase in lake area from 43.3 km2 in 2012 to the current 70 km2 as April 2020.