Food security threat as L. Victoria's Nile Perch, Dagaa stocks drop over pollution


Fish mongers clean catch from Lake Victoria. Rising pollution in Lake Victoria has contributed to a drop in the popular Nile Perch and Dagaa fish stocks, signalling a new threat to food security. . FILE PHOTO | TOM OTIENO | NMG

Rising pollution in Lake Victoria has contributed to a drop in the popular Nile Perch and Dagaa fish stocks, signalling a new threat to food security.

A new report published this week notes that the population Nile Perch species has dropped by up to a quarter while dagaa stocks have almost halved (49 per cent).

It notes that the popular fish stocks have dropped because the water is increasingly not supportive of breeding or habitation.

The report draws its conclusion from a survey, "The Lake Wide Hydro-acoustic and Environmental Survey" conducted between August and September last year by Lake Victoria Fisheries Organisation, a Jinja-based fish research body.

The report says that for fish to thrive, the water they live in must be of good visibility to allow enough sunshine which would enable plants to thrive and provide food and for fish to see it, must be free from toxins and should have sufficient oxygen.

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Highest decline

The Tanzania portion of the Lake, which is the largest of the three East African nations, recorded the highest decline in these fish species population by 33 per cent, followed by Kenya at 31 per cent while Nile Perch in Uganda declined 13 per cent, the report shows.

Kenya Marine and Fisheries Research Institute Director Inland Fishing and Limnology, Kisumu Chrispine Nyamweya, commenting on the report, said decline in water quality affects dagaa species and the indigenous species.

“The conditions of a water body directly affects fish stock density, species composition, stability, productivity and physiological condition of indigenous populations of aquatic organisms,” said Dr Nyamweya.

“The Nile Perch are known to have some seasonal migrations moving either North or South of the lake. Intense fishing pressure is another cause of low density in Migingo Island,” said Dr Nyamweya.

In Tanzania the Nile Perch stock dropped from 651,353 tonnes in September 2014 to 417,936 tonnes in August 2016.

Uganda’s Nile Perch production dropped from 513,133 tonnes in 2014 to 393,353 tons while Kenya production reduced from 1,230,247 tonnes to 851,461 tonnes.

Juvenile species

“The declining trend become apparent from 2014. There is overfishing of juvenile of Nile Perch species in the lake, fishing pressure and migration of the species in search of feeds,” says the report.

The Nile Perch biomass of the Kenya, Tanzania and Uganda has dropped from 1.13 million tonnes in 2015 to 0.851 million tonnes in 2016.

Traditionally, the Migingo area records high Nile Perch densities. However, this was not the case in the current survey.

He said the reduction of the prey species is caused by deteriorating water quality.

The report recommends banning of juvenile fishing in breeding areas and self-policing at community levels across the three countries.

Dr Nyamweya said before reviewing the regulations, the stakeholders should comply with existing regulations.

“There is a lot of non-compliance to the regulations, use of illegal gear and people fishing in breeding grounds,” he said.