Feature: Scientists intensify research on dwindling fish stock in Lake Victoria

A group of scientists are currently working on a research project to unearth the cause of rapid slump in high value fish species like tilapia and Nile Perch in Africa's largest fresh water body mass Lake Victoria.

Drawn from Kenya, Uganda, Tanzania and the U.S.-based National Science Foundation (NSF), these scientists have been traversing the lake in the last 10 days determined to find a lasting solution to loss of critical fish species that sustains millions of livelihoods across the eastern African region.

The new research project came on the heels of launch of a new study titled "Nile Perch and Transformation of Lake Victoria" published in the Africa Journal of Aquatic Science 2016 which indicated that haplochromines - diverse groups of small fish found in East Africa's lakes - now form 60 percent of the lake's biomass.

The study noted that the remaining 40 percent is made up of Nile perch, tilapia, catfish and lungfish, among other species.

Kenya Marine and Fisheries Research Institute (KEMFRI)'s assistant director for Freshwater Systems Research, Christopher Aura noted there are indications the ongoing research will help in identifying the possible cause of habitat imbalances in Lake Victoria.

"This shift is one of the key reasons that has led the scientists to venture into Lake Victoria and conduct several studies with keen interest on the haplochromines, water quality and cage culture and its implication on wild fish stock," he added.

Dr Chrisphine Nyamweya, a scientist at KEMFRI said the increase in haplochromines could be as a result of the Nile Perch decrease as it relies on the small species for food.

"Before the introduction of Nile Perch to the L.Victoria in the 1950s, there were over 500 species. Nile perch drove most of the species to extinction. We want to understand the biology and ecology of haplochromine to be able to find a sustainable way for the Nile perch stocks to thrive," Nyamweya said.

The scientists will try to ascertain the size of fish population in the fresh water lake as well as the current species and the different areas where they thrive without interruptions.

Even though the haplochromines biomass is rising, it still falls below 83 per cent, the volumes recorded in the 1950s.

Back then, the Lake's water was unpolluted, but commercial productivity remained inconsequential as the fish catch was mainly for domestic markets.

Kenya, Tanzania and Uganda's production capacities for Nile perch currently stand at 54,000; 393,000; and 365,000 tons respectively.

In 1999, the volume of silver cyprinid whose local name is Omena stood at 200,000 tons but in 2016 researchers said they had recovered at least 1.3 million tons.

Before introduction of Nile Perch, there were up to 500 endemic species but these gradually became extinct, leaving only a few to survive.

Scientists argue that the depletion of native fish biomass by Nile Perch may have been the source of eutrophication of the lake, which is to blame for deaths of major fish species.

The fishing industry currently generates an estimated 165 million U.S. dollars to the Kenyan economy. It contributes 0.5 percent to the country's GDP besides providing sustainable revenue streams to thousands of youth. Endit