In the second year of our campaign to save Lake Victoria, Vision Group media platforms will until June 5, run investigative articles, programmes and commentaries highlighting the irresponsible human activities threatening the world’s second largest fresh water lake. Today, GERALD TENYWA looks at the threats to the survival of the Nile Perch on Lake Victoria
The Nile Perch, one of the most popular and economically most viable fish species on Lake Victoria makes 60 years since it was introduced on Ugandan lakes.
But with the lake besieged by both over-fishing and pollution, experts say this prolific predator, that has devoured over 200 species to extinction, might also be wiped out in the next decade.
The Nile Perch is a fresh water fish. It is therefore known to be intolerant to pollution yet effluent from factories and sewage from the urban areas including Kampala ends up in the lake.
With wetlands and forests that used to protect the shores from erosion and siltation heavily degraded, the Nile Perch may soon have nowhere to hide. Is Uganda going to conserve the Nile Perch so that it can reach its 70th birthday in Lake Victoria?
“I do not see Nile Perch making it for another 10 years if fisheries regulations remain on the shelf.”
The 60 years of Nile Perch
This is a special time in the history of the Nile Perch also known as Oreochromis niloticus or Mputa in Lake Victoria.
The Nile Perch, a giant carnivorous fish was introduced to Lake Victoria in 1954 where it has become a money spinner. But there are no lakeside celebrations or a birthday party organised to sing hooray to the creature that has catapulted thousands of people in East Africa into riches.
Previously, Nile Perch was a native of the Albert Nile but somehow found its way into the second largest fresh water lake in the world.
This, Richard Kimbowa, the director of Uganda Coalition for Sustainable Development argued, was bound to end badly for the native fish given that Nile Perch is a predator on small fish. And true to his word, about 200 species of sardine-like fish species in Lake Victoria have become extinct thanks to the gluttonous Nile Perch that preys on the smaller fish.
“We do not know whether to celebrate or mourn at the 60th birthday of the Nile Perch,” said Kimbowa, adding that the Nile Perch is like a double edged sword.
“We do not know whether the Nile Perch has made us winners or losers.”
Nile Perch being cleaning inside Ngenge fish factory. PHOTO/Nicholas Kajoba
On one hand the Nile perch created employment for thousands, income for the people who depend on fish directly and indirectly and foreign exchange earnings for the country. On the other hand it is seen as an ecological disaster since it has led to massive loss of bio-diversity, which has pushed experts to conclude that the lake has lost its richness.
“We had pride in the lake because of its variety in the fish species,” said Moses Kasozi, a resident of Katosi landing site, Mukono but now the fish, which were tastier have been replaced by the fatty and smelly Nile Perch.
Apart from the sardine fish species, he also named the extinct species as Ningu, (Labeo victorianus) and Kasulu (Orthochromis kasulensis).
“The fish was good and some of it was easy for people including children to eat since it did not have big bones,” Kasozi says.
Love it or hate it, the Nile Perch has come to stay in the lake with its good and bad side. Irresponsible fishers have added an ugly side to it when it comes to over-fishing, which is one of the problems plaguing Lake Victoria.
Dr. Owori Wadunde, a senior research officer at the Aquaculture Research and Development Centre at Kajjansi told New Vision that the human population has increased and so is the fish demand. In addition, the lucrative fish export business has led to increased competition for fish in the lake resulting into over-fishing.
“When the big fish is over, fishermen go for the mother and the younger ones at the same time,” says Owori, adding that what this means is that the lake is being fished without replenishment.
How did Nile Perch end up in Lake Victoria?
The ancestral homeland for Nile Perch is Lake Albert and the Albert Nile, which is about 250 kilometers from Lake Victoria. So, how did this fish get into Lake Victoria?
John Balirwa, a senior researcher at the Fisheries Resources Research Institute says the introduction of Nile Perch into the country is traced back to the colonial administrators who were interested in sport fishing.
Instead of going up to the distant Murchison Falls National Park, they wanted to spend their leisure time engaging in sport fishing in a place not far from Entebbe. Before its introduction into Lake Victoria, the first stop over for the Nile Perch was Lake Kyoga.
This, according to Balirwa was supposed to be a holding ground for experiments before introduction into Lake Victoria, which is a shared ecological system.
But before studies were concluded, researchers at that time discovered that the Nile Perch had already made its way into Lake Victoria, says Balirwa.
Other sources say the Nile Perch was deliberately introduced to get rid of the tiny bony fish.
Nile Perch ready for processing at Ngenge fish factory. PHOTO/Nicholas Kajoba
Nile Perch, the domineering species
In less than three decades after its introduction, Nile Perch had become dominant. This is not surprising to scientists like Dr. Victoria Namulawa, a researcher at Kajjansi. She says Nile Perch is a versatile predator that even preys on its own fingerlings.
“Breeding takes place between August, September, October, November and December and the female will produce an average of 15 million offspring every breeding season (most of which don’t make it to maturity), she said, adding that the eggs take only 20 hours to hatch.
“It is common among primitive animals that do not look after their babies to produce many eggs.”
Nile Perch, she said lays eggs in batches near the shores of the lake but goes back to the deep water where it resides when it is not breeding.
“It prefers areas where Oxygen is not a problem,” says Namulawa, adding that Nile Perch avoids polluted water and moves to virgin areas.
From smelly fish to popular dish
Previously, the Nile Perch was despised as a smelly fish when it made its first appearance on the dining tables within Uganda, according to Owori.
But the competition between the local consumers and the European consumers has washed away the negative image. Nile Perch no longer comes to local dining tables cheaply. It has also overtaken beef and chicken in terms of price in the local markets.
Ugandans have realized that it a rich source of protein. Over-fishing pushes Nile Perch into early maturity.
While the Nile Perch has won an ecological war in which it has out competed over 200 species of native fish, the monster is facing a losing battle against over-fishing and pollution.
Over-fishing has been so bad in the recent years that the Nile Perch which used to mature at a body length of 90cm in the early 1990s now matures at 59cm.
“The increasing hunting pressure has pushed Nile Perch to change by re-producing early.”
Nile Perch weighs more than 200 kilogrammes with body length of 200cm when it is matures. Its lifespan is estimated at 15 years and maturing is estimated at three years.
Also, the small fish species such as the fresh sardines (mukene) that were disappearing in the lake are coming back. As the hunter (Nile Perch) gets hunted, the prey (mukene) has got some breathing space.