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NILE PERCH AND THE FUTURE OF LAKE VICTORIA.
by OSORO P J NYAWANGAH
Many people leaving around the lake basin have been made to believe that lake Victoria's ecology and natural resource base has been dramatically altered through the introduction of the Nile perch (lates niloticus).
The following is the story of Lake Victoria or Nyanza (as called by local people) and the results of an historic meeting in which scientific, policy makers, and resource managers came together to create an agenda to rehabilitate it.
Many people leaving around the lake basin have been made to believe that lake Victoria's ecology and natural resource base has been dramatically altered through the introduction of the Nile perch (lates niloticus). In the 1950s, a proposal to increase fish catches in the lake introducing the Nile perch (mbutta or Sangara) was adamantly opposed by scientists who feared that lack of a natural predator for the fish would result in the imminent destruction of the lakes bountiful ecosystem.
Despite the controversy, a colonial fisheries officer was ordered to clandestinely put the Nile perch into the portion of the lake that is in Uganda in 1952. Thereafter, it was introduced intentionally in both 1962 and 1963. And by 1994 Mbutta or Sangara was recorded in Tanzania, by 1970 it was well established in Kenya, and by the early 1980s it was abundant through out Tanzania, Kenya and Uganda, the three countries surrounding the lake.
Now in fifty years' time or less, virtually the entire natural, biological ‘wealth' unique to Lake Victoria has bech destroyed. At one time, the lake contained over 350 endemic species of haplochromines whose extraordinary diversity, and speed of evolution were inspiring to scientists concerned with the forces that create and maintain the richness of life everywhere! Today, a were handful of species exists, threatened on one hand of a fear some enemy - the Nile perch, and on the other by the lake's changing conditions.
Due to the presence of the Nile perch, the natural balance of the lake's eco system has been disrupted. The food chain is being altered and in some cases, broken by the indiscriminate eating habits of the Nile perch.
The subsequent decrease of in the member of algal - eating fish allows the algal to grow at an alarming rate, there by choking the lake. The increasing amounts of algal, in turn, increase the amount of detritus (dead plant material) that falls to the deeper portions of the lake before decomposing. As a by-product of this the oxygen levels in the deeper layer of water are being depleted.
Without oxygen, any aerobic life (such as fish) cannot exist in the deeper parts of the lake, forcing all life to exist within a narrow range of depth.
In this way, the Nile perch has degrade the diverse and thriving of ecosystem that was once Lake Victoria. The abundance of aquatic life are not only dependents of the lake, more than thirty million people in Tanzania, Kenya and Uganda rely on the lake forits natural resources.
The fishing industry, in particular, is suffering. With traditional food sources all but extinct; and nets continuously damaged from the sheer force of the Nile perch, local fisheries have to abandon their work. The cools of scarce wood that is burned to dry the fish and of large processing plants that are built to prepare the fish for market preclude many fisheries from entering the Nile perch market.
The only fisheries with large financial stand have been able to switch to catching the fish. Given time, however, the supply of Nile perch is diminishing as its food Supply dwindles, causing these fisheries unsustainable.
Having no natural predators in the lake and plethora of food, The Nile Peach flourished often reaching up to 240 Kgs, forcing it self. Such eating habits are no longer sustainable.
The fish has caused mass extinctions among haplochromine populations. And with a little available food sources remaining, the Nile Peach has taken to cannibalism with the larger fish feasting on the smaller ones.
Hundreds of endemic species that evolved under the special conditions offered by protection of Lake Victoria have been lost due to extinction, and several more are still threatened. Their loss is devastating for the lake, the fields of ecology, genetics and evolution biology, and more evidently, for the local fisheries.Local fisheries once depended on catching the lungfishes, tilapias, carps and catfishes that comprise the local diet.
Today, the compositions and yields of such fish catches are virtually negligible.Extensive fish kills, Nile Perch, loss of habitat and over fishing have caused many fisheries to collapse and many protein sources to be unavailable at the market for local consumption. Few fisheries, though, have been able to make the switch to catching the Nile Peach that requires a significant amount of capital resources.
Traditionally, the fish catches for the local market must be dried over a fire, relying on large amounts of scarce wood for fuel that in turn has increased the rate of deforestation. After drying, the fish is either transported to the local markets or prepared for export. Selling Nile Perch at the local markets is not the most profitable option for the fisheries. Its scarcity has kept it from being fully integrated into the local diet, hence leaving the market with the fish skeleton, famously known as Panki or Mazara.
Major reason for this is that there are few fisheries with the capital, technology and infrastructure to move the fish further than local market, let alone export them; so local market prices are kept relatively low by surplus of supply over demand.
With big number of processing plants established all around the lake to filet, freeze and prepare the Nile Peach for export to Europe and Israel, where it is receiving a higher market value, the local habitat have nothing to care about the lake's well-being.
About the Author
freelance journalist, district political party secretary and african cultural advocate.
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