CONTENTS | ANB-BIA HOMEPAGE | WEEKLY NEWS
by Isaac Nyangeri, Kenya, August 1999
THEME = ECOLOGY
Lake Victoria is the world's second largest lake and
Africa's largest fresh-water lake, but its waters hardly experience tranquillity,
as a myriad of problems face it every now and then.
Lake Victoria - which is shared by Kenya, Uganda and Tanzania -
has a fishing potential of up to half a million metric tonnes of three hundred species,
however, this great potential is threatened
One of the problems is the introduction of exotic predatory fish species such as the Nile Perch (commonly known as "mbuta"). Nile Perch was introduced into the lake by the Japanese in the early 1950s. It is a ravenous eater and the World Watch Institute (WWI) says that two hundred types of endemic fish have disappeared since it was introduced.
Pollution is also a major problem. On the Tanzanian side of the lake, there is pollution from mercury used by small-scale miners in areas along the shores. However, domestic waste is still the largest source of pollution. On the Ugandan side, a lot of corpses floated into the lake via the River Kagera during the ethnic genocides in Rwanda and Burundi. In Kenya, two factories are accused of indiscriminate pollution. Pan African Paper mills in Webuye (Western Province) pours dangerous chemicals into the River Nzoia which empties into the lake. The other is a Kisumu- based (Nyanza Province) match-box factory which dumps its pollutant wastes directly into the lake.
Insecurity is another source of serious concern, as piracy has risen to threatening proportions. In one incident, pirates said to have been in two boats, robbed fishermen, taking about ten outboard engines and other fishing gear. The well- equipped pirates (they were armed with rifles and had powerful motorboats, were suspected to have come from Tanzania), struck at 2 a.m. It is thought that such pirates are in collusion with people on the Kenyan side, for they target boats with new engines, with disturbing accuracy.
One of the greatest problems is the invasion of the water hyacinth. The hyacinth appears attractively beautiful: it has green leaves with inviting lavender flowers. But its destructive nature has made it acquire non-too-pleasant tags in various parts of the world. In the southern USA, it is called the "Florida Devil", in south-east Asia it is dubbed the "Bengal Terror", while a researcher in the early 1970s called it the "Beautiful Blue Devil".
The water hyacinth was first reported in the Ugandan section of the lake in 1989. It was believed to have entered the lake through the River Kagera. It was the second weed to have invaded the natural water system in Eastern Africa, the first being the water fern or "Kariba" weed which appeared in Lake Naivasha (Kenya) in 1962.
The hyacinth originates from Venezuela, in tropical South America. When it is in an environment which is free from its natural enemies such as insects and viruses, it grows at an unusually high rate, being able to double its biomass in a few days. The weed covers a large area and the floating "mats" of weed reduce the amount of oxygen and light in the water, thereby killing off the microscopic algae which form the basis of aquatic food chains.
The water hyacinth also harbours both human and animal diseases such as malaria, yellow-fever, bilharzia, river blindness and encephalitis. The thick mats of vegetation impede navigation and foul fishing nets and traps. At times, people are stranded in the middle of the lake surrounded by the weed, while some portions have been known to detach themselves from the main mass with people "aboard".
There are four methods of weed control.
Dr Kisia Abok from Kisumu has offered a controversial solution for a financial use of the water hyacinth. He said: "The best way to control the water hyacinth is to economically exploit it". Dr Abok went on to explain that the hyacinth can be used to make cattle feed and as a constituent of biscuits for humans, as well as for making paper.
Also, the existence of the water hyacinth has made possible the increase in indigenous fish species which were almost wiped out by the introduction of carnivorous exotic types. These indigenous fish, owing to their smaller sizes, hide under the hyacinth's thick carpet. However, not everyone agrees with this development as the population cannot live on traditional delicacies alone.
There is a serious problem affecting the fishing industry and that is fishing by using poison. This practice is believed to have originated from the Ugandan side of Lake Victoria. At one time, explosives were also used in Tanzanian territorial waters but the use of poison gained ground after explosives were banned. The use of poison for fishing purposes was first detected in Kenya in April 1998 in Busia District, Western Province. The chemicals used included Thiodon, Diazinon and Triatix which were bought locally from agricultural suppliers.
A serious aspect to this method of fishing is that the fish must be sold in inland markets for they have features which can be detected with relative ease by those used to handling fish - blood oozing from the gills and eyes; a swollen body; a bluish- green hue. When eaten, poisoned fish can trigger-off diarrhoea, vomiting, excessive sweating and abnormal salivation.
Yes, Lake Victoria's waters continue to be troubled in many ways.
END
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