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2008-11-13 | News

Over fishing of Nile perch in Lake Victoria

EfD Tanzania Pressrelease 2008-11-02

Nile perch stocks in Lake Victoria have declined dramatically over the last years. Ten factories around the lake have closed and the remaining 25 are operating below capacity, according to the Jinja, a Uganda based inter-governmental organization. At the Department of Economics at University of Dar es Salaam (UDSM) several researchers have studied the problem with over fishing in general and the Lake Victoria fisheries in particular.

“The depletion of the Nile perch stock in Lake Victoria is part of a similar problem occurring globally with fish stocks being depleted. When access to fisheries is free, too many vessels and too many fishers will use too many nets ultimately depleting stocks”, says Dr Razack Lokina, coordinator of Environment for development a research initiative supported by Swedish International Development Agency (Sida) at UDSM.

In the early 1980s there were approximately 10,000 vessels fishing in Lake Victoria with approximately five crew members on each, while at the turn of the millennium there were 60,000 vessels with approximately three crew members.

“We have seen clear signs of this decline over the last 20 years in Lake Victoria. In 1989 the catch per vessel peaked, after that landings stayed high for a long period but that was the result of an continues increase in vessels and even more so in terms of the amount of gill nets used per boat”, Dr Lokina continues.

According to Dr Lokina, the most urgent measure is that Tanzania, Kenya and Uganda, the three countries sharing the fish stocks of Lake Victoria, agree on common regulations. Tanzania has introduced a minimum mesh size for Nile perch gill nets of five inches. If that can be agreed unanimously, smaller specimen will not be caught and most important female fish will live long enough to spawn and secure recruitment of new fish. Equally important is the practice among factories of not paying for fish below a minimum size that had a strong effect on not using too small mesh size among Tanzanian fishers.

Unfortunately the same practice has not been applied in Kenya, leading to undersized fish being caught and sold to Kenyan plants by Tanzanian fishers. Professor Håkan Eggert from the University of Gothenburg, is currently a residential advisor of EfD and a visiting professor at UDSM.

“We know what must be done. Access to fisheries cannot be free for all. A recent study published in the international journal Science studied fisheries all around the world and found that rights based managed fisheries run a much lower risk of stock depletion. Simply put, any successful management of fisheries includes defining clearly who is entitled to fish and who is not. It means that the number of fishers and fishing vessels must be reduced in Lake Victoria, it may sound unfair but we are all better off if fisheries can be managed sustainably compared to if stocks collapse and no one can fish”, says Professor Eggert.

Ten years ago Tanzania fisheries management started beach management units (BMUs) around Lake Victoria in collaboration with the World Bank. All fishermen landing their catch at the same beach collaborate in maintaining the facilities used and choose a leader. The initial aim was to eliminate fishing practice using dynamite and poison.

“The BMUs seem to have been successful in eliminating those detrimental fishing practices, but we have not been able to identify a clear effect of BMUs on reducing the use of nets with too small mesh sizes. Still, BMUs are a promising road to go. Today, membership in a BMU is mandatory for Tanzanian fishers, but entry is open to anyone. A necessary step in the future is to limit entry, when some fishers exit for other jobs or retirement they should not be replaced by new ones”, says Dr Lokina.

The high fishing pressure on the predator fish Nile perch have partly lead to an increase in the stocks of the prey fish Dagaa, which is sold locally and regionally. The Dagaa fishery is also open access, and even though fishermen have been able to increase landings of Dagaa over the last ten years, current landings are likely not sustainable. Dagaa is usually caught when it is dark and the moon is not too bright, which leads to approximately 15 fishing days per month. Still, management of Dagaa with a common regulation between the three sharing countries is also necessary in the long run, the two researchers conclude.