ALCOM's action programme “Utilization of Small Water Bodies” had as its objective to increase the fish production from reservoirs in Southern Africa. In order to reach this objective it was necessary to quantify in a certain way the fish stocks present in these reservoirs. It was necessary to determine what species were present and in what quantities. Although it was impractical or even impossible to determine the absolute abundance of a fish species, it should be possible to obtain an indication of abundance.
The Institute of Freshwater Research (IFR), Drottningholm, Sweden, had developed a sampling method using multi-mesh gillnets that proved suitable for monitoring fish stocks in acidified lakes in Sweden. The ALCOM programme in collaboration with the IFR tested this method in 7 reservoirs in Zambia in 1989, and concluded that the method was functional, and that it could be used to study the relative densities in regard to seasonal variations, fishing intensity, etc (Fjalling and Furst, 1991). It was also stressed that modification of original procedures should be made after careful considerations. Since 1989 ALCOM has used the “Drottningholm” sampling method in a large number of reservoirs in 5 countries in Southern Africa. This paper gives the results of these sampling exercises and discusses the appropriateness of the method in the context of monitoring management of reservoir fisheries in Southern Africa.
