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No Thumbnail AvailableBook (series)Small pelagic fishes and fisheries in African inland waters / Espéces de petits pélagiques el leurs pecheries dans les eaux intérieures de l'Afrique 1984
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No results found.This is a brief review of small pelagic fishes and fisheries of Africa's large lakes and reservoirs. Small pelagic fishes have an important role to play in increasing Africa's inland water fish supply because the available potential generally has been underutilized. Pelagic communities in African inland waters usually consist of small zooplanktivorous species and a group of predators which feed upon them. In addition to being small these prey fishes usually have a short life-cycle and high produ ctive potential. There are four major families which include pelagic species with actual or potential fishery importance in Africa. The general biological characteristics of these species are discussed and the major pelagic fisheries in Africa are described. -
No Thumbnail AvailableBook (stand-alone)Selected bibliography on major African reservoirs. / Bibliographie choisie sur les grands réservoirs africains. 1983
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No Thumbnail AvailableProjectThe use of multimesh gillnets for sampling fish stocks in reservoirs in Southern Africa 1995
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No results found.In order improve the management of a fishery it is necessary to determine which species are present and in what quantities. Sampling of the fish stock is thus needed. For monitoring the effects of certain management strategies, it will also be necessary to gather information concerning the fish stocks. Gillnets are often used for sampling fish stocks because they are easy to use, relatively cheap, catch a wide variety of species, and their use can be standardized. Gillnets are however, selective towards the species they catch, the size of fish they catch and the amounts of fish they catch. Also outside factors influence the effectiveness of the nets. ALCOM used multimesh gillnets in 34 reservoirs in 5 countries in southern Africa over a period of 5 years to collect information on the fish stocks of these reservoirs. The analysis of the results of these samplings showed that the gears were useful to collect general information of the fish stocks, but also demonstrated that the catch per unit of effort could not be used as a reliable indication of abundance. The reasons for this were that the fluctuation in the catches were too great, not all species could be sampled with the required precision and, although a wide range of mesh sizes were used, the gears were still size selective. Furthermore it was agrued that the effects on the fish population of different management strategies would not be detected by sampling with gillnets alone. The effects of outside factors, and especia lly of the water level fluctuation of the reservoirs, would easily confound the effects of the fisheries management on the reservoirs. It was recommended to concentrate the studies on the target species, to determine the effects of the water fluctuatiuon of fish production, and to use the existing fishery in the collection of data.
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