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Changes in the fish and fisheries ecology of a large man‐made lake in Tanzania, 1965–94
Author(s) -
BAILEY R. G.
Publication year - 1996
Publication title -
fisheries management and ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 55
eISSN - 1365-2400
pISSN - 0969-997X
DOI - 10.1111/j.1365-2400.1996.tb00152.x
Subject(s) - fishery , littoral zone , fishing , tanzania , periphyton , tilapia , fish <actinopterygii> , plankton , geography , biology , ecology , nutrient , environmental planning
Nyumba ya Mungu Reservoir in northern Tanzania has a maximum surface area of 180 km 2 , an average depth of 6 m, and contains moderately saline, fertile water. The postimpoundment decade, 1965–74, was characterised by a spectacular rise and fall of a tilapiabased fishery. Since then a gill‐net fishery catching large numbers of large, periphyton‐grazing tilapias has given way to a mainly beach‐seine fishery producing large numbers of small, phytoplankton‐feeding Oreochromis esculentus (Graham). Yields remain higher than preimpoundment predictions but the size at maturity of all tilapia species has fallen and few larger than 15 cm TL are caught. These changes, and others in the fish community trophic structure, are chiefly explained by changes in the littoral environment and fishing pressures. Nyumba ya Mungu provides a case history of developments in the tilapia fishery of a man‐made river lake conducted on an essentially laissez‐faire basis.