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Fisheries Science

Growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in the northern arm of Lake Volta, Ghana


Estimates of growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in Lake Volta were obtained from length composition data compiled in 1995 and 1996. The von Bertalanffy growth function (VBGF) estimates were: Loo = 44.5 cm standard length; K= 0.62 year -1 and to = – 0.23 years. Natural mortality rate, M, was 1.20 year-1 Total mortality rate, Z, was computed as 4.39 year -1 and the exploitation ratio (E = F/Z) was 0.72. Although the fish is estimated to have longevity of about 5 years, those exploited are normally less than 2 years of age, which is indicative of growth over-fishing. In order to arrest over-exploitation of the species, there is a need to establish `lake reserves’. In addition, the fisheries management should be devolved from the state to the local level to compel fishermen to take greater responsibility for the sustainability and conservation of the fisheries.

 

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Name of Author(s):
P. K. OFORI-DANSON1, C. J. VANDERPUYE2, G. J. de GRAAF3
Institutional Affiliation:
1Water Research Institute, Council for Scientific and Industrial Research, Achimota, Ghana; 2Department of Oceanography and Fisheries, University of Ghana, Legon, Ghana; 3NEFISCO, Amsterdam, and EUROCONSULT, Arnhem, the Netherlands
Type of Publication:
Journal Article
Name of Publisher or Journal:
Fisheries Management and Ecology
Date of Publication:
2001
Number of Pages:
8