The Cichlid Fishes of Lake Malawi, Africa

Abstract of Publication

Jambo, C., and T. Hecht. 2001. Effects of overfishing on reproductive potential of major cichlid fish species in southern Lake Malombe (Malawi): Need for "closed area" strategy as a complementary management option? Pp. 105-113 in: Weyl, O.L.F., and M.V. Weyl (Eds). Proceedings of the Lake Malawi Fisheries Management Symposium, 4th-9th June 2001, Capital Hotel, Lilongwe. National Aquatic Resource Management Programme (NARMAP), Monkey Bay. 272 pp.  

The three major species Lethrinops 'pinkhead', Otopharynx argyrosoma 'red' and Copadichromis cf. virginalis, which used to contribute about 75% to the total catches (by weight) of Lake Malombe in the last decade were investigated. The main aim of the investigation was to assess the impact of fishing intensity on reproductive potential of the three species. Fecundity, reproductive seasonality, sexual maturity, and sex ratio were related to habitat types of the south western side (heavily fished) and south eastern side (lightly fished). The three species have low fecundity and they are synchronous spawners, with a breeding peak during July to October period. Females of all three species mature earlier than males while the sex ratio of the three species was not significantly different from 1:1 in both sides of the lake. The length-fecundity relationships for L. 'pinkhead' and O. argyrosoma 'red' indicated that fecundity was more closely related to length in the south eastern side than in the western side. The frequency occurrence of mature females and juveniles was greater in the south eastern side than in the south western side of the lake. Juveniles of Oreochromis spp. (chambo) were also abundant in the south eastern side. The south eastern side of the lake is characterised by low fishing intensity, muddy substratum and aquatic macrophytes. It is also functioning as a spawning area for Oreochromis spp. and nursery area for the three haplochromines. These findings provisionally suggest that the efficacy of closed area method [sic] as an additional management tool in Lake Malombe. Such a management tool would protect juveniles and breeding stocks of the main species, hence meet the criteria of ensuring the sustainability and utilisation of fish stocks in Lake Malombe.




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