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.