Populations of two prey groups of pelagic
mainly zooplanktivorous fish with differing life history strategies, were
simulated with a Lotka-Volterra model with predation. Group r fish are
r-selected species and have a high rate of biomass increase. These
comprise of [sic] the small pelagic cyprinids of Lakes Malawi and Victoria
and the clupeids of Lake Tanganyika. Group K fish are K-selected species
and have a lower intrinsic rate of biomass increase. These comprise of [sic]
the haplochromine cichlids of Lakes Victoria and Malawi. Piscivorous
cichlids and Lates spp. form the predators. The model shows that the
different rates of increase of the two prey groups and the relative
predation pressure upon them, determines the equilibrium biomasses. The
cyprinid/clupeid Group r fish only have a high biomass when heavy
predation reduces the cichlid Group K fish populations. This is because
more food is available to Group r fish, as well as a reduction in
predation pressure from the piscivorous cichlids. Group K cichlid fish
only have a high biomass when predation pressure is low. This occurs when
adult zooplanktivorous cichlids are too large too be eaten by predators.