Relationship between the water levels and the fish catches in lakes Mweru and Mweru wa Ntipa, Zambia

The relationships between water level and catch per effort in two Zambian lakes are compared. In the relatively stable Lake Mweru, a positive correlation exists which can be used, with certain reservations, to predict the state of the fishery two years in advance. The cause of the relationship is probably the effect of water level on the marshy and swampy breeding areas, where at least the most common species in the commercial catch (Tilapia macruchir) has definite limits for the depth of water in which it will breed. For Mweru wa Ntipa, a consistant definite relationship does not exist, probably because the water level and extent of the lake fluctuate widely.