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been done for a tlpical population. Graham (1968) attempted this for a population living Lake
Ttrrkana, Kenya, but admits that this may not be representative of other populations in Africa
as the lake is sunounded by a desed. He also assumed a rate of feeding extrapolated ftom
scanty data on captive animals.
If the boundaries ofthe fishing areas on the Zimbabwean side of Lake Kariba are examined in
relation to concentrations ofcrocodiles it can be seen that $ey are generally mutually exclusive
(Figure 3). There are some exceptions to this but it would appear that most of thscrocodiles
are concentrated in the ver estuaries which are closed to artisanal fishing. The exclusion of
the estuaries was not for the protection ofthe crocodiles but rather to protecthe fish and allow
them to breed in these areas.
If the estimate of total offtake is accepted then crocodiles (working with the upper estimate of
the population size) are only eating the approximatequivalent of 10 % ofwhat is removed by
the artisanal fishery (6.3 % ifthe mean population estimare is used). It should be stressed that
they are not t^king lOTo of the fishermens crop but rather an additional tonnage. Using a
production estimate of fish tonnage per annum (44091 t yearl fo. the Iittoral spe;ies in Lake
Kariba; calculated by multiplying fte sranding crop by a production ro biomass ratio which is
specific to species - Hustler and Matshall, 1990; Malon and Balon, 1977) it can be seen that
the crocodile population is removing only 0.5 % of this amount. Lookjng at rhe problem ftom
another aspect it is speculated that an average female crocodile wjl eat approximately 1 g41
kg of fish in an 80 year life span while a male will consume I 671 ks.
CONCLUSION
In conclusion it appears that there is no major competition between the crocodiles and
fishermen for the fish resources of Lake Kariba. The crocodile industry is valuable and
provides income at both the local and nationalevel and also generates foieign currency (an
estimated US $ 3 million in 1990). Further zonation ofthe shoreline to exclude fishermen ftom
crocodile areas is not a desirable option but perhaps thought should be given to removing
crocodiles from heavily fished areas, preferably by trapping as it is possible that these animals
will eventually be caught in nets aDd drowned. Their removal will also be seen as an aEemDr
to balance issues affecting the artisanal fishery as perhaps the major source ofconflict betw;n
fishermen and crocodiles is the destruction of nets; these are expensive to replace and time
consuming to repair. This exercise is already underway with the removal of43lirge crocodiles
fiom sensitive areas in 1992.
Although there may be several sources of error in the estimate of intake of fish by crocodiles
from Lake Kariba (e.g. numbers, feeding interval, mean prey size) it is evidenth;t this study
has achieved its major objective. Information of this nature will be ext.emelv imDortant when
management decisions are made, especially as one can only expect the conilict (real or
imagined) between crocodiles and fishe(men to infiease. Lake Kariba may be representative
of other lakes which sustain African arrisanal fisheries (eg. Lakes Victoria, Tanganyik and
Malawi).