The Great Lakes of East Africa are not only the repositories of the world's three richest
lacustrine fish faunas but also harbour unique assemblages of invertebrates. A few of these
animals are illustrated. These lakes are of immense scientific interest, not merely by
virtue of their richness in species, nor even because so many species are endemic, but as
field laboratories of evolution whose operations we have scarcely begun to understand.
They are also natural resources of great value, being enormous reservoirs of pure water,
and the sites of fisheries producing many thousands of tons of fish per annum. Evidence
is presented which unequivocally indicates that, by virtue of their tropical location and
hydrological regimes, these lakes are much more susceptible to the damaging influences of
oxygen-demanding pollution than their temperate-zone counterparts, and that, should they
become contaminated, their renewal times are so great that a virtually irreversible
catastrophe is possible. Evidence of the mismanagement of the fisheries of Lake Victoria
is also presented and the danger of further uninformed exploitation pointed out. Certain
apparent remedies are shown to be highly dangerous. The technology of fishing has advanced
more rapidly than our scientific understanding of the extremely complex ecosystems involved.