It is not easy to define precisely what is meant by the term “small water body” and any classification will be subjective and imprecise. What might be regarded as a large water body in arid Namibia, for example, might be seen as a small one in Tanzania, which has access to several large lakes. Broadly speaking, small water bodies include reservoirs and lakes with an area of less than 10 km2, small ponds, canals, irrigation canals, swamps and small, seasonal, inland floodplains. They may be permanent or temporary and, for convenience, can be separated into natural waters or man-made ones (Anderson, 1989).
Mangrove swamps or coastal lagoons which may have intensive fisheries have specific development and management problems and are not considered to be small water bodies. Neither are ponds specifically constructed for intensive aquaculture considered to be small water bodies. Much the same applies to small rivers and streams (less than 100 km in length), even though Anderson (1989) suggests that they can be regarded as small water bodies. This is because even very small rivers can be subjected to multiple demands and serve a variety of users; this makes it very difficult to manage their fisheries effectively.
The possibility of effective control and management would seem to be a useful criterion by which to define small water bodies. Fisheries on large lakes and rivers in Africa were traditionally open access and unregulated, and tend to remain so. The development of new fisheries, such as the industrial pelagic fishery on Lake Tanganyika, have led to a measure of regulation but, in general, the control of fisheries on large systems has proved to be very difficult. This was the case even for completely new fisheries, such as those on man-made lakes. For example, although the inshore fishery on the Zimbabwean side of Lake Kariba is strictly regulated, it is estimated that unlicensed fishers catch at least as much as the licensed ones (Lake Kariba Fisheries Research Institute, personal communication). This situation is unlikely to change, since few fisheries departments have adequate resources to police large fisheries.
By contrast, it should be possible to regulate the fisheries in small water bodies more closely and effectively. Except in South Africa and Zimbabwe, there are few privately-owned waters in the region. Nevertheless, most are controlled by some authority, such as the central or local governments, or by communities themselves through their traditional leaders. This makes it possible to manage the fisheries much more closely and increases the possibilities of being able to enhance them through active management.