Background

Broadly speaking, small water bodies (SWBs) 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 can be separated into natural waters or constructed ones.

The world distribution of small water bodies, in terms of risks for fisheries (drying out or losing significant volume that would negatively impact fish production) shows that about 60 percent of the global land mass is too dry for perennial small water bodies, or volumes would fluctuate widely (see image). About 11 percent could support small water bodies with cost-adding modifications (moderately high risk), in about 6 percent water would be sufficient with little or no cost-adding modifications (low risk), and some 23 percent would have ample water (very low risk).

Comparing across continents

Examining continents, Europe possesses the largest relative amount of territory favouring small water bodies, about 40 percent, while Africa, South and North America share a similar capacity with 18 to 20 percent. The Commonwealth of Independent States and the Baltic States (former USSR) as well as Oceania have less of this capacity.

There are uncounted millions of multipurpose SWBs around the globe that could contribute more importantly to food production if they were managed appropriately and in a way that is compatible with their other uses. More than 11 000 SWBs have been inventoried in Zimbabwe and the larger ones have been mapped and characterized, with the total for southern Africa estimated at anything between 50 000 and 100 000.

Management of small water bodies

Fisheries in small water bodies complement those in large inland waters or the sea, but are as opposed to larger waterbodies mainly fished by part-time fishers including women and children. They provide an opportunity to increase food production in local areas, but are usually also used for other purposes. Management therefore requires a multidisciplinary problem-solving approach.

In southern Africa, the potential fish yield from small water bodies and reservoirs is estimated to be between 1 to 3 million tonnes per year. A comparative study of small water bodies and reservoirs in seven countries in three continents shows extreme variations in the contribution of small and medium-sized water bodies to national fish production.

As a large number of SWBs already exists, no capital expenditure is required to build them. They are located in rural, often semi-arid areas, and are potentially highly productive. This means that they are a possible source of protein and employment in places where both are in short supply. SWBs are relatively easy to manage as fishers can operate over most of the area of a small water body (Haight, 1990). This is especially significant because it increases the possibility of effective management, as compared to large water bodies with open access character.

Small water bodies are well-suited to being managed by local communities, and this may be the best way of realizing their productive potential. The current interest in SWBs derives mainly from their use for fisheries enhancement, which involves guidance on stocking, exploitation and species management, in order to obtain optimum yield on a sustainable basis. Small water bodies are well-suited to being managed by local communities, and this may be the best way of realizing their productive potential. However, conflicts often arise where people who traditionally have fished the waterbodies no longer have access due to new management regulations.