9. THE NATURE OF FISHERIES IN SMALL WATER BODIES

9.1 NUMBERS AND STATUS OF FISHERS

Fisheries in small water bodies usually operate at a basic level, being open to anyone, and so provide an opportunity for the poorest people to supplement their diet. Simple gear such as traps or rod-and-line is often used, and in most southern African countries no licence or fee is required for the use of such fishing methods. They are generally considered to be a subsistence fishery by most Fisheries Departments (South Africa is a possible exception to this). In some areas, traditional fisheries play an important part in the social life of the people. This is exemplified by the fonya fish drives carried out by the Tembe-Thonga people living on the Pongolo floodplain of northern Zululand, South Africa (Heeg and Breen, 1982). Their annual fish drives take place when the pans adjoining the river have begun to recede after the rains, and are major social events in the life of the people. Similar fish-drives take place elsewhere in the region and some, like that of the Shangaan people in south-eastern Zimbabwe (Jubb, 1967), which were banned by colonial authorities have since been reinstated.

Certain fish species may also be highly valued for special occasions and the ability to obtain them locally may be an important function of small water bodies in some areas. In the Eastern Province of Zambia, for example, tilapias are in demand for weddings and Christmas parties (J.C. Mutale, Zambian Fisheries Department, personal communication).

The commercial or semi-commercial exploitation of small water bodies is more frequently regulated by some kind of licensing or permit system, although this varies widely between the southern African countries. The fishers themselves may be independent, owning their own boats and fishing gear, or salaried employees. The time devoted to fishing varies greatly as well, and may be influenced by factors like the success of their crops or the availability of employment in areas away from the water body. Some are professionals, and spend all their working time fishing (e.g., some of the Zimbabwean fishing cooperatives). Others are part-time fishers, who are farmers but fish regularly, or occasional fishers, who fish only seasonally or when crops fail through drought or other causes. In southern Africa, most people who fish in small water bodies are part-time or occasional fishers, but the number of professionals may be increasing in some of them.

Relatively little is known about the extent to which small water bodies are used for fish production in southern Africa. Many of them support fishers, many perhaps only people who fish occasionally, but there are few data on their numbers or the quantity of fish that they catch. The intensity of the fisheries varies between countries and between the water bodies themselves. In Tanzania, for example, there was an average of 11.9 fishers/km² on 14 small water bodies (Table 18). There was a tendency towards a higher density of fishers on the smaller waters, but there were exceptions, which may reflect differences in productivity of the lakes.

Less is known about the numbers of fishers in countries to the south. The density of fishers on two small dams in Zambia and one in Zimbabwe was between 1.5 and 5.3/ha (150 – 530/km²) (Table 19). The density of those using gillnets in the Zambian dams was comparable with that on the Tanzanian lakes, but the density on the Zimbabwean lake was much lower. This probably reflects the fact that Zimbabwe exercises much more stringent controls on the use of gillnets. The number of people who fish with rods and lines in these dams is striking, and suggests that this activity is underestimated in most African waters (the Tanzanian data in Table 18 almost certainly excludes them).

Table 18. Areas of, and mean density of fishers and boats on, some small water bodies in Tanzania

(Data from Vanden Bossche and Bernacsek, 1990)

Table 19. Density of fishers on two dams in Zambia (Z) and one in Zimbabwe (Zw)

(Data from ALCOM)

There are few data from elsewhere in the region. However, fishing is relatively unimportant in arid countries like Botswana, or mountainous ones like Lesotho, where few suitable waters exist. Indeed, Botswana appears to be unique in the region, because its people have no tradition of eating fish or fishing. This was attributed to a fear of water and a lack of knowledge about fish rather than a distaste for eating them (Sen, 1990)

Table 20. Variations in the number of fishers on some small water bodies in Tanzania, 1967–1979

Key: Bb = Lake Babati;
Bs = Lake Basuto;
K = Lake Kindai;
Sa = Lake Singida;
Tw = Lake Tlawi;
HR = Hombolo Reservoir;
MgR = Mgori reservoir;
MjR = Mianji Reservoir;
and NR = Ngwazi Reservoir.

(Data from Vanden Bossche and Bernacsek, 1990)

The numbers of fishers on small lakes appears to be very variable, as illustrated by data from Tanzanian reservoirs (Table 20). Many factors, including the success of farming, employment opportunities elsewhere or general economic conditions will influence these changes, and they have been poorly studied. In some cases the changes might indicate a collapse of the fishery, as in Lake Basuto, where the numbers fell from 290 in 1976 to 35 in 1977 and 16 in 1978. In others, the numbers increased steadily, as on the Mgori reservoir, where there were 5 fishers in 1972 and 82 in 1978, which could indicate that the fishery was growing and that yields were being maintained. The movements of fishers and changes in the intensity of fishing will be important factors in the management of small water bodies and there is a need to learn more about them.

9.2 RECREATIONAL FISHERIES

The high proportion of people using rods and lines highlights the importance of subsistence and recreational angling in small water bodies. In South Africa, angling is probably the most important fishery in inland waters; the entire yield of the Hartbeespoort Dam, for example, was accounted for by angling and it was estimated that 200 000 angler-days were spent there in 1976 (Cochrane, 1987). This number has undoubtedly increased greatly since then, and the revenue from fishing permits must be a major source of income for the bodies responsible for fisheries management in the country. The other countries in the region do not regulate anglers as closely, except in specific areas such as National Parks or trout fisheries in mountainous regions.

Recreational fisheries can be very productive. Thus the entire yield from the Hartbeespoort Dam, which amounted to 248 kg/ha annually in 1982–84, came from anglers (Cochrane, 1987). In 1976, the fish production from Lake Chivero was estimated to be 120 kg/ha, of which 49% came from the commercial fishery, 27% from recreational anglers and 24% from subsistence anglers (Marshall, 1978). Angling is therefore a highly valued activity in many small water bodies, especially those that are within reach of large urban centres. Provided the resource is well-managed, angling is one way in which local communities might be able to enhance the value of their fisheries. An attempt to do this has been made in the eastern highlands of Zimbabwe, where a local community leases the rights to trout fishing on a section of the Gairesi River. Unfortunately, the scheme has not yet yielded any revenue because trout populations have fallen to a such a low level that they no longer provide any income (Butler, in press).

Although this particular project has not yet succeeded, investigations into this way of managing fisheries should not be abandoned. The demand for recreational fisheries will increase as populations become more urbanized and affluent, and some steps have been taken in this direction. In 1994, the Mufurudzi Dam Fisheries Committee (Zimbabwe) included fees and regulations for sport fishing in their bylaws. The intensity of the fishery will be proportional to the size of (a) the local urban population, (b) the demand for tourism, and (c) the accessibility of the water body. Recreational fishing is unlikely to have a major impact on fish stocks in large dams, but may be more important in smaller ones. There is a clear need to include recreational fishing in general management programmes, but so far it has been largely ignored in the planning of fishery projects. There is a clear need to investigate both its extent and its potential in more detail.

9.3 COMMERCIAL AND SEMI-COMMERCIAL FISHERIES

Most African fisheries are exploited to provide food, either for sale or for consumption by the fishers and their families. Consumption is likely to be the most important consideration in small water bodies, since their total yield might not provide a large enough surplus to be sold. When managed in traditional ways, with limited access and low fishing intensity, many of these fisheries can be productive and perform a useful economic and social service to local communities. Nevertheless, because of their small size they are vulnerable, and can be adversely affected by increases in fishing effort. This can come about through the growth of the local population, an influx of outside fishers or by an increased use of inappropriate fishing gear. These problems have been reported from Malawi, Zambia and Zimbabwe, for example, but can be expected to occur wherever Fishery Departments or local leaders cannot control fishing effort or illegal gear, such as mosquito nets or gillnets with very small mesh sizes.

The range of fishing methods employed in small water bodies is as diverse as the water bodies themselves. Because it is inefficient to use one type of fishing gear continuously, many fishers change from one to another as circumstances dictate. Their choice of gear depends on various factors, such as the water depth, which varies with season; physical conditions in the water body; or the behaviour, abundance and availability of the fish. Some methods vary with the age of the fisher: in Zambia, for example, the youngest use hooks and lines whilst the oldest use traps (Anon., 1990b). In some cases fishers choose gillnets because of their effectiveness, but traps because they are cheap, whilst hooks and lines are readily obtainable (Anon., 1990b). Most fishing gears are highly selective, but fishers are able to exploit a wide range of species if they use several of them.

Rod-and-line fishing is used to catch many types of fish, including Bagrus spp., Clarias spp. and tilapias. Although fewer fish are caught than with gillnets, this method has the advantage of being cheap and easy to use. Locally available materials, such as maize meal porridge or algae, can be used as baits, and some selectivity can be achieved by using hooks of various sizes. The quantities of fish caught by rod and line can be impressive: in Lake Chivero, Zimbabwe, rod-and-line fishers were able to catch up to 2.2 kg of fish per day (Marshall, 1978). Catches can be improved through the use of longlines, sometimes with up to 200 hooks, which are set overnight. This technique is not widely used in southern Africa, but elsewhere, e.g., Uganda and Zaïre, longlines are used to complement gillnets (Maes, 1991; Maes, Leendertse and Bazolana, 1991).

Traps are easy to use because they can be made out of local materials and set anywhere. Basket traps are extensively used in marshes or floodplains, often being set across the river channels that form the entrances to and exits from seasonally flooded areas (Tweddle, Hastings and Jones, 1978). Fish traps of this kind have been traditionally used for centuries in most African waters, but are increasingly being superseded by modern techniques. Their use should be encouraged, however, because they are cheap, needing only local materials for their construction, and they can be very profitable at times when the water level is falling and draining the flooded areas. Furthermore, while small traps are less likely to be as detrimental to the fish stocks as some of the netting methods, large barriers or trap systems can seriously affect stocks of migratory species. For example, the stocks of Labeo altivelis in Lake Mweru and Labeo victorianus in Lake Victoria were destroyed by excessive trapping of this kind (Jackson, 1976; Cadwalladr, 1965).

In most African small water bodies, fisheries are at a subsistence level and the gear is sometimes manufactured by the fishers themselves and shared with other members of the fishing community. For example, in Botswana, the nets are mounted locally; in the Okavango Delta some even make their own nets by using the thread from old tyres. Used batteries from transistor radios are used as sinkers, whilst floats are made from the stalks of reeds or papyrus or pieces of styrofoam waste (Nermark and Mmopelwa, in prep.).

However, most fishers purchase their own gillnets, which are usually manufactured from multifilament nylon. Because of their relatively low cost and the ease with which they can be used and maintained, gillnets have become the most widespread commercial fishing gear in African fisheries. This applies to nearly all the commercial inland fisheries in southern Africa. Most countries in the region require licences or permits for their use, although the regulations governing their use, and the extent to which those regulations are enforced, vary from one country to another.

The selectivity of gillnets can be regulated through restrictions on the mesh sizes that can be used and many countries impose limitations (e.g., the minimum mesh size permitted in Zimbabwean reservoirs is 75 mm, except for Lake Kariba, where it is 100 mm). This is important, because the efficiency of gillnets is such that, without restrictions, they can have a severe effect on the fish stocks. The rationale for such restrictions should be explained to fishers, since the use of illicit mesh sizes can often provide a substantial increase in the catch over the short term. They should also be encouraged to avoid unorthodox methods of using gillnets, such as “strike” fishing, which is sometimes used to catch tilapias in shallow water and leaves juvenile fish without protection in the breeding areas. In many areas, gillnets are also used as beach seines, which can also be detrimental because the mesh sizes are often smaller than those in conventional beach seines.

Beach seines are also widely used and are relatively unselective. Many small water bodies, especially man-made ones, are unsuitable for this gear because of drowned trees, submerged rocks or irregular bottoms, but beach seines can be extremely effective in areas that allow their use. When used improperly they can seriously affect fish stocks, and their use should be carefully regulated.

A growing problem seems to be the use of small-meshed nets, often gillnets with a mesh of less than 10 mm or mosquito gauze, as improvised beach seines. This problem has been reported both from large water bodies like Lake Tanganyika, where they catch juvenile clupeids (Phiri, 1993), and from smaller ones, like the rivers of northern Namibia (Haight and Ersdal, 1994). This practice is especially damaging when used to catch tilapias in their breeding areas, since the nets destroy vegetation in the nursery areas in addition to catching the fish themselves.

Fish poisons obtained from ichthyotoxic plants is a traditional method of catching fish in many parts of Africa. Most of these poisons suffocate the fish, since they are either vasoconstrictors or affect the red blood cells. The fish rise to the surface where they can be easily captured and poisoning can be an effective way of capturing fish. It is also very wasteful because many fish die and do not come to the surface and, being unselective, is very damaging to fish stocks if used extensively (Von Brandt, 1984). For this reason, many countries (e.g., Botswana, Lesotho, Zambia and Zimbabwe) have prohibited the use of this method.