Department of Game and Fisheries
The main features of the three types of fish culture operations that have developed in the rural areas of Zambia are briefly described. Comparative data are presented to show the greater value of conservation dams compared with family ponds, in terms of benefit in cash and protein food to rural peoples and in making the best use of available financial and skilled manpower resources. The construction of artificial lakes is advocated in preference to small family ponds even in regions of high rainfall where there is less immediate need for conservation works.
ESSAI DE PISCICULTURE RATIONELLE DANS LES ZONES RURALES DE LA ZAMBIE
Cette communication contient une brève description des principales caractéristiques des trois systèmes de pisciculture qui ont été expérimentés dans les régions rurales de Zambie. Selon des données comparatives, les barrages de retenue sont supérieurs aux étangs familiaux, car ils fournissent à la population rurale un meilleur rapport en espèces et d'avantage d'aliments protéiques, tout en permettant de tirer le meilleur parti possible des ressources disponibles en capitaux et en main-d'oeuvre qualifiée. L'auteur préconise l'aménagement de lacs artificiels plutôt que de petits étangs familiaux, même dans les régions où, en raison des précipitations abondantes, la construction d'ouvrages de conservation des eaux est moins nécessaire.
ENFOQUE RACIONAL DE LA PISCICULTURA EN LAS ZONAS DE ZAMBIA
Se describen brevemente las características principales de los tres sistemas de poscicultura practicados en las zonas rurales de Zambia. Se presentan datos comparativos para mostrar el mayor valor de las presas de conservación comparadas con los estanques familiares, tanto en beneficios en metálico como en los alimentos proteínicos que aportan a las poblaciones rurales y el mejor aprovechamiento de los recursos financieros y de mano de obra capacitada disponibles. Se propugna la construcción de lagos artificiales con preferencia a los pequeños estanques familiares incluso en regiones de elevadas precipitaciones donde es menor la necesidad inmediata de obras de conservación.
For over 20 years, fish ponds have been advocated in many parts of Africa as one means of providing animal protein to peoples in regions where there is a protein deficiency. Zambia, formerly Northern Rhodesia, was one of the first countries of Africa south of the Sahara, to investigate and to develop the production of fish from ponds and other artificial waters. Because Zambia has large natural fisheries from which the annual fish catch is currently of the order of 41,000 metric tons, the development of fish culture, necessarily has been limited in extent and localized in areas.
As a result of fish culture investigations and practical experiences over some 20 years, it has become apparent in Zambia that the general and widespread development of fish ponds is not necessarily the best, simplest and most advantageous way to utilize financial and manpower resources available to improve the protein diet of peoples in those regions where it is most needed.
Three systems of fish culture that have developed in Zambia are described here briefly and are compared in terms of benefit to rural populations and use of financial and manpower resources.
In order to appreciate fully the pattern of fish culture development in Zambia, it is necessary to mention briefly certain of the general features of the country.
Zambia is a landlocked country of southern Central Africa lying between latitudes 8 and 18 degrees South and between longitudes 22 degrees and 34 degrees East. About 752,000 square kilometres (290,586 square miles) in area, the country is largely plateau, at an altitude between about 1,100 and 1,400 metres (3,500 to 4,500 feet). The climate is a three-season type; hot and wet; cold and dry; hot and dry. Ambient plateau temperatures are generally within the range of 20°C to 35°C with somewhat higher temperatures in the main valleys and somewhat lower on the limited areas of higher ground.
The northern, north western and western regions of the country have a generally higher rainfall of over 1,000 mm (40 inches) and better surface water supplies than the southern and eastern regions (below 1,000 mm). The areas of highest agricultural potential are, generally speaking, in the low rainfall regions and are limited in those of high rainfall.
Despite the adequacy of surface water supplies in high rainfall regions, the rivers and streams of the plateau have limited exploitable fish populations.
Large natural fisheries in the form of lakes, swamps, large rivers and flood plains are located in the northern regions and in the south and west as indicated in Fig. 1. Production from these is distributed either to the industrial towns of the line-of-rail, or within the immediate vicinity of the fisheries. The greatest need for improving the protein diet of the peoples of Zambia is in the high rainfall areas of low agricultural potential, in particular the north-western and parts of the northern regions.
Three basic forms of fish culture have developed in Zambia. These are culture in family ponds, in irrigated small holdings, and in conservation dams (small artificial lakes.
FIG. 1 THE REPUBLIC OF ZAMBIA
In areas of the high rainfall regions, family ponds have developed with the following features.
Ponds are small in surface area, generally about 20 ares (0.2 ha or 0.5 acre). In recent years ponds less than this size are not stocked. Ponds are generally badly constructed, the walls being uneven and weakest where they should be strongest; often ponds are just pits dug in the ground. They seldom have proper drain pipes, screened inflows and overflows or any protection against predators. Ponds are often badly sited, since owners do not always avail themselves of technical advice, and ponds may not have even a perennial water supply.
As a consequence of a low population density in the country, ponds are widely scattered and all too often located some distance from habitation; seldom does an owner have more than a couple of very small ponds, and more commonly only one.
Pond owners have their ponds stocked free of charge from Government Stations, with Tilapia melanopleura and Tilapia macrochir and sometimes, T. andersonii or T. mossambica at the rate of 224 to 336 kg per ha (200 to 300 lb per acre).
Once stocked, ponds seldom receive adequate attention from their owners, who mostly assume that the fish will grow and breed without any effort on their part, in feeding, water control and general maintenance.
Most family ponds are located in the regions of high rainfall and where surface water supplies are best, and have been discouraged in low rainfall areas where surface water supplies are generally poor. However, the quality of the waters of high rainfall plateau regions is generally poor, of low alkalinity and with few salts in solution. As a consequence, the natural production from fish ponds is low, being of the order of 224 kg per ha per annum (200 lb per acre per annum), but can be improved by the use of supplementary feeds and fertilizers, to the order of 897 to 1,121 kg per ha per annum (800 to 1,000 lb per acre per annum). The availability of supplementary feeds is poor due to the low agricultural potential and lack of farm wastes. Feeds are generally limited to cassava and cassava wastes, grass and other green vegetation.
Because of the small size of ponds, the actual annual production available to the owner with say two ponds totalling four ares (0.1 acre) in area is only 9 kg (20 lb) without, and 36 to 45 kg (80 to 100 lb) with supplementary feeding.
Little difficulty has been experienced in the rural areas of Zambia in getting people to build fish ponds. Rural peoples are only too keen to build the ponds, usually after having heard about or having seen a publicity or instructional film or paying a visit to a demonstration unit. The greatest difficulties have been in providing the necessary practical assistance to pond owners, since it has been found that frequent and regular visits are absolutely essential if pond owners are to obtain good production.
Irrigated small holdings are a feature of the peri-urban areas of the Copper Belt and some other towns of Zambia. The holdings produce vegetables and may include livestock such as poultry. The addition of fish ponds to irrigated small holdings has been shown to be a practical proposition (Mortimer, Ruth and Muluwa, 1963; Ruth, 1965). A demonstration-teaching unit with facilities for raising ducks, 16 ares (0.4 acre) for growing vegetables and 16 ares (0.4 acre) of fish ponds, has provided over four years a total net profit of £91 per annum of which 24 percent was contributed by the fish ponds. One of the main areas where small holdings have developed is the Ndola Rural District close to the Copper Belt, where fish ponds have been a fairly successful addition. The number of holdings with ponds in this area are included in Table I.
The distribution of fish ponds in Zambia, 1965
|Number||Approximate total surface area|
|North Western Province*|
* The number of fish ponds in the North Western Province is not known accurately
The distribution of small conservation dams and weirs (artificial lakes) in Zambia, 1965
|Number||Total surface area|
Note: Artificial lakes with a surface area of more than 200 ha (500 acres) are not included. The total area of these lakes is about 12,100 ha (30,000 acres)
Small holding ponds are generally better constructed and managed than family type ponds. This is very largely due to the units being less scattered and more accessible, thus making frequent and regular visits by limited extension staff practicable. In addition agricultural extension staff advising on agricultural matters are able to assist to some extent with fish culture work.
The production of fish from ponds in small holdings is potentially higher than in family ponds due to the availability of agricultural wastes for supplementary feeding and the better attention that can be given to management by the owner, who, of necessity attends to his adjacent garden on most days and so does not have to make special visits to his ponds. Crops from ponds are of the order of 1,100 to 1,700 kg per ha per annum. (1,000 lb to 1,500 lb per acre per annum).
Another feature of small holding ponds compared with family ponds is their larger size and number, which gives a greater actual supply of fish to the owner. The aim in development is to have units of six or twelve ponds of about four ares (0.1 acre) surface area, which would give the owner a fair monthly return in fish or cash. Ponds larger than about four ares in area are not favoured by most owners, as they take too long to construct; an owner is better able to build a number of small ponds than one or two large ones, furthermore, it has been found that small ponds of about four ares tend to produce a relatively greater fish crop than larger ponds of say 20 ares (0.5 acre) surface area.
Because of the commercial aspect, the extent of development of small-holdings that include ponds in rural areas is necessarily limited to the availability of an accessible cash market; a very large number of holdings would be necessary in a rural area to justify transporting produce long distances to urban markets.
Mortimer (1964) reported on the conservation dam fisheries of Zambia from 1951 to 1961 and drew attention (1965) to the value of impoundments in improving fish production from streams.
The main feature of conservation dams, or artificial lakes as they could be more correctly described, is that once constructed and stocked with fish, crops can be taken every year. At subsistence level, fish are caught with rod and line, thus fish can be obtained by all levels of the population, and with only little assistance of extension workers. With little additional extension assistance, annual cash crops can be obtained from small dams by fishing with nets.
As Mortimer (1964) recorded, the magnitude of the annual crop from conservation dams in Zambia is related to the size of the dam; in general small dams give a larger crop per unit area than do large dams. From dams of about four ha (10 acres) production is of the order of 112 kg per ha per annum (100 lb per acre per annum) whereas from dams of 20 to 40 ha (50 to 100 acres) surface area the production is only of the order of 34 kg per ha per annum (30 lb per acre per annum). Potential crops from dams are estimated to be three to four times those actually obtained at present.
Another important feature of conservation dams is that even in areas of poor water fertility, annual crops of at least 112 kg per ha (100 lb per acre) have been obtained from dams of up to 16 ha (40 acres) in surface area.
In 1965 there were nearly 1,000 small water conservation works in Zambia (Table II) mostly with a surface area of 2 to 12 ha (5 to 30 acres) with a total surface area of about 670 ha (16,500 acres) and which produced about 800 tons of fish, mainly at subsistence level. This crop represents nearly 1 kg (actually 2 lb) of fish a week for 16,000 people.
In many ways it is unfortunate that the majority of conservation dams are constructed primarily for agricultural and other purposes and not for fish production and are located mainly in those areas of greatest farming potential, where the need for additional protein is least.
The advisability of constructing artificial lakes on their merits for fish production is not yet generally accepted in Zambia, possibly because the high capital outlay required must be justified by something more spectacular than fish, such as hydroelectric works, irrigation projects, domestic water supplies or cattle raising.
Zambia, like other developing countries in Africa, at this time has problems in obtaining skilled manpower, has large and varied demands on cash resources and a need to improve the standard of living of people in rural areas. This being so, it is not without significance to try and compare the costs of development of different fish culture methods, their skilled manpower requirements and the long and short term benefits in terms of fish production.
Development costs are always difficult to assess because of the many hidden items such as administration expenses and central services. In making comparisons, only those costs that can be defined clearly are itemized and an allowance is made for undefinable costs.
Field staff requirements in fish culture development and extension work in Zambia are at four levels. At the lowest level are daily paid workers who operate demonstration-stock units. At the next level are junior extension staff who are Civil Service employees with a standard of education between Standard VI (pre high school) and Form II (mid high school). Senior extension staff, Technical Assistants and Technical Officers are also Civil Service employees and normally must have had a high school education followed by technical training. A number of Technical Assistants in charge of areas would be under the supervision of a Technical Officer.
Ideally the development of family ponds in an area is preceded by the construction of a pond unit to demonstrate precisely the type of pond layout, construction and management suitable to the area and to provide stock fish for private owners; at the same time junior staff are recruited and trained for extension work in the ratio of one extension worker to 20 expected pond owners. This ideal order of development is seldom attained in Zambia, the provision of a demonstration-stock pond unit and extension staff having to be justified by a number of private ponds already in existence in an area.
Ponds are added to irrigated small holdings after their establishment and seldom is the unit planned as a whole. Since small holdings tend to be grouped in relatively small areas and agricultural extension staff are available for advisory work that can include fish culture, the number of fisheries extension staff required is somewhat less than is required for family ponds, being of the order of one to 25 owners. Although a demonstration-teaching small holding is desirable, in practice only one is required for several development areas, which is a saving in expenditure and trained manpower.
The successful utilization of conservation dams for fish production require comparatively little in the way of extension work. A centrally located demonstration dam, as typical as possible of others in a region, is used for demonstrations and as a source of stock and from which a mobile extension team can operate. A mobile team consisting of a Technical Assistant and five junior staff can effectively service a region with 200 to 300 dams.
In Table III a comparison is made of the costs of fish culture development and extension work from which it can be seen that per unit weight of fish produced, conservation dams show a far better return for cash expended than either small holdings or family ponds, the ratio being about 1:6:20.
To produce the same benefit in terms of fish as 240 conservation dams impounding about 1,100 ha (2,700 acres) at an annual expense of £8,200 and utilizing one senior and five junior extension staff, 1,350 units of family ponds would be needed, even allowing for an increase from 4 to 10 ares (0.1 to 0.25 acres) of ponds per family, and would cost annually about £58,000 for extension services and would require six senior and 60 junior staff. The latter staff requirements represent 50 percent and nearly 30 percent respectively of the 1965 establishment of staff available for all fisheries development and extension work in Zambia.
Allowing the cost of a conservation dam of about 4.5 ha (11 acres) in area at about £2,000, 240 dams represent a capital outlay of about £480,000 which in turn represents in 1965 20,000 man-months of employment (half the capital cost being expended in labour). Over 20 years this capital investment is at the rate of £24,000 per annum. Thus it can be said that 240 conservation dams in capital construction and recurrent extension costs represent £32,200 per annum and show a return of at least 122,500 kg (270,000 lb) of fish a year. To produce this same amount of fish from family ponds requires an annual expenditure of £58,000 in extension services alone without the added advantage of providing paid employment since pond owners are not subsidized for construction work. To pay the construction and ancillary costs of ponds as well would require at least another £50,000 annually.
In addition to the advantages of lower costs and manpower requirements for development and extension work there are other advantages of artificial lakes over family ponds in rural areas of Zambia. For example in areas of poor agricultural potential, where shifting cultivation is practised, there have been a number of instances of people building ponds only to abandon them after a couple of years. Artificial lakes, however, allow for a shifting population, since it is necessary only that a villager go to a dam and catch fish; there is no management required on his part. Management requirements of conservation dams are few; annual inspection and maintenance can be either a central or local government concern - a service provided to the public.
Another feature of dams that has been mentioned already is that they can be fished at subsistence level by all levels of the population; thus even young children can and do catch fish for themselves. The tendency amongst some pond owners to treat the fish in their ponds as wealth and not to crop them is not experienced with dam fisheries, since the fish in them are not owned by any one person.
The recurrent criticism that conservation dams are reservoirs for bilharzia and malaria vectors is for small dams largely invalid. In a dam that is properly constructed and stocked with fish of suitable species bilharzia and malaria vectors are not a serious problem.
The comparative cost of fish culture development and extension work
|Family ponds||Small holdings||Conservation dams|
|CAPITAL COSTS £|
|ANNUAL COSTS £|
|Salaries and allowances|
|Unit running costs||300||300||300|
|Capital depreciation (20 years)||1,000||350||800|
|Central services(20 percent)||1,600||750||1,400|
|TOTAL ANNUAL COSTS £||9,600||4,700||8,200|
|Average annual production||lb per acre||800||1,000||100|
|kg per ha||896.6||1,121||112|
|Annual total production||lb||16,000||25,000||270,000|
|Annual expenditure per unit weight of fish produced (shillings)||per kg||26.4||8.4||1.32|
The need to provide additional protein in the diets of rural peoples in Zambia, generally speaking, is greatest in plateau regions of high rainfall and low agricultural potential and poor water fertility. The small family ponds that have developed in these regions have low yields of fish and require a relatively large expenditure for extension and advisory work.
Mixed irrigated small holdings are located mainly in peri-urban areas of Zambia, but where fish ponds can contribute substantially to the cash income of the unit.
Small conservation dams (artificial lakes) are a feature of low rainfall regions, where their primary function is water storage for domestic, industrial or agricultural purposes, yet produce substantial quantities of fish.
In terms of benefit in cash and food to rural communities making the best use of available skilled manpower and financial resources, conservation dams show a better return than do small family ponds; for expenditure in extension and advisory work, the return from conservation dams is about 20 times the return from family ponds.
Mortimer, M.A.E., 1964 A report on the conservation dam fisheries of Northern Rhodesia, 1951–1961. Rep.jt Fish.Res.Org.Nth.Rhod., (11):73–121
Mortimer, M.A.E., 1965 Fish production from a stream in Northern Rhodesia. In Proceedings of the Central African Scientific and Medical Congress, Lusaka, 1963, pp.405–14
Mortimer, M.A.E., 1963 D.J. Ruth and L. Muluwa, Ducks, vegetables and fish. Rhod.agric.J., 60(3):82–7
Ruth, D.J., 1965 Ducks, vegetables and fish. Fish.Res.Bull.Zambia, 1963–1964:161–8