PART I
PERSPECTIVES, PROSPECTS, PLANNING AND PROBLEMS IN RIVER BASIN MANAGEMENT AND DEVELOPMENT/PERSPECTIVES, AVENIR, PLANIFICATION ET PROBLEMES EN MATIERE D'AMENAGEMENT ET DE LA MISE EN VALEUR DES BASSINS HYDROGRAPHIQUES (continued)

SESSION II   PLANNING AND DEVELOPMENT OF FISHERIES IN INDIVIDUAL RIVER AND LAKE BASINS/PLANIFICATION ET DEVELOPPEMENT DES PECHERIES DANS DIVERS BASSINS FLUVIAUX ET LACUSTRES (continued)

DEVELOPMENT OF THE FISHERIES OF THE WHITE NILE

DEVELOPPEMENT DE LA PECHE DANS LE NIL BLANC (continued)

5. CONCLUSIONS

Everybody thought that the FISHCOD programme was very well conceived. Everybody who could contribute, benefit or be affected by the programme was consulted at the stage of planning. And it is working - but not without difficulties. These have been many.

The fishermen and boatbuilders trained in the Fisheries Training Centre, inspite of their exposure to cooperative lessons during the course of training, started to demand Government employment rather than cooperative membership.

Expatriate experts were difficult to find for Malakal, Kongor and Bor, these being hardship duty stations.

Even the local staff was not anxious to accept life in fishing camps and long-distance travel.

Consumers goods and fishing gear were not readily available.

Shortage of fuel for land and water transport presented a problem.

Timber for boatbuilding was not available when required. Carpentry tools were in short supply.

Boatbuilders, being illiterate, could follow designs and specifications of a boat only with great difficulty.

Repair of boats and engines was not easily available.

Funds for extending credit were less than the demand for them.

Fishermen preferred to sell their catch directly to the private trader.

Fishing camps were started without taking into consideration the richness in fish of the fishing ground.

Maintenance of accounts proved to be cumbersome.

Despite these difficulties, FISHCOD is functioning. Its activities are expanding. The problems were connected with logistics and are not conceptual.

Understanding and acceptance of the programme is increasing in all quarters - fishermen, boatbuilders, staff, local authorities and politicians. And this augers well for the future. No substantial change in the programme is required until the impact on ecology of the Jonglei canal becomes clear.

THE IMPACT FORESEEN OF THE JONGLEI CANAL SCHEME ON THE FISHERIES ON THE SUDD REGION: THE PROBLEMS AND SOLUTIONS

REPERCUSSIONS PREVISIBLES DU PROJET DE CANAL DE JONGLEI SUR LES PECHERIES DANS LA REGION DE SUDD: PROBLEMES ET SOLUTIONS

by

V.G. Krishnamurthy
Associate Professor of Fisheries
College of Natural Resources and Environmental Studies
University of Juba
Juba, Sudan

1. INTRODUCTION

The proposed Jonglei Canal Scheme in the Sudd region of the Jonglei Province of southern Sudan has caused both cheer and concern among the people of the region and brought attention from scientists all over the world. On completion of the first phase of the scheme, the Jonglei Canal, connecting Bahr el Jebel (at Bor) and River Sobat (at Doleib Hill), is expected to enable improved utilization of Nile water for irrigation purposes. The canal will drain 4.66 billion m³ of water, a total of 42 billion m³ which is lost annually in the swamps and on the floodplains. The drainage of water through the canal is expected to reduce the water level of the swamps by about 10 percent during flood season and by about 20 percent during the dry season. There will also be a reduction in the area of toich (floodplain) underwater because of the reduction of spill over into the toich. The area that will be deprived of waters is not known. Presently about 80 000 km² remain flooded during the flood season which includes an area of 8 300 km² of permanent swamps (Figures 1 and 2). The shallow floodplains flood during the months of July, August and September. The flood starts receding on all sides at the onset of the dry season from November onwards and the floodplain then gets cut off from the swamps, except where river channels exist and eventually dries during the summer from February to April (Figure 3). Such an annual oscillation is considered necessary for the maintenance of the particular ecological state on which the fauna, flora, the agricultural practices and the livelihood of the people of the region depend. When Phase II of the scheme is completed, a strictly regulated flow of water through the river and efficient drainage through the canal(s) are likely to leave the entire floodplain exposed. The level of swamp is also likely to fall considerably. Nothing is documented about the possible impact of such a scheme on the fauna and flora of the region. Soon after the grant of final approval to go ahead with the scheme in 1974 several analysts have indicated possible impacts of the scheme, particularly the socio-economic and environmental aspects (Van Hoek, Zanen and Deng, 1978; Mann, 1977; Platenkamp, 1978). Some concern about the possible changes in the ecological conditions of the region that would seriously affect the life of plants and animals was expressed. However, the precise nature of ecological changes and the specific nature of adverse effects were not spelt out. There is no technical paper devoted to a detailed study of fisheries of this region with reference to the Jonglei Canal Scheme. Recommendations for a research programme to investigate the hydrobiological effects of the proposed Jonglei Canal Scheme were made, but not much has been done so far.

This paper considers the advantages and disadvantages of the Jonglei Canal Scheme on the fisheries of this region, makes a critical analysis to evaluate the magnitude of the adverse effects, if any, the scheme may bring about for fisheries, and offers some suggestions for the development of fisheries of these vast productive waters.

2. THE CANAL PLAN

The first phase of the Jonglei Canal Scheme consists of digging a canal of about 360 km in length and installation of hydraulic structures (Figure 2). This work is supposed to be completed by the end of 1981. Completion of Phase I of the scheme is expected to bring about only a minor change in the fluctuation of the water regime, which it is hoped, will not affect the ecosystem of flooded areas drastically.

Implementation of Phase II of the scheme could cause serious damage to the fisheries of the region if proper precautions are not taken.

It is estimated that the water that is channelled for irrigation at the completion of Phase I of the scheme would bring an annual revenue of £.Sd. 56 million. Obviously, the agricultural benefits of Phase II of the scheme will be severalfold. As Phase I of the scheme is already underway, it will be prudent to plan suitable fisheries development projects for this region that will go in hand with the Jonglei Canal Scheme. It would take a considerable amount of time to start Phase II of the scheme and much longer to complete it. The consequences of Phase II of the scheme are difficult to envisage at present because even the effects of Phase I of the scheme are not yet properly known. However fisheries projects could be developed and implemented, bearing in mind the anticipated effects of Phase II of the scheme so that it will not affect the projects already undertaken or those contemplated for future development.

Figure 1 The floodplain area in south Sudan

Figure 2 The Jonglei Canal, rivers and permanent swamps

Figure 3 Schematic cross-section of the river and floodplain (a) before and after (b) the construction of the Jonglei Canal

To suggest promising fisheries development projects which have to be implemented simultaneously with the Jonglei Canal Scheme, information on the following subjects will be necessary:

1. the current state of fisheries of the region;
2. the impact anticipated due to implementation of Phase I of the Jonglei Canal Scheme;
3. suggestions for development and on evaluation or further data needed for successful implementation of fisheries development projects.

The following paragraphs will be devoted to a presentation and interpretation of the information presently available.

3. PROBLEMS AND ANALYSIS

3.1 Current State of the Fisheries of the Sudd Region

Fishing is a seasonal activity in most parts of the Sudd region. It is also not a full-time profession of any of the tribes, viz., Dinka, Shilluk and Nuer. Small numbers of Shilluk and Dinka living on the edges of rivers have now started specializing in fishing and use gillnets and cast nets. Intensive fishing practices are undertaken only during the dry season. Fishing activity follows a regular pattern every year which is detailed hereunder.

During the rainy season (May–September) the river overflows, flooding the vast stretch of swamps and toich (floodplain). Fishes, big and small, migrate into the toich with the spillover and through the river channels. As the water of the toich recedes (November onwards), the fishes move from shallow areas to deeper pools and lagoons during which time they are easily caught by the people who migrate along the receding toich in search of good pasture and fishing grounds. This period (January and early February) constitutes the first phase of intensive fishing activity. This is followed by a second peak of fishing duringlate February and March when the pools and seasonal river channels (khors) are the smallest and fishes are collected from them effortlessly in large quantities. The catch during this period is the highest. During April the people start moving toward their permanent settlements in the highlands to prepare their lands for agriculture. When it starts raining again in May the river waters spill over into the toich. There is no fishing activity during this season. A small number of fishermen have erected clay platforms right in the middle of the swamps on which they have constructed their houses and made space for drying and storing fish where they engage themselves in fishing activities.

In addition to the traditional fishing practices - fishing spears, harpoons and traps - cast nets and drag nets are used nowadays by Dinkas. Fishermen have started to venture into the main river and deeper parts of the swamps with cast nets and gillnets, though not with success. The number of fishermen, crafts and gears operating in different areas of the Sudd region are not known. It could be said, however, that they are not as high as they could be. Fishing is done at random. Because of such random activities fisheries resources have remained underexploited, for several reasons explained in the next paragraph, in most of the areas of the Sudd region. However indiscriminate fishing under the name “commercial operations” has started showing some effects which ultimately may lead to overfishing in places such as Lake Shambe (Gumaa, 1979; Nyang and Gumaa, 1981). If fishing is permitted in the same way in this and other areas of the Sudd region, soon these areas may be overfished, not because innumerable fishermen operate, but because there is a tendency to concentrate on one area and wipe it out of its resources. However it may be hoped that overfishing might not occur too soon, especially in an underexploited riverine/floodplain system.

Reports state that the zone comprising Shambe, Kenisa and upper Zeraf and the area between the River Atem and Fangak (see Figure 2), are the regions of enormous natural fisheries resources. This almost covers the permanent swamps of the Sudd region. The reasons for inadequate exploitation (limited fishing) of this vast fishery resource are several. These are detailed below:

1. Fishing is only a seasonal activity and not a year-round profession for most of the people of the region. This limits the possibility of profitable exploitation of some of the species of fishes.

2. The level of technological development of the region is very low.

3. Non-availability of efficient gears keeps the catch low.

4. There is no incentive for the fishermen to catch more because of the problems of transportation and marketing. Local markets in fishing centres do not fetch a worthy price for the catch.

5. Excepting some areas of the region, such as Shambe and Malakal, fishing areas are thinly populated.

6. Dense vegetation in the swamps makes most of the areas inaccessible for fishing.

7. Above all, the tribes in general consider fishing as a profession inferior to cattle raising and agriculture.

3.2 Impact Foreseen of the Jonglei Canal Scheme on the Fisheries of the Sudd Region

The following information compiled from reports on the Jonglei Canal Scheme will give some perspective on the possible impacts of the scheme on fisheries of the Sudd region (van Hoek, Zanen and Deng, 1978; Jonglei Project Phase I, 1975; Mann, 1977; Platenkamp, 1978).

1. Because of the lowering of the water level, the fish species that depend upon fringe waters for feeding and shelter will be seriously affected.

2. The habitat for fish in the swamps and toich will be considerably reduced and this will reflect on the catch from these areas.

3. The changes in the water regime would necessitate a change in fishing patterns. This would cause a disruption in the present pattern which efficiently coordinates the mode of life, agricultural practices and cattle raising by the people of the region.

4. It is generally believed, and in some cases certain, that fishes utilize the shallow floodplains for breeding and nursery areas. The diminuation of these plains will radically affect the breeding of fishes and thereby the fish population.

5. Loss of fisheries potential will be considerable. The production potential is expected to fall by 17 000 t from an estimated 34 455 t/y at present.

6. Some indigenous methods of fishing may become less effective because of the new regime of fluctuations of water.

7. The canal will not offer the same kind of environment as that of the toich and swamps. Therefore the new habitat will not compensate for the loss.

8. Introduction of new and efficient gear, which will be necessary to enable the inhabitants to fish perennial waters, which could make up for the losses, might lead to overexploitation of fishery resources.

3.3 Analysis of the Impacts Foreseen

It will be appropriate to bring to recollection at this stage that efficient drainage of water through the canal will not completely deprive the swamps and toich of water. The drainage would cause only a shift in the fringes of swamp waters toward the river and the toich waters toward the centre of toich, along with their floating vegetation and fauna in a fashion more or less similar to that occurring during the normal seasonal oscillation from wet to dry season. Of these two areas, the toich and swamps, the toich is likely to be more affected because the spillover from the swamps into the toich will be minimized. In proportion, more area of toich will be permanently deprived of flood water and acquire the characteristics of ‘intermediate land’. While the chemical and biological characters of the waters are likely to remain the same, toich waters will dry sooner than usual. The toich area on the eastern side of the permanent swamps will be traversed by the canal dividing it into a broader toich on the eastern side of the canal (TESC) and a narrow toich on the western side of the canal (TWSC). The TESC will have an adequate store of rain water, but will be completely deprived of river spill. Any spillover on the eastern side from the swamps will be collected into TWSC. The khors on the TESC will be completely blocked by the canal.

Some of the adverse effects that were considered possible, detailed in eight points in the previous section of this paper, pertain to the swamps and river, and others pertain to the toichs. Project analysts, while expressing concern about the adverse effects, did not clearly distinguish those on toich and those on swamps. To avoid any confusion, the swamps and toich will be dealt with separately in the subsequent sections of this paper.

The toich: It is only temporarily lacustrine. The fish species expected in the toich are those which migrate laterally in search of shallow waters for spawning and those which are incidentally carried along with the flow beyond the regions of permanent swamps. Species that spawn in other environments (running waters, permanent swamps and deeper lentic waters) and most of the non-spawning individuals of riverine species may not drift so far away from their normal range as to be trapped in the toich because of their territoriality. Therefore the population density of fish in the toich will not be as much as that in the permanent waters of the same size even under normal conditions. Also, the temporary nature of the toich does not guarantee a permanent stock of fish in it. It is true that the quantity of the fish that will be trapped in the toich will be reduced because of the reduction of spillover into the toich. As the permanent river channels and the khors will still connect the swamps and TWSC during flood season, the fish population of TWSC will be derived from these sources. On the whole, the reduction of the fish population in the toich may not be significant enough to ruin the fisheries of this area. After the construction of the canal, the entire fish population will remain concentrated in the TWSC. The eastern section (i.e., TESC) might have a very low fish population, provided that some fish migrate from the Sobat River during the rainy season. When the TWSC gets cut off from the swamps and when the waters starts drying up, hugh quantities of fish could be collected from this area. It will be relatively easy to collect fish from TWSC because this area will be considerably reduced. The TWSC is expected to dry sooner than the TESC because of its shallowness and reduction in its breadth.

The reduction in the flooded area of the toich may not necessitate a change in fishing patterns because the same type of annual oscillation is expected to occur, but over a reduced area of toich. However the people may have to cross the canal for fishing on its western side. There may be some difficulty in combining fishing with cattle herding because of the separation of pasture and fishing grounds for people living on the eastern side of the canal. The people may also have to travel farther west from their settlements to reach the TWSC if they wish to catch fish. However the majority of the population from Bor to Kongor will live on the western side of the canal.

At present the vast area of toich is not being covered by fishermen at the appropriate time to catch all the trapped fishes. It is well known that a considerable percentage of the fishes that are trapped in the fast-drying shallow pools and lagoons die without being caught. Therefore it would be better to catch all the available fishes by using efficient gear than to allow them to perish in the toich.

The breeding requirements of a great number of Nile fishes are not known. Table 1 gives a list of the common fishes of the Sudd region and the breeding grounds and breeding seasons of some of them. It can be seen that only two species are definitely known to breed in the toich. Two more species, which normally breed in swamps, may breed in the toich also if they get lodged in the toich areas during their migration. That the toich is the breeding ground of several riverine species is a misconception. Where the river is not shallow and where there is no spillover of water onto the floodplain, the riverine species reach shallow waters through the tributaries and spawn in catchment areas or in the areas adjacent to river channels. In fact, the juveniles are surer to reach the river from such waters than from pools and lagoons in the toich, which are located far away from the main river, or permanent river side channels. Also, it is well known that the mortality of fish in any tropical floodplain can be high because of rapid drying which results in the increase of temperature and decrease of oxygen in the shallow waters. The problem of predation adds to the adverse conditions to which the juveniles can easily succumb. Thus under normal conditions only a small percentage of fry and fingerlings produced in the toich would manage to reach permanent river channels, and the majority of them would perish in the toich.

Migration of mature fishes into the TWSC will not be seriously affected. They will manage to reach the TWSC partly through river overspill and partly through the permanent and seasonal river channels. The toich on the western side of the swamps will not be affected as much as that on the eastern side of the swamps. The toich area for which the fishes have free access will be adequate for their breeding and spawning activities.

The swamps: The construction of the Jonglei Canal and diversion of 20 million m³ of water every day from Bahr el Jebel, is expected to cause a fall in the level of the swamps by 29 cm during flood season and by 70 cm during the dry season. Because of a corresponding reduction in the area of swamps, it has been estimated that the production potential might fall by about 50 percent. Considering the quantity of water reportedly lost from the Sudd swamps and the toich (42 billion m³) every year and considering the difference between the high and low level of the Sudd swamps and the water that could be contained in that space, calculations would show that during flood season the swamps will be full and some quantity of water will spill over into the toich (Figure 3). At the end of the flood season, the swamp fringes will recede at a quicker pace than normal because of a reduction of flow in the river. The net effect will be that the oscillation (between the high- and low-water mark) will extend over a greater area of the swamp than before the construction of the canal. Most probably the swamp ecology, as well as the fish population, will not be drastically affected. However nothing more definite can be said now.

The question of whether the use of more efficient gear would cause a decline in the fish population can not be answered unless some basic investigations pertaining to the biology and stock assessment of fishes of this region are undertaken. It can be said that fishing could be more intensive than what it is now.

4. DISCUSSION

It is not now known to what extent fish capture could be intensified in different areas of the Sudd region. Considering the intensity of fishing operations and the expanse of water available, it appears that the entire region is only lightly fished. Although it is hoped that Phase I of the Jonglei Canal Scheme may not drastically affect the population and reproductive behaviour of fishes of the Sudd region, development projects must be undertaken for making good use of the existing potential and to save the fisheries from the possible peril because of the construction of the canal.

There is plenty of scope to undertake culture practices while organizing capture fisheries on a scientific basis but economic studies would be required to determine if a real need for fish culture exists while technical feasibility studies would be necessary to specify the most promising fish culture methods.

Table 1

Common fishes of the Sudd region, their breeding grounds and breeding seasons in Sudan and in other places

^a Some of these species may spawn in toich when trapped
^b Species known to spawn in Gambian swamps
^c Genus known to spawn in Gambian swamps
^d Species known to spawn in floodplains of Niger
^e Breder and Rosen, 1966
^f Santon, 1950

A few possibilities for development of fish culture might include construction of a series of nursery and rearing ponds along the sides of the banks of the canal with training of local people to collect juvenile fishes for stocking. It is possible to dig large ponds deep enough to hold adequate amounts of water until the end of the dry season and to teach the people the basic techniques of fish culture such as transplantation. This work could be started when the need for it has been demonstrated.

The swamps will remain an important source of fish even after the construction of the canal. To make good use of the fisheries potential of the swamps a study of the biology of fishes and of exploratory fishing to estimate the abundance and composition of the stocks in different areas should be undertaken.

It is possible to lay a strong scientific foundation for the development of the Sudd fisheries and to systematically develop all aspects. A scientific approach to fisheries development in its major aspects is schematically represented in Figure 4. It will be clear that availability to consumers at a reasonable price would depend upon a regular yield. It will also be clear that planning for utilization at a commercial level is difficult if the potential yield is not known. To estimate the potential yield, the stocks should be assessed. Specific information required for a first approximation of potential yield includes basic data on present catch, species composition and a general assessment of the economics of the fishery. More precise assessments of potential have to be based on population parameters of growth, reproduction and mortality. Information presently available about the stock, growth rate, reproductive capacity and mortality of fish populations in different areas of the Sudd region is very close to nil. Therefore it is now difficult to decide on suitable techniques to maximize yield with an intention of developing commercial fisheries. Once at least a first approximation of the potential yield is made, development aspects could be undertaken and the possibilities for smooth progress could be enhanced. Unfortunately, there is no short-cut for success in matters concerning fisheries development as in the case of any other development. Needless to say, that the work on data collection to comprehend the present status of the fishery of the Sudd region should be undertaken immediately. Data collected now will be required later to assess the impact of the canal on the fisheries of this region so that adequate measures could be taken to save and develop the fishery potential.

It will be highly appropriate to give the following caution for anyone undertaking any kind of fisheries development in the Sudd region.

“When only a few fishermen are fishing with primitive and ineffective gear, the waters would seem inexhaustible. Subsistence fisheries in freshwaters traditionally have been pursued with the idea of harvesting as much usable protein as possible with the least amount of effort. Generally, the history of such a fishery is that as more fishermen enter the activity and as better gear is devised, the capacity of the fish population to produce large numbers of large fish is diminished. This becomes evident in the smaller size of the fish landed, in the increased amount of effort needed to harvest the catch and possibly in an absolute decrease in the weight of annual harvest. These are symptoms of overfishing and they can be recognized even in the absence of environmental degradation. An unexploited or lightly used fish stock often has a significant portion of its biomass in the slow growing, older brood stock. These large individuals may represent, because of the peculiarities of fish population dynamics, a deterrent to the recruitment of great numbers of smaller fishes into the usable size classes. Also these mature fish constitute a bonanza for the fishermen who first exploit the stock and may attract the fishing pressure that can eventually result in reducing the number of spawners to the point where optimum numbers of recruits cannot be found. Aquatic ecosystems are not inexhaustible because of the factors that limit biological productivity. Man's activity can alter natural processes either through impact upon the population themselves or upon the environment which the fish populations depend. Because productivity of future fisheries may be contingent upon current treatment of fish populations and the ecosystems that produce them, management of the fisheries to protect their capacity for producing a sustained yield is highly desirable” (Bond, 1979).

Unorthodox thinking and a haphazard approach with short-term objectives is bound to lead to disappointment because the success of any fisheries development programme cannot be guaranteed as long as it is not based on progressive theories and as long as general problems, such as transport, marketing facilities, storage, living space for fishermen, etc., are not investigated.

Fortunately, human interference and alterations of the natural environment of the Sudd region have remained minimal. This situation will facilitate application of simpler techniques in management of fisheries.

Figure 4 Schematic diagram showing the relationship of catch to stock assessment and utilization

The mode of exploitation of the natural resources of the Sudd region appears to be in equilibrium with present ecological conditions. The corollary will be that any development will result in some change in the ecological conditions and/or the mode of life of the people of the region. These should be weighed against the advantages the development projects will bring. As far as the fishery is concerned, the Jonglei Canal Scheme has in plenty to contribute to its development. If fishery development is carefully planned, the adverse effects of the main scheme, if any, can be overshadowed by the benefits of the development programmes.

Local opinion about the Jonglei Canal Scheme is one of welcome so as to get the benefits of the scheme and all associated development projects. In fact, the people of several areas are impatient about the delay in the execution of the work (Gumaa, 1979).

5. CONCLUSIONS

(1) The fishery resources of the swamps, toich and the rivers of the Sudd region appear only lightly exploited.

(2) Construction of the Jonglei canal, limiting the extent of the swamp, may not greatly change the fish population of the swamps.

(3) Fishing activity of the swamps could be intensified to get a higher yield. Assessment of the potential fishery yield would help in planning for the intensification of fishing activity and for fishery development activities.

(4) Although the toich will be greatly reduced, yield from it may not be significantly reduced.

(5) Intensifying fishing activity on trapped fishes will do no harm because these fish would otherwise perish.

(6) It will be necessary to undertake development projects for capture fisheries to realize the potential of the region.

(7) It is possible to train the people in fry and fingerling collection and transplantation techniques so that fish culture practices would take root in this region.

(8) Lack of basic data forms a big handicap for organizing capture fisheries. Studies of existing fisheries, fishery biology and socio-economic aspects are necessary background for major fisheries development projects and to assess any adverse effects the canal may bring on the fish and fisheries of this region.

REFERENCES

Bond, C.E., 1979 Biology of fishes. Philadelphia, W.B. Suanders Co., 514 p.

Breder, C.M. and D.E. Rosen, 1966 Modes of reproduction in fishes. Garden City, New York, Natural History Press for the American Museum of Natural History, 941 p.

Gumaa, S.A., 1979 A report on the fisheries of the area between Malakal and Aliab valley that might be affected by the Jonglei Canal Scheme. (Unpubl. MS)

Hoek, B. van, S. Zanen and P.L. Deng, 1978 Socio-anthropological aspects of the Jonglei Development Projects in South Sudan: a field report. Leiden, University of Leiden

Jonglei Project Phase I, 1975 Executive organ for the development projects in Jonglei area. Khartoum, Democratic Republic of Sudan

Krishnamurthy, V.G., 1980 Research and fisheries development in Southern Sudan: need for basic data collection. Paper presented to the conference on Research for Agricultural Development in the Southern Region. Juba, Sudan, 2–6 June 1980

Mann, O., 1977 The Jonglei canal: environmental and social aspects. Nairobi, Environment Liaison Centre

Nyang, B.B., and S.A. Gumaa, 1981 Fisheries resources development of the White Nile. Paper presented to the CIFA/FAO Seminar on River Basin Management and Development. Blantyre, Malawi, 8–12 December 1980

Platenkamp, D.M., 1978 The Jonglei canal, its impact on the integrated system in the Southern Region. Leiden, University of Leiden

Sandon, H., 1950 An illustrated guide to the freshwater fishes of the Sudan. Khartoum, Sudan notes and records, 61 p.

THE IMPACT OF THE KAFUE GORGE DAM ON THE KAFUE FLOODPLAIN FISHERY

INFLUENCE DU BARRAGE-RESERVOIR DE KAFUE SUR LA PECHE DANS LA PLAINE D'INONDATION

by

P.M. Chipungu
Department of Fisheries
Chilanga, Zambia

1. INTRODUCTION

Zambia is a landlocked country covering 752 620 km² in area. Most of the country lies on a high plateau with elevations ranging from 1 067 to 1 372 m above sea level. In the north the elevation is over 1 807 m.

In spite of being landlocked, Zambia is blessed with a proportionately large area of water surface in the form of rivers, floodplains, lakes and swamps (Figure 1). The total water surface area is approximately 45 157 km² (6 percent of the whole country). This can be broken down as follows:

Figure 1 Main fish producing areas in Zambia

This paper is a short review of the effects of the development of the Kafue River and floodplain fishery.

2. DESCRIPTION OF THE FISHERY AREA

The Kafue River is one of the two major tributaries of the Zambezi River. It arises near the Zambia/Zaire border and meanders southwestward, a distance of approximately 400 km, then eastward a further 280 km before discharging its waters into the Zambezi. Fishing development along the Kafue River has taken place mainly on a stretch popularly known as the Kafue Flats (Figure 2). This area lies between the Kafue Gorge Dam and the new Itezhi-tezhi Dam, a straight distance of about 240 km with a river length of 448 km. The area of the Kafue Flats is about 14 000 km², of which 6 600 km² is liable to flooding in a year of average rainfall.

2.1 Flooding Regime

Prior to 1973, water could start rising shortly after the start of the rain season towards the end of November. The highest water levels used to occur in April or May, shortly after the end of the rain season. The extent and duration of flooding depended on the amount of rain and therefore varied from year to year.

Since the closure of the Gorge Dam in 1973, the pattern and duration of flooding have changed significantly. Large tracts of land are permanently under water in the eastern part of the flats. The flooding period over the whole area is now longer than was previously the case. Water level regulation is unpredictable. It should, however, be noted that the mean flood elevation has not changed.

2.2 Economic and Social Activities

Fishing is the leading economic activity of the people living along the Kafue River and will be discussed in more detail later. In this section I wish to briefly mention other social and economic interests of the area.

Hydroelectricity

As stated earlier, the need to generate electric power was the primary reason for the construction of both the Gorge Dam and the Itezhi-tezhi Dam. It is little wonder, therefore, that the water level regulation is primarily to serve this requirement.

Wildlife conservation

The area under review has three national parks established for the protection of numerous bird species and wild animals (mainly the Kafue Leche; Kobus leche kafensis). Two of the parks, Lochinvar and Blue Lagoon, are on the Kafue Flats, while about 90 percent of Itezhi-tezhi Reservoir lies in the Kafue National Park. For conservation and tourism purposes, these areas are not wholly available for fishing. However arrangements were made for some fishermen to gain entry to the park areas using special permits.

Figure 2 The Kafue Flats

Agricultural activities

(a) Cattle grazing

The indigenous villagers of the Kafue Flats area are traditionally cattle herders. A large number of cattle used to graze in this area, particularly during the dry season. The present unpredictable water level regulation has created hardship among the traditional cattle herdsmen.

(b) Crop farming

A large sugar-growing scheme is one of the many crop-farming schemes on the Kafue Flats. This, together with the wheat irrigation scheme, call for the application of large amounts of herbicides and fertilizers which are eventually washed down the river.

Industrial and domestic water supplies

Kafue (town), a rapidly expanding industrial centre, is among the many towns making extensive use of the Kafue River water for domestic and industrial purposes. The town is strategically spread out along the river bank. Manufacturing companies such as Kafue Textiles Ltd., Nitrogen Chemicals Ltd., Bata Shoe Company Ltd., Lee Yeast and many others, discharge their effluents in settlement tanks situated on the river bank.

2.3 Pre-Impoundment Studies

Research activities of a routine nature started on the Kafue floodplain in the late 1950s. Towards the end of the 1960s it became apparent that a hydroelectric scheme that would disrupt the natural flooding regime was in the offing. It was, therefore, decided to carry out a pre-impoundment study of the area to be affected.

Between 1968 and 1971, and prior to the closure of the Kafue Gorge Dam, ecological and biological studies were carried out by three study groups, namely, the Department of Fisheries (Zambian Government), the University of Idaho and the University of Michigan. Dr T. Scudder, a renowned anthropologist from the University of California (Berkeley Campus), studied sociological aspects of the inundation on the fishing communities. The ecological and biological studies were aimed at studying the fish and fisheries of the area and prediction of the probable effects of the Gorge Dam on this fishery. The sociological observations were aimed at understanding the social structure and set-up of the fishing community and to assess probable reaction of the fishermen to the proposed damming of the river. It was also hoped that potential damage to property and extent of flooding on seasonally inhabited highlands of the floodplain would be estimated. From 1975, there was a follow-up programme designed to monitor deviations for the predicted trend and the effect of these deviations on the fishery. Dr Muncy conducted a brief survey of the fishery between 1972 and 1973. Dr Dudley, one of the participants in the pre-impoundment studies, returned between 1975 and 1976 and conducted a review study for ten months (Dudley, 1976). Since then only routine monitoring has been taking place on the flats. At Itezhi-tezhi an active ecological and biological research programme is being carried out.

From 1978 to 1979, Messrs M. Appleman and J.C.M. Van de Meerendont studied social and economic aspects of the fishing industry on the Kafue Flats.

2.4 Results of Pre-Impoundment Studies

The fish

Of the 67 fish species known to occur in the Kafue fishery, 21 are of some commercial significance. Of these, 10 make up about 90 percent of the total catch. These are:

Sarotherodon andersoni
Sarotherodon macrochir
Clarias gariepinus
Clarias ngamensis
Serranochromis angusticeps
Tilapia rendalli
Tilapia sparmani
Schilbe mystus
Hepstus odoe
Labeo molybdinus

Fishing activities

It was observed that commercial fishing was being carried out in only a small area of the available water area. At high water mainly gillnets were being used, while at low water seine nets were the main gear in both the main river and the lagoons. The gillnet catch per net averaged 12.5 kg/night, while the average catch per seine net haul was 84 kg/night. An average hauling operation lasted about 45 minutes. One of the pre-impoundment studies (University of Michigan, 1971) estimated ichthyomass of the flats area at an average of 76 634.5 t during the high-water phase. It was stated at the time that this ichthyomass was composed of about 78% exploitable-sized individuals of the commercial species, 5% undersized individuals of commercial species and 17% in species not exploitable because of the small size of their component individuals.

Research work carried out between June and September 1970, showed that there was an approximate loss in total ichthyomass of 38 000 t of which 30 600 t (81%) were of commercial species of exploitable size. Of the latter, fishing mortality accounted for only 18%, and natural mortality apparently accounted for the remaining 25 042 t. A clear indication of underfishing.

Fish production from the Kafue Flats during the five-year period leading to the filling of the dam was as follows:

Table 1

Physio-chemical aspects

Water depth fluctuation through the years averaged 3.1 m. Water temperature depended on air temperature, and the monthly mean for the coldest month (July) and the hottest month (October) were 17°C and 30°C, respectively. Rainfall used to play a major role in the water regime of the floodplain area.

The chemical composition of the Kafue River and floodplain waters varied approximately inversely with water level. It is also probable that seasonal variation in rate of primary production affected chemical content. For instance, it was observed that as water receded, silicon dioxide quickly disappeared and concentration of sulphates decreased. The former could be attributed to uptake by diatoms and the latter due to utilization by vegetation.

During the dry season when flood waters go down, large numbers of wild animals (especially lechwe, zebra and wildbeast) feed in the area and their droppings enrich the soil in food organisms. As flood water rises, decaying vegetation and animal wastes are accumulated by inundation and by rainfall run-off. Fish leave the main river and move to the flooded areas to breed and feed.

The decaying vegetation and animal wastes accumulated by inundation cause a high bio-chemical oxygen demand. In the course of satisfying the demand, large areas of the flood-plain may become deoxygenated during the early stages of the flood. One such instance of deoxygenation did coincide with observations of large numbers of dead fish in the area (University of Idaho, 1971).

2.5 Commercial Fishing

A combination of a long record of statistical data and research data has helped us keep track of the events on the Kafue Flats area of the fishery.

Initially, fishing on the Kafue Flats was only practised by local tribesmen whose villages stood on mounds. In the 1920s and 1930s migrant fishermen started moving into the area. By the 1950s fishing assumed a new importance, moulting from subsistence activity to a commercially-oriented means of existence. By 1978 nearly 90 percent of the inhabitants of the flats and Itezhi-tezhi Dam areas were migrants from other parts of the country and nonnationals.

Since the construction of the Kafue Gorge Dam the number of permanent settlements has been going down. Permanent flooding of a large portion of the eastern part of the flats area and increased hardships in obtaining provisions are two main reasons for the decline in the number of settlements.

Table 2

At the time of the filling of the Gorge Dam in 1973, there was an exodus of fishermen from the area and this caused a temporary reduction in numbers of villages, fishermen and fishing boats. Since then fishermen have moved back into the area and except for the number of settlements which has continued to decline, numbers of fishermen and boats have by far exceeded that of the period before and during the dam filling.

In the case of fish, there were some noticeable post-impoundment changes in relative abundance by weight of the 21 important commercial species. As before, members of the family Cichlidae remained in the largest proportion of the commercial fish catch of both the Kafue floodplain and the Itezhi-tezhi Reservoir. On the Kafue Flats the five most significant cichilids occurred in the following proportions:

Predators of the family Claridae and Characidae have increased their proportionate output by weight as follows:

The above changes in relative abundance of selected species may be attributed to post-impoundment changes in three factors of the environment, namely, food availability, amount of shelter and predator/prey interaction.

S. andersoni is a plankton feeder and mouth brooder. The increase in food availability on the floodplain was expected to result in an increase in stocks. Unfortunately, due to the fish exposure to predators in the marginal areas, survivorship of the fry and fingerlings was low and left the fish relative abundance almost unchanged.

S. macrochir, T. rendalli and T. sparmani are macrophagous herbivores. The longer period of flooding has forced these fish further out into the marginal areas where predation by other fish, as well as game birds on the young, is bound to be heavy in shallow water. Also the breeding nests of the two Tilapia spp. are liable to destruction by wading lecwhe whose grazing area on the floodplain now remains flooded for a longer period.

The observed increase in the relative abundance of predators may, by the same token, be attributed to increased availability of food. It is, however, necessary to mention here that although there is a proportionate increase in relative abundance by weight, the average size of fish has dropped significantly.

Compared to the period leading to the filling of the dam, the fish production trend from the Kafue Flats has taken a slight upswing:

Table 3

As can be seen from Table 2, the increase has been achieved after significantly increasing fishing effort. The actual catch per boat per night has fallen in contrast to the predicted increase in ichthyomass. The reasons for the decline are not yet clear to us at this moment. It is, however, obvious to us now that the pre-impoundment predictions for an increase in ichthyomass and due to improvements in breeding, success and lowering of natural mortality have not come true. We have not been able to assign a professional officer to critically analyse all post-impoundment data in search of a solution to the puzzle. I am, therefore, not in a position to advance any logical theories over the matter at the moment.

3. CONSTRAINTS ON DEVELOPMENT

The following have been tentatively identified as some of the constraints to the realization of higher fish yields from the Kafue floodplain:

1. Inconclusive information regarding available fish stocks;

2. Poor access routes in the area, especially on the northern approach to the floodplain;

3. The flooding of the flats brings with it germination of a wide variety of aquatic vegetation communities. The vegetation cover on the Kafue fishery was estimated to be at 25 percent of the surface area;

4. Lack of primary marketing facilities, i.e., shelter, wash basins, store rooms and scales at terminals of access routes;

5. Lack of fish-keeping facilities, such as cold rooms at markets. Alongside this there is now the problem of shortage of firewood for smoking fish, particularly during the wet season when sun-drying becomes impracticable.

4. CONCLUSIONS

The Kafue Flats have been subjected to various forms of social and economic developments of which the construction of a dam for hydroelectricity generation is the most significant. The regulation of water level has become unpredictable and is thus inconvenient to the settlers in the fishing camps. It would appear that the impoundment has failed to produce predicted elevation of the ichthyomass in the reservoir.

REFERENCES

Dudley, R.G., 1976 Status of major fishes of the Kafue floodplain, Zambia five years after completion of the Kafue Gorge Dam. Final Report submitted to the National Science Foundation Scientists and Engineers in Economic Development Programme. Athens, George, University of Georgia Grant No. OIP75-09239. 15 March 1975–30 April 1977, 71 p.

Muyanga, E.D. and P.M. Chipungu, 1978 A short review of the Kafue fishery since 1968. (Unpublished MS)

University of Michigan, et al., 1971 The fisheries of the Kafue River Flats, Zambia, in relation to the Kafue Gorge Dam. Report prepared for FAO of the UN (acting as executing agency for the UNDP). Central Fisheries Research Institute, Chilanga, Zambia. Ann Arbor, Michigan, University of Michigan, FI:SF/ZAM 11 Technical report 1:161 p.

University of Idaho, et al., 1971 Ecology of fishes in the Kafue River. Report prepared for FAO of the UN (acting as executing agency for the UNDP). Central Fisheries Research Institute, Chilanga, Zambia. Moscow, Idaho, University of Idaho, FI:SF/ZAM 11 Technical report 2:66 p.

DEVELOPMENT OF FISHERIES OF THE ZIMBABWEAN WATERS OF LAKE KARIBA

AMENAGEMENT HALIEUTIQUE DANS LES EAUX ZIMBABWEENNES DU LAC KARIBA

by

F.J.R. Junor
Principal Ecologist
Branch of Aquatic Ecology
Department of National Parks and Wildlife Management
Zimbabwe

1. INTRODUCTION

Kariba was the first of the great man-made lakes in Africa and began filling in December 1958. Lake level peaked at 487.4 m above sea level in 1963 and has since fluctuated around a mean operating level of 485 m, at which level the surface area is 536 km².

Planning for the future commercial fisheries took place long before wall construction was completed and large tracts of land were bush-cleared for future use as fishing pitches. Background data on which to make reasonably accurate predictions regarding expected fish yield was totally lacking and estimates for expected fish production varied from 8 000 to 20 000 t/y; these were ‘guesstimates’, however, with no real information to support them. However, they were made by fisheries experts and with recent developments in the establishment of a pelagic fishery, their predictions (though considered too high when only gillnet fisheries operated) may in time prove to be reasonably accurate when applied to the lake as a whole.

Two distinct types of fisheries have developed on the Zimbabwean side of the lake; an inshore artisanal gillnet fishery and an open-water industrial type. The former started in 1962 during the fourth year after the process of filling began and the latter in July 1973.

Careful monitoring of effort, landings, composition of the catch, price structure of fish and gear and the number of fishermen (self-employed and paid workers) has been an ongoing process. As explosive development of inshore fish stocks always occurs during lake formation and for a number of years thereafter in African man-made lakes, it is pointless to draw conclusions about expected production on a sustained yield basis during this unstable period.

Indications are that production stabilized during the 1969/70 period, 10 to 11 years after filling began. Only the period from 1969 to the present is therefore covered in any detail in this report.

2. THE GILLNET FISHERIES

2.1 Areas Allocated

The size and location of each area as set aside within the five basins of Lake Kariba (Begg, 1970) for the purpose of commercial fishing by means of gillnets and also changes in size and location which have taken place since the inception of the fisheries are shown in Figures la, b and c.

Coke (1968) showed that the species taken in gillnets, all of which are riverine in origin, seldom extend to more than 50 ft (15.4 m) in depth (Figure 2). This depth has been generally applied to all basins and used accordingly in estimating the area of fishable water in the allocated fishing grounds.

2.2 Fishery Production

This highest production of 2 631 t (46 kg/ha^-1/y) was attained in 1964, two years after gillnetting started and in the sixth year after filling began. Landings then gradually declined to 1 508 t (26 kg/ha^-1/y) in 1969 which was followed by a marked drop to 1 070 t (19 kg/ha^-1/y) in 1970, a level of production which remained relatively constant over the next two years. The 1970–73 production would probably have been maintained over the next six years, but for a reduction in the size of the total allocated fishing area by 20 percent in 1972. More changes in fishing areas in 1976 and the phased closure of fishing villages in basins 3 and 4 from 1976 to 1978 because of the war brought about a further decline of the total catch. Conditions in Zimbabwe have now reverted to normal and fishermen are in the process of re-establishing in fishing villages. The 46 990 ha of fishable water used for commercial gillnetting should produce a sustained yield of 950–1 000 t/y (or 19–20 kg/ha^-1) in the future.

2.3 Composition of the Catch and Price Structure

Table 1

Percent composition of the catch, by weight, according to area
(1969–79)

^a Fishing confined to one area in the eastern section of basin 4

Fish prices are dictated by certain species; the cichlids, for example, are worth three times as much as the clariids. Careful monitoring of the species composition by weight of the catch is therefore necessary (Table 1). The relative changes in the values of the landed catch (Table 20 indicates a substantial increase in the price of fish over the last 10 years, which has compensated, to some extent, for lower production levels. In years such as 1975 and 1979, total sale value actually exceeded that for 1969 although catches were nearly half as much (Table 3). The increase in price has fortunately kept pace with the increase in the cost of gear; gillnets, for example, have increased in price by 170 percent since 1970.

It is noticeable that in basins 3, 4 and 5, cichlids comprise over 60 percent of the catch while in basins 1 and 2 the riverine families, Cyprinidae and Distichodidae, are dominant because of the strong influence of the Zambezi River in this area.

Figure 1a

Figure 1b

Figure 1c

Figure 1 Gillnet fishing areas in Lake Kariba (Zimbabwean side); (a) 1962–July 1972; (b) August 1972–November 1976; (c) December 1976 to present. Artisanal areas shown in black and commercial concession areas stippled. Lake basin numbers encircled

Table 2

Sale price per ton according to species groups and time in various areas (US$)

Table 3

Total production in tons from the gillnet fisheries and its sale price at source (US$)

Fishermen in basin 5 have received on average substantially higher prices for their fish than those in the more remote basins 3 and 4. This is primarily due to high running costs of boats, owned by a large firm with a factory and freezing facilities at Kariba, which service all areas in basins 3, 4 and 5 on a daily basis. The greater the distance travelled, the lower the purchase price for fish.

It is expected that as fishing returns to normal during 1980, competitive buying by large firms and the increased demand for fish will result in more stable and higher purchase prices being paid in the more remote areas.

2.4 Numbers of Fishermen and Yearly Earnings

There are 26 villages along the Zimbabwean shore. Seven in basins 1 and 2, eight in basin 3, five in basin 4 and six in basin 5, but the number of fishermen varies from month to month and from year to year. There was a marked drop in the number of fishermen in 1970 which is consistent with the drop in fish production from 1969 to 1970. During the period 1970–74 the number of fishermen ranged between 210 and 280, then declined to between 130 and 140 in 1977. Numbers for 1978–79 are not known.

Annual earnings per fisherman were as low as US$ 213 in 1969, but there has generally been some improvement since; 1971 - US$ 320 to 330; 1973 - US$ 390 to 400; 1974 - US$ 590 to 600; 1975 - US$ 550 to 570; 1976 - US$ 620 to 625.

The 1974 period may be taken as the norm (before fishing activity was disrupted by the war) with an expected average earning per fisherman of US$ 590 to 600 per year. This is, of course, subject to their average numbers not exceeding 210 to 220 active fishermen.

3. THE PELAGIC FISHERY

The pelagic Lake Tanganyika clupeid, Limnothrissa miodon, was introduced into Lake Kariba in 1967–68 and commercial fishing began in the Zimbabwean waters in 1973. The 1980 catch will be very close to 6 000 t (Table 4).

Table 4

L. miodon landings and value at source in US$ over the period 1973–80

By 1980, 37 companies, each requiring a land base for processing the catch (80–85 percent of which is brined and sun-dried), warehouse facilities and boat maintenance and moorage, were engaged in sardine fishing. Eighteen of these are based at Kariba township and the remainder operate from allocated land bases scattered along the southern shore (Figure 3).

As is to be expected in a developing industry, the number of fishing craft increased yearly from 1 in 1973 to 100 in 1980 (Figure 4). In expressing unit of effort, the type of gear and its catching power were used as the main criteria. The three basic types of nets used at present are conical shaped dip nets, square lift nets and purse seines. Their catching power in terms of units, is as follows: dip net of 25–30 m circumference - 1 unit; dip, lift or seine nets of 31 m up to 100 m in circumference or length - 1 ½ units; purse seines of 100–200 m in length - 2 units. A total of 174 units were operating in 1980. The fishing effort will not be increased for a number of years.

Figure 2 Relationships between gillnet catches and depth. Redrawn from Coke (1968)

3.1 Number of People Employed in the Fishing Industry

Up to 1974 only ±290 people made a direct living from the fishing industry; because of the sardine industry the number rose to over 2 000 in 1980, of which over 900 are employed in the Kariba township alone. The economic impact on the township has been considerable.

4. DISCUSSION

The economic role of the fisheries in the development of the Kariba basin has been greatly enhanced by the introduction of the exotic clupeid, Limnothrissa miodon; the fishery has developed from what was basically a sub-economic one to a highly lucrative industry. The history of the Lake Kariba fisheries now provides data which can be used for similar reservoirs which might be built in the future. Yield prediction is now better understood and planning of secondary activities connected with the industry should be more efficient.

Figure 3 Sardine fishing bases Lake Kariba southern shore. Numbers in brackets refer to licence holders at each site

Figure 4 Number of sardine fishing boats 1973–80

REFERENCES

Begg, G.W., 1970 Limnological observations on Lake Kariba during 1967 with emphasis on some special features. Limnol.Oceanogr., 15:776–88

Coke, M., 1968 Depth distribution of fish on a bush-cleared area of Lake Kariba, Central Africa. Trans.Am.Fish.Soc., 97:460–5