SECTION I: PRESENT STATUS OF AQUACULTURE AND POTENTIAL FOR DEVELOPMENT (contd.)

THE HISTORY AND STATUS OF FISH CULTURE IN SUDAN AND THE URGENCY OF AN EXPERIMENTAL PROJECT FOR ITS DEVELOPMENT INTO AN INDUSTRY A REVIEW

by

T.T. George
Fisheries and Hydrobiological Research Section
Khartoum - Sudan

Abstract

The Sudan has an area of 2.5 million km², a coastline of 480 km and over 6 400 km of river waters covering an estimated 2 million ha. In the Sudd Region, at latitude 5–9 degrees north along the White Nile (Bahr el Gebel) there is an area of about a hundred thousand km² consisting of permanent and temporary swamps.

Besides river water resources, there are ponds, ‘haffirs’, reservoirs and irrigation canals with individual water capacities ranging from thousands to few million cubic metres and depth of 1 to 20 m. In the Gezira Scheme, the canal network consists of 5 649 km with a depth range of 0.50 to 0.75 m; similarly there are other canal systems in the Managil Extension, Guneid Sugar Estate and Kashm El Girba Project. In the Sudd Region, a highly productive fish breeding and growing area is available in the swamps of the river flood plain. The productivity of the reservoirs (0.5–9.0 m depth) of this area can be as high as 100–110 kg/ha while river waters may have a productivity up to 30 kg/ha, as is the case in the 120 000 ha fishing area of Jebel Aulia Dam. In addition, the inland waters of Sudan, with the exception of the Gezira canals to some extent, are free of all types of pollution.

In spite of this vast resource of inland waters, animal protein in the form of fish is beyond the reach of farmers and rural communities in Western Sudan, Kassala Province, and even in the Gezira, an inland between the Blue and White Niles; in Equatoria Province there is a chronic shortage of meat due to the ravages of the tsetse fly particularly in the Zandi Region. Similar conditions exist in other areas which are remote from the location of the major fisheries.

All investigations carried out in Sudan have recommended fish culture as a remedy not only to this acute problem of malnutrition but also as a compensatory measure in marshes reclaimed under the Jonglei Scheme and for which purpose the Experimental Fish Farm at “Shagarra” was established in 1953. This farm was meant to develop the technological know-how for the development of fish culture in the country but the lack of trained personnel and expertise in the field and inadequate planning have been major impediments to this end. Fish culture in Sudan is, therefore, still in its infancy.

It is recommended that the development of fish culture in the country, including training and extension, proceed through a well planned and long term experimental field project to be implemented with international or bilateral assistance.

Résumé

Le Soudan, qui couvre une superficie de 2,5 millions de km², possède 480 km de côtes et plus de 6 400 km de cours d'eau dont la surface est estimée à 2 millions d'hectares. Dans la région de Sudd, à hauteur de la latitude 5–9° N le long du Nil blanc (Bahr el Gebel), se trouve une zone d'une centaine de milliers de kilomètres carrés constituée de marais aussi bien permanents que temporaires.

En dehors des cours d'eau, le pays dispose d'étangs, de “haffirs”, de réservoirs et de canaux d'irrigation dont la capacité en eau varie entre quelques milliers et quelques millions de mètres cubes, et la profondeur entre 1 et 20 m. Dans le périmètre de Gezira, le réseau de canaux a une longueur de 5 649 km et une profondeur comprise entre 0,50 et 0,75 m; d'autres systèmes de canaux peuvent être cités: Managil Extension, Guneid Sugar Estate et Kashm El Girba Project. Dans la région de Sudd, les marais de la plaine d'inondation du fleuve représentent une zone très productive pour la reproduction et l'élevage des poissons. La productivité des réservoirs (0,5–9,0 m de profondeur) de cette zone peut atteindre 100 à 110 kg/ha, alors que celle des cours d'eau pourrait être de 30 kg/ha au maximum, comme tel est le cas dans les 120 000 ha du périmètre de pêche du barrage de Jebel Aulia. De plus, les eaux intérieures du Soudan, à l'exception des canaux de Gezira dans une certaine mesure, ne sont absolument pas polluées.

En dépit de ces immenses ressources en eaux intérieures, les protéines animales sous forme de poisson sont hors d'atteinte des agriculteurs et des communautés rurales du Soudan occidental, de la province de Kassala et même de Gezira, île située entre le Nil bleu et le Nil blanc; dans la province d'Equatoria, on observe une pénurie chronique de viande du fait des ravages exercés par la mouche tsé-tsé, en particulier dans la région de Zandi. Des situations analogues se rencontrent dans d'autres zones éloignées des principales pêcheries.

Toutes les enquêtes effectuées au Soudan recommandent la pisciculture non seulement comme solution au problème aigu de la malnutrition, mais encore comme mesure compensatoire dans les marais mis en valeur au titre du programme Jonglei pour lequel l'exploitation piscicole expérimentale de “Shagarra” a été créée en 1953. Cette exploitation devait permettre d'élargir les connaissances technologiques nécessaires pour le développement de la pisciculture dans le pays, mais le manque de personnel qualifié et de compétences spécialisées ainsi qu'une mauvaise planification ont été les principaux obstacles à la réalisation de ce but. La pisciculture soudanaise en est donc toujours à un stade embryonnaire.

L'auteur recommande que le développement de la pisciculture nationale, et notamment de la formation et de la vulgarisation en la matière, fasse l'objet d'un projet de terrain expérimental, bien planifié et à long terme, qui serait mis en oeuvre grâce à une assistance internationale ou bilatérale.

1. INTRODUCTION

The Sudan (Fig. 1) lies within the tropics, between latitudes 23° and 3° North and longitudes 22° and 39° East. It is the largest country in Africa with an area of 2.5 million km². This vast plain is isolated on the north by desert through which the Nile flows, and on the east by the elevated tract bordering the Red Sea. It has predominantly tropical continental climate, but the Red Sea gives its coastal plain and the eastern slopes of the hills therein a maritime characteristic.

The fisheries resources of Sudan include both inland and marine fisheries. The Red Sea, with a coastline of approximately 480 km, forms the marine fisheries resources. The inland fisheries resources, on the other hand, are centred in the White Nile, the Blue Nile, the main River Nile and their tributaries; also there are several big lakes formed by the construction of dams. There are 6 500 km of river waters covering an estimated 2 million ha, to which must be added 100 000 km² swamp area.

Besides the river water resources, there are the waters of the irrigation canals of the Gezira Scheme, Managil Extension and Guneid Sugar Estate, ponds, “haffirs” and reservoirs. The extent of these waters, as will be discussed later in detail, is enormous and will increase by several million acres the area of cultivable inland waters. It must be emphasized that these inland waters are practically free from pollution with domestic, industrial and agricultural wastes; the only site where occasional pollution and hence fish mortality takes place, due to aerial spraying with pesticides and molluscicides, is in some irrigation canals of the Gezira Scheme. Together with the swamps of the Sudd Region, these cultivable waters provide an opportunity for the development of fish farming. Sandon (1951) stated that “the adoption of modern fish farming methods to the conditions of this country has been advocated on a number of occasions by specialists such as Bertram, Worthington and Hickling and I know of no factor likely to invalidate their conclusion that this is a most promising line of development”.

Fish farming is a recent development in Sudan; proper extension of fish culture practices has been greatly hampered and the area utilized remains very small when compared to the available cultivable inland waters. This is mainly due to lack of trained personnel and consequently insufficient knowledge of the basic technical aspects of the field and inadequate planning for its development.

Fish was not much used for food in Sudan (Pekkola, 1918). However, at present, there is a great demand for it and the Government should make concerted efforts to develop fish culture on a large scale as a source of animal protein. The value of growing fish in ponds is obvious since this will serve as a direct contribution to the food of the rural population without involving problems attendant on large-scale production.

In Sudan, there is only one Experimental Fish Farm, at Shagarra (Gordon's Tree), and the object of this paper, therefore, is to review the history of this farm, the work undertaken to date and discuss the potential for fish culture and some broad guidelines which might be followed in its development through international or bilateral assistance. The need for an experimental project extending to not less than seven years is discussed.

2. HISTORICAL BACKGROUND

2.1 Development of fish culture

Initiation of fish farming was recommended as early as 1950 in connexion with the development of the Jonglei Canal Scheme. At that time, it was suggested that two or three experimental fish ponds of ½ ac (0.2 ha) each be attached to the Jonglei Experimental Pump Scheme south of Malakal and a larger experimental fish farm be constructed on part of the swamp land on the river bank opposite Malakal.

The Fisheries Standing Committee (FSC) during its sixth meeting in October 1950, agreed to recommend this scheme for endorsement by Dr. C.F. Hickling, the Colonial Office Advisor on Fisheries. In 1951 Dr. Hickling drafted a five-point plan for the development of fisheries and proposed, in connexion with fish farming, that a total area of 100 feddans (42 ha) be set aside for pond development to allow for expansion should experiments prove successful. He also proposed the construction of eight 4-ac (1.6-ha) ponds instead of fourteen small ponds recommended earlier. He emphasized very strongly “the need for keeping research and development quite separate; research work should be reported direct to the Fisheries Committee which should also lay down a programme of research work”. According to him “the purpose of the experimental farm was to establish the feasibility of the method, to investigate the cropping potentialities, to demonstrate that method and to evolve any necessary modifications for local conditions. If successful, the experiments would point the way for wider fish culture practice which was particularly suitable for agriculturally marginal lands and might even eventually be introduced into agricultural rotations”.

The FSC decided to establish the first experimental fish farm at Gordon's Tree (now Shagarra). The decision was based on the availability of land and buildings (abandoned BOAC flying-boat service base) and possible technical support from nearby Gordon College. In addition, it was pointed out that fish farming prospects were best in the northern part of the country where aquaculture might take its place in a general, mixed agricultural economy and provide a valuable variation in diet.

2.2 Experimental Fish Farm at Shagarra (Gordon's Tree) and the fisheries

The first Fish Farm Demonstration Scheme 220 was set up at Shagarra, six miles south of Khartoum on the White Nile, as one of the schemes of the Sudan Government's Five-Years Development Budget Plan, 1951–1956, “to study problems regarding fish culture in the Sudan and investigate its application to authochthonus and also, perhaps to other species” (Anon., 1955).

The work on the construction of the eight 4-ac (1.6-ha) ponds (each 124 × 121 m) was undertaken by the Public Works Department and took about 2½ years to be completed. The ponds are fed by water pumped from the White Nile and are disposed by fours, one series on each side of a central feeding canal. The inlet is placed in one corner of each pond and the outlet on the opposite corner. A Hydrobiological Research Unit was also set up in the Zoology Department, University College of Khartoum, to undertake scientific investigations into the biology of the Nile with a special reference to inland fisheries (Hamerton, 1964).

At the end of the 1951–1956 Development Budget Plan it was recommended to terminate the Fish Farm Demonstration Scheme and to continue the organization of inland fisheries research in a new Development Budget Scheme, called “Inland Fisheries Research Institute” (Hofstede, 1956–1957). This is because the research carried out by the University was almost of the pure scientific kind only and it was decided that the Government should pay more attention to applied scientific research aimed at execution of investigations with the purpose of early implementation of findings for the promotion and/or extension of fisheries production. Thus the original Fish Farm Demonstration Scheme was transferred into a new five-years plan (commenced on 1 July 1957), called the “Inland Fisheries Research Institute” (now the Fisheries and Hydrobiological Research Section) with a budget of £.Sd. 115 000¹. This Institute aims at the execution of fisheries research in natural waters and in ponds and also the demonstration of pond culture practices suitable for conditions in the Sudan (Anon., 1958).

Since 1956, the Experimental Fish Farm has been modified and expanded; at present (Fig. 2) it has a total area of 60 ha (141.3 feddans) comprising the following earthen ponds:

1. Spawning ponds : 4 ponds, each 15 × 8 m

2. Nursery ponds : 12 ponds, each 10 × 4 m (total area of about ½ ha)

3. Rearing ponds : 6 ponds, each 25 × 12 m (total area 1 ha) 8 ponds, each 55 × 27.5 m (total area 1.6 ha)

4. Growing ponds : 7 ponds, each 124 × 121 m (total area 11.4 ha).

The farm is now managed by two scientists (Diploma in Fisheries Science; M.Sc. in Fish Culture), one technologist (Matriculation level), four fishermen and five labourers. A small laboratory provided with the necessary equipment for biological and limnological studies, an office and a store room complete the existing facilities of this experimental farm.

3. SPECIES OF FISH CULTURED

3.1 Indigenous

There are over 200 species of fish in the Nile System (Pekkola, 1918) and of these, there are three species in Sudan which belong to the genus Tilapia (local name - Bulti): T. nilotica, T. galilaea and T. zillii; T. nilotica are highly desirable for use in fish culture. Other suitable species include Lates niloticus (Ijel), Labeo niloticus (Dabs) and Clarias vulgaris (Quarmont).

3.2 Exotic

Until 1974 no exotic fish had been introduced into the Experimental Fish Farm at Shagarra. However, Cambusia affinis (local name - Samak Al Namous) was introduced to Northern Sudan as a larvivore from Italy through Egypt in 1929. Testing of this species as a larvivore was begun only in May 1972 in four minor canals of the Gezira Scheme (Mahmoud, 1973); no comparative studies in relation to the indigenous species were ever made.

¹ U.S.$ 1 = £.Sd. 0.35

The introduction of the weed-eating Tilapia melanopleura into the canals of the Gezira Scheme was recommended (Worthington, 1950) so that the control of weeds and therefore the control of bilharzia by fish might be combined with fish production. On the whole, the results were disappointing. Factors which reduce the value of T. melanopleura are:

1. recent work in Uganda suggests that this fish can feed largely on diatoms and need not eat flowering plants;

2. it does not eat Potamogeton nodosus;

3. breeding and introducing the fish is no simple matter;

4. many fish are necessary to destroy weeds, and, as mentioned, they cannot destroy a thick growth and are reduced by predators;

5. the fish are not likely to eat much weed till they are 10 cm long.

Again, Huet (1959) on a fish culture mission to Sudan, proposed the introduction of T. melanopleura to be associated with T. nilotica to give an additional production. But all Tilapia species suffer from the disadvantage that they breed too freely, and a pond will soon be overcrowded, causing ‘runting’ of the fish (Prowse, 1961). In fact, the need for pond-breeding and fast-growing species other than tilapia was felt and George (1970, 1973, 1974) suggested the introduction of the common carp, Cyprinus carpio (local name - Karb Aadi). In May 1973 a consignment of C. carpio fingerlings (400) was introduced but unfortunately the fish were erradicated after six months on the basis of illegal introduction and for fear of creating some environmental problems. However, in accordance with a request from the Government of Sudan for advice to develop fish culture on a commercial scale in irrigation schemes where land is not suitable for agriculture, an expert deputed by the Arab Organization for Agricultural Development of the Arab League of Nations recommended in his report the introduction of the common carp, C. carpio, on a commercial scale (Al-Kholi, 1974).

For increasing the production of Tilapia species or C. carpio, pond fertilization and artificial feeding are necessary. “But there can be no question of increasing fish production in the ‘haffirs’ by fertilization or artificial feeding since water is intended to be supplied for drinking purpose and therefore must be kept free from taint” (Huet, 1959). With a view to finding a suitable alternative for stocking the ‘haffirs’ in Western Sudan and possibly the control of weeds in the Gezira canals and therefore bilharzia, George (1973, 1974) also recommended the introduction of the phytophagous Chinese grass carp, Ctenopharyngodon idella (local name - Karb Al Hashaesh) because it feeds on weeds which can easily be supplied and will thus convert this food into fish flesh without artificial feeding or fertilization; besides the ‘haffirs’ will be cleared from any aquatic macro-vegetation which otherwise remain mostly unutilized and may create weed problem. Furthermore, the stocking rate of grass carp can be controlled since it is incapable of reproducing in confined waters without hypophysation.

Since then, necessary steps have been taken to introduce the grass carp and common carp (var. communis) from India and the common carp (var. specularis) from Arab Republic of Egypt. On 1 January 1975 the Government of India presented to the Government of Sudan a gift consignment of 10 000 common/grass carp (SUNA, 1975) and George (1975, in preparation) acclimatized these exotic species to Sudanese pond waters.

4. EXPERIMENTAL WORK AND EXTENSION SERVICE

4.1 Early work undertaken (1954–1962)

The most important data on Tilapia nilotica culture and observations regarding other species can be summarized from reports by Hofstede (1955–1956, 1958) and Huet (1959).

4.1.1 Tilapia nilotica culture

Production tests with T. nilotica were mostly based on natural pond productivity; fish were not fed and ponds received no fertilization. Under these conditions it was difficult to produce marketable fish (23–25 cm in length) even in two years. It has been observed that a 5 cm long T. nilotica will reach 18–20 cm in 12 months and 25 cm in 18–24 months. In the presence of Lates niloticus, T. nilotica shows good growth: 22–23 cm in 10–11 months. Yearly yields of 250–500 kg/ha have been seldom reached and Hofstede mentioned one of the best yields to be 165 kg/ha/year during 1956–57 (394 kg in 18 months for 4 ac). Good results were obtained by stocking 4 ac with 500 tilapia of 17–18 cm and 1 300 tilapia of 11 cm.

From April to September, females breed 3–4 times in nests on the bottom at a depth of at least 75 cm when they are about 15 cm in length (perhaps 13 cm in overcrowded waters) and, according to their size, would give 400–1 000 eggs. The spawning season coincides with that in the White Nile near Gordon's Tree. After spawning, females grow more slowly than males.

4.1.2 Observations regarding other species

The species, let in with pumped waters when still fingerlings are, in order of predominance, the Alestes species, the Labeo sp., Lates niloticus, Hydrocyon sp., Synodontis sp., Auchenoglanis sp., Tetradon sp., Citharinus sp., and Distichodus sp.:

(a) Alestes species

Alestes species enter the ponds mainly about May/June. A. baremose is the most numerous and in most cases, accompanied by a few A. dentex. In some instances A. nurse forms the big majority. The peak invasion period in the ponds is around June. A. baremose and A. dentex reach a length of 18 cm in the first year, and around 28 cm in the second year; A. nurse about 13 cm in the first year and 18 cm in the second year. A. baremose and A. dentex reach their first sexual maturity towards the end of the second year at a length of 25–30 cm; A. nurse matures at the end of the first year when 12–15 cm in length. During sexual maturity, the sex can be distinguished externally by prolonged central rays in the anal fin. In the immature fish, gonads can hardly be seen, but in the mature condition, the testes are whitish, hose-like and the ovaries flattened, reddish-yellow and rather transparent. Females grow to substantially larger size than males during the same period.

(b) Labeo species

Labeo species enter the ponds around July and grow to a size of about 35 cm in one year when they are 350–400 g; growth is retarded after an average length of 35 cm and also during winter months. They reach spawning maturity at a length of around 35 cm; whether or not they spawn in the ponds could not be established but, in any case, the females were found full of eggs and the males delivered milt during the months May/June. It seems that females grow to slightly larger sizes than males.

Hofstede considered Labeo sp. a very suitable fish for pond culture and mentioned that “if the Sudanese appreciate it as a consumption fish, it is recommendable to start investigations with the culture of these species”.

(c) Lates niloticus

This species enters the ponds from the Nile almost throughout the whole year but mainly between March and September, with a peak in August. This fish is delicate, does not stand manipulation too well but gives satisfactory growth in ponds: 42 cm, 50 cm and 58 cm in six, nine and twelve months respectively. No reproduction has been obtained in ponds but males larger than 30 cm were found ripe whilst almost all females were immature. By dissecting immature Lates niloticus sex could be determined: the smaller posterior portion of the thin thread-like gonad is white in males and yellowish-red in females.

(d) Hydrocyon species

All three species occur in ponds, H. forskalii, H. lineatus and H. brevis. They rarely occur in big numbers and hence fewer observations were made.

4.2 Recent work undertaken (1962–1974)

4.2.1 Tilapia nilotica culture

Research on artificial feeding and on the use of organic and inorganic fertilizers has been a recent approach. It was found that broad beans (Vicia faba L.) are suitable as an artificial food for T. nilotica (Bishai, 1962). With a combination of superphosphate and poultry manure, production increased and fish reached 32 cm in six months (George, 1969–1970 in press). Results of the beneficial use of these fertilizers were also reported by Mishrigi (1970–1972 in press): the final percentage increase per unit length was 250 percent in the pond treated with a mixture of poultry manure and superphosphate, followed by an increase of 235 percent and 230 percent in ponds treated with mixtures of blood plus superphosphate and blood plus poultry manure respectively. In monosex culture of T. nilotica, it was observed that the weight of males was threefold that of females and about four times that of mixed stocks (George, 1972).

Until recently, T. nilotica seed was collected from rivers. In this method, only fingerlings are caught in the siene net, besides the method is uneconomic and many fish die during transport. T. nilotica is a mouth brooder; and taking advantage of this fact many females were netted during the breeding season and fertilized eggs and larvae collected by inducing the females to spit out their mouth contents into a container with some water; about 625 and 900 larvae were collected from a 14 cm and 24 cm female respectively. The eggs were allowed to hatch in enamel trays in the laboratory and the hatchlings successfully reared in glass jars, a plastic pool and, on a commercial scale, in an out-door cement tank up to attainment of the fry stage, being fed on zooplankton supplied or raised in the environment itself by manuring (George, 1974, unpublished). The objective of these experiments is to develop nursery pond management techniques as no attention was ever paid to growing spawn in nurseries before stocking them in larger ponds; the traditional fish culture practice lacked a scientific background and consisted of fishing fingerlings from the Jebel Aulia Dam, putting them in a pond and finally reaping a poor harvest at the end of a few months. Besides, observations were made on the destruction of T. nilotica fry by fish enemies, insects and their larvae, frogs and aquatic birds (George, 1974, unpublished).

Additional experimentation is under way. Mishrigi (1974–1975) is carrying out experiments to increase productivity through the use of the fertilizers already proved to be effective, avoiding the effect of intensive breeding habits by population thinning (removal of fertilized eggs and hatchlings and seining of fingerlings) and through feeding with cotton-seed cake. This experiment is carried out with the following objectives: (a) to confirm the results of increasing productivity by using a mixture of poultry manure and superphosphate fertilizers, (b) to achieve higher productivity for longer periods than had been achieved previously and (c) to further increase productivity by applying an artificial feed like cotton-seed cake. After evaluating the final results of this experiment, work on the same lines will be continued to include new factors such as thinning of parent fishes in order to give a chance for their fingerlings to grow; the reason being that the increment increase in weight is well marked in the fry stage up to about 280 g (6 months) after which growth more or less levels off.

Experiments on the use of local brewery wastes as an artificial feed for T. nilotica and on the transport of fry in polythene bags under pressurized oxygen will be continued; also experiments on pond fertilization with superphosphate and poultry manure at various levels to demonstrate the over-fertilization effect and thus standardize the technique will be initiated.

4.2.2 Observations regarding other species

Hofstede (1958) tried to breed Labeo species and found that they reach spawning maturity at a length of around 35 cm (males delivering milt with pressure on the belly, females full of eggs) but whether or not they actually spawn in ponds was not determined. According to him “certain artificial tricks may be needed”. Accordingly an experiment was initiated in a 4-ac pond where aquatic macro-vegetation (Typha augustifolia) was growing intensively at one corner. This pond was stocked with fingerlings of Labeo niloticus brought from Jebel Aulia Dam; Mishrigi (1971) later established the fact of L. niloticus breeding for the first time in a Sudanese pond.

Rearing experiments of 2–5 cm Lates niloticus in 5-l glass aquaria showed that a 4.5 cm L. niloticus, weighing 0.9 g increased to 5.8 cm and weighed 2.5 g during a period of 17 days when fed on 60 hatchlings of T. nilotica per day; when fed on a similar number per day of a small aquatic insect, it increased from 5.8 cm to 6.5 cm in length and from 2.5 g to 3 g only in weight within a period of 35 days (George, 1974, unpublished).

Comparative studies on the exotic mosquito fish, Gambusia affinis and T. nilotica as larvivores are in progress (George, 1974–1975 under experimentation). More work regarding the acclimatization and compatibility of the other exotic species, C. carpio and C. idella, introduced in January 1975 will be undertaken. The experimental work on these species will be highly restricted to the ponds of the Fish Farm at Shagarra. This is because great caution should be taken in regard to the introduction of exotic species for cultural purposes since they might upset the biological balance of the indigenous fisheries on chance entry into the Nile. Later on, the results of successful experiments will be implemented in the field, mainly in the ‘haffirs’, and artificial ponds, far away from the river systems and the Nile and thus develop the supply of fish in these regions.

In this connexion, a Fish Culture Research Camp for Training and Production was set up at Shagarra during January 1975 to make closer studies of these exotic species.

4.3 Extension service

In November 1957 El Ain Reservoir, 30 km from El Obeid and with an area of 10 ha, was stocked with a number of 15-cm Tilapia nilotica. In 1959, Golo and Mellit Reservoirs, 10 km and 60 km from El Fasher and 5 and 20–30 ha in area respectively, were stocked with 12–15-cm T. nilotica. In the Zandi Region where heavy rains prevail during the greatest part of the year and due to favourable topographic conditions and natural springs, many barrage ponds were constructed (El Ahmadi, 1956–1960, in official records). George (1969, in official records) made a survey of Miri Bara Dam (water capacity 4 221 500 m³) and recommended polyculture, e.g., T. nilotica, Labeo niloticus, etc. Besides, the construction of a number of ponds was encouraged in 15 private farms intended for mixed farming and situated mainly in the vicinity of Khartoum Province, Hasa-Heisa and Wad Medani.

The extension service, now under the Fisheries and Hydrobiological Administration Section, selects the site for ponds, provides construction specifications and free T. nilotica fingerlings for stocking. During 1974, nursery, rearing and growing ponds were constructed in Baboud's farm. All ponds so far constructed by the extension service are big growing ponds; construction of additional nursery, rearing and growing ponds should be encouraged in future by the extension service for cultivation of T. nilotica and other exotic species (C. carpio and C. idella) after the basic studies are made.

There is inadequate information about the status of fish culture in the reservoirs and private farms and the bottle-neck is shortage of trained and experienced officers; extension service cannot successfully cope with all matters that come up. More accurate information and statistical data must be provided to the researchers for planning future research programmes, the results of which must be implemented by the extension service. More association and cooperation are needed between research extension services.

5. DISCUSSION

In order to increase the availability of protein-rich food, a clear-cut strategy for the development of inland fishery resources is required with special emphasis on raising fish under controlled conditions. There is considerable scope, in Sudan, for development of large-scale fish culture in inland waters, which, unlike in many parts of the world, are still free from pollution. Therefore, fish culture practices should be perfected and popularized. This is best achieved by initiating an experimental project for large-scale fish farming in Sudan through international and/or bilateral assistance; outside assistance is required due to shortage of technical man-power. The duration of this project should not be less than seven years. The objectives, justification for and methodology of such a project are discussed hereinafter.

5.1 Objectives and justification

It was stated (Anon., 1955) that “piscicultural practices, although they are not a matter of particular urgency at present will be of great value in future, particularly with regard to the supply of protein in the Sudd Region when it has been reclaimed”. Also it was stated (Anon., 1958) that “in a country such as the Sudan, which has great resources of both meat and fish (from natural waters), introduction of fish culture in ponds is no urgent matter. This may be expected to become important in future and therefore some research is important but not with the purpose of immediate application. Of far greater importance is management of natural waters”. However, in my opinion, there is great urgency at present to develop fish culture in Sudan as a source of animal protein for the under-privileged communities in Western Sudan (Kordofan and Darfur), for the farmers and poor rural communities of the Gezira Scheme, Blue Nile Province, Kassala Province and the Provinces of the Upper Nile and Equatoria in the Southern Region.

Animal protein is dangerously lacking in the every-day diet of much of the population, shown in Table I, and the disturbing feature of the situation is the slow tempo of economic development. Protein deficiency is responsible for a great deal of ill-health, poor growth, muscular and bone weakness and an increased susceptibility to many diseases. A solution to this acute problem is of such vital importance to the health and stability of the community that every conceivable effort must be made to solve it.

TABLE I
Population in the Provinces where fish culture should develop

¹ In 1974 each of Kordofan and Darfur Provinces was divided into two new Provinces, while the Blue Nile Province into three

Western Sudan is far removed from the country's great river systems and the main River Nile, hence remote from large wild fisheries. The whole population depend for their drinking on rainwater stored mainly in the ‘haffirs’ or reservoirs (Fig. 3) formed by dams constructed across seasonal streams. The ‘haffirs’ and reservoirs in Kordofan Province (now North and South Kordofan Provinces) up to 1974 total 335 in number with another 123 in Darfur Province (now North and South Darfur Provinces). The depth of water in the ‘haffirs’ ranges from 1.5 m in North Kordofan to 5 m in South Kordofan and between 2 m and 3 m in North and South Darfur Provinces. In Kassala Province, Eastern Sudan, the total number of ‘haffirs’ and reservoirs amount to 125 (Fig. 1.) and the water depth ranges between 6 m and 9 m. Most of these ‘haffirs’ dry up towards the end of the summer season; the perennial ‘haffirs’ and reservoirs are given in Tables II and III.

TABLE II
Perennial ‘haffirs’ in the Provinces of Kordofan (North and South) and the Blue Nile (Gezira, White Nile and Blue Nile)

TABLE III
Perennial ‘haffirs’ in the Provinces of Darfur (North and South) and Kassala

In the Gezira Scheme, the canalization network consists of the following:

1. the main canal and branch canals with a total length of 341 km;

2. major distributories with a total length of 680 km;

3. minor distributories (Fig. 4) with a total length of 3 670 km;

4. escapes with a total length of 38 km;

5. surface water drain with a total length of 916 km.

Thus the total length of canals is 5 649 km or about 3 530 mi, the canals ranging from 8 m to more than 20 m in width and 0.50 m to 0.75 m in depth (Anon., 1955). Besides, there are the canalization networks of the Managil Extension and Guneid Sugar Estate and 171 ‘haffirs’ in the Blue Nile Province (now divided into Gezira, White Nile and Blue Nile).

In the Upper Nile Province there are 78 ‘haffirs’. North of Malakal, there are small-sized reservoirs excavated in a flat area and measuring 75 × 40 m with a depth of 15–20 m. These reservoirs are fed by rainwater but communicate through a channel with a dead arm of the Nile (Huet, 1959) during the flooding season.

In the Sudd Region, at latitude 5–9° N along the White Nile (Bahr el Gebel) and tributaries, there are about 100 000 km² of permanent and temporary swamps. Due to the river rise and inundation of these swamps and the marshland along its flooding plain, a vast and highly productive breeding and growing area is made available for a great variety of fish. Worthington (1950) stated that “the system as a whole may be compared to a gigantic fish farm. The inundated swamps are comparable to “Growing Ponds”, which are filled and stocked each year. After the growing period, these ponds are drained and the crop is taken as the fish become concentrated. The permanent water of the rivers and Khors is comparable to “Stock Ponds” which supply the fish for annually stocking the “Growing Ponds””.

In Equatoria Province there are artificial ponds, private and Governmental, and dams distributed in several localities: Yei, Maridi, Yambio, Nzara, Ezo and Li-Yu-Bu. “The Haggar ponds at Ywatoca include 3 small dam-ponds which are small barrage ponds, stretched out (50–100 m) and extending approximately over 10, 15 and 8 ac with maximum depth of 1.50 m. At Maridi there is a dam 4 m high, damming the water which covers some 10 ha and a small dampond of some 10 ac (4 ha). At Nzara there are 2 dam ponds set in succession, rectangular in shape, covering respectively about 80 and 120 m. Around Yambio there is a small pond at Nisikisa of about 150 × 15 m covering 7–8 ac (2.8–3.2 ha) and another small barrage-pond at Sagana of 25 × 60 m covering some 7 or 8 ac. At Ezo there is a dam-pond 40 × 80 × 10 m covering some 40 ac. At Li-Yu-Bu there is a dam-pond 80 × 20 × 40 m covering some 25 ac” (Huet, 1959).

In spite of these vast culture inland resources, animal protein in the form of fish is beyond the reach of the farmers and rural communities in Western Sudan, Kassala Province and even in the Gezira which is an island between the Blue and White Niles. Large-scale fish farming would certainly be a solution to this problem. In the Gezira, fish farming would also solve other problems such as the control of the serious growth of weeds in the canals, which, besides harbouring the snail vector of bilharzia, entail heavy expenditure each year for their removal. In this connexion, Worthington (1950) stated “it seems possible, therefore that the weed problem in the Gezira canals (and perhaps also the bilharzia problem) might be reduced and high supplies from the canals increased by establishing a carefully-adjusted and controlled system of fish stocking and fish cropping in which a weed-eating species (e.g., Tilapia melanopleura) would play an important part”.

With respect to Equatoria Province, there is a chronic shortage of meat due to the ravages of the tsetse fly particularly in the Zandi Region (FAO, 1973). Namoura (1963) mentioned that “special Districts of Equatoria Province which are southern part from the lines conjunctioned at the following places: Nzara, Maridi, Amadi and Juba, are difficult to obtain protein from the meat of animals because of difficulties of breeding such animals for the sake of sleeping sickness and in consequence of this, the people living in these parts should take protein from fish. As there are no big fishing areas besides around Juba as Bahr el Jebel and some lakes, the fish farming as well as fishing on tributaries should be encouraged particularly”. Also Bishai (1963) mentioned “the diet of the people in Equatoria Province, Sudan, like that of many other tropical peoples is lacking in protein, particularly animal protein. It is unlikely that meat production can be improved sufficiently to remedy this. Fish farming is one of the most effective ways of increasing the supply of animal protein in the diet, and inland fisheries are important in the economic and community life of the Western Equatoria Province”. According to Huet (1959), “the Nisikisa and Li-Yu-Bu dam-ponds can be taken as a type of rural community ponds”.

In the Sudd Region fish culture on a large-scale would be essential as a compensatory measure in the reclaimed marshes under the Jonglei Scheme or the Equatorial Nile Project. Hickling (1950 in official records) pointed out that “the proposed works for regulating the Nile under the Jonglei Scheme will completely change the regime of large parts of the Sudd, thus fundamentally altering the nature of the fisheries and probably the supply of fishes”. The Jonglei Report (1948–53) mentioned that “it is manifest that in those reaches where the present area of the flooded plain will be partly or totally deprived of spill-water from the river, the fish will remain confined to the perennial channels and a big reduction in numbers will be inevitable; the seasonal migration of fish into these flooded areas is a distinct characteristic of their life-cycle. Apart from reductions in the fish population, other adverse effects on fisheries may be expected. The amount of fish available for the population will decrease substantially unless more modern fishing techniques are employed because under the present circumstances fishing methods are rudimentary and generally only effective in shallow water where the fish are comparatively concentrated”. The Soviet Nile Expedition (1964) also stated that “the water supply of many lakes situated on the flood-lands will be so reduced by the Jonglei Canal Scheme that they will lose their significance as fishing areas”.

In fact, fish plays an important part in the diet of the population of the Sudd Region at certain times of the year and the high prices for sun-dried salted fish have led to the rapid development of commercial fisheries in the area. The Monythany Dinka of Bor District rely entirely on fishing for their livelihood. The Shulluk are the most skilled and enterprising fishermen. However, three main sets of people will be affected by the altered hydological regime under the Equatorial Nile Project:

1. the Madi, Bari and Mandori tribes of Equatoria Province - about 60 000 will be directly affected;

2. the majority of the Nilotic tribes: Dinka, Nuer and Shulluk - about 480 000 will be directly affected and 400 000 indirectly;

3. the Pastoral (Baggara) Arabs and other Northern Sudanese lying between the boundaries of the Upper Nile Province and Kosti - 120 000 will be directly affected;

(Jonglei Report, 1948–53). However the case may be, whether the Jonglei Canal Scheme is executed by the Government of Sudan or not, in my opinion, it is essential that fish culture practice be popularized in areas requiring additional protein and in suitable areas within the Jonglei area.

From the foregoing detail account it becomes clear that the urgency for providing protein-rich food to the undernourished population and also to those who will be affected by the diversion of the White Nile through the Jonglei Cut cannot be denied. This fact drew the attention of the Government, around 1950, towards research and development of fisheries. Although T. nilotica was introduced in a number of ‘haffirs’ and ponds of the mentioned provinces, yet a great deal has to be achieved. A systematic cultivation of quick-growing species of fish - indigenous and exotic - in these extensive, widely-distributed, non-polluted inland waters will be one good way of ensuring an adequate supply of a cheap, protein-rich food which is sorely lacking in the diet of our people. Therefore, proper application of the results achieved in applied research undertaken in an experimental fish culture project, as is proposed now, will no doubt contribute to considerable enhancement of fish production in the localities already referred to and will improve the physiological, social and economic well-being of many of our people who are now suffering from hunger and malnutrition.

5.2 Methodology

The development of fish culture in Sudan requires integrated research activity. This necessitates the availability of research centres and laboratories for the utilization of modern research methods and for the perfection of techniques of exploitation. A more important factor is technical manpower: the scientiests and technicians whose joint activities will be needed to build up the industry.

With this objective in view, the existing Experimental Fish Farm at Shagarra should be devoted entirely to experimental work and should form the nucleus for establishing other similar farms at Lake Nubia, El Obeid and Malakal. Sub-stations or demonstration units for extension service should be located at strategic areas after an exhaustive survey of fish farming possibilities in various parts of the country is made to provide a more complete picture. These sub-stations are to meet local demands and to test results obtained elsewhere under different conditions of soil, climate, water, etc.

The Experimental Fish Farm at Shagarra needs substantial extension of facilities and equipment. For example, a hatchery comprising glass jars with running water supply should first be established. Furthermore, building up adequate cadres of well-trained personnel has to be undertaken to develop the following sections: pond culture, fish breeding, exotic fish culture, limnology and fish farm engineering. Besides, much work in fish culture research should be undertaken. A break-through should be achieved in the development of nursery and rearing pond management techniques to raise fry. Investigations should be taken up to increase the efficiency of fish culture by applying to the pond microcosm the science of ecology, manuring with organic and inorganic fertilizers as well as artificial feeding of fish. Some indigenous species such as L. niloticus do not readily breed in confined waters. With a view to circumventing this difficulty, work on artificial breeding of such fish in confined waters should be taken up. Success of induced breeding will open up a new phase in the development of aquaculture since selective breeding and hybridization of fishes will make it possible to produce hybrids. From recent work it is known that monesex culture of tilapias improves production but sexing is a very tedious task for stocking large ponds. A practical method through hybridization should be secured to produce a monosex culture without the tedium of sexing. Also equilibrium tests between mixed populations of Tilapia and Lates should be made.

It has been claimed that fish culture could not be practised in the irrigation canals of the Gezira Scheme because the application of molluscicides to eradicate the intermediate snail host, Bulinus truncatus (Audouim) and Biompholoria pfeifferi (Krauss), of S. mansoni and S. heamatobium, would cause fish mortality. Actually fish mortality in the Gezira canals is not caused only by molluscicides, because the author during recent short surveys (August-September 1974) eye-witnessed large numbers of dead Tilapia nilotica (Fig. 5) immediately after an aerial spray of cotton with pesticides (both Chlorinated Hydrocarbon and organophosphorous groups) usually carried out several times a year between September and February. Also, this may partly be due to the chemicals used in anti-malaria measures. A proper survey for determining water characteristics during an entire year should, therefore, be undertaken in the Gezira canals.

A practical technique for the application of biological control against snail hosts of schistosomes should be found: the fruits, seeds and leaves of some indigenous plants have been observed to have molluscicidal properties (Abdel Nabi, 1966). There are many predators of bilharzia vector snails, e.g., fish, ducks, insect (particularly Sciomyzid) larvae, leeches and predator snails (Hunter, 1968). Mahdi and Amin (1966) in an attempt to control bilharzia by fish, suggested that “field work should be carried out to confirm the ability of Protopterus aethiopicus to eat snails infected with bilharziasis”. But perhaps, “Schistosomes could be controlled by introducing edible weed-eating fish, such as T. zillii, thereby eliminate the breeding ground of infected snail” (Prowse, 1964). Lewis (1953 in official records) introduced Tilapia melanopleura in the Gezira canals for serving this purpose but the results were disappointing; also T. zillii is not better than T. melanopleura in this respect. However, the Chinese grass carp, C. idella, may prove better than both species of tilapia because it is an efficient weed-eater. In any case, the introduction of any exotic species into these irrigation canals should be carried out with great care so as to ensure the fish do not find their way into the natural waters of the Nile. Research on Gambusia affinis in comparison to other local species such as T. nilotica and the annual fishes of the genera Epiplatys and Aplocheilackthys as effective larvivores should be undertaken (George, 1974, unpublished). With respect to the exotic species already introduced, their culture could be practised in cages in case the minor canals are found to be connected with the Nile.

The potential for development of inland fisheries and fish culture in the Sudd Region has been pointed out. According to Prowse (1964) “huge swamps such as the papyrus ‘Sudd’ in Sudan and Uganda are obvious choices for fish culture, but considerably more research needs to be carried out on these swamps before they can be utilized to raise reasonable crops of fish due to the vast deposits of peat formed from the decaying vegetation under the anerobic conditions produced by bacterial action which may deplete the overlying water of oxygen”. However, “a scientific study of the fisheries resources of the Jonglei area is required of distribution, breeding habits and relative yields, before an attempt is made on the diversion of the White Nile through the Jonglei Cut” (Jonglei Report 1948–53). Intensive research should therefore be carried out, before and after the Jonglei Canal is completed, to develop fish culture in suitable sites within the Jonglei area.

Research should be carried out, at the Experimental Fish Farm at Shagarra, on the indigenous T. nilotica and other species (Lates niloticus, Labeo niloticus, Barbus bynni, Clarias angularis, etc.) as well as on the exotic species already introduced. In the other experimental farm, to be established at Lake Nubia, research should involve hatchery propagation to augment stocks of naturally occurring major commercial species and thus avoid the state of over-fishing or over-exploitation of the fishery resource in the near future (George, 1973); also it has been shown that if juvenile fish can be reared to a later stage before release they may alternately contribute significantly to fisheries (Bardach et al., 1972). This work would also throw much-needed light on the breeding habits of the important Nile fishes. Similarly, the other farms at El Obeid and Malakal will be the experimental centres for Western Sudan and the Southern Region respectively. The programmes and activities of the main fish farms should be synchronized.

As previously emphasized, the success of a large-scale fish farming project in Sudan will also depend to a large extent on the availability of trained personnel. Considerable technological know-how has to be developed. The lack of a Department of Fisheries within the Faculty of Science in the University of Khartoum necessitates overseas training of university graduates in this field. Extension service also involves the use of trained staff and the provision of adequate staff is most essential to ensure dissemination of the knowledge gained as a result of research conducted in the main experimental fish farms. A proper and comprehensive course in fish culture should be included in the curriculum of the local fisheries officers.

Fish culturists stationed at the proposed fish farms should be responsible for fish farming work and should be given adequate staff to carry out these duties. Administrative officers should be appointed to look after the routine administrative work at each farm.

The above review highlights the fact that the status of fish culture in Sudan is in its infancy but the potential for future development, within the framework of the proposed experimental project, is excellent. To start the proposed project on a sound basis, it is of paramout importance to recruit foreign experts in the various aspects of fish culture to:

1. prepare plans for experimental pond culture including studies on stocking rate, feeding, spawning, pond fertilization, disease control, etc., and to participate in this work,

2. establish and conduct training courses at the experimental station for counterpart personnel and fishermen and to arrange for the overseas training of university graduates in the various aspects of fish culture and

3. to assist in the formulation of a programme of Governmental services to promote and assist the adoption of fish culture practices and the development of the industry generally.

Under this project, emphasis should be laid on the field application of experimental results. It is advisable not to initiate commercial fish culture, particularly of exotic species, before first adapting known techniques to Sudan conditions (George, 1974, in press). In other words, laboratory research should provide the foundation for field application and support those modifications and improvements which operational practices may require. Long-term planning is needed and this necessitates careful consideration as to the guidelines along which development should be carried out.

6. ACKNOWLEDGEMENTS

I am deeply indebted to Dr. Hussein Idris, Minister of State for Agriculture, Food and Natural Resources for granting Government permission to introduce the exotic species, to Mr. A.A. Salaam, Director Surface Water, for providing the information on the ‘haffirs’ of Sudan, to Mr. A. Mubarak, Controller of Printing, Survey Department, for printing the maps and to Mr. A.A.J. Udo, Assistant Resident Representative, UNDP, Khartoum, for reading the manuscript.

7. REFERENCES

Abdel-Nabi, O., 1966 Control Measures against Bilharziasis in Sudan. Symposium on Schistosomiasis in Sudan. Al Hakeem, 111–71

Al-Kholi, A.R., 1974 Report on Fish Culture Project at Kukoo, Soba and Esilaat in the Democratic Republic of Sudan. (In Arabic) Arab Organization for Agricultural Development, Arab League of Nations

Bay, E.L., 1972 A preliminary assessment of the potentialities of larvivorousfishes for anopheles control in West Africa. WHO/UBC/72, 402

Bardach, J.E. et al., 1972 Aquaculture. The Farming Husbandry of Freshwater and Marine Organisms. Wiley-Inter-Science, A division of John Wiley and Sons, Inc.

Bishai, H.M., 1962 Experiments on the suitability of broad beans (Vicia faba L.) as diet for fish. Hydrobiologia, 20:31–9

Bishai, H.M., 1963 Fish Farming in Equatoria Province. University of Khartoum, Hydrobiological Research Unit Special Publication No. 1

El-Ahmadi, M.S.A., Monthly reports. 1956–60 (Unpublished)

FAO, 1963 The Basic Freedom - Freedom from Hunger. A selection of speeches made by B.R. Sen, Director-General of the Food and Agriculture Organization of the United Nations, on the Freedom from Hunger Campaign. Italy

FAO, 1973 Perspective study of agricultural development for the Democratic Republic of the Sudan. The Fisheries Sector. ESP/FIE/PS/SUD/73/11

George, T.T., Report on the possibilities of fish culture in Miri Bara Dam-Kordofan Province. (In Arabic) 1969 (Unpublished)

George, T.T., 1969–70 Observations on the growth of Tilapia nilotica L. in tropical freshwater fish ponds treated with different fertilizers. (In press)

George, T.T., A report on the Egyptian Fisheries with recommendations. (In Arabic) 1970 (Unpublished)

George, T.T., 1972 A note on the growth of Tilapia nilotica L. in monosex culture. Rep. C.I.F.E. Annual Day, Souvenir, Bombay

George, T.T., 1973 Preliminary Account of the Fish and Fisheries of Lake Nubia during 1967–1968. Journ.Ind.Fish.Assoc., 1(2):65–88

George, T.T., Report: Two-Years Scholarship (1971–1973) in India for the M.Sc. degree of the University of Bombay in Fish Culture. 1973 (Unpublished)

George, T.T., 1974 Carp Culture for Sudan Ponds and Reservoirs. Fish Farm. Inter., No.3

George, T.T., Rearing of Tilapia nilotica hatchlings under laboratory conditions and on a commercial scale. 1974 (Unpublished)

George, T.T., A note on the destruction of Tilapia nilotica fry by fish enemies in a tropical freshwater fish pond. 1974 (Unpublished)

George, T.T., 1974 Gambusia as an exotic larvivore fish in the Sudan. (In preparation)

George, T.T., 1974 A note on commercial fish culture in Sudan. (In press)

George, T.T., 1974 A note on the exotic species, C. carpio (L.) and C. idella (Val.) with particular reference to aquaculture in Sudan. (In press)

George, T.T., 1975 Acclimatisation of the common carp, Cyprinus carpio (var. communis), and the Chinese grass carp, Ctenopharyngodon idella, to Sudanese pond waters. (In preparation)

Grinko, E., N. Khatunzev and Y. Kopylov, 1964 Technical and Economic Report on the Expediency of Building a Fish Canning Factory in Sudan. (Soviet Nile Expedition)

Hamerton, D., 1964 Hydrobiological Research in the Sudan. Past, Present and Future. Rep.12th Annual Symposium

Hofstede, A.E., Annual Report. 1956–57 (Unpublished)

Hofstede, A.E., Final Report. 1958 (Unpublished)

Huet, M., 1959 Report on a Fish Culture Mission. Technical Assistance Mission to Sudan. Brussels

Hunter, P.J., 1968 Control of Bilharzia Transmitters in the Gezira Irrigation System. S.N. and R.Vol.49, Shorter Notes

Job, T.J., 1966 Status of Fish Culture in the Near East Region. FAO World Symposium on Warm-Water Pond Fish Culture. FR;1/RR-4

Mahdi, M.A. and M.A. Amin, 1966 An Attempt to Control Bilharziasis by Fish. Hydrobiologia, XXVIII 66–72

Mahmoud, A.A., 1973 Biological Control in the Gezira Irrigation Area through Gambusia Fish. (Unpublished)

Mishrigi, S.Y., 1971 Labeo niloticus in Sudanese Fish Pond. Rev.Zool.Bot.Afr., LXXX(IV):3–4

Mishrigi, S.Y., 1970–72 Observation on the effect of fertilizers on Sudanese fish ponds. (In press)

Motabar, M., 1973 Assignment Report. Malaria Control Programme, Sudan. WHO, EM/117 Sudan 2001/R

Namoura, M., Report on Sudanese Fisheries and its Technical Suggestions. 1963 (Unpublished)

Pekkola, W., 1918 Seasonal Occurrence and Edibility of Fish at Khartoum. 1918; Sudan Notes and Records, (1):88–98

Ponedelke, B.I. et al., Report of the Soviet Complex Expedition to the Republic of Sudan. Study of the Fish Resources of the White Nile. 1964 (Unpublished)

Prowse, G.A., 1961 More Food from Fish

Prowse, G.A., 1964 More Fish for the Hungry. Angler's Annual, 22–9

Rihan, M.H., Notes on Fish Farm at Gordon's Tree. 1954 (Unpublished)

Sandon, ?, 1951 Problems of Fisheries. Sudan Notes and Records, (32):5–36

SUNA, 1975 The Fisheries and Hydrobiological Research Section Introduces Carp Culture for Sudan Ponds and Reservoirs. SUNA-Daily Bulletin, Issue No.1431, 7

WHO, 1973 Conference on the Safety of Biological Agents for Arthropod Control. VBC/73.1

Worthington, E.B., Notes on the Sudan. Appendix I: Nimule Game Reserve. Appendix II: Fishery Research and Development in the Sudan Inland Waters. 1950 (Unpublished)

Anon., 1948 Note for the Fishery Committee. Board of Economics and Trade

Anon., 1949 Record of the second meeting of the Fishery Standing Committee of the Board of Economics and Trade at Khartoum

Anon., 1948–53 Report of the Jonglei Investigation Team. The Equatorial Nile Project and its Effects in the Anglo-Egyptian Sudan

Anon., 1951 Record of the sixth meeting of the Fishery Standing Committee of the Board of Economics and Trade

Anon., 1955 The Sudan Today. Social and Economic Progress. Ministry of Social Affairs, Sudan Government

Anon., 1958 Sudan Almanac. An Official Handbook. The Republic of Sudan, Khartoum

Anon., 1958 National FAO Committee Report to the Food and Agriculture Organization of the United Nations

Scale 1 : 8.000.000

Fig. 1. Map of Sudan.

Fig. 2. Aerial photograph of the Experimental Fish Farm at “Shagarra” (4-ac ponds and nursery).

Fig. 3. El Ain reservoir (1954), square-shaped of about 10 ha feeding El Obeid with drinkable water.

Fig. 4. Abu Seneina minor canal and intensive growth of aquatic weeds.

Fig. 5. Mortality of large numbers of T. nilotica in the Gezira Canals due to aerial spraying.

PROGRESS AND PRESENT STATUS OF AQUACULTURE IN TANZANIA

by

K.H. Ibrahim,
Freshwater Fisheries Institute, Nyegezi, P.B. 1213, Mwanza, Tanzania

Abstract

A comprehensive survey of the aquacultural practices and their potential in Tanzania has not yet been undertaken. However, fish culture has been in practice, particularly in the West Lake and Ruvuma regions, for a long time. By 1968 there were about 8 000 ponds in Tanzania, most of them small and some measuring only 3 m × 4.5 m. The present fish cultural practices in Tanzania, their advantages and disadvantages with suitable lines for improvement have been discussed.

Coastal aquaculture is not practised in Tanzania to any appreciable extent but possible lines of approach and species available are discussed. A detailed list of potentially important cultivable organisms is appended. Preliminary attempts carried out with tilapia have indicated a production of about 4 432 kg/ha in 4 months in stagnant ponds. Tilapia culture carried out in paddy fields has given a production of 2.5 tons of paddy and 112 kg of fish/ha/yr. Experimental work carried out has indicated the feasibility of culturing tilapia in floating cages. About 2 364 kg of fish and 1 000 ducks could be obtained from a 1.2 ha pond through duck-cum-fish culture; the total revenue realized was about T.Shs. 15 494.65 (Tan.Sh.7.11 = U.S.$1) in 1973.

Hybridization between T. zillii x T. andersonii resulted in 100 percent males and the hybrids had intermediacy in pharyngeal teeth structure and gill rakers count. The common plant Commelina sp. and a locally prepared supplementary feed (brewery waste and fish meal) proved suitable for T. zillii. T. andersonii, a reportedly late and non-prolific breeder in Zambia, when introduced into Tanzania did not come up to expectation.

Résumé

Aucune enquête détaillé sur la situation actuelle et le potentiel de l'aquiculture en Tanzanie n'a encore été conduite. La pisciculture se pratique toutefois depuis longtemps, notamment dans les régions du West Lake et du Ruvuma. En 1968, la Tanzanie comptait environ 8 000 étangs, pour la plupart petits et dont quelques-uns ne mesuraient que 3 m sur 4,5 m. Les méthodes de pisciculture actuellement appliquées en Tanzanie, leurs avantages et leurs inconvénients, ainsi que les grandes lignes a suivre pour leur amélioration, ont été soumises à examen.

En Tanzanie l'aquiculture côtière ne s'est pas encore développée dans une mesure appréciable, mais l'on envisage des orientations possibles et examine les espèces disponibles; on trouvera en annexe une liste détaillée des espèces dont l'élevage pourrait revêtir de l'importance. Des essais préliminaires effectués avec Tilapia ont indiqué une productivité d'environ 4 432 kg/ha en 4 mois dans des étangs d'eau stagnante. On a élevé Tilapia dans des champs de paddy et obtenu 2,5 tonnes de paddy et 112 kg de poissons par hectare par an. Les travaux expérimentaux ont indiqué qu'il serait possible d'élever Tilapia dans des nasses. L'association de la pisciculture à l'élevage du canard pourrait permettre d'obtenir environ 2 364 kg de poissons et 1 000 canards avec un étang de 1,2 ha; au total, les recettes réalisées se sont élevées à environ 15 494,65 Tan.Sh. (1 dollar E.-U. = 7,11 Tan.Sh.) en 1973.

L'hybridation T. zillii x T. andersonii a donné 100 pour cent de mâles, et les hybrides ont présenté une conformation intermédiaire du point de vue de la disposition des dents pharyngiennes et du nombre de filaments des branchies. La plante vulgaire Commelina sp. et un aliment d'appoint (déchets de brasserie et farine de poisson) préparé sur place ont trouvé une utilisation satisfaisante avec T. zillii. Par contre, T. andersonii, reproducteur notoirement tardif et peu prolifique en Zambie, n'a pas donné les résultats escomptés après introduction en Tanzanie.

1. INTRODUCTION

A bountiful supply of fish from the numerous natural lakes - a natural and extremely potential fishery asset of East Africa - has probably not given aquaculture its deserving position as a technique of increasing fish production in Tanzania. This is probably one of the reasons why fish culture did not make much headway in the West Lake and southern regions, where fish culture has been practised since olden days.

During the ‘explosive’ fish culture development or the so-called fish culture ‘boom’ days in Africa (Meschkat, 1967) in the fifties and early sixties, fish culture interest in Tanzania also showed conspicuous awakening. A comprehensive and systematic survey of the present status and future potential of aquaculture in Tanzania has not yet been undertaken. In 1963 FAO (FAO, 1964) recommended Songea (southern region) as having good possibilities for developing fish farming. Dibbs (FAO, 1964) in his economic survey of Marine and Inland fisheries of Tanganyika, recommended Songea area for expansion of fish culture because of the presence of many perennial streams. According to him, by 1964, there were over 5 000 ponds in Ruvuma region, but most of them were too small to yield good production. However, his final conclusions did not favour fish culture, since natural resources were deemed by far the cheapest source of fish and this did not ‘justify further development of fish farming in general’. By 1968, it was reported that there were over 8 000 fish ponds in Tanzania (FAO, 1968).

In recent times, a few attempts have been made on some sort of preliminary survey of the aquaculture situation in Tanzania (Ibrahim, 1970; Ibrahim and Lema, 1972). Fish culture in Tanzania is not uniformly developed. Regions like West Lake and Ruvuma are comparatively more developed in the sense that more ponds have been constructed in these areas. The total area in which fish culture is being practised is not clearly known yet; however, a recent survey conducted by the author has revealed the following salient features:

1. Fish culture is still being carried out as a part-time activity.

2. Ponds are constructed with little technical consideration; most of the ponds being too small, some even as small as 15 × 10 ft (4.5 × 3.0 m).

3. An interested person after stocking some tilapia fingerlings feels the work is completed and thinks of harvesting fish at a later stage, at irregular intervals and extending over several years.

4. Systematic pond management is not practised.

5. Most of the ponds are too shallow (Fig. 1).

6. Proper species identification is not practised and several species enter ponds adventitiously.

7. Most of the ponds have large numbers of stunted tilapia; these are supplied to interested persons as fingerlings.

8. Ponds have not been drained, treated or manured for a number of years.

9. No proper record of fish production is maintained, which makes it difficult to assess pond productivity.

10. Prisons in Tanzania have large numbers of properly constructed ponds; for example, the prison ponds at Korogwe in Tanga Region have an area of about 30 acres (12 hectares) and the prison ponds at Moshi have an area of about 15 acres (6 hectares). The necessity for fish in the diets of the inmates as well as the availability of cheap labour are probably the factors that have contributed to this condition.

2. FRESHWATER FISH CULTURE

2.1 Fish production and research

2.1.1 Fish production

Reliable data on fish production from ponds are not available. Even though fish culture has been practised for several years now by private individuals and public institutions like schools and prisons, etc., most of these do not have any production figures. When data are available, it is usually in terms of number of fish harvested at irregular intervals than in terms of weight of fish obtained at systematic and planned cropping.

2.1.2 Research

Aquaculture research had necessarily to lag behind in the absence of established farms and suitable personnel. However, as early as 1950, some experimental work was carried out at the experimental fish farm at Korogwe, Tanga Region (Fig. 2). At this farm, fish culture was carried out with the following local as well as introduced species (Gould, 1951):

When T. nilotica (?) fingerlings were stocked at 3 000 per acre (7 500 per hectare) a production of about 2 400 lb/acre/yr (2 688 kg/hectare) could be obtained with supplementary feeding. The fish produced were of 9–10 inches (228–254 mm) size.

In a 0.18 hectare pond near Moshi when 800 fingerlings of T. rendalli and T. pangani were stocked in August 1973, table size fish (250–450 mm) could be harvested by July 1974. In July 1974, 225 kg of fish were harvested and the pond is now being regularly harvested.

Experimental work carried out at the Freshwater Fisheries Institute, Nyegezi (Ibrahim and Lema, 1974a) indicated that when T. esculenta and T. zillii fry of 12–15 mm were stocked in a pond of 0.2 acre (0.08 hectare) at a density of 36 000 per acre (90 000 per hectare), a production of 1 772 kg/acre (4 432 kg/hectare) could be obtained in four months time. The growth rates of the species were satisfactory, attaining an average size of 179 mm/127 g (T. zillii) and 191 mm/125 g (T. esculenta). The fish were fed daily with local brewery waste and fish meal mixture (10:1) and the common plant Commelina sp.

2.2 Fish culture in paddy fields

At the experimental fish farm at Korogwe in 1950, some preliminary experiments on fish culture in paddy fields were carried out in about 7 acres (2.8 hectares) area. These experiments gave a production of about one ton of paddy and 100 lb of fish per acre per year (2.5 tons + 112 kg/hectare/yr). The experiments, however, were not continued (Gould, 1951).

2.3 Fish culture in floating cages

One of the most spectacular developments in aquaculture in recent times is the wide-spread interest shown in rearing fish in floating cages. Preliminary work carried out at the Freshwater Fisheries Institute, Nyegezi (Ibrahim et al., 1974) has indicated that floating cages of 3.5 × 3.5 × 3.5 m and 5 × 5 × 5 m, fabricated with locally available materials like bamboo poles, empty drums and fish net material, could be used to rear T. esculenta and T. zillii. An average growth rate of 153 mm and 83 g with T. zillii and 162 mm and 82 g with T. esculenta could be obtained in a five-month period with intensive feeding with brewery waste - fish meal mixture and Commelina sp.

2.4 Duck-cum-fish culture

In Morogoro Region, a 1.2 hectare pond is being used by the prison authorities for this purpose (Fig. 3). The pond is stocked with T. rendalli and Clarias mossambicus; over 1 000 ducks (Muscovy) are also reared near the ponds. The fish harvested are large and table size. The production figures available for 1973–74 are given below:

Source: Data by courtesy of prison authorities.

^a U.S.$ 1 = Tan.Sh. 7.11

This is perhaps the only place in Tanzania where this interesting line of fish culture is being attempted and, as the figures indicate, is quite productive and should be encouraged.

2.5 Sewage pond fish culture

At present, this system of fish culture is not being practised in Tanzania. However, there is a well laid out series of ponds at Kibaha near Dar-es-Salaam (Fig. 4) and water from the last series of oxidation ponds flows into a larger and open tank nearby. The fish production from this large pond is reported to be good and large sized tilapia are being caught. Since there are several more sewage ponds in the country, there is ample scope for further experimental development of this type of fish culture.

2.6 Fish hybridization

Production of monosex hybrids among a few species of tilapia and their use in fish culture has been accepted as one of the methods to overcome excessive breeding and resultant stunted growth in tilapia ponds in Africa (Meschkat, 1967). Hybridization between T. zillii x T. andersonii (Castelnau), carried out at the Freshwater Fisheries Institute, Nyegezi, has resulted in 100 percent male hybrids (Ibrahim and Lema, 1974b). Intermediacy was recorded in the external morphometric characters as well as in the number of gill rakers and pharyngeal teeth complex. Hence the hybrids probably have a wider feeding spectrum than the parental forms (Fig. 5).

2.7 Supplementary feeds

The necessity and importance of adopting systematic supplementary feeding in fish culture has not yet been fully recognized by many people in Tanzania. The approach of most people to this aspect is casual. Usually leaves of cassava or sweet potato are thrown into the pond and considered as a complete feeding schedule. It is well known that T. rendalli and T. zillii can consume large amounts of aquatic weeds and leaves of terrestrial plants.

In rearing other types of tilapia, various other feeds have been tried. Detailed work carried out at the Freshwater Fisheries Institute, Nyegezi, regarding supplementary feeds for herbivorous tilapia has indicated that in large scale rearing of these fish, feeding with leaves of cassava, sweet potato, papaya, cabbage and cauliflower, etc. is not practicable since the supply was not reliable. However, it was found that the common plant Commelina sp. was voraciously eaten by T. zillii and, since this was present locally in large quantities, it was used as a constant component of supplementary feeds.

Another component of supplementary feed tried was the locally available brewery waste. Brewery waste (which could be from maize, millet or banana) was dried, powdered and mixed with fish meal in 10:1 ratio and this was readily accepted by T. esculenta, T. zillii and T. andersonii (Ibrahim and Lema, 1974a). The product was available in plenty locally, the average price of the product being less than Tan.Sh. 00.30/kg.

2.8 Introduction of T. andersonii (Castelnau)

In view of the reported late maturation and breeding of T. andersonii in Zambia (Meecham, 1962; Maar et al., 1966) and presuming that this species of tilapia could probably fare better in this country, this species was introduced into Tanzania in 1968 (Anon., 1971; Ibrahim and Lema, 1974b). Subsequent work carried out at the Malya fish farm confirmed that this species behaved like other tilapia regarding early maturation, breeding, growth, etc. in ponds in Tanzania (Anon., 1971; Lema et al., 1975).

2.9 Tilapia breeding

In ponds at Nyegezi, both T. esculenta and T. zillii started breeding in less than five months time at a size of about 130–140 mm (Ibrahim and Lema, 1974a). It is well known that most of the species of tilapia breed in ponds (Fig. 6). However, work carried out at the Freshwater Fisheries Institute, Nyegezi, has indicated that for purposes of breeding T. esculenta and T. zillii for production of fingerlings, medium-size cement cisterns (5 × 3 × 1½ m) filled with tap water could be conveniently used. In the absence of a sand or soil bed for making breeding pits, T. esculenta (a mouth brooder) utilized the cistern bed itself (Fig. 7) while T. zillii (a substratum brooder) with semi-adhesive eggs, deposited eggs on the sides of the cistern. Thus it was found that even where pond facilities were not available, tilapia breeding could be undertaken in cement cisterns and fry supplied to local fish culturists.

2.10 Trout culture

Rainbow trout (Salmo gairdneri) and brown trout (Salmo trutta) have been introduced into the colder regions of Kilmanjaro and Mbeya. At present, these fishes are available in streams and rivers of these high altitude regions. To date, little effort has been made to culture these fishes, despite the great potential in this line of work.

3. COASTAL AQUACULTURE

3.1 Shrimp culture

Very little work has been done on shrimp culture in Tanzania, in spite of the availability of well over 800 km of coast line, vast brackishwater areas, estuaries and vast areas of mangrove swamps. A preliminary survey conducted by a Japanese team (Anon., 1972) recommended establishment of experimental shrimp culture at Udofu Creek near Tanga, Mzinga Creek near Dar-es-Salaam and at the Rufiji Delta in the south. Among the locally available species of prawns, Penaeus indicus (H.M. Edwards), Penaeus mondon (Fabricius), Penaeus semisulcatus (De Maan) and Metapenaeus monoceros (Fabricius) are economically important (Sankarankutty, 1974) and culture of these species can be attempted initially.

3.2 Culture of oysters, lobsters and brackishwater fishes

Matthes (1974), in his review of coastal and estuarine aquaculture in Tanzania, suggested initiation of culture with locally available species of Oysters (Crassotrea cucullata) (Born), mussels and clams, shelter rearing of lobsters (Palinurus and Thenus), sea cucumbers (Holothuroidea), edible sea weeds and fishes (Mugil cephalus (Linn.), Tachysurus dussumeri (Val.) and Chanos chanos (Forsk.)).

Coastal aquaculture or mariculture is not being practised in Tanzania at present to any significant extent. However, there is a growing realization that this highly potential and virgin resource can be exploited to add to the nation's total fish production.

4. DISCUSSION

Though initiated several years ago, aquaculture in Tanzania is still in its early stages. As has happened in many African countries, after an initial awakening of interest, further progress in aquaculture was arrested in the early or middle sixties. There were many reasons for this; recently, however, there has been a growing realization that both freshwater and coastal aquaculture, under scientific management, could add considerably to the total annual fish production of the country. Further, the advantages of the production of fresh fish locally, especially in the interior of the country, are obvious.

At present, the fish most cultivated in Tanzania are Tilapia spp. Other species available locally for cultivation are: Clarias mossambicus, Bagrus docmac, Labeo victorianus, Lates niloticus, Barbus spp., Citharinus sp. and trout, etc.

Introduction of exotic fish is prohibited by law and hence addition of other fast growing species like the common carp, Indian and Chinese carps, etc. is not being considered here. However, results of such introductions in the neighbouring countries like Kenya, Uganda and Zambia are being watched with keen interest.

One of the major factors that appeared in the analysis of factors that have led to the present poor status of fish culture is the lack of knowledge among the fish culturists of modern pond management techniques. Hence extension work through field fishery officers and demonstration ponds has to be intensified. Suggestions on similar lines have also been made by Bardach et al. (1972).

One of the basic pre-requisites for successful fish culture is the availability of good quality fish fry/fingerlings to the fish culturists at the proper time. In tilapia culture, it is common practice to construct a small pond, stock a few tilapia and call it a breeding pond. Fingerlings are supplied to interested parties for stocking purposes from such ponds. In these breeding ponds, fish are allowed to stay indefinitely and consequently breed repeatedly, resulting in overcrowding and stunting of fish. The age and parentage of these so-called fingerlings are not known and these stunted fishes, on release into a new pond, will commence breeding immediately or in a very short time. This type of fingerling production and supply is not ideal in terms of quality and is anti-selective. A proper and systematic breeding schedule has to be adopted to supply tilapia fingerlings of known age and parentage which will no doubt yield better results in culture.

Very little production can be expected at present from the very large number of small and shallow ponds. A systematic scheme has to be initiated for deepening, enlarging and/or the reconstruction of these ponds so that modern fish culture techniques could be practised and transmitted to fish culturists.

5. LIST OF CULTIVABLE AQUATIC SPECIES ORGANISMS AVAILABLE IN TANZANIA

5.1 Fresh water

5.1.1 Family Cichlidae

Tilapia esculenta Graham
T. nilotica (Linn.)
T. zillii (Gervais)
T. rendalli (Boulenger)
T. macrochir (Boulenger)
T. variabilis (Boulenger)
T. leucosticta Trewavas
T. mossambica (Peters)
T. pangani Lowe 1955
T. jipe Lowe 1955
T. rukwaensis Hilgendorf and Pappenheim
T. andersonii (Castelnau)
T. ruvumae
T. sparrmanii A. Smith
T. heudeloti Dumeril
T. manyarae
T. amphimelas Hilgendorf

5.1.2 Family Lepidosirenidae

Protopterus aethiopicus Heckel

5.1.3 Family Claridae

Clarias mossambicus Peters

5.1.4 Family Bagridae

Bagrus docmac Forskal
Bagrus spp.
Auchenoglanis occidentalis Boulenger

5.1.5 Family Schilbidae

Schilbe mystus Linn.

5.1.6 Family Cyprinidae

Labeo victorianus Boulenger
Labeo cylindricus Peters
Barbus altianalis radcliff Worthington
Barilius microcephalus

5.1.7 Family Anguillidae

Anguilla nebulosa labiata Peters 1852

5.1.8 Family Citharinidae

Citharinus spp.

5.1.9 Family Characidae

Alestes spp.
Hydrocynus spp.

5.1.10 Family Mormiridae

Gnathonemus spp.
Marcusenius spp.
Mormyrus spp.

5.1.11 Family Centropomidae

Lates niloticus albertianus Worthington
Lates spp.

5.1.12 Family Salmonidae

Rainbow Trout - Salmo gairdneri
Brown Trout - Salmo trutta

5.1.13 Family Centrarchidae

Black Bass - Micropterus salmoides

5.2 Brackish water

5.2.1 Fishes

Chanos chanos Forskal
Tachysurus dussumeri
Mugil cephalus Linn.
Elops saurus
Megalops cyprinoides
Trachynotus sp. (Pompano)

5.2.2 Prawns

Penaeus indicus H.M. Edwards
P. monodon Fabricius
P. semisulcatus De Maan
Metapenaeus monoceros (Fabricius)

5.2.3 Lobsters

Palinurus ornatus
P. versicolor
P. longipes
Thenus orientalis

5.2.4 Molluscs

Oysters - Crassostrea cucullata (Born)
- Ostrea amasa

Mussels - Mytilus sp.
- Septifer sp.
- Modiolus sp.

Clams and others - Andara antiquata (Linn.)
Donax sp.
Cypraea tigris (Linn.)
Cypraecassis rufa (Linn.)

5.2.5 Sea Cucumbers

Holothuroidea - Holothuria scabra

5.2.6 Edible Seaweeds

Brown seaweed - Sargassum sp.
Turbinaria sp.

Red seaweed - Eucheuma sp.
Hypnea sp.
Gracillaria sp.

6. REFERENCES

Bardac, J.E., J.H. Ryther and W.O. McLarney, 1972 Aquaculture. The farming and husbandry of freshwater and marine organisms. John Wiley and Sons, Inc., New York

FAO/UN, 1964 Report to the Government of Tanganyika on an economic survey of marine and inland fisheries of Tanganyika. Based on the work of J.L. Dibbs. Rep.FAO/EPTA, (1828):59 p.

FAO/UN, 1968 FAO Fish.Cult.Bull., 1(1):11 p.

Gould, R.E., 1951 Progress of fish farming in Tanganyika. Fisheries Series Pamphlet, No.2

Ibrahim, K.H., 1970 Tanzanian fisheries and its potential. Bull.Ministry of Agri.Food and Co-op., Dar-es-Salaam, p.16

Ibrahim, K.H. and R. Lema, 1972 Fish culture development scheme for Kondoa District. Bull.Fresh Water Fish.Inst.Nyegezi, 7 p.

Ibrahim, K.H. and R. Lema, 1974a Growth rates of T. esculenta and T. zillii under cultivation in ponds at Nyegezi, Tanzania. East African Community Symposium on Aquatic Resources of East and Central Africa, Kampala, 1974. E.Afri.J.Trop.Hydrobiol.and Fisheries (In press)

Ibrahim, K.H. and R. Lema, 1974b Hybridization between T. zillii x T. andersonii at the Freshwater Fisheries Institute, Nyegezi, Tanzania. East African Community Symposium on Aquatic Resources of East and Central Africa, Kampala, 1974. E.Afri.J.Trop.Hydrobiol. and Fisheries (In press)

Ibrahim, K.H., T. Nozawa and R. Lema, 1974 Preliminary observations on cage culture of T. esculenta and T. zillii in Lake Victoria waters at the Freshwater Fisheries Institute, Nyegezi, Tanzania. East African Community Symposium on Aquatic Resources of East and Central Africa, Kampala, 1974. E.Afri.J.Trop.Hydrobiol. and Fisheries (In press)

Lema, R., B. Giadom and K.H. Ibrahim, 1975 Observations on the introduction of T. andersonii (Cast.) into Tanzania from Zambia. FAO Symposium on Aquaculture in Africa, 1975

Maar, A., M.A.E. Mortimer and I.V.D.Lingen, 1966 Fish culture in Central East Africa. FAO, Rome, 1966, pp.158

Matthes, H., 1974 Coastal and Estuarine Aquaculture. Conference on Marine Resources Development, Dar-es-Salaam, April 1974

Meecham, K., 1962 Report on Fish Farming in Africa. Internal Report to the Government of Ghana, 5 p. (MS.)

Meschkat, A., 1967 The Status of Warm Water Fish Culture in Africa. FAO Fish.Rep., (44)2:88–123

Sankarankutty, C., 1974 Coastal and Estuarine Aquaculture; a case for introducing prawn culture in Tanzania. Conference on Marine Resources Development, Dar-es-Salaam, 1974

Anon., 1971 Experiments on T. andersonii. Report to the Ministry of Natural Resources and Tourism, 1971 (MS.)

Anon., 1972 Report of survey of the planning of brackishwater shrimp culture in Tanzania. Japanese shrimp culture survey mission, 42 p. (internal report, mimeo)

Fig. 1. A view of a typical pond illustrating inadequate water depth.

Fig. 2. A view of the 12 ha Experimental Fish Farm at Korogwe, Tanga Region

Fig. 3. Duck-cum-fish culture in Morogoro.

Fig. 4. A view of the Kibaha Sewage ponds.

Fig. 5. Tilapia zillii (Gervais) x Tilapia andersonii (Cast.) hybrids produced at the Freshwater Fisheries Institute, Nyegezi.

Fig. 6. Breeding areas of Tilapia esculenta in a shallow pond.

Fig. 7. Bottom of cement cistern used for breeding Tilapia esculenta. Nesting areas appear as white spots.

Fig. 8. A typical catch of small sized tilapias from a small pond. Clarias mossambicus has been used as a predator to keep a check on the population.