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

TABLEAU XI (a)
Pêche continentale production de poisson en mariculture (tonnes)

Le recensement est incomplet

TABLEAU XI (b)
Pêche continentale production d'anguille (tonnes)

Comme précédemment le recensement n'est pas au complet

TABLEAU XII
Pêche continentale superficie des plans d'eau par sous-préfecture

TABLEAU XIII
Pêche continentale superficie des plans d'eau par préfecture

TABLEAU XIV
Potentiel de l'aquiculture en Afrique (Madagascar 1973)

^a y compris les lagunes du Sud-Est
^b seulement les Pangalanes-Est

AQUACULTURE IN MALAWI

by

K. Meecham
UNDP/FAO Promotion of Integrated Fishery Development Project
P.O. Box 593, Lilongwe, Malawi

Abstract

Fish farming is relatively new to Malawi, with the introduction over the past twenty years of small subsistence ponds and a few larger, drainable ponds on estate farms. In all, some 200 ha of water, including ponds and reservoirs, are cultivated or managed, producing about 50 t of fish per annum with additional catches from sport fishing. The Government has set up a demonstration, training and fry production centre, and a pilot estate-type fish farm of about 20 ha. Polyculture of monosex Tilapia spp. and combined culture of Tilapia spp. and predators, Serranochromis sp. and/or Clarias sp. are the predominant culture practices. A total of 1 100 workers are employed in aquaculture and reservoir management. It is estimated that some 20 000 ha are suitable for fish farming in the Lower Shire River marshes; expansion of pond area in the next decade is estimated at 200 ha or more. The main problems in development of the industry are of a sociological nature and relate to the novelty of the practice and the need for trained manpower.

Résumé

La pisciculture est une activité relativement récente au Malawi; en effet, la création de petits étangs de subsistance et de quelques étangs vidangeables plus importants sur de grandes exploitations n'a été entreprise qu'au cours des vingt dernières années. Au total, quelque 200 ha de plans d'eau, y compris étangs et lacs artificiels, sont aménagés ou utilisés à des fins piscicoles et produisent environ 50 tonnes de poissons par an, la pêche sportive fourissant un complément de captures. Le Gouvernement a créé un centre de démonstration, de formation et de production d'alevins et une ferme piscicole pilote du type de la grande propriété, s'étendant sur quelque 20 ha. La polyculture de Tilapia spp. d'un seul sexe et la culture combinée d'espèces de Tilapia et de prédateurs (Serranochromis sp. et/ou Clarias sp.) constituent les principaux types d'élevage piscicoles pratiqués. Au total, 1 100 travailleurs sont employés à des travaux d'aquiculture et d'aménagement de lacs artificiels. On estime qu'environ 20 000 ha conviennent à la pisciculture dans les marais de la basse Shire; on évalue à 200 ha au moins l'extension possible de la superficie des étangs piscicoles au cours de la prochaine décennie. Les principaux problèmes posés par le développement de la pisciculture sont de nature sociologique et sont liés à la nouveauté que représente ce secteur et à la nécessité de disposer d'une main-d'oeuvre spécialement formée.

1. INTRODUCTION

Fishfarming is relatively new to Malawi, with the introduction over the past twenty years of small ancillary subsistence ponds, and a few, larger drainable ponds on large estates. The Government has set up a demonstration, training and fry production centre, and a pilot estate-type fishfarm of some 20 ha, and has embarked on an experimental prawn culture centre.

In a landlocked country, a quarter of whose territory is water, fishfarming plays a tiny part in the country's economy, although fish is the major source of animal protein to the population.

The country's development programme is planned to assist subsistence fish culture, evaluate large-scale food fish production and examine the possibilities of luxury aquatic products for cash crop enterprises.

2. AREA AND SCOPE

About 700 undrainable farm ponds scattered throughout the country, particularly in the north, cover an area less than 100 ha. The Government offers assistance and advice with stocking, mainly Tilapia shirana, an indigenous shallow-water tilapia with catfish and a predatory cichlid Serranochromis robustus. Several estate reservoirs, to a total of perhaps 50 ha, are stocked with these cichlids and occasionally black bass, Micropterus salmoides, for modest food production and a little sport fishing.

Sport fishing has been encouraged by the Government in highland forest and game reserves with rainbow trout stocking and rearing covering some 30 ha. The only large-scale fishfarm of drainable ponds for food production is at the pilot stage at present on an experimental irrigation farm in the southern lowlands extending over 20 ha. Tilapia and other species are produced in multispecific and single species monosex cultures to optimize production. The 5 ha of present demonstration fish ponds also providing fry for subsistence fish ponds are partly being converted and developed for prawn culture.

In all, then, some 200 ha of water are cultivated or managed, producing about 50 t of fish per annum, with additional benefits of a little sport fishing. In addition to this, an attempt was made in 1968 to assist the recovery of the fishery of Lake Chilwa, a shallow lake of 2 000 km², which dried up. Over a quarter of a million marked fry and fingerlings were stocked, but subsequent catch sampling revealed that this was of relatively small effect in the natural recovery of the lake.

3. MANPOWER

In the subsistence pond fishery, one, or at most two families are concerned with each pond, so 700 to 1 000 part-time workers are involved. Estate dam management concerns some 30 or 40 workers and fishfarming in drainable ponds employs 15 more. Sport fishing hatchery and control occupies 10 men, and the experimental prawn culture will employ another ten. In all, 1 100 workers are employed.

4. SPECIES CULTURED

5. AQUACULTURE FACILITIES

6. SOURCE OF SEED

T. shirana, the commonest cultivated fish, was first taken from the Shire River and Lake Chilwa, as were most of the indigenous species. Micropterus fry were brought from Rhodesia and fertilized trout ova came from South Africa. Restocking is carried out with fry and fingerlings from existing ponds.

7. CULTURE PRACTICES

7.1 Estate farm

In monosex culture, T. melanopleura and T. shirana are stocked at 6 000 ha; ponds are fertilized with superphosphate as required (which is very little) and fish are fed with maize bran and germ meal, raw and cooked, at 5 percent body weight daily (unless food given earlier was not eaten). The commonest parasite, Lernea sp., is controlled by application of a bromine compound. No other disease control is practised, beyond regular examination. Management and maintenance are carried out at present by an FAO fish farm supervisor and his counterpart, visits by an FAO fish culturist and full-time work by his counterpart and a labour force of 5 men.

At the same place, mixed culture of T. shirana, T. melanopleura, Serranochromis sp., and Clarias sp. are being tried at different proportions, in the order of 90–95 percent herbivores, with aggregate stocking rates of 10 000/ha.

Yields from these ponds are approaching 2 000 kg/ha as feeding and stocking rates have improved. Cropping is at present timed at five-monthly intervals allowing a one-month fallow period after each harvest. Growth rate curves on T. shirana indicate, however, that three or four crops a year may be more productive. Table I presents cost/benefit data for the Kasinthula fish farm.

7.2 Reservoir management

Stocking rates vary enormously in these reservoirs and cannot be generalized in this paper. Fertilizing and feeding is usually negligible and disease control incidental to management in the rate of angling permitted. These reservoirs are not normally drainable and are not therefore harvested as such except by angling. Cost/benefit calculations would probably reveal a financial loss but the practice provides a very useful amenity and food for employees.

7.3 Subsistence ponds

These ponds vary in size from 0.1 to 0.5 ha; stocking, by the Government Fisheries Department, is carried out at the rate of between 2 000 and 5 000 fry per ha, usually of mixed species with 5 to 10 percent predators. Little is known of independently stocked ponds. Some farmers throw occasional feed such as kitchen waste, banana leaves, etc., into the ponds but this is at best haphazard and cannot be accurately evaluated. There is no disease control but avian predators are often driven away by the farmer's family.

There is little or no management and maintenance is carried out, as necessary, as part of the general farm operations. Harvesting is usually by netting at weekly or less frequent intervals, yielding some 150 to 200 kg/ha. The cost/benefit ratio of such practices is only maintained favourably when labour factors are ignored; pond labour merges with other farm duties and is often carried out by younger members of the farmer's family.

8. DEVELOPMENT

8.1 Development plans

In the extensive area of the Lower Shire River marshes it has been estimated that some 20 000 ha of dry or marsh land are potentially suitable for fishfarming, having heavy, saline, alkaline soils. Within the coming decade it is planned that, depending on the success of the pilot venture at Kasinthula, fishfarm expansion should be in the order of 200 ha or more. There are no plans for expanding estate reservoirs as such although there will no doubt be need for such reservoirs as livestock development proceeds. Although assistance will be given to subsistence pond development, this will take low priority in the nation's aquaculture plans. It is too early at this stage to view the intended prawn culture in terms of further development.

8.2 Development problems

The principal problem in the introduction of aquaculture to Malawi appears to be sociological. Aquaculture is relatively novel in Malawi and the careful and intensive husbandry practices necessary for successful fishfarming have yet to be taught to more than a very small nucleus of Malawian farmers. Fishfarming is a relatively high capital cost venture in terms of yield per acre and is again foreign to the traditional concept of agriculture in this country. Development programmes must be supported by the Government, probably assisted by foreign aid.

8.3 Recommendations

Although it is early yet to assess the value of estate-type farming in Malawi, this is clearly the better direction for future development. In spite of the general rule in Malawi for labour-intensive development, it is recommended that fishfarming should be classified as an intensive industry demanding as much mechanization as possible.

TABLE I
REVISED RUNNING COST/BENEFIT FOR KASINTHULA (1974)

		Kwachas2 (K)
		Per ha	20 ha		100 ha
Fingerlings:	10 000/ha at 25 g each at K200/t	50	1 000		5 000
Fertilizer:	nominal, say 100 kg at K150/t	15	300		1 500
Food: either:	3:1 ratio to ultimate yield 3 t/ha (i.e., 358 g/fish at cropping) so:
	at K30/t	300	6 000	average say 8 000	30 000	average say 40 000
or:	4% fish weight/day × 160 days × 2 crops/yr
	less 5 000 × 300 g taken after 100 days:
	say	500	10 000		50 000
	(but 4% × 160 days = 6.4:1 ratio)
Water at K35/ha		35	700		3 500
Management 320 m/d1/ha		1 000	1 000		1 000
Labour at	50 m/d/ha at 25 t/m/d for 20 ha
	40 m/d/ha at 25 t/m/d for 100 ha	80	250		1 000
Tradesmen	5 m/d/ha at K1.50/m/d	7.50	150		750
		1 587.50	11 400		52 750
	3 t fish at K200	600	12 000		60 000
	Loss: (approximate)	K1 000	profit 600		profit 7 250
If polyculture can reduce food ratio to 1.5:1 then 20 ha profit K4 600; 100 ha K27 250

¹ m/d = man days
² 1 U.S.$ = 0.83 Kwachas

THE STATUS OF AQUACULTURE IN MAURITIUS

by

Ministry of Fisheries
Port Louis, Mauritius

Abstract

Traditional aquaculture practice in Mauritius consists of extensive culture of finfish and shellfish in coastal brackish- or saltwater enclosures. Due to the pervious nature of the retaining walls, uncontrolled water levels and inclusion of fresh water, enhancement of water fertility through fertilization is not possible, and artificial feeding is not practised. Management consists of occasional fishing out of predators and repair of the retaining wall. Siganus spp. and Mugil spp. are the principal fish stocked together with the crab Scylla serrata; the local oyster Crassostrea cuculata is cultivated in the intertidal zones of some enclosures.

Freshwater fish introduced for cultivation include rainbow trout, blue gills (Lepomis sp.), black bass (Micropterus sp.) and Tilapia spp.; till now, none of these have become the subject of commercial aquaculture.

The Indian carps Catla catla and Labeo rohita were introduced recently for culture purposes. The freshwater prawn, Macrobrachium rosenbergii, was introduced in 1972; two hatcheries for this species are now operational and about 12 ha stocked. Two additional commercial hatcheries are planned as well as an additional 30 ha of grow-out ponds. A mullet/tilapia polyculture programme will also be implemented in the near future.

Modern aquaculture is still new to Mauritius and there is need for technical expertise. The high cost of land and rising labour costs constitute major constraints to aquaculture development except in the case of sugar estates and the Government, both of which have available land and water resources.

Résumé

On pratique traditionnellement à l'île Maurice l'élevage extensif de poissons et de crustacés dans des enclos côtiers d'eau saumâtre ou salée. Compte tenu de la perméabilité des murettes de retenue, du niveau incontrôlé de l'eau et des apports d'eau douce, il n'est pas possible d'accroître la fertilité des eaux en y ajoutant des engrais et l'on ne pratique pas le nourissement artificiel. L'aménagement se borne donc en tout et pour tout à capturer occasionnellement des prédateurs pour les éliminer et à réparer les murs de retenue. Les principales espèces élevées sont: Siganus spp. et Mugil spp., associées au crabe Scylla serrata; l'huître locale Crassostrea cuculata est élevée dans les zones intercotidales de certains enclos.

Les poissons d'eau douce introduits depuis peu sont la truit arc-en-ciel, le blue gill (Lepomis sp.), le black bass (Micropterus sp.) et différentes espèces de Tilapia; aucune de ces espèces n'a encore été produite sur une échelle commerciale.

Les carpes indiennes Catla catla et Labeo rohita ont été introduites récemment. La crevette d'eau douce Macrobrachium rosenbergii est élevée depuis 1972; deux écloseries fonctionnement maintenant pour cette dernière espèce et 12 ha ont été mis en charge. L'onverture de deux nouvelles écloseries commerciales est prévue, ainsi que celle de 30 ha d'étangs de croissance. Un programme d'élevage associé de mulets et de tilapias doit également être lancé très prochainement.

Les méthodes d'aquiculture moderne ne sont pas encore très répandues à l'île Maurice qui a besoin de techniciens. Le prix élevé des terrains et l'augmentation du coût de la main-d'oeuvre sont les principaux obstacles au développement de l'aquiculture, sauf pour les plantations de sucre et le Gouvernement, qui disposent à la fois de terrains et d'eau.

1. INTRODUCTION

Mauritius is an island, and until the end of the last decade, the supply of high-quality fresh fish from the lagoon and shelf area, together with frozen fish from a distant water fishery which has developed within the last 15 years, have largely sufficed for local consumption. Consequently, aquaculture has received little attention until very recently.

The per caput consumption of fish in the island, however, is now increasing at a very rapid rate, partly because of improved living standards, also because of rapidly rising prices for other animal protein foods. At the same time, the possibility of concentrating on high-value species such as crustaceans and oysters and the reduced catch per unit effort for wild stocks of these species due to overfishing, have swung the economics of aquaculture into a much more favourable position, so that the private sector is anxious to invest in aquaculture, and the Government is now placing a great deal of emphasis on research in this field.

2. AREA AND SCOPE

The traditional form of aquaculture in Mauritius has been the use of shallow brackish-or saltwater lagoons enclosed by semi-permeable rock walls fitted with sluice gates and allowing tidal exchange of water. Despite the small tide range (about 60 cm), it is estimated that 30–50 percent of the water in an enclosure is changed with each tide, so that no control of water conditions is possible. Freshwater infiltrations and, at times streams, further complicate matters, as wide fluctuations in salinity occur after heavy rains, often causing kills of stenohaline species. The consequence of these conditions is that no water enrichment is possible, and even supplemental feeding is difficult, so that only extensive fish culture has been practised.

Despite the low productivity of these enclosures (200 kg/ha in the best managed ponds), there are 21 to be found around the coast, about half of which (268 ha) are actively maintained. The area of individual enclosures varies from 0.5–50 ha. Although some of the fish produced are sold, in many cases these ponds are kept by large sugar estates mainly as reserves of fresh fish and for recreational use.

Recently, with the depletion of wild stocks, several of those enclosures have been used for oyster culture primarily, although fish are stocked as well. The oysters are invariably grown on wire mesh trays maintained in the intertidal zone where there is a minimum of fouling and of parasitism. In these cases, the aim is commercial, despite low productivity.

In fresh water, attempts have been made to introduce species of fish suitable for aquaculture, but with littlé success to date. The species introduced include: (a) rainbow trout, which did not survive, blue gills and black bass, which have become established in some inland reservoirs and support a small sport fishery but have no commercial value; (b) Tilapia, which have colonized most of the reservoirs and streams of the island and are fished by the inland populations for their home consumption but do not support a commercial fishery; and (c) the Indian carps, Catla catla and Labeo rohita, which were recently introduced on an experimental basis.

Since 1972, the giant freshwater prawn, Macrobrachium rosenbergii, has been introduced and is being bred locally in a development programme aimed eventually at commercial mass-culture. Two hatcheries are now operational, one government and one private, and about 12 ha of ponds have been stocked or are ready for stocking. In addition, two commercial-scale hatcheries are to be built, and there is an initial commitment for at least 30 ha of ponds.

A mullet-rearing programme has recently been elaborated, but this is still in the early experimental phase.

3. MANPOWER

The manpower employed in the sea enclosures is mainly for the purposes of repair and maintenance. Although precise statistics are not available, it is estimated that at least 200 people are employed full time, although this figure may be greatly increased sporadically in the sugarcane intercrop season when excess labour is available. This manpower is employed both for fish and for oyster culture.

The Macrobrachium programme is estimated to employ about 50 individuals on a permanent basis, plus the manpower employed for pond and hatchery construction.

4. SPECIES CULTURED

4.1 Brackishwater enclosures

4.1.1 Finfish

4.1.2 Oysters

1. Crassostrea cuculata - the Bombay oyster, which occurs wild in Mauritius.

2. Attempts were made to introduce cultch-free seed of C. gigas, C. virginica and Ostrea edulis in 1971 and 1972, but survival of these species was very poor and the project was discontinued in order to avoid the risk of introducing pathogens.

4.2 Freshwater fish culture

1. Osphronemus goramy (Gouramier) - introduced during the 18th century from southeast Asia. Established in many of the fresh- and brackishwater areas of Mauritius, but in process of being displaced by Tilapia. No commercial aquaculture.

2. Salmo gairdnerii (rainbow trout) - introduction in 1929 failed.

3. Lepomis macrochirus (blue gill) - introduced in the early fifties mainly for sports fishery.

4. Micropterus sp. (black bass - largemouth) - introduced in the early fifties mainly for sports fishery.

5. Tilapia melanopleura - introduced in 1954; T. macrochir and T. nilotica - introduced in 1956 from Korongwe, Tanganyika; T. zillii - introduced in 1957 from Madagascar;

   Trial culture of these species has been carried out (Johnson, 1959) but there has been no commercial follow-up.

6. Catla catla and Labeo rohita fingerlings were introduced from India in 1973. Due mainly to an airline strike, which greatly delayed delivery of the fingerlings, only a few specimens arrived in Mauritius alive. These have grown fairly well, but adaptive research still needs to be done on the culture of these species.

7. Experiments have just started on stocking freshwater ponds with Mugil cephalus. These may be raised in polyculture with various Tilapia species.

8. The freshwater prawn, Macrobrachium lar, which is endemic, has been raised in small streams as a luxury item for many years. In 1972, M. rosenbergii was introduced from Hawaii, and will shortly form the basis for an aquaculture industry. Monosex Tilapia nilotica and T. macrochir has been stocked successfully with M. rosenbergii in order to control algal growth in the ponds.

5. CULTURE PRACTICES

Wild fry are caught in the lagoon by means of small-mesh drag seines and stocked directly into the coastal enclosures without any period of acclimation. Stocking rates aimed at are in the order of 2 000 fry/ha, principally of Siganus canaliculatus and Mugil cephalus, although Lethrinus nebulosus and Rhabdosargus sp. are also caught but in lesser numbers. In general, the enclosures are not subdivided, and no attempts are made at management other than sporadic predator control. The enclosures are generally fished once or twice yearly by means of drag seines. When available, small crabs (Scylla serrata) are stocked also, again with no attempt at intensive culture. The adult crabs are caught at night with dipnets. Berried females do not fetch a higher price on the Mauritian market, and no particular effort is made to catch them.

Three enclosures are used for oyster culture as well as for raising finned fish. Since an administrative ban has been placed on the import of oyster seed, only the local oyster, Crassostrea cuculata is cultivated. Young oysters (height about 15 mm) are collected from wild beds and grown on wire mesh trays maintained by stakes in the intertidal zone where it has been observed that parasitism and the growth of encrusting coralline algae, etc., is minimized by the daily exposure to the air. The growth rate of these oysters is extremely slow, taking 3–4 years to reach market size (height 60–70 mm). This is thought to be due to the extremely low primary productivity of the waters around Mauritius, nutrient levels in the water being very low. Oysters are marketed mainly during the winter months when glycogen levels are highest, generally after having been purged for at least 48 h in clean sea water.

The Macrobrachium culture situation has been described comprehensively in a paper submitted to this symposium. Briefly, the methods used are those described by Fujimura (1966, 1972). Two pilot-scale hatcheries are operational on the island, each with a production potential of 750 000–1 million juveniles/year. Forty-five ponds have been built to date, totalling 13 ha, and it is expected that some 30 ha of additional ponds will be built during the coming year.

Juvenile prawns of 12 mm size are stocked into 0.2–0.4-ha ponds at a rate of 175 000/ha. The ponds are fertilized with NPK prior to stocking, and phytoplankton blooms are maintained thereafter with chicken manure. Harvesting of the prawns begins after 7–8 months, when 3 percent of the population would have reached the market size of 50 g; each pond is seined twice monthly thereafter. When the population is estimated to be about 25 percent of the initial number stocked, the ponds are re-stocked with juveniles without interrupting the fishing programme. The prawns are fed with chicken feed (broiler starter) on demand, the amount of feed averaging 3 percent of the biomass of prawns. Yearly production/ha is expected to be 3 000–4 000 kg. Two commercial-size hatcheries are now in the planning and construction phase, each with a production capacity of 10 million juveniles annually. These hatcheries will require about 120 ha of ponds when in full production. Macrobrachium wholesale price is U.S.$ 5.00/kg at present. Profit margins should vary between U.S.$ 3 000 and 7 000/ha depending on production levels attained.

6. PROBLEMS

Capital investment for aquaculture in Mauritius is variable depending on the investor. In the case of sugar estates and the Government, both of which have land available frequently at nominal accountancy costing and have a seasonal excess of labour or employ relief labour, investment can be very reasonable. For outside investors, however, capital costs are high, as land available for purchase is very limited and expensive and labour costs are rising rapidly. This situation is reflected in the fact that there is very little independent investment in aquaculture other than from sugar estates which are not acutely concerned with the profitability of operations which can be written off against losses in agricultural diversification programmes. The positive aspect of this state of affairs, however, is that investment in the Macrobrachium programme has been ahead, if anything, of proof on the economic viability of the project. The negative aspect is that the investment tends to be fragmentary and that the estates do not employ sufficiently competent personnel to ensure viability of the project, thus requiring a great deal of extension support from the Government. It must be said that this reflects a situation where technical knowledge in sugar production is very high, but where knowledge of aquaculture is very deficient. Grouping of investment to form companies specialized in aquaculture would certainly improve the situation, and it is to be hoped that this will eventually take place.

Problems in aquaculture exist with respect to the supply of seed, of feed, and with marketing, but it must be emphasized that this industry is very new to Mauritius and that the problems are of an order which should see fairly rapid solutions.

7. REFERENCES

Ardill, D., 1973 et al., The Introduction of the Freshwater Prawn, Macrobrachium rosenbergii (de Man), into Mauritius. Revue Agricole et Sucrière de l'Ile Maurice, 52:6–11

Brusca, G. and D. Ardill, 1975 Growth and Survival of the Oysters Crassostrea gigas, C. virginica and Ostrea edulis in Mauritius. Revue Agricole et Sucrière de l'Ile Maurice, Vol. 53

Fujimura, T., 1966 Note on the development of a practical mass culturing technique of the giant prawn, Macrobrachium rosenbergii. I.P.F.C. 12th Session, Honolulu, Hawaii, U.S.A., 3–17 October 1966

Fujimura, T. and H. Okamoto, 1972 Notes on progress in developing a mass culture technique for Macrobrachium rosenbergii in Hawaii. I.P.F.C. 14th Session, Bangkok, Thailand, 18–27 November 1970

Johnson, L., 1959 Investigation on the culture of Tilapia in Mauritius. Revue Agricole et Sucrière de l'Ile Maurice 38(3): 109–26 and 38(4): 158–71

Lubet, P.E., 1959 Rapport du Dr. P.E. Lubet sur l'ostréiculture à Maurice. Printed for the colony of Mauritius by the Mauritius Printing Co. (pp. 1–43)

Motwani, M.P., 1971 Techno-Economic Survey of Mauritius, Vol. III Fisheries, 1–127

PRESENT STATUS AND PROSPECTS FOR AQUACULTURE IN NIGERIA

by

B.F. Dada
Acting Director, Federal Department of Fisheries
P.M.B. 12529, Lagos, Nigeria

Abstract

Although modern fish farming is relatively new to Nigeria fish production from flood plains has been going on for generations. Current production from aquaculture represents less than ten per cent of total annual domestic fish production. However, there is considerable potential for large scale aquaculture; approximately 1 million hectars of swamp land are available in the delta area for brackishwater fish culture.

Major species of fish cultured include Tilapia spp., Cyprinus carpio, Christichthys nigrodigitatus and Mugil spp. Yield per hectare varies from 750 kg to 3 000 kg depending on management techniques.

In the Third National Development Plan 1975–80 a total of ₦10 million (₦ = U.S.$1.6) has been earmarked for aquaculture development and research in the public sector. The programme would involve the stocking of irrigation dams and reservoirs as well as the construction of modern fish farms.

Résumé

Quoique la pisciculture moderne soit relativement récente au Nigeria, les plaines inondées sont exploitées depuis des générations. La production courante de la pisciculture représente moins de 10 pour cent de la production piscicole annuelle. Néanmoins, il y a un potentiel considérable pour une pisciculture à grande échelle au Nigeria; environ 1 million d'hectares de zones inondées existent dans le delta pour une aquaculture en eaux saumâtres.

On emploie surtout les espèces suivantes: Tilapia spp., Cyprinus carpio, Chrisichthys nigrodigitatus et Mugil spp. Le rendement par hectare varie de 750 kg à 3 000 kg en fonction des techniques employées.

Dans le Troisième Plan National de Développement, un montant de 10 millions de Naira a été inscrit pour le développement de l'aquaculture et de la recherche piscicole dans le secteur public. Le programme comprendra la mise en valeur de barrages de retenue et de réservoirs ainsi que la construction de fermes de pisciculture modernes.

1. INTRODUCTION

Fish culture has been practised, though at subsistence level, for a long time in Nigeria. Indeed fish production from flood plains has been going on for generations. However, modern fish culture practices were started fairly recently. In 1951 the former Northern Nigeria Government started the construction of a pilot fish farm at Panyam near Jos with a view to culturing the common carp. The construction of homestead fish ponds was also, at about the same time, encouraged by the Governments in the then Western and Eastern Regions. In response to a request by the Federal Government the development of brackishwater fish culture was initiated in the Niger Delta area in 1965 by FAO and this was followed by a second project in Lagos in 1968. There has since been a steady growth in the number of fish ponds and fish farms all over the Federation.

Although there is considerable potential for aquaculture in Nigeria the present contribution to domestic fish production from this sector is still rather low. Out of the estimated annual production of 700 000 metric tons less than 10 per cent comes from fish pond production. On the other hand fresh water fish command high prices in the market because of consumers' preference for this type of fish.

2. AREA AND SCOPE

About 2 000 homestead freshwater fish ponds, covering an area of about 1 000 hectares, are at present scattered all over the country. Most of these are owned by communities, schools and other institutions, co-operative societies as well as private individuals. The majority are built through the construction of simple earthen dams across streams and rivulets. Perennial “fadamas” in the Northern parts of the country are estimated to cover about 20 000 hectares. About 750 000 to 1 million hectares of swamp land are available in the delta area for brackishwater culture. No modern mariculture is at present practised in Nigeria.

3. MANPOWER

The construction of fish ponds as practised at present is labour-intensive especially during the construction phase. Invariably fish pond farming is a part-time operation. It is is, however, estimated that not less than half a million people are involved in one phase of aquaculture or the other.

For Government experimental and demonstration fish farms some States have well-trained extension staff who could carry out surveys and supervision of pond construction and management. In many of the States, however, the staff are inadequate and have not got the necessary training and background for the required extension work. As of now not less than 5 Research Officers, 20 Fisheries Officers, 60 Technical Assistants of various grades as well as 200 junior workers are employed in aquaculture in the Federal and the twelve States of the Federation.

4. SPECIES CULTURED

Species of fish of proven suitability in Nigeria for aquaculture operations either singly (monoculture) or in combination (polyculture) are listed below:

Fresh Water Species:

1. Tilapia spp.

   Preferred species: T. nilotica, T. melanopleura and T. galilea

2. Cyprinus carpio (Israeli or European Carp)

   Three varieties Cyprinus carpio var. Specularis, Cyprinus carpio var. Nudus and Cyprinus carpio var. Communis

3. Heterotis sp.

4. Labeo sp.

5. Gymnarchus sp.

6. Lates niloticus (The Niger Perch)

7. Clarias sp.

Brackishwater Species:

1. Chrysichthys nigrodigitatus (Cat fish)

2. Hemichromis fasciatus

3. Lutjanus spp.

4. Gymnarchus sp.

5. Elops sp.

6. Heterotis sp.

7. Ethmalosa fimbriata (Bonga)

8. Penaeus duorarum and Macrobrachium sp.

9. Mugil spp. (Mullets)

A combination of carp plus mullets or Chrysichthys plus tilapia has been found to be ideal for polyculture.

5. AQUACULTURE FACILITIES

The following types of aquaculture installations are built in different parts of the country:

1. Hatcheries and breeding centres - Some of the States Fisheries Divisions at present have breeding centres for raising fish seed which are then distributed to Government production farms and private fish ponds. There are plans to build more of these in the Third National Development Plan 1975–80.

2. Pond farms - These are of varying sizes from. 1 hectare to nearly 400 hectares as in the case of the proposed fish farms in the Western and Mid-western States.

3. Man-made lakes and reservoirs - These occupy an important position with regard to large scale freshwater fish production. Hitherto reservoirs for drinking water are stocked by Government Fisheries Departments and harvested by local fishermen under licence by the respective water corporations or boards.

4. Cages - These are purely for experimental and research purposes and have been tried by both the Federal Department of Fisheries and the Kainji Lake Research Project.

5. Indoor tanks - These are also for research purposes and have been used for the study of Clarias, Tilapia Chrysichthys spp.

6. Oyster/mussel parks - There are none at present but plans are under way to set up oyster farms.

6. SOURCE OF SEED

Fish fry and fingerlings are obtained from the following sources:

1. Natural waters - Species collected from natural waters such as estuaries, lagoons and rivers include mullets (7 spp.); snappers (Lutjanus sp.), Hemichromis spp., Clarias spp., Chrysichthys spp. and Tilapia spp.

2. Pond breeding - Carp, Tilapia and Clarias fingerlings are obtained from Government-owned demonstration ponds and Breeding Centres.

3. Induced breeding by hormone - This is not widely practised as yet but there are plans to use hormones to induce the breeding of Chrysichthys nigrodigitatus where natural breeding in ponds and enclosures fails.

4. Hatchery operations - Practised in some States to some extent for the common carp-Cyprinus carpio.

5. Importation of seed - Apart from carp seedlings introduced into the country in the early fifties Nigerian aquaculture practices do not depend on fish seed importation. There are plans, however, to import the grass carp - Ctenopharyngodon idella - primarily to combat weed problems in ponds.

7. AQUACULTURE PRACTICES

1. Stocking rates - Development of a proper combination of species and their densities to exploit all available food strata within a pond is being worked out in experimental ponds.

2. Feed and fertiliser - Information on fertiliser and food requirements is inadequate; most private ponds are only stocked with fry and neither fertiliser nor supplementary feed is given. On the other hand, Government-owned fish farms receive fertiliser and feed. Feeds generally used in the country include groundnut cake, spoilt groundnut, palm kernel cake, rice bran, guinea corn/sorghum and maize.

3. Harvesting - As of now

   1. The average production recorded from privately-owned ponds which receive very little attention is approximately 750 kg/ha - mostly of Clarias spp. and Tilapia spp.

   2. Production from experimental ponds with or without fertilisers and supplementary feed are given below:

      Freshwater (1974 statistics)
      Species: Common carp
      	Fertiliser only	=	1024 kg/ha
      	Feed only	=	1600 kg/ha
      	Fertiliser and feed	=	2030 kg/ha
      Brackishwater - Polyculture (1974)
      Species: Catfish, tilapia, mullets
      	Neither fertiliser nor feed	=	879 kg/ha
      	Fertiliser only	=	200 kg/ha
      	Feed only	=	2400 kg/ha
      	Fertiliser and feed	=	3000 kg/ha

   3. Production from commercial ponds which do not receive as much attention as experimental ponds may be lower than the above while natural productivity of ponds in some areas are higher than in others. The national average (1974) therefore has been worked out as follows:

      Type of culture	Natural Production	With fertiliser	With supplementary feed and fertiliser
      Monoculture kg/ha	560	1120	2240
      Polyculture kg/ha	670	1350	2690

8. SOCIAL AND ECONOMIC ASPECTS

Appendix I gives the cost and returns for one hectare of fish farm under polyculture. The figures are based on fish farms operated by Government Departments.

Experiments have also demonstrated that an acre of water is capable of producing more proteins than an acre of land. In a well-managed fish farm up to 3 000 kg of fish can be harvested annually on a sustained yield basis per hectare. Table I shows that fish production of 3 000 kg per hectare per year is six times more than cowpeas and three times more than groundnut for the same unit area.

Table I Comparative Yields and Value of Agricultural Commodieis and Fish per hectare in Nigeria ¹

¹ Source: For Agricultural Crops: Federal Department of Agriculture Publications 1971–72
For Fish: Federal Department of Fisheries Research Station Papers

The above is not intended to suggest that aquaculture is ready to replace cash crops in Nigeria. Rather it furnishes a convincing argument that aquaculture is not any less paying and, as a complementary to agricultural effort, could add a substantial income to crop farmers.

9. DEVELOPMENT

The major factors of production namely land, labour and capital do not constitute bottlenecks for aquaculture development in Nigeria. The main problem is technical skill. For instance, in the current Five-Year Development Plan 1975–80 approximately N10 million has been earmarked for aquaculture development and research. This amount represents approximately 10 per cent of the total capital outlay of N101.5 million for Fisheries Development and Research during the Plan period. the programme envisaged includes the stocking of over half a million hectares of irrigation and other reservoirs which are to be built in the agriculture sector, as well as the development of modern fish farms in different parts of the Federation.

The Government is prepared to invest more money in aquaculture provided the economic viability can be practically demonstrated. To implement viable intensive fish farming UNDP/FAO assistance has been sought. Already FAO experts have visited a number of the existing fish ponds and farms in the country with a view to recommending measures to be adopted in increasing the low productivity of most of the ponds. It is anticipated that by the adoption of improved fish farm management techniques, valuable technical and economic information would be gathered to assist in the planning of large scale fish farming investment and expansion in the country.

10. REFERENCES

Anon, 1968 The economics of small-scale fish farming in Western Nigeria. Paper prepared by the Fisheries Division, Ministry of Agriculture and Natural Resources, Ibadan, Nigeria

Ezenwa, B., 1973 Acclimatization experiments with mullet fry for culture in freshwater ponds. Annual Report, Federal Department of Fisheries, Lagos, Nigeria, pages 60–65

FAO/UN 1965 Investigations of the possibility of brackishwater fish culture in the Niger Delta. Based on the work of T.V.R. Pillay, Report No. 1973 52pp

Sivalingam, S., 1970 Fish culture possibilities around Lagos Lagoon and results of recent trials. Federal Fisheries Occasional Paper No. 13, Nigeria

Sivalingam, S. 1974 A Guide to Construction of Fish Ponds. Federal Fisheries Occasional Paper No.20 Nigeria

Appendix

COST AND RETURNS FOR 1 ha. FISH FARM UNDER POLYCULTURE
(Ground area 1.5 ha. Production area 1 ha.)