I/E-3
POND FISH CULTURE DEVELOPMENT IN GHANA

by

F.M.K. DENYOH
Inland Fisheries Division, Ministry of Fisheries
Accra, Ghana

Abstract

Ghana has had an experimental fish farming program for 12 years. During this period much has been learned and the information obtained could now be used in a program of commercial fish production. Earlier attempts at commercial fish culture were not successful due to lack of trained personnel and difficulties in obtaining field equipment. Experiments indicated that the fishes which can be cultured successfully in Ghana are of the genera Tilapia, Labeo, Lates, Synodontis and Bagrus. Due to prolific breeding populations of Tilapia species are hard to control. It was found that an easy way of controlling them is by the use of Lates niloticus and Hydrocyon species as predators. It has also been noticed that fish production could be stepped up considerably through the use of fertilizers and by keeping pigs by the ponds for utilization of their urine and wastes to fertilize pond water.

Stocking ponds with a number of species at a time, has been demonstrated to yield good results. Enough information has been obtained to guarantee successful commercial pond fish culture in the country.

DEVELOPPEMENT DE LA PISCICULTURE EN ETANG AU GHANA

Résumé

Un programme de pisciculture expérimentale existe au Ghana depuis douze ans. Au cours de cette période, une expérience considérable a été acquise et l'on dispose maintenant de données suffisantes pour passer au stade de l'exploitation commerciale. Les précédents essais de pisciculture commerciale s'étaient soldés par un échec en raison du manque de personnel qualifié et de l'insuffisance de matériel. Les expériences menées avec Tilapia, Labeo, Lates, Synodontis et Bagrus indiquent que ces espéces peuvent être élevées avec succés au Ghana. Les populations de Tilapia s'avèrent difficiles à contrôler en raison de leur tendance à proliférer. Une manière facile de surmonter cette difficulté consiste à introduire dans les étangs à Tilapia des prédateurs appartenant aux espèces Lates niloticus et Hydrocyon. On a également noté qu'il était possible d'augmenter considérablement la production en utilisant des engrais et en élevant des porcs aux alentours des étangs afin d'utiliser l'urine et les excréments de ces animaux pour fertiliser les eaux.

Les essais d'empoissonnement simultané avec plusieurs espèces ont donné de bons résultats. Suffisamment de données ont été recueillies pour garantir le succès de la pisciculture en étang de type commercial.

DESARROLLO DE LA PISCICULTURA EN ESTANQUES EN GHANA

Extracto

Ghana dispone de un programa de piscicultura experimental desde hace doce años. Durante este período se ha aprendido mucho y la información obtenida podría actualmente ser utilizada en un programa de producción de pescado en escala comercial. Los anteriores intentos de cultivo comercial de peces no dieron resultado debido a la falta de personal capacitado y a las dificultades para obtener equipo de campo. Los experimentos mostraron que los peces que pueden ser cultivados con éxito en Ghana son los géneros Tilapia, Labeo, Lates, Synodontis y Bagrus. Dada su prolificidad, las poblaciones de las especies de Tilapia son difíciles de controlar. Se averiguó que una forma sencilla de controlarlas es mediante el empleo de Lates niloticus y especies de Hydrocyon como peces predadores. Igualmente se ha observado que la producción íctica podría elevarse considerablemente con el uso de fertilizantes y aprovechando la orina y desechos del ganado porcino próximo a los estanques para fertilizar el agua de éstos.

Se ha visto que da buenos resultados la población de los estanques con varias especies a la vez. Se ha logrado obtener información suficiente para garantizar el éxito de una piscicultura comercial en el país.

1 INTRODUCTION

Ghana, situated on the Gulf of Guinea, West Africa, has an area of 91,844 square miles (1,469,504 sq km) and a population of about seven million people. The mean water temperatures are between 26° and 31°C.

Before the creation of the Volta Lake the only lake, a natural lake, existing in Ghana was Lake Bosomtwi near Kumasi. This lake has not supported any large-scale fishery; the physical features of the land around it render it inaccessible. Until recent years the supply of fish in markets all over the country was very limited. Fish obtained from the sea was not enough to satisfy demands because efficient modern fishing craft were not in use. This limited supply of fish, coupled with poor communications and transportation, meant that fish could not be evenly distributed to all parts of the country.

As protein deficiency was most common in the northern parts of Ghana, it was decided that fish culture should be tackled first in these areas. The northern portion of Ghana, about one third of the country, is mostly savanna grassland. Unlike the rest of the country it has only one rainy season a year beginning in April and ending in early October. A good number of streams and creeks are available in these areas but most of them soon dry up when the rains are over. In 1949 the Fisheries Department, despite few personnel, embarked on a program of work on stream improvements in the Lawra and Wa districts. Weirs were built across a number of streams to form pools during the dry season. These pools became a source of fish supply for many of the inhabitants nearby. One problem which came up at that time was that the local people knew nothing about fishing techniques and the staff of the department had to teach the people the techniques of fishing. This program of stream improvement could not proceed for long because there were not enough trained personnel, and facilities for doing this work were not easily obtained. The program was therefore abandoned, and in 1953 the construction of fish ponds started.

A number of small ponds were constructed at Turi-Kalsari near Lawra in the north-west. These ponds were sited below a water conservation dam built by the Tsetse Control Unit then operating in the area and had their water supply from the reservoir created by the dam. This fish farm was to serve as a research station, a demonstration centre for farmers and as a source of supply of Tilapia fry for other farms. These ponds were stocked with Tilapia nilotica, Tilapia zillii and Tilapia galilaea, and two species of Labeo (L. coubie and L. senegalensis). The fishes were obtained from the Kamba and the Black Volta with traps, seine nets and cast nets. The culture of these species in the experimental ponds was proving successful and soon many fry were being produced, but attempts to get the idea of fish farming over to the farmers proved unsuccessful as they had no means of constructing ponds.

2 MANAGEMENT OF WATER CONSERVATION RESERVOIRS AND PONDS

As it became impracticable to construct fish farms the whole project was suspended but fortunately at about the same time, in 1954, the conservation division of the Ministry of Agriculture started construction of water conservation dams in areas around Wa, Navrongo, Bolgatanga and Bawku. The reservoirs were created as sources of water supply for domestic use, for irrigation and for livestock. In the Wa area 17, and in the Navrongo, Bolgatanga and Bawku areas about 150, of these reservoirs have been constructed. They range in size from about 10 acres to about 80 acres (4 to 32 ha) in surface area. The Fisheries Department decided to utilize these reservoirs and 15 of them were stocked in the Wa district with fish obtained from the Turi-Kalsari fish farm.

Stocking of these reservoirs commenced in 1956 in the Wa area, and in 1958 in Bawku, Bolgatanga and Novrongo areas. In 1961 a station was opened at Bawku to coordinate work in these areas. All species involved in this fish culture program except one species belonging to the family Cichlidae are indigenous. The only introduced species, Tilapia macrochir was, as records show, introduced from East Africa into some reservoirs in the Bawku area. The name of the person responsible for this introduction is not on record.

2.1 Species cultured

Species cultured belong mostly to the families Cichlidae, Cyprinidae and Bagridae. The cichlids include Tilapia nilotica, T. zillii, T. galilaea, T. melanopleura, T. macrochir, Hemichromis bimaculatus and H. fasciatus. The cyprinids include Labeo senegalensis and L. coubie. The bagrids include Bagrus bayad, B. docmac, Chrysichthys nigrodigitatus and C. walkeri.

Species belonging to the families Cyprinidae and Cichlidae breed very well in small ponds but the species of the family Bagridae do not often breed in small ponds, although they do breed well in large reservoirs. Occasionally some undesired species appear in these reservoirs. Either they are wrongly introduced or they somehow find their way into these ponds. In so doing they cause the reservoir to be overcrowded and result in desired species becoming stunted.

Some of the species often found present in this way are Clarias spp., Alestes spp., Barbus spp., and some species of the family Schilbeidae.

2.2 Population control in ponds

Besides the presence of undesirable species in these ponds which in many cases cannot be prevented, it is also known from experience that Tilapia are prolific breeders and their populations are hard to control. As a result Tilapia species in such ponds never grow to desired size. Experiments indicated that the use of the predatory Nile perch, Lates niloticus and the tiger fish, Hydrocyon brevis and H. forskali in these ponds is very useful in population control. Not only do these species help to raise desired fish to the required size, but they themselves are good food fish which can be harvested whenever required.

2.3 Production

Annual catch records are maintained by the staff of the Fisheries Department. These figures represent catches made by people dwelling in villages around these reservoirs and and the figures for Wa and Bawku districts are shown in Table I.

Table I
Fish production in four reservoirs in Ghana

Species present in these reservoirs included Tilapia nilotica, T. galilaea, T. zillii, T. macrochir, Labeo senegalensis, L. coubie and species of the families Bagridae, Mormyridae and Siluridae. Production figures obtained for these reservoirs since the time they were stocked have not been very encouraging.

2.4 Experiments in rice field fish culture

These experiments were started in 1960 in two ponds (A and B) each of about ¼ acre (0.1 ha) in size in the Turi-Kalsari experimental fish farm. Pond B was the experimental pond and pond A the control. Experimental pond B was first fertilized with about 10 lbs (4.5 kg) of superphosphate before sowing with swamp rice. After the rice had germinated, the pond was flooded with water and then stocked with 820 Tilapia fingerlings on 13 June 1960. Species used were T. nilotica, T. zillii and T. galilaea (all less than 8 cm long). The same number and size of fingerlings were stocked in control pond A which was flooded with water only and no fertilizers used.

The numbers and sizes of fish harvested are shown in Table II.

Table II
Fish production in experimental ponds in Ghana

This experiment was repeated in 1961. But this time no fertilizer was used in the rice pond. At the beginning of the rains in May the ponds were filled with water after pond B had been sown with rice. Both were stocked with 710 Tilapia fingerlings (all less than 8 cm long). Again the species used were T. nilotica, T. zillii and T. galilaea. The fish harvested in November of the same year, six months after stocking, are also shown in Table II.

Results obtained from the above experiments were very encouraging and rice farmers who have their fields flooded during the rains were often advised to stock their fields with Tilapia fingerlings. This idea however did not become popular because the farmers had some difficulties. Most of them had their farms very far away from the Turi-Kalsari fish farm, or far away from any other fish pond where they could obtain fingerlings. Transportation facilities were not easily available to them and the idea could not get good publicity.

2.5 Fish culture and livestock

Another way of improving fish production in ponds involves keeping pigs by the ponds and utilizing their wastes as a source of nitrates for the ponds. A small channel constructed to link the sty and the pond enables pig urine to drain directly into the pond. This is being tried at the Turi-Kalsari fish farm and in the Bawku district. No specific data have been obtained as yet but the general indications are that such ponds are often rich in plankton.

In areas where the reservoirs are intended to provide water supply for livestock, these animals spend most of their time feeding around the catchment areas. Most of their droppings are therefore washed by rains into these reservoirs, enriching them with animal manure. Indications are that such reservoirs are more productive than those providing water for irrigation or for domestic uses. Similarly those reservoirs located in areas of good fertile soil are more productive than those located in areas having poor soil and poor vegetation.

2.6 Other stocking programs

In 1962 a similar program of producing fish in water conservation reservoirs was initiated. A station was opened at Sogakope, 70 miles (112 km) east of Accra, where several reservoirs were stocked with Tilapia species. Production figures for this area are not yet available for inclusion in this paper.

Fish farm construction was also started in 1964 at Dawhenya, 25 miles (40 km) east of Accra. Here three of 13 ponds completed have already been stocked with species of Tilapia and Labeo.

3. PROBLEMS ASSOCIATED WITH FISH CULTURE IN GHANA

(i) Evaporation: Many of these reservoirs dry up completely, or the volume of water becomes very much reduced during the six months dry season, due to high rate of evaporation. This high rate of evaporation coupled with seepage in some of the reservoirs renders them completely unsuitable for fish production.

(ii) Lack of fishing skill: In some cases inhabitants dwelling around these reservoirs have little or no knowledge of fishing techniques and therefore are unable to do any reasonable fishing in them. The result is overcrowding and stunted fish due to insufficient fishing. The Fisheries Department is now teaching these people fishing techniques and methods of making simple fishing gear.

(iii) Fish diseases: So far no serious outbreaks of diseases have been observed in any of the ponds or conservation reservoirs. However, during the rains many of the ponds are heavily infested with leeches, external parasites which attach themselves onto fish skin to suck blood. They have not been observed to cause death in fish.

In the Tongu district where pond fish culture was recently started a parasitic copepod, a species of Lernaea, has been observed to attack Tilapia species in many of the ponds and reservoirs. This parasite causes a red coloured swelling on the body of the fish but has not been observed to cause any mortality.

Pond fish diseases in Ghana need further study.

(iv) Aquatic vegetation: Aquatic weeds commonly present problems in many of the ponds and reservoirs. Sometimes they are not controlled as only mechanical methods of control are applied. Green and blue-green algae sometimes form blooms, and typical land plants sometimes form thick vegetation on the banks, but floating and submerged aquatic weeds are the most common. These include species of Pistia, Ceratophyllum, Nymphaea, Elodea, Potomogeton, the duckweeds, the bladderwort and some swamp grass. The use of herbicides has not been tried as yet, but this should be used if aquatic vegetation is to be kept under control.

4 CONCLUSIONS

Although pond fish culture was initiated some 12 years ago in Ghana, and since then attempts have been made to develop and expand work on it, many problems have hampered progress. The first and foremost problem has been lack of trained field technicians who could handle this work successfully. Another problem has been lack of equipment for field work. However, it is encouraging to observe that with a limited number of field staff some progress has been made. Efforts are being made to train enough field technicians to handle this work successfully. Once these problems are solved, Ghana can look forward to a prosperous program of pond fish culture which would contribute much to her economy.

5 REFERENCES

Davis, H.S., 1961 Culture and disease of game fishes. Berkeley and Los Angeles, University of California Press, 332 p.

Irvine, F.R., 1949 Fishes and fisheries of the Gold Coast. London, The Crown Agents for Colonies, 352 p.

Tal, S. and S. Sarig, 1961 Fish culture in Israel. Israel, Foreign Training Department, Extension Service, 35 p. (mimeo)

Ghana. Fisheries Department, Annual Reports:1957, 1958, 1959, 1960, 1961, 1962

Hoffman, G.L. and C.J. Sindermann, 1962 Common parasites of fishes. Circ.U.S.Fish Wildl.Serv., (144):17 p.