based on the work of
Ulf N. Wijkstrom (FAO Consultant Economist)
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 1990
1. General
The Agricultural Restructuring Programme is emphasising that production should take place in the private sector and that the public sector should be reduced and made more effective. Thus, any proposal for increasing the activities of the public sector needs to be justified in economic terms.
One aspect of the economics of development of fish farming in Ghana is the relatively high costs of transport, and the relatively low cost of personnel. The former implies that it is useful initially to find a region where there are a relatively large number of potential fish farmers, located within two to three hours travel from the headquarters of the fish farming development expert.
The analysis in terms of regions is also useful in terms of the application of the Geographical Information System.
2. Size of critical mass
In view of the “optimization” of the use of the public service, it would seem that the critical mass should be linked to the work possibilities of one senior Fish Culture Extension Officer. As explained elsewhere in this report, the mission considers that the day to day work of extending aquaculture technology should be handled through the agricultural extension service. The role of the Fisheries Department should be one of “consultant” or “instructor” to the agricultural extension service.
Thus, the Senior Fish Culture Extension Officer should divide his time between training agriculutral extension officers and advising fish farmers, generally while visiting their ponds. It can be assumed that the officers spends 50 days a year on training agricultural extension officers and 200 days a year visiting fish farmers, both active and potential, in the company of agricultural extension agents. Furthermore, we specify that he will spend at the most one day a year with each farmer, once they are established.
The officer should be able to develop his area within a period of five years (on average, 40 new farmers per year). Given the generally small size of holdings in Southern Ghana, an average pond surface area of 1000 m square per holding would seem to be the largest possible. The surface area is likely to be split up in three to four ponds. The total surface area in the “critical mass” area would then be of the order of (200 × 0.1 =) 20 ha.
3. Economic implications
Assuming an average productivity of 4 tons/ha/year (in two crops), the total production would be of the order of 80 tons per year. At a pond-side price of 300 cedis per kg, the production would be worth about C. 24 millions.
The expenditure on extension would be modest in comparision. The salary of the Senior Extension Officer would be less than 0.5 million. The main expenditure would be the transport required by the officer. That will total some 2 to 3 million cedis per year.
4. Inputs needs
For the purpose of the GIS, the minimum requirements of inputs are as follows:
pig manure 1 pig per 100 square metre, or 100 per hectare, thus a total of 2.000 pigs.
chicken droppings: 15 chickens per 100 square metres or 30.000 chickens for 20 hectares.
rice bran: for a 0.4 ha mixed sex O. niloticus farming operation of two cycles per year, about 8 tons of rice bran are required. Thus, a 20 hectare scheme, based on rice bran and monoculture of O. niloticus, would need (20/0.4 × 8 =) 400 tons of rice bran during one year. Given that rice bran, in weight, is equivalent to 2 to 4% of the paddy, the paddy requirement is 13 300 tons, or a rice requirement of 8 860 tons. Given that a yield for a single crop of paddy is about 1.5 tons/ha/year for non-irrigated rice, the surface area requirement is equivalent to 5 900 ha, from which all rice bran is given over to fish farming.
