based on the work of
Ulf N. Wijkstrom (FAO Consultant Economist)
M.M.J. Vincke (FAO Senior Aquaculturist)
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 1990
1. Number and size of fingerlings needed.
Suggested stocking rate: 1000 fingerlings/hectare (= one per 10 m. square).
Water bodies to be stocked: dug-outs, not subject to flooding and subsequent natural stocking.
Total surface area:
those that regularly dry out: in the Northern Province, say 100 with an average surface area of 2 hectares (at maximum), thus 200 hectares.
those which are perennial and have not been stocked, say 100 with an average surface area of 3 hectares (at maximum), thus 300 hectares.
Dug-outs which are seasonal need to be stocked at the onset of the rains (that is, in the period May - June). The fingerlings need not be particularly large, as few predators should be present in these dugouts. Fish of 5 to 10 g should be sufficient.
A total of (200 × 1000 =) 200.000 should be ready at this point in time.
The stocking of the perennial dug-outs (for which some 300.000 fingerlings would be required) can be done at other times of the year. Thus, this requirement does not influence the size of the fingerling production facility. However, the fingerlings need to be larger, about 20 g, in order for a reasonable number to survive and establish a population in the dug-out. Predation from Clarias can be expected.
2. Size of fingerling production facility
The basic requirement is for a facility which has available some 200.000 fingerlings in early May for transportation to seasonal, non-flooded dug-outs.
The production of larvae (0.5 g) can be calculated at the rate of 20/m2/month. It takes about a month for these larvae to grow to a weight of 5 grams (Kestemont, P; J.C. Micha & U. Falter “Les methodes de production d'alevins de Tilapia nilotica”; FAO, ADCP; 1989, page 24). Thus, in order to obtain 200.000 fingerlings of 5 grams at the beginning of May, the reproduction should start at the beginning of March and the grow-out of larvae at the beginning of April.
Given the production of 20 larvae per m2/month, it would be necessary to have about (200.000/20=) 10.000 m2, or one hectare, of fingerling production ponds. However, it might be more economic to produce one lot of 30 day old fingerlings, weighing about 5 grams, and one lot of fingerlings, 60 days old, weighing about 10 to 15 g. The fingerling production ponds would then only need to have a surface of about half a hectare, as the larvae of two succeeding months would be used.
Larvae (0.5g) O. niloticus can be stocked at a density of 50 to 100 individuals per m2 in ponds fertilized with chicken manure. Rice bran will be added as supplementary feed. Assuming the lower stocking ratio of 50/m2, the pond surface areas for fingerling grow-outs would be as follows:
one batch approach (that is, all 200 000 to be of 5g each), 200.000/50= 4.000 m2.
the two-batch approach (100.000 at 5 grams and 100.000 at 10 to 15 grams), would need a slightly larger growout area as the larger fish can not be stocked at the same number/m2 as the smaller fish. Thus, (2.000 + 5.000 =) 7.000 m2.
The brood-stock will be kept in ponds at a stocking ratio of no more than 2 fish per m2. One female can produce at the rate of 200 to 300 larvae per month. One male is needed for four females. Thus, a promedium of 500 larvae for 4 fish in a period of 2 months. In order to produce 200.000 larvae, about (200.000/500=) 400 females are needed and 100 males.
Thus, in terms of surface area, the requirements for a stocking programme are rather small. With the one-batch approach it is (10.000 + 4.000 =) 14.000 m2.
With the two-batch alternative, the surface area requirements are (5.000 + 7.000 =) 12.000 m2. .
3. Economic aspects
3.1 Investment
The mission has estimated the cost of a one acre (4.000 m2) pond to be 0.5 million cedis. Thus, the ponds needed for the production of 0.2 million O. niloticus fingerlings, for yearly distribution starting at the beginning of May, would cost about 1.5 million, possibly a bit less, given the savings in construction of pond walls which is possible with contiguous ponds. Add to this 0.5 million cedis for seine nets, weighing scales, buckets, a store and a watchman's hut.
3.2 Operating costs
The direct operating expenditures for the fingerling production facility will consist essentially of salaries and chicken manure. However, from the point of view of the culture based fisheries operation, the cost of transport is going to be significant.
Staff. The fingerling production facility will need a staff of three during the fingerling production period (4 months) and a staff of two during the rest of the year. At C. 18.000/month for the foreman and C. 14.000 for the other two, the yearly bill will come to about (18.000 × 12 + 14.000 × 12 + 14.000 × 4 =) C. 446.000.
Feed. Feed will be a minor cost. The brood-stock of 500 fish, equivalent to some 115 kgs of fish (at 350 g average weight for males, and 200 g for females), will be fed with rice bran at the rate of 4 % of body-weight per day. In addition about 200.000 fingerlings, at maximum 20g each, should be fed for one month.
The total fish weight for the year is (150 + 200.000 ×. 02/12=) 483 kg. At a rice-bran feeding rate of 4% of bodyweight per day, and a price for rice bran of C. 20 per kg (mainly transportation costs) the total cost becomes (483×0.04×365×20=) approximately C. 140 000. This may seem like a substantial amount, but it is in fact no more than C. 400 per day.
3.3 Cost per fingerling
Placing the depreciation of the pond at 5 % per year, and of other equipment at 10% per year, the depreciation comes to about C. 125.000. The operating expenditures are C. 586.000 for feed and salaries. Add 20 % for unforeseens and the yearly cost is of the order of C. 700.000. Thus, the cost is of the order of C. 3 to C 4 for each fingerling. Thus, a price, ex-fingerling production centre, of Cedis 5 to 6 per fingerling seems reasonable.
