ANNEX 9
ECONOMIC APPRAISAL OF TYPICAL AQUACULTURE PRODUCTION UNITS (contd.)

6. RACEWAY CULTURE OF TILAPIA

This type of culture can be implemented in fresh water, in brackish water and in salt water. Only fresh water is envisaged in the following paragraphs.

6.1 Management of Production Unit

The culture of T. nilotica in raceways is a technically more complicated activity than its farming in ponds, and therefore this type of unit will need daily attendance of a well-qualified technician. It is envisaged that the raceway culture of tilapia will be one of several activities on the farm. The farm attendant in charge of the raceway will have gone through intensive, on-the-job oriented training of about three months duration at the pilot raceway unit to be constructed by the IFU.

6.2 Facilities

One production unit will consist of 10 concrete raceways, each measuring 10 m × 2 m and having a depth of 1.20 m (all inner measurements), water depth maintained at 1 m (0.2 m freeboard), and therefore the total volume of water per raceway is 20 m³.

In this example, it is assumed that water is supplied by gravity from a stream. Water can also be supplied by gravity from an irrigation system or through pumping from a well.

The reserves will be constructed in series making it possible for the water to be led from the first to the second raceway; from the second raceway to the third, etc. A shed will be constructed close to the unit. It will serve as a store for feed and provide a room for the night watchman. The raceway unit will be fenced off from the rest of the farm.

The farm unit must have some means of transport (for fingerlings, feed, spare parts, etc.). However, it cannot carry the charges of a vehicle full time, which it does not need, and it is assumed that it shares the use of a small pick-up truck with the rest of the farm.

6.3 Inputs during Culture Operations

Male fingerlings of T. nilotica (average weight 25 g) are bought from commercial (private or state-owned) hatcheries. The water in the raceway is gradually changed, permitting a water exchange of 2–4 times every 24 hours. However, as the surface area of the raceway is minimal, 200 m³, virtually no water is lost through evaporation. In fact the water is borrowed only and let out of the system with more nutrients (which can act as fertilizers) than it had when it entered.

The feed is of the compound type, containing 20–25 percent proteins (plant origin) and is given twice a day at a rate of 2 percent of the estimated body weight of the fish per 24 hours (that is, the equivalent of 1 percent of body weight in the morning and 1 percent in the afternoon). No fertilizers are used. The estimated feed conversion rate is 1.7 kg of feed to 1 kg of tilapia produced.

If two men work at the culture unit, the labour input is ample. They should both be trained in raceway culture and should take turns with the night shift.

6.4 Sequence of Culture Operations

6.4.1 Stocking

The stocking ratio is 200 male fingerlings of T. nilotica per cubic metre. This means that to stock one raceway of 20 m³, a total of 4 000 fingerlings are needed, i.e., 100 kg of fingerlings (4 000 × 25 g).

6.4.2 Feeding

Of the feeds available in Jamaica, Hi-Pro No. 3 or No. 4 (29 percent protein) may be used. However, in principle, any compound feed with 20–25 percent protein can be used. The quantity of feed distributed daily will be adjusted every two weeks in order to make it correspond to the guideline of 2 percent of body weight per 24 hours. The adjustment will be made on the basis of a random sample of fish in the raceway.

6.4.3 Care of stock

Water inflow should be checked regularly to avoid depletion in the water. The staff should have some knowledge of fish diseases and how to cure them.

6.4.4 Harvesting

The harvesting can be done, for small quantities, with dipnets. For complete harvesting, the raceways will be drained.

6.4.5 Marketing

The fish will be sold fresh at the farm for a wholesale price of J$ 1.70/1b, the equivalent to J$ 3.75/kg.

6.5 Yield

It is assumed that the growth rate will be of the order of about 1.8 grams/24 hours/fish on the average (as compared to 2.2 grams/24 hours/fish and higher - for pond grown fish). Also, which is natural, the fish needs a more complete diet and more feed, as the concrete tank prevents any contribution of nutrients to come from the side of the tank, as it does from the bottom and sides of ponds. Therefore, the conversion ratio is placed at 1.7 (kgs of feed for one kg of fish) instead of 1.3 as calculated for the pond grown fish.

The survival in the raceways has been placed at 90 percent. Thus, of the 4 000 fish stocked per raceway, 3 600 will grow to an average size of about 240 grams in a period of 120 days (17 weeks of four months). The total production per raceway is thus (3 600 × 240 =) 864 kg per culture cycle. One raceway can be used in three cycles during the year and thus produces 2 592 kgs in a 12 month period. The family unit of 10 raceways will thus produce just under 26 tons (about 57 000 1bs) in the year.

6.6 Returns on Effort

The table showing costs and income demonstrates that income and cost just balance, at a price of J$ 1.70/1b (J$ 3.75/kg). The returns to management and land therefore are low. The production per man-year of employment is high, about 13 t of fish per man and year employed.

7. POND CULTURE OF FRESHWATER PRAWN

7.1 Management of Production Unit

The culture of freshwater shrimp is a technically more complicated activity than the culture of tilapia. Thus this type of unit will be run, at least initially, by technologically qualified managers on farms which probably also have other activities. The farm attendant in charge of the ponds will have gone through intensive on-the-job oriented training of at least three months duration.

7.2 Facilities

The fresh water supply is by gravity from an irrigation channel for which irrigation dues are paid. Drainage is by pumping; the water is returned to the irrigation system. The farm unit consists of eight ponds of half an acre each. A storage shed is built close to the ponds inside the wire fence. The shed houses the night guard.

7.3 Inputs during Culture Operations

Post harvest larvae of M. rosenbergii are bought from commercial (private or state-owned) hatcheries. The culture system is of the batch type, which means that the stock is harvested in principle on one occasion, through drainage of the ponds. Feed of a compound type is given. The labour input is amplé if two men work full time at the unit; in principle, both should be trained in fresh water shrimp culture, taking turns with the night shift.

7.4 Sequence of Operations

7.4.1 Stocking

The recommended stocking rate is 20 post-larvae (PL) per m² which equals 80 000 PL/acre or 200 000 PL/ha. Post larvae of 1–4 weeks of age (after metamorphosis) will be used.

7.4.2 Feeding

Different diets can be utilized, but compounded diets are generally more efficient than other feeds. Protein content should be 20–30 percent with a conversion ratio of about 2.5 to 1. Tilapia feeds (Hi-Pro No. 3 and No. 4) can be used. One can also mix several ingredients such as rice bran, trash fish, poultry offal and grind them in a meat grinder.

7.4.3 Harvesting

At the end of the nine-month rearing period, the ponds will be drained. It is expected that the weight of the Macrobrachium will then have reached 30 g (head on). However, there is normally a wide divergence in the growth rate of a population of M. rosenbergii raised in ponds. Therefore, it is possible to obtain marketable sized shrimps also at the end of the seventh or eighth month through the seining of the pond. Smaller prawns, captured by the seine are returned to the pond for further growth. The seine net should have a mesh size (stretched) of between 3.8 and 5.0 cm (1 1/2 – 2 in).

7.4.4 Post harvest operations and marketing

Initially, shrimps will be sold in Jamaica. In the Jamaican market, the shrimp will be sold live or on ice, or frozen. For the fresh market, the shrimp should be killed through immersion in iced water and then blanched for 15–20 seconds in water with a temperature of between 60°C and 65°C. After blanching, the shrimps are iced and transported to wholesale and/or retail outlets.

Table 9.5.1

Investments

Type of aquaculture production unit: Pond culture of tilapia

Table 9.5.2

Costs of Operation and Income

^a All inputs are available in Jamaica

Type of aquaculture production unit: Pond culture of tilapia Length of period studied: Grow-out period is 13 weeks, 2 weeks downtime for pond preparation makes a total cycle of 15 weeks. Assumed 3.25 cycles/year

Table 9.6.1

Investments

Type of aquaculture production unit: Raceway culture of tilapia

Table 9.6.2

Costs of Operation and Income

Type of aquaculture production unit: Raceway culture of tilapia Length of period studied: One production cycle of four months

Table 9.7.1

Investments

Type of aquaculture production unit: Pond culture of freshwater prawn

Table 9.7.2

Costs of Operation and Income

Type of aquaculture production unit: Pond culture of fresh water prawn Length of period studied: Duration of one cycle of production in a batch culture system, estimated at 9 months

7.5 Yield

Expected survival is 50 percent for shrimps grown up to an average size of 30 g (the variation in size is likely to be considerable) after a nine month growing period. Thus the production per acre is (0.5 × 20 × 4 000 × 30) 1 200 000 g which is the same as 1 200 kg (or about 2 640 1b/acre).

7.6 Return on Effort

Return to management per farm and year is of the order of J$ 8 000.

8. COMMERCIAL PRODUCTION OF MALE T. NILOTICA FINGERLINGS

8.1 Management of Production Unit

The fingerling production farm is independent of tilapia grow-out operations. It does not have any tilapia grow-out ponds. It is operated for profit and owned by private entrepreneurs. The farm superintendent should be an experienced aquaculturist.

8.2 Facilities

The farm unit consists of 10 ponds for holding brood fish, each with a surface of about 550 m² (55 × 10 m) and 20 fry grow-out ponds, each with a surface of 2 000 m² (20 × 100 m). Ponds are fed by gravity and drained by pumping. The farm has full use of one pick-up truck. A storage shed is available on the farm unit. The ponds containing brood stock are surrounded by a security fence.

8.3 Inputs during Culture Operations

The main inputs are labour and feed. The farm has a full-time staff of 12 which is made necessary essentially by the labour intensive task of hand-sexing tilapia fingerlings. Standard pelletized composit feeds are used.

8.4 Sequence of Culture Operations

8.4.1 Stocking

Parent brood fish of about 150 g average weight for males and 100 g average weight for females are stocked at a ratio of one fish to one square metre in brood-stock ponds. The cost projections assume that all brood-stock is replaced once a year.

Fry is stocked in fry grow-out ponds at a ratio of 17.5 fishes/m². This means each half acre pond (2 000 m²) receives 35 000 fry for grow-out to fingerlings.

8.4.2 Feed and fertilizer

Both brood-stock and fry are fed pelleted feed at four percent body weight per day. Fertilizers are applied weekly to brood-stock ponds and grow-out ponds. The choice of fertilizer will depend on availability and price. Chicken manure gives better blooms and growth results than chemical fertilizers. If available for two cents or less a kilo within a distance of 15–20 km, it might be a better alternative than chemical fertilizers. It should be applied at the rate of 160 kg fortnightly in half-acre ponds.

8.4.3 Harvesting

Fry are harvested at about seven week intervals from the brood ponds, usually by seining. Harvesting of fingerlings in fry grow-out ponds is done through drainage.

8.4.4 Marketing

Fingerlings will be sold ex-farm at a price of J$ 0.18 each. If the customer wants delivery to their ponds, this will be charged extra.

8.5 Yield

The fry production is based on the observed fact that a female T. nilotica produces about 1 400 fry per year. Mortality in the brood ponds has been put at 10 percent.

During the seven week fry grow-out period, the mortality has been put at 55 percent. This means that the average yield per fry grow-out pond and seven week period is 15 000 fingerlings from 35 000 fry.

8.6 Return on Effort

Costs are covered if an average price of J$ 0.18 is charged per fingerling produced. This price assures return to land (if assumed that a rent of J$ 200/acre/year is satisfactory), but leaves almost no return to management. For management to obtain a return of J$ 10 000/year, the average fingerling price must increase to 18.5 cents.

Table 9.8.1

Investments

Type of aquaculture production unit: Commercial production of male T. nilotica fingerlings - 1 million per year

Table 9.8.2

Cost of Operation and Income

Type of aquaculture production unit: Commercial production of male T. nilotica fingerlings - one million per year