ANNEX 9
ECONOMIC APPRAISAL OF TYPICAL AQUACULTURE PRODUCTION UNITS

1. Culture of mangrove oysters on rafts

2. Culture of penaeid (marine shrimps) in ponds

3. Culture of tilapia in pens in salt water

4. Cage culture of tilapia in salt water

5. Pond culture of tilapia

6. Raceway culture of tilapia

7. Pond culture of fresh water prawn

8. Commercial production of male T. nilotica fingerlings

Notes on the Method of Economic Appraisal

A table showing investments and a table showing the costs and income for a typical production period (usually one year) is included for each typical aquaculture production unit. Unit prices and number of units (of inputs and outputs) are given in these tables. Unit prices are those valid at the beginning of 1983.

The purpose of the analysis is to obtain an idea of the likelihood that a certain aquaculture production unit (believed to have such characteristics that it can become typical) can become economically viable. The analysis is brief. It concentrates on the important items of cost and is intended to reflect the situation expected to prevail when the unit has overcome its teething problems.

The analysis is based on the assumption that inflation is zero. This is equivalent to the assumption that the inflation which will occur will affect all prices to the same extent. Therefore, the interest rate used, 12 percent per year, is in fact a high interest rate (for technical reasons this interest rate has been applied on half the investment in order to obtain an idea of the typical annual capital cost).

1. CULTURE OF MANGROVE OYSTERS ON RAFTS

1.1 Production Unit

A production unit of 16 rafts is envisaged consisting of four family-sized units each composed of four rafts. Each four-raft unit will be operated intermittently by two to three men, except during harvesting when additional workers will be hired. The family will receive technical advice to establish itself and to market its first crops, after which, support will be gradually withdrawn. Initially, oyster seed and some materials will be provided free of charge.

1.2 Facilities

The rafts will be constructed of bamboo poles and will have dimensions of approximately 8 m × 5 m and will be floated by 44 gal empty drums. The rafts will be anchored to concrete weights in water of not less than two metres depth. For the initial launching of the raft, an outboard engine powered boat will be used. For subsequent monitoring of the growing out oysters, the farms will utilize a canoe.

1.3 Inputs during Culture Operations

Oyster spat will be supplied from the central seed collecting farm at Bowden, on cultch already strung up for growing-out. These spat will average 1.0–1.5 cm in length. Strings of oyster laden cultch will be monitored once a week for foulings and string chafing. The husbandry operation will engage the farmer for one day per raft each month for five months.

1.4 Sequence of Culture Operations

1.4.1 Stocking

The cultch strings with spat are to be securely hung from the beams of the raft (approximately 40 cm between each string) and the bottom cultch on each string should be at least 50 cm clear off the bottom (at low tide).

1.4.2 Care of oysters

A sample of the cultch strings will be inspected at least once a week for chafing of the strings and degree of fouling organisms present. Chafed strings should be changed and the fouled cultch strings exposed by laying them out on top of the rafts in the sunlight for a period not exceeding six hours.

1.4.3 Harvesting

Harvesting will be done on shore by carefully removing oysters at the end of a 5–6 month growth period. They will then be washed, sorted, graded and chilled.

1.4.4 Marketing

Orders will be secured for oysters prior to the harvest date and the oysters will be delivered to door.

1.4.5 Yield

While each raft is provided with at least 10 000 spat, the marketable production has been calculated at 6 000/raft, a loss of 40 percent in number of oysters being foreseen.

1.4.6 Return on effort

At an ex-raft price of J$ 1.80 per 12 oysters, the return to management, after all costs, is in the order of J$ 400/year. This is small, and it would seem likely that the family-sized unit should have a larger number of rafts than foreseen in this example.

Table 9.1.1 - Investment

Type of aquaculture production unit: Culture of mangrove oysters on rafts

Table 9.1.2 - Cost of Operation and Income

Type of aquaculture production units: Culture of mangrove oysters on rafts Length of production period in months: 5 months + 1 month turn around time Date prepared: 5 February 1983

2. CULTURE OF PENAEID (MARINE) SHRIMPS IN PONDS

2.1 Management and Location of Production Unit

A production unit of 10 ha (water area) would be operated by an entrepreneur, partnership or corporation, employing a farm staff of hired workers.

The following criteria should be observed in choosing the site for the farm:

1. land elevation from 30 cm to 50 cm above high water mark;

2. nearness to clean sea water;

3. impermeable, though not necessarily heavy clay, soils; and

4. availability of fresh water from a perennial river uncontaminated by sewage, pesticides, acid run-offs and industrial pollution.

2.2 Facilities

The farm will have ten 1 m deep, l ha rectangular ponds, five on each side of a central water supply channel, and drain canals at the opposite ends to provide a flow-through system of water management. Due to the narrow tidal amplitude, water will be supplied to a large extent by pumps; drainage will be by gravity. Fresh water will be used to control salinity for optimal and rapid growth of the shrimp. Perimeter dikes will be motorable; all dikes constructed to prevent seepage. There will be a building with offices and storerooms for feeds, ice and equipment; a garage and sufficient space for open shed work. A concrete chilling tank will be part of the work area, and clean running water will be piped in.

Other equipment will include a 1-ton pick-up, ice crusher, portable centrifugal pumps, weighing scales, nets and seines and laboratory equipment for determining water quality (Annex 1).

2.3 Inputs during Culture Operations

The main inputs will be post-larvae of either Penaeus vannamei or P. stylirostris (which will be imported until hatchery produced fry are available locally) and imported pelleted feeds prepared by a special extrusion process that produces pellets with water stability up to six hours. Farm operations will be managed by a trained technician, assisted by a work force of caretakers/guards and a driver/mechanic. Casual labourers will be hired as required, particularly during the harvest time.

2.4 Sequence of Operations

2.4.1 Pond preparation

The ponds will be drained after each harvest and dried for two weeks following which they will be filled with new water, by pumping. By passing incoming water through proper filters, entry of shrimp predators will be prevented.

2.4.2 Stocking and care of stock

Stocking will be at the rate of 60 000/ha. The post-larvae shrimp will be properly acclimatized to temperature and salinity before they are released in the ponds. Feed will be given shortly after dark each day. A part of the water in each pond (about 7 percent) will be changed daily. Water quality, particularly salinity, dissolved oxygen and temperature will be monitored regularly. Stock will be sampled randomly every two weeks to determine the daily quantity of food to be fed.

2.4.3 Harvesting

The harvesting will be done by draining. Bag nets will be fitted to the drain gates, and the shrimp collected as they are caught. Harvested shrimp will be washed, chilled, packed in ice in small fish boxes and brought to the market centres.

2.5 Yield

At the end of a grow-out cycle of four months, shrimps are expected to average 20 g in weight. Survival is placed at 50 percent. This gives a total production per hectare of pond (60 000 × 0.5 × 20) as 600 kg (about 1 320 1b) of shrimp.

2.6 Return on Effort

The total costs of production, however, not including land rent, is of the order of J$ 22.70/kg live weight. This is higher than the Jamaican or foreign market can be expected to afford.

3. CULTURE OF TILAPIA IN PENS IN SALT WATER

3.1 Production Unit

The fish pen will cover an area of two hectares. It will be operated by hired labour for a corporate body (cooperative, private entrepreneurs).

3.2 Facilities

The pen will be constructed in a shallow bay with protected waters. The average depth of the pen will be about 1.2 m. Full details of supplies, materials and equipment are given in Table 9.2.1. The pen will need some shore-based facilities for conditioning of fingerlings, storage of feeds, handling of harvested fish. A minimum of two small boats (dugouts) will be needed for the operations, one for use in the pens and one for use between the pens and land.

3.3 Inputs during Culture Operations

The pens will be stocked with T. mossambica and/or T. nilotica if the latter are found to prosper well in marine conditions also. The fish will be fed and employment will be provided for two labourers. It has been the experience elsewhere (e.g. the Philippines) that T. mossambica when grown in salt water has a more appealing taste than when grown in fresh water.

3.4 Sequence of Operations

3.4.1 Stocking

Tilapia fingerlings collected from inland waters or grown in ponds will be stocked after they have been acclimatized for 24–48 hours to seawater conditions.

3.4.2 Feeding

The fish will be fed two to four times daily with artificial diet containing 25 percent protein mainly from plant origin, the quantity of feed adjusted every two weeks, based on growth response and the estimated fish biomass.

3.4.3 Care of pens

The pens will be inspected daily for rents or tears and repaired immediately. Anchorage to the bottom should also be checked regularly.

Table 9.2.1

Investments

Type of aquaculture production unit: Culture of marine shrimps in ponds Corporate management of 10 ha (water surface area) unit

Table 9.2.2

Cost of Operation and Income

^a This price is slightly below the comparable import price for frozen (in the 36–40 count), headless and deveined shrimps. It is well above an average ex-boat price for whole shrimp landed by the US shrimp fishing fleet.

Type of aqauculture production unit: Culture of marine shrimps in ponds Corporate management of 10 ha (water surface area) unit Length of period studied: One year. The cycle is projected as just under 5 months, including three weeks down-time between cycles

3.4.4 Harvesting

A lift net (about 10 × 10 m) will be used. The net will be laid on the bottom; feed will be broadcast over it to attract fish, and then the net will be lifted vertically. Harvested fish will be brailed, after a short struggle, into the chilling tank which is filled to one-third with iced sea water. After succumbing, the fish will be packed in fish boxes with alternate layers of crushed ice.

3.5 Yield

The average tilapia is expected to weigh 250 g. The total number expected to be harvested is 12 000 tilapia per hectare and cycle. At the stocking rate of 20 000/ha, this means a survival of 60 percent. The targeted growth rate is an average of 1.3 g/day.

3.6 Return on Effort

At the current wholesale price for tilapia grown in fresh water (J$ 3.75/kg), the return to management is low, about J$ 1 500/year. However, the likelihood that tilapia grown in salt water will fetch a better price than those reared in fresh water is good. A price of J$ 4.00/kg would increase the return to management to about J$ 3 000/year.

4. CAGE CULTURE OF TILAPIA IN SALT WATER

4.1 Management of Production Units

The cages will be owned by families. For reasons of security it is expected that development will take place only in those sheltered bays where space is available for not less than 10 such family units. The families can then form a supplies and marketing cooperative which would also jointly undertake the surveillance of cages.

4.2 Facilities

The cages will be constructed of synthetic nets and will measure approximately 3 m wide, 3 m long and 3 m deep. Four such cages will be attached to one floating raft. The cages are generally maintaining a free board of at least 0.5 m open, but should be fitted with flaps where predation by birds might be a problem. One family unit would consist of two such rafts. A canoe and some minor pieces of equipment would be needed for operations. (see Table 9.3.1, Investments, for details). Cages will be located in sheltered bays in areas with a depth of at least 3.5 m.

4.3 Inputs during Culture Operations

The cages will be stocked with 40–50 g fingerlings of T. mossambica or T. nilotica if the strain available in Jamaica is found to do well in salt water. Both male and female fingerlings will be used. The fish will be fed. As no skills are needed for the feeding and maintenance of cages, it is well suited for non-wage earners.

4.4 Sequence of Operation

4.4.1 Placement of unit

The rafts and cages having been constructed on land are towed to sites and anchored.

4.4.2 Stocking

Fingerlings collected from inland waters will be acclimatized for a period of 24–48 hours to seawater conditions and then stocked in the cages. The stocking rate will be at least 20 per cubic metre.

4.4.3 Care and feeding of stock

Feeding will be the principal activity after stocking. Feeds can be prepared by the operators, using simple grinders/mincers, and fed at regular intervals, either as moist or sundried pellets two to four times daily. Feeds with 25 percent protein derived mainly from plant origin will be sufficient for tilapia. Diseases should be watched out for and immediately treated. For external parasites, fungus and bacterial infection, dipping or bathing in chemical solution is recommended; for internal diseases responding to drugs, incorporation of the drugs with the food is the most practical.

Table 9.3.1

Investments

Type of aquaculture production unit: Culture of tilapia in pens in salt water

4.4.4 Harvesting

There will be two growing cycles a year. If the fish are of uniform size, harvesting will be done as soon as they reach 250 g weight. Otherwise, culling will be done with the bigger fish taken out from time to time. However, care should be exercised to prevent body harm to the remaining fish as a precaution against onset of disease. Harvested fish, while still alive, will be bailed into a container filled one-third with chilled sea water and after they have succumbed, packed alternately with layers of crushed ice in fish boxes. This operation is to ensure prolonged freshness.

4.4.5 Care of rafts and cages

Rafts should be rigid, floats checked for rust and replaced if found defective. Cages should be inspected each day for tears. After each crop, cages will be lifted out, hung in the shade and beaten to loosen and remove dried fouling organisms.

4.5 Yield

Cages are stocked each with 450 juveniles, of which 80 percent are expected to survive and grow to marketable size. Estimated production therefore is 90 kg/cage (450 × 0.8 × 0.25).

4.6 Return on Effort

The total cost of production is more than J$ 5.00/kg of live fish at cage side. Given present tilapia prices, this return is not interesting.

5. POND CULTURE OF TILAPIA

5.1 Management of Production Unit

It is presupposed that this fish farm unit be established on an agricultural farm of some size which is used for rearing livestock or chickens. The farm manager will pay only occasional attention to the fish farm and it is assumed that the fish farm attendant will have obtained some on-the-spot training/instruction with regard to the sequence of operations (see below). However, the farm is independent of Government support, possibly with the exception of the supply of male fingerlings (which will be sold at cost price).

5.2 Facilities

The fresh water supply is by gravity but originating in an irrigation canal (and therefore dues are paid for the water). Drainage is by pumping. The farm unit consists of four 1 acre ponds (100 × 40 m). A storage shed is built close to the ponds. It also has a room for the overnight guard.

5.3 Inputs during Culture Operations

Male fingerlings of T. nilotica are purchased from a commercial hatchery. It is assumed that they have an average weight of 25–30 g. Ponds are fertilized and fish are fed with granulated composite fish feeds manufactured by the local animal feed industry. Average labour input will amount to one labourer per day of operation, or one labourer per year.

5.4 Sequence of Culture Operation

5.4.1 Stocking

Male fingerlings are stocked at a rate of 6 000/acre/cycle (15 000/ha/cycle). Before stocking takes place 400 lb (180 kg) of fertilizer (12–24–12) has been supplied per acre of pond (only one application during the grow-out period).

Table 9.3.2

Cost of Operation and Income

Type of aquaculture production unit: Culture of tilapia in pens in salt water Length of production period in months: 180 days (including stocking and harvesting operations)

Table 9.4.1

Investments

Type of aquaculture production unit: Cage culture of tilapia in salt water

Table 9.4.2

Cost of Operation and Income

Type of aquaculture production unit: Cage culture of tilapia in salt water Length of production period: 170–180 days

5.4.2 Feeding

Feeding with compound feed is done at the rate of an estimated 2 percent of body weight and day. Feed is broadcast from the pond dikes.

5.4.3 Harvesting

Harvesting is done initially by seining, and at the end of the 13 weeks growing cycle, by complete drainage of ponds through pumping (through gravity flow whenever possible).

5.4.4 Marketing

Fish will be sold wholesale at pond-side (or ex-farm gate) at a price of J$ 1.70/lb which is equal to J$ 3.75/kg.

5.5 Yield

The yield is placed at 2 500 lb of half pound fish per acre per cycle of 13 weeks (91 days). This means that the survival (5 000 fish out of 6 000) is about 83 percent. The average growth rate (227–27) is 200 g over a 13 week period, or about 2.2 g/fish/day.

5.6 Returns on Effort

If fish is sold at J$ 1.70/lb, the return to management (assuming a land rent of J$ 375 per acre of pond surface area per year) is about J$ 9 000/year for the fish farm as a whole.

Fish production is equivalent to about 3.6 t/acre/year and 14.7 t/labourer/year. This later figure indicates a much higher productivity than that normally associated with artisanal marine fishing for example.