A number of considerations must be made to determine possibilities for developing aquaculture. Markets and technologies must be evaluated; so must the availability of the inputs to the production process. The study group's assessment of these aspects have been expressed in the previous chapter. In this chapter the discussion is focused on the technologies, or culture systems, which appear most likely to develop given species and sites (see annexes 5, 6, 7 and 8).
The study group came to the conclusion that there are principally four mariculture technologies of immediate interest for Jamaica. They are:
culture of marine fish in pens
culture of marine fish in cages
culture of marine shrimps in ponds
oyster culture on rafts
Culture of marine algae (Irish moss in particular), conch (Strombus gigas), sea urchins and turtles were considered not to be of immediate interest for the island. The reasons are given in Annex 7.
The main advantage of cage culture of fish is the relatively low investment (compared to ponds) that is required in culture activities. This is so partly because comparatively large quantities of fish can be held in relatively small volumes of water. This is made possible only because the fish is provided virtually all its feed requirements in the form of pellets or trash fish. In addition, there is constant replenishment of oxygen - and removal of waste products - as water flows through the walls of the cages, which are usually made of synthetic netting.
Two recent developments in design of fish cages are of interest. First, cylindrical cages are used for sea bass culture. They are rotated in the water, permitting removal of fouling algae on the net walls. Second, some cages are now moored so that they are submergible. This is very useful in hurricane-prone areas as it protects the cages from wind damage.
As indicated in Annex 8 there are a number of sites on the Jamaican coast where cages could be installed. Their construction from locally available material does not constitute a problem.
Marine cage culture of fish has so far been done primarily with yellow tails, salmonids, groupers, snappers and sea bass. These species are cultured in cages in Japan, Malaysia, U.S.A., Europe, Singapore and Hong Kong. Fingerlings and juveniles are required to start an operation and should either be obtained by fishing or from nurseries. Supply of sufficient quantities of the reef species in Jamaica is unlikely. First, they are considered marketable already when they reach a size of 100 to 150 grams; and secondly, they sell at J$ 6.60/kg or more in retail markets. A pen or cage culturist could not afford such a price. However, the possibility of T. mossambica and/or T. nilotica being used is highly promising with stocking material from fresh water gradually made to adapt to salt water by acclimatisation.
The study group appraised the economics of a family-managed cage culture unit. It would comprise four cages, require an investment of about J$ 8 000 (including the working capital) and produce an estimated 1 400 kgs of fish per year. However, given present unit prices of inputs and outputs, such a family ‘farm’ would not be able to cover its operating costs (see Annex 9, section 4).
Pens, usually are located in water with a depth of up to 3 metres. In Jamaica a depth of between 1 and 2 metres would be most appropriate. Several bays with suitable conditions exist in Jamaica (for details see Annex 8).
The main difference between fish cages and pens is that cages are small (about 27 m3 each in Hong Kong) and movable. Pens are large (from a few hundred square metres up to 20 ha) and stationary. Fish pens have walls of synthetic netting, kept in place by posts set into the bottom of the bay or cove. The bottom edges of the nets are weighted down and buried in the substrate. A free-board is maintained above the water level. This is meant to prevent the water surface at highest tide from rising above the edge of the netting. The materials needed for construction of fish pens are available in Jamaica.
The species which can be cultured in cages can also be cultured in pens. As the food available naturally in the pens would not be sufficient to support the required stocking densities, supplementary feeding is likewise required.
For reasons similar to those advanced regarding selection of species for cages, the study group has appraised the economics of pen culture based on monoculture of tilapia. The unit is expected to be operated by hired labour. It consists of one pen of two hectare size, with an estimated production of 6 000 kg, split in two production cycles per year. The group's appraisal concludes that costs will be covered by the income generated. More details are available in section 3 of Annex 9.
Fish and/or shrimps can be raised in brackish water ponds, located in inter-tidal zones. Preferably the sites should have: (i) impermeable soils which are free from acid sulphate; (ii) fresh water to regulate salinities, and (iii) sufficient tidal head for water management by gravity. In the Far East such areas are usually low-lying mangrove swamps. In Jamaica mangrove swamps exist but their acreage is small (see Annex 10) and the Government is keen to maintain them undisturbed so as not to upset existing ecological balances.
However, the operation of brackish water ponds on the Jamaican coastal lowlands faces a more formidable obstacle: the insufficiency of the tide. A minimum amplitude of 1.2 m is necessary to ensure adequate water exchange even in a shallow (30 cm) leveed pond. As the normal differences in tidal levels are only on the order of 15 to 20 cm in Jamaica, sea water must be pumped into or out of the ponds in order to ensure the required water exchange.
There are only relatively few areas in Jamaica that are ideally suited for the construction of this type of pond. The study group has identified the areas just east of the mouth of Black River as the best site. Other areas where it would seem feasible to construct brackish water ponds at a reasonable cost have been listed in section 4.2.2 above. None of those areas would seem to be any larger in extent than the site at Black River. The study group's appraisal of the sites is of a preliminary nature and the suitability of each needs to be confirmed through detailed, on-the-spot surveys of soil and hydrological characteristics.
Iversen, Monro (1969) and Steele (1983) report six species of marine shrimps as indigenous to Jamaica. The species are: Penaeus schmitti, P. duorarum, P. aztecus, P. braziliensis, xiphopenaeus kroyeri, xiphopenaeus sp. and Trachypenaeus sp. Experimental and commercial mariculture has been carried out elsewhere with the first four species.
Given the fact that neither U.S. mariculturists nor anyone else has as yet managed to develop commercially satisfactory systems in the Caribbean area, the study group is of the view that entrepreneurs willing to invest resources in pilot shrimp culture ventures in Jamaica should consider the possibility of using non-indigenous species. P. vannamei and P. stylirostris have been and are presently being cultured in Panama, and are being cultured in Ecuador. Both species were tried in the Philippines and did well there. The Indo-Pacific tiger shrimp, P. monodon, and the Japanese prawn, P. japonicus, have been bred using eye-stalk ablation techniques in areas outside of their native habitats. P. japonicus is now being cultured in Brazil.
The study group consequently has based its appraisal of a shrimp culture unit (pond culture) on the use of P. vannamei (juveniles to be imported from a commercial hatchery in Panama and commercial feed from the U.S.). The unit has 10 one hectare ponds, each expected to have a yearly production of 1 500 kg (in two and a half crops). The study group concluded that a farm of this type would not be economically viable. The figures leading up to this conclusion are given in Annex 9, Section 2.
The development of pond-based mariculture is slow. Part of the reason is found in the need to stabilize ponds after construction and the time it takes for good bottom soil to develop. Therefore it seems that even if the first steps towards establishing a shrimp culture industry in Jamaica were taken in mid 1983, the first commercial production would not be available until some time in 1986, at the earliest.
The study group is of the view that the oyster culture project has done a good job of adapting the raft culture technology to local conditions. The technical feasibility of the culture has been proven and it does not seem evident that the productivity of the system can be improved to any great extent, either by using other material for rafts or cultch, or by introducing a radically different technology of culture.
The study group appraised a hypothetical commercial oyster culture unit. It was postulated to be family-operated and consist of four rafts with a yearly production capacity (in two production cycles) of 4 000 dozen oysters per year. The investment required is on the order of J$ 3 500. The study group concluded that this unit would be economically viable. More details are found in Annex 9, Section 1.
While the economics of operation of the individual oyster culture unit are assured, the Government of Jamaica is now facing the need to start commercial oyster culture somewhere. If not, the practice will not spread. However, assuming that this can be done, what would be a reasonable magnitude for the oyster culture industry in the future, assuming that oyster culturists would have priority access to all suitable areas? The study group concluded that given certain Government development support (identified in section 5.3) the industry might be able to expand to about the equivalent of 80 rafts by 1986 and 160 rafts by 1991.
There is little indication that the culture of the other naturally occurring flat oyster (Isognomon alatus) would lead to a larger production overall, or to a better economic return on individual operations.
Raft culture of oysters inside a fish pen might lead to a symbiotic relationship between the oysters and the fish. If so, the production from the combined activity should prove larger than the total production of the two when carried out in isolation from each other.
In water, the oyster shells, cultch, spacers and even the floats attract marine organisms and periphyton, which in turn become focal points where other invertebrates converge. The resulting build-up of biological mass leads to less food availability to the oyster, and to smothering. Also, the oysters are subject to stress when taken out of the water as practiced to facilitate removal of the fouling organisms. Growth is interrupted during this period.
However, if the oyster raft is placed in a pen, the oysters would be kept clean if stocked with a fish (such as tilapia) that can use the periphyton. The oysters, in turn, might be able to take up food the fish have left undigested or filter particulates of the supplementary feed which will be provided for the fish.
The study group does not know of any location where this type of polyculture has been tried. However, it seems to be a way of more fully using space and manpower which would have to be employed in fish pen culture or oyster culture respectively.
Available organisms for culture in fresh and brackish waters in Jamaica (see Annex 5), are the fishes Tilapia nilotica, T. mossambica, the common carp (Cyprinus carpio), the grass carp (Ctenopharyngodon idella), the bighead carp (Aristichthys nobilis), the silver carp (Hypophthalmichthys molitrix), the mullets (Mugil cephalus, M. curema) and the freshwater shrimp (Macrobrachium rosenbergii).
Fish can be reared in ponds, floating cages, enclosures and raceways, in monoculture or in polyculture, or integrated with animal husbandry (pigs, chickens, ducks) or in ricefields (rice-cum-fish culture or rizipisciculture).
Macrobrachium can be cultured in ponds in monoculture or in polyculture with T. nilotica or with common carp and with Chinese carps.
Out of these species, the bighead and silver carps are still reared on an experimental basis in Jamaica and have not yet been distributed to fish farmers. It is expected that once the trials on induced breeding of these Chinese carps will have become a “routine” operation, grow-out trials will start at the Twickenham Park fish farm. The aim of the trials should focus mainly on the possibilities of polyculture, combining the different Chinese carps, the common carp and T. nilotica. The best combinations should be introduced as soon as possible among the more progressive fish farmers.
There is at present no market for carps in Jamaica. A small market for Chinese carps can probably be developed amongst residents of Chinese origin. Thereafter a concerted effort would probably have to be made to introduce these species in the local fresh fish market. In any event, test-marketing and careful economic analysis should precede any determined effort by the IFU to make local aquaculturists start polyculture with Chinese carps.
Mullets occur in natural waters but have not yet been cultured in the country. Since they do not reproduce naturally in captivity, and artificial reproduction of mullets is still in an experimental phase, fry have to be collected in the wild. Detailed information about the availability of mullet fry is not yet available in Jamaica.
Any polyculture of mullets in fresh water would depend on a stable supply of mullet fingerlings. Thus it would seem that if this culture is considered of interest, the first step would be to conduct a fry survey, and secondly to conduct culture trials.
Since Jamaica has no big fresh water bodies, cage culture and fish rearing in enclosures is of limited importance, and therefore these culture systems have not been selected by the study group. Rice-cum-fish culture has yet less importance since the Government has changed its policy concerning the irrigated rice programme in the BRUMDEC area. In this particular field, information is available in the report “Aquaculture Development in the Caribbean” (ADCP, 1981).
After discussions, the study group concluded that there are principally four fresh water culture systems of immediate interest for Jamaica, as follows:
pond culture of Tilapia nilotica;
raceway culture of T. nilotica;
pond culture of Macrobrachium rosenbergii, and
commercial production of male T. nilotica fingerlings.
Pond culture of tilapia has been practiced successfully in Jamaica since 1978. Farmers are actually using T. nilotica male fingerlings produced partly by the farmers themselves and partly by IFU. The most common culture practices are described in Annex 9, section 5.
The study group appraised the economics of a family-managed pond culture unit, comprising four 0.4 ha (1 acre) ponds producing 1 135 kg (2 500 lbs) of 225 g fish per 0.4 ha and per cycle of 13 weeks. The return to management is about J$ 9 000, which is substantial. Costs include a 12 percent interest charge plus cost of tilapia male fingerlings at a price 50 percent higher than that charged by the IFU. In view of these earnings it seems likely that the commercial farm sector will expand into aquaculture - provided it can obtain the know-how.
This is a more sophisticated technology, and particularly well adapted to areas where land availability is steadily decreasing and where soils are not suitable for pond construction. This is particularly the case in mountainous or hilly areas.
Raceways are rectangular tanks, generally constructed in concrete, and having an inlet and an outlet. The system is based on running water (to maintain a high dissolved oxygen level), high stocking rates and artificial feeding of the fish.
All male fingerlings (average weight: 25 g) are stocked in the raceways at a density of 200 fingerlings/m3 of water. The rearing period is 120 days. More details about raceway culture are given in Annex 9, section 6.
The study group appraised a hypothetical commercial raceway unit consisting of 10 concrete raceways of 20 m3 each, the farm as a whole producing about 26 tons of fish per year (in three cycles). Water is supplied by gravity. The study group has estimated the capital needed to start such a unit at about J$ 110 000. The analysis (Annex 9, section 6) shows that the return to management is low; about J$ 1 500 per year.
The giant freshwater prawn Macrobrachium rosenbergii is not yet commercially cultured in Jamaica, but experimental rearing is implemented in ponds by Jamaica Aqua-Farms at Ferris Cross near Savanna-la-Mar, where they have re-opened their hatchery.
According to New and Singholka (1982), M. rosenbergii is farmed in considerable quantities in many countries including Hawaii, Honduras, Mauritius, Taiwan and Thailand, and new farms are now being established in Costa Rica, Indonesia, Israel, Malaysia, Mexico, the Philippines and Zimbabwe.
Since the rearing site requirements for shrimp rearing, such as water temperature (18–34°C, but optimum between 29° and 31°C); pH (between 7.0 and 8.5); total hardness (between 40 and 150, as CaCo) and dissolved oxygen (more than 75 percent saturation) and no polluted water in Jamaica, pond culture of M. rosenbergii can thus be considered.
The study group appraised a freshwater shrimp production unit consisting of 8 ponds of 0.2 ha each. Expected yield is 1 200 kg/0.4 ha (or about 2 640 lbs/acre) after a nine-month growing period. The investment needed is slightly higher, J$ 120 000, than that estimated for the raceway culture of tilapia. The return to management per year of operation is estimated at J$ 8 000, assuming that the shrimps can be sold in the local hotel trade at J$ 12 per kg (live weight). The return is less interesting than that identified for monoculture of male Tilapia nilotica in ponds. Nevertheless, it is likely to attract a number of investors in the commercial farming sector.
Male T. nilotica fingerlings are produced by IFU (950 000 in 1982) and by the private sector (533 000 fingerlings in 1982). The demand is increasing every year and the projections for 1986 would point to a need of about 10 million fingerlings.
IFU sells male fingerlings to fish farmers at the price of J$ 0.12 each, delivered at the pond site. This price does not cover all costs of producing a male fingerling of about 25 g (hand sexing). As long as IFU sells its fingerlings below the cost of production, the private sector will not be encouraged to establish commercial fingerling production farms.
The study group has appraised the economics of a fingerling production farm (independent of tilapia grow-out operations). It is supposed to be operated for profit and owned by private entrepreneurs. The farm unit consists of 10 brood ponds, each with a surface of about 550 m2 and 20 fry grow-out ponds of 2 000 m2 each. More details about the farm are given in Annex 9, Section 8.
In this fingerling production farm the cost for each male is between J$ 0.18 and 0.20 if production totals slightly more than one million male fingerlings per year. With appropriate Government policies it would seem possible to make local entrepreneurs enter into this specialized type of aquaculture. In the previous analysis of tilapia culture in raceways and ponds, a unit price of J$ 0.19 per male fingerling has been used.
The preceding sections of this chapter have identified the type of culture systems which seem the most likely to develop in Jamaica during the coming decade. It has done so focusing on the likely results of typical production units.
With one or two exceptions, it seems likely that the Government of Jamaica will have to take the initiative to make the potentials reality. It is rational to know what development effort the Government would have to spend before recommending that the Government develops the types of aquaculture production systems which have been previously identified. The study group has attempted to identify in a more exact manner what is involved, It has considered what manpower and budgetary resources the Government would have to allocate to this effort in order to develop a self-sustained industry (that is, one that will survive without specific Government development support in the form of extension or research). The study group has also identified the quantity of production that could result from such an effort.
The study group spent considerable time discussing these questions. The results are given in graphs 2 and 3 and in Table 2. It should be emphasized that the estimates of aquaculture production in 1986 and 1991 are dependent on the Government making the effort outlined in Table 2. If such an effort is not made, the projected production is not likely to come about.