The possibility of development of a profitable aquaculture industry, especially in seawater, will rely on the simultaneous satisfaction of four major requirements :
the existence of a species, whose biological characteristics are compatible with captivity, and which can be considered to be well adapted to the existing environment (chiefly temperature and salinity). Juveniles must be available either through wild fish caught from natural stocks or through artificial breeding in hatcheries.
adequate fish feed for commercial production, whether using local products or foreign imports.
significant market demand with high initial prices for the fish product so that the cost of culture may be covered.
certain preconditions :
legal (a framework allowing the fast development of the activity). Each has to be evaluated with respect to concurrent, medium and long term productions.
local capability to solve the biological problems (nutrition, pathology), which will undoubtedly appear in the research/development phase.
A critical analysis follows of how the situation in Jamaica matches these requirements, but some major biological and economic considerations should be recalled.
As opposed to terrestrial animals, organisms living in aquatic environments have no mechanisms to regulate their internal temperature and body fluids. Consequently they are highly sensitive to environmental conditions which regulate all major biological functions : respiration, excretion, growth, and reproduction. Each species is thus characterized by optimal environmental conditions, especially temperature and salinity, under which physiological comfort will be maximum, and energy expenditure will be minimum. Under these conditions, the growth rate will be optimal, and morbidity will be low. This explains why each species is found only in specific types of environment, and is not suited for culture under other conditions. Although for each species there is a “tolerable” range of temperature, there will be significant differences in growth rate under different temperature regimes. For instance, the European Sea bass reach the market size of 450 g in 14 months in southern Greece (18–26°C) but only after 20 to 24 months on the mediterranean coast of France (14–23°C).
When compared to animal husbandry, which involves only a limited number of species “domesticated” over many centuries, aquatic species remain “wild animals”, and not all of them are suited to captivity. At present, very few species have proved to be amenable to fish culture, and there is wide variability within a given species between geographic strains or races, as has been proven with salmon.
Any production scheme has to be planned with its potential market in mind, and markets are sensitive to specific characteristics such as size, colour, quality and price, which in the initial phase of fish culture development will approximately correspond to the characteristics of the equivalent wild product.
The cost of production has to be significantly lower than the market price in order to allow profitability. Moreover, when production increases, the market price decreases, and only the most competitive systems of production can survive. An aquaculture system has to be planned with projections well into the future, in order to ensure long term profitability.
Two factors represent the majority of the production costs : juveniles and feed. The respective proportions may vary considerably depending on the choices made with respect to the following alternatives:
extensive production at low density (a part of the energy requirements being provided by natural food), or intensive rearing at high density (all feed being provided by the grower). Marine cage farming implies the second choice.
the use of young wild fish (caught), or of fingerlings artificially produced in a hatchery. In the latter case, the present state of the art for hatchery-reared juveniles (fish fry) leads to production costs in the range of US$ 0.40 to 1.80 per juvenile of 1 to 5g. More extensive methods for producing fry may provide some cheaper opportunities, but are generally associated with more variability in quality.
Table 5 :
Evaluation of farm-gate production costs for various cultured fish
(in US$/kg, October 1992)
|Species||Trout||Salmon||Sea Bass||Red Drum||Tilapia||Tilapia|
|weight range g||4–250||50–3000||1–400||4–700||2–350||1–285|
HD = high density intensive production,
LD = low density extensive production.
Compiled from various sourcesincluding BJORNDAHL (1990), HANLEY, 1991 updated, 1992.
Table 6 :
Indicative beach-landing price of various fish in the Lesser Antilles
(in US$/kg, October 1992)
|Cat||Species||Gren||St Vi||St Lu||Anti||St Ki||Nevis||Virgl||Barb|
Big eye jack
Grenada, St Vincent, St Lucia, Antigua, St Kitts, Nevis, Virgin Is. Barbuda. (Source: IFREMER)
Table 7 :
Estimation of the beach-landing prices in Jamaica
(US$Kg, october 1992)
|Category 4||Parrot fish||2.70|
|Category 5||“soup fish”||1.80|
source: P.D. BUNTING, pers. comm, 1992)
Any attempt to establish an aquaculture activity with a new aquatic species (or even with an introduced species reared elsewhere) must go through four major stages (whether the actor is government or private industry) :
a preliminary phase, in which the objectives and the means to achieve them are determined precisely.
an initial exploration phase, which is extremely important, during which the aquaculture technology is tried and tested with rigour and method on a small scale, in order to solve the technical problems which will undoubtedly arise; and to develop a “standard rearing method”.
a “pilot” or “demonstration” phase, during which the findings of the exploratory phase are “validated” on a larger scale. The volumes used and quantities produced will be the standard for the development phase. The future fish farmers should be associated or at least informed in detail during the pilot phase and the operators should receive training in the application of the technology developed.
a development phase, during which appropriate policies for facilitating a smooth and gradual take-off of the commercial activity should be in place, in order to avoid major problems such as : shortage of juveniles (leading in turn to an increase of their cost); production increasing too rapidly with regards of the target markets (leading to an abrupt decrease of selling price).
Japanese Yellowtail farming was initiated in Japan in the 1960s, and reached the industrial development phase in the 1970s. Breeding in captivity was difficult when compared to the many other species reared in Japan, and larval rearing extremely difficult. On the other hand, juveniles were very hardy and grew rapidly at high densities when reared in an appropriate environment with specially adapted feed. Japanese fishermen and the National Fisheries authorities were aware of the nursery areas where juveniles were gathering, and a national policy allowing the capture of a certain number of juveniles, with careful management of the resource, enabled a very profitable aquaculture activity to emerge (now stable at around 150 000 tons per year), without affecting the wild catch (stable around 60 000 tons).
18.104.22.168. With temperate species
Twenty years ago, the only species being reared industrially were trout (Oncorhynchus mykiss) and catfish (Ictalurus sp.), both of which being produced in freshwater, either through extensive farming in earthen ponds, or intensive culture in concrete raceways. The former, originally being found only in the west part of North America, has been widely introduced all over the world, and has given birth to fruitful aquaculture industries. The latter, species also native to the North American continent has been developed only in U.S.A, and most attempts to farm it in other different environments have failed.
The marine cage-culture of salmon, initiated in Norway at the end of the 1960's (100 tons produced in 1970), was still a pre-industrial activity in 1980 (4 000 tons production in Norway), then very rapidly expanded, both with the Atlantic species (Salmo salar) and the Pacific species (Oncorhynchus kisutch and O. tschawytscha). The technology, and the well genetically adapted strains, have been spread over many countries, leading to a world production reaching 250 000 tons in 1992, among which Norway alone produced 135 000 tons.
Availability of juveniles (smolts), produced in freshwater hatcheries, has been the major bottleneck in the development phase, the shortage of juveniles conditioning the advancement of production.
Evolution of world salmon aquaculture production
IFREMER, 1993, (compiled from various sources (FAO, Fish farmer, Salmon, World aquaculture…)
The cage-culture of marine species has expanded over the last ten years, both in Japan, with the culture of new species such as the Japanese imperial bream or red-snapper (Pagrus major) and Japanese halibut (Paralychtis olivaceus), and in Europe with Mediterranean or Atlantic species.
Sea-bass (Dicentrarchus labrax) and sea bream (Sparus aurata) culture in the Mediterranean (Greece, France, Spain, Italy) is expanding rapidly, with a production of about 14 000 tons in 1992, with projections of 20 000 tons by 1995. In both cases, production takes place mostly in sea cages (though part of the production occurs in shore based ponds and raceways), starting with juveniles (1 to 2 g) produced in hatcheries, and using basically two techniques: intensive production in clear water (France, Greece) ; or at lower densities in green water ponds (Spain). The grow-out period (up to the commercial size of 350–450 g) takes from 14 to 24 months according to the rearing temperatures.
22.214.171.124. With tropical species
Numerous tropical species have been investigated for aquaculture potential, and have been the target of significant research effort. But among these, only the Asian tropical sea-bass or Barramundi (Lates calcarifer) has resulted in a significant production, mainly in Thailand (about 3000 tons in 1991). Production begins with juveniles, either from wild adults collected during the spawning season, or from captive brood stock. The juveniles are obtained either through extensive production in earth ponds, or in hatcheries at a higher density.
Figure 4 : Evolution of sea bass and sea bream production in the Mediteranean
(Sources : The Greek Federation of Fish Culture, and European Aquaculture Society conference)
The occurence of a picorna virus, identified in 1988 has been a major difficulty in the production of fry. The species has been introduced to the French territory of Tahiti, where it has demonstrated excellent potential for growth at temperatures of 28–30°C (average market size of 600 g reached after 6–8 months from first feeding).
The production of Grouper, the fry of which is particularly difficult to produce within hatcheries, is also showing some interesting results in South East Asia, however all other attempts with other species are still at the research level, or at best in the pilot-demonstration phase.
As part of a programme initiated in 1981, aimed at the selection of potential candidates for marine fish culture in the Caribbean area (see § 3.5.2 for more details), the red drum was introduced from Texas in 1987. The species showed an excellent aptitude to grow rapidly when fed with dry pellets (a commercial size of 600g obtained 8 months after first feeding), to reproduce in captivity, and to provide viable outputs through the larval rearing phase. After an initial research phase, which allowed a “standard method” for larval rearing to be defined, the programme entered the pilot phase, both for larval rearing and grow-out, completed in 1993.
The technology has been transferred from the initial research institution to the local association in charge of development (Association pour le Developpement de l'Aquaculture en Martinique -ADAM), with the appropriate training provided for all phases of production. The economic assessment was completed in 1993, and will possibly lead to a development phase.
A programme for selecting finfish species suitable for aquaculture in French Polynesia was undertaken by IFREMER between 1983 and 87, (FUCHS et. al., 1990) to identify the most suitable species for aquaculture. A literature review, based on the economic interest of each species and the existence of previous research in Tahiti or abroad, led to the selection of four local families of fish (Carangidae, Coryphaenidae, Serranidae, Siganidae) and two families introduced from south east Asia (Centropomidae, Cichlidae).
In a second step, species were selected according to the following criteria : growth rate potential, acceptance of dry pelleted feed, reproduction and spawning in captivity, larval rearing and fry production, pathology and resistance to stress, economic interest on the local market. The trials resulted in a classification into 3 groups:
species with a very high potential for aquaculture, permitting development in the short term : the tropical sea bass (Lates calcarifer, Centropomidae), originating from S.E. Asia.
species with potential, but presenting some drawbacks, such as difficulties with larval rearing, (like grouper - Epinephelus microdon, Serranidae) and dolfin fish - Coryphaena sp., Coryphaenidae), or affected by pathological problems during the grow-out phase in marine cages (such as red Tilapia strain - Oreochromis sp.)
species considered as difficult to rear and not warranting further consideration (like the rabbit fish Siganus argenteus, Siganidae - poor economical value and unsuccessfull larval rearing), or Caranx ignobilis, Carangidae - no acceptance of dry feed). However, it should be emphasized that this species has a very high market value in certain South East Asian countries).
The results of these trials are summarized in the table 8. The sea bass (Lates calcarifer) was undoubtedly the most promising species for marine aquaculture in the area.
Table 8 : Synthesis of selection of the most suitable species
for aquaculture in French Polynesia
(From J. FUCHS, G. NEDELLEC and E. GASSET, 1990)
|species||Seabass||Red Tilapia||Grouper||Dolfin fish||Rabbit fish||Jackfish|
|growth||A> 500 g|
300< B< 500 g
|adaptation to dry pellet||A=easy|
|maturation & spawning||A=natural|
|larval rearing fry production||A=easy|
|B||no trial||C||C||C||no trial|
|group 1||group 2||group 2||group 2||group 3||group 3|
Since 1981, a similar program has been conducted in Martinique (THOUARD et al., 1990) to assess the aquaculture potential of the following species
|-yellowtail snapper||(Ocyurus chrysurus)|
|-mutton snapper||(Lutjanus analis)|
|-school master||(Lutjanus apodus)|
|-lane snapper||(Lutjanus synagris)|
|-gray snapper||(Lutjanus griseus)|
|-red drum||(Sciaenops ocellata)|
|-red Tilapia||(Oreochromis sp.)|
Zootechnical and socio-economic constraints have led to the choice of three species (either endemic or introduced) for further trials: the Palometa, Red Drum and red Tilapia hybrid:
Palometa showed good growth performance (400g after 7 months from 17g juveniles), it accepted dry pellets and showed a high resistance to disease. However, the onset of maturation and spawning either natural or injection-induced appeared difficult. For two years, 88 females received hormonal injections, but only 43, 000 viable eggs were released, not permitting serious larval rearing trials. A reliable technology thus remains to be developed for this species.
Red drum, an exotic species from the Gulf of Mexico, introduced from Texas and Florida stocks, gave encouraging results, facilitated by the extensive research done in the USA. The best survival rates after two months reached 17% (2–5 g fry), and they grew to an average weight of 300g in six months and 600g seven months after hatching.
Red Tilapia was introduced in Martinique in 1986 : the strain reared was the red Florida hybrid, imported from Jamaica. Broodstock, larvae and fingerlings were reared in brackish water (19 ppt), and grow-out was conducted in tanks (with recirculated freshwater and seawater), and in net cages in the sea. Various problems were encountered in cage-rearing in full seawater (36 ppt), such as vulnerability to parasites when cages were in shallow waters plus loss of scales and mucus during handling. These two species were considered as the most appropriate candidates for a possible development of their production in the Lesser Antilles. WATANABE et al., (1990) provided a review of the possibilities of farming Tilapia in sea water.
Table 9 :
Synthesis of results of the grow-out phase of selected species in Martinique
(From E. THOUARD, P. SOLETCHNIK and J.P. MARION, 1990)
|Species||Origin||Growth experiment periods||Number of fish||Av. final weight (g)/duration (months)||Pathology|
|Ocyurus chrysurus||wild||10/81–01/85||20 000||300g/18m||“nutritional”|
|Scianops ocellata||hatchery||07/87–01/88||4 000||500g/6m||no|
|Oreochromis sp (red hybrid)||hatchery||since 1987||350g/6m||parasitism|
in full sea water
In a complete review, TUCKER & JORY (1991), stated that "most marine fish culture in the Caribbean is experimental and there are few commercial operations. “Ornamental fish” have been raised commercially since the early 1970's, but the only “food fish” being raised commercially in saltwater on a reasonable (but relatively small) scale are Tilapia and red-drum, with two other candidates having reached pre-commercial size : mutton snapper (Lutjanus analis) and white mullet (Mugil curema). Table 10 gives a synthesis of the existing investigations in 1991.
|Some fish with potential for farming in the Caribbean region|
|Common name||Scientific name||Types||Units||Locations|
|Tilapia||Oreochromis sp||CH;EH||P C T||Bahamas, Bonaire, Colombia, Cuba, Curaçao, Dominican Republic, Florida, Haiti, Jamaica, Martinique, Puerto Rico|
|Red drum||Sciaenops ocellatus||CH;EH||P C T||Alabama, Bahamas, Florida, Louisiana, Martinique, Mississippi, Panama, South Carolina, Texas|
|Spotted seatrout||Cynoscion nebulosus||EH||PT||Alabama, Florida, South Carolina, Texas|
|Whitemouth croaker||Micropogonias fumieri||EH||T|
|Dolphin||Coryphaena hippurus||EH||CT||Bermuda, Florida, North Carolina|
|Florida pompano||Trachinotus carolinus||E H W||C T||Alabama, Bahamas, Dominican Republic, Florida, Venezuela|
|Palometa||Trachinotus goodei||E H W||C T||Martinique, Venezuela|
|Permit||Trachinotus falcatus||E W||C T||Florida, Martinique, Venezuela|
|European sea bass||Dicentrarchus labrax||E H||C T||Martinique|
|Common snook||Centropomus undecimalis||E H||P T||Brazil, Colombia, Florida, Venezuela|
|Nassau grouper||Epinephelus striatus||E H||T||Cuba, Florida, Grand Cayman|
|Red grouper||Epinephelus morio||E||T||Florida, Mexico|
|Jewfish||Epinephelus itajara||E W||C T||Florida, Venezula|
|Gag||Mycteroperce microlepis||E H||T||Florida|
|Black grouper||Mycteroperce bonaci||E W||C T||Venezuela|
|Sand perch||Diplectrum formosum||E H||T||Venezuela|
|Black sea bass||Centropristis striata||E H||T||Florida, North Carolina|
|Gray snapper||Lutjanus griseus||E H W||C T||Cuba, Florida, Martinique|
|Lane snapper||Lutjanus syhagris||E H W||C T||Cuba, Florida, Martinique|
|Mutton snapper||Lutjanus analis||C W;E W||C T||Florida, Martinique, Venezuela|
|Red snapper||Lutjanus campechanus||E H||T||Alabama, Texas|
|Schoolmaster||Lutjanus apodus||E W||C T||Martinique|
|Yellowtail snapper||Ocyurus chrysurus||E H||C T||Florida, Grand Cayman, Martinique|
|Sheepshead||Archosargus probatocephalus||E H||P T||Florida|
|Sea bream||Archosargus rhomboidalis||E H W||P||Florida, Venezuela|
|Gilthead sea bream||Sparus auratus||E H||C T||Martinique|
|Porgies||Calamus spp||E W||Venezuela|
|Atlanitic spadefish||Chaetodipterus faber||E H W||C||Venezuela|
|Striped mojarra||Diapterus plumieri||E H W||T||Cuba, Venezuela|
|Tarpon||Megalops atlanticus||A W||P||Colombia|
|Striped mullet||Mugil cephalus||F||P|
|White mullet||Mugil curema||C W; E H||P||Brazil, Cuba, Venezuela|
|Liza||Mugil liza||E H W||P||Brazil, Cuba|
|Mugil spp||C W||P||Brazil, Colombia, Mexico, Venezuela|
|Crucifix sea catfish||Arius proops||E W||P||Colombia|
|New Granada sea catfish||Arius bonillai||E W||P||Colombia|
|Pemecou sea catfish||Arius herzbergii||E W||T||Venezuela|
TABLE 10: Some fish with potential for farming in the Caribbean region. FROM TUCKER & JORY (1991)
(E=experimental, C=commercial, W=wild, H=hatchery ; P=ponds, C=cages, T=tanks)
Of all the attempts to domesticate and farm aquatic species, only a few can be called “successes”, and several may definitely be called failures due to different reasons: biological or behavioural characteristics not conforming to aquaculture practices; environment maladaptation; or lack of competitiveness in the market place.
: the european Dover Sole (Solea solea)
This demersal flatfish, high priced on the european market (US $ 15/kg), reproduces normally in captivity, and the mass production of juveniles in hatcheries has proved to be relatively easy to achieve. However, during the grow-out phase, after weaning to artificial feed, the fish has specific behavioural requirements, which makes economical rearing almost impossible: they need tanks with a sandy bottom allowing normal burying behaviour, and do not easily accept concrete or plastic surfaces (injuries, necrosis etc...). Moreover, while larvae and young fry actively feed on live prey and after weaning on artificial feeds, fingerlings and adults are not attracted by the food, and feed only at night very slowly on food particles settled on the bottom of the tanks. Subsequently, specific nutritional problems (leaching of soluble matter and vitamins) and slow growth have been observed.
: Salmon in southern Europe, Penaeid shrimp in France, Seabass and Seabream in Martinique.
Salmon and trout grow very rapidly in winter in coastal waters of southwestern Europe, but face some difficulties during the summer months (mortalities due to “environmental pathology”). Subsequently, global technical performance (survival, growth, feed conversion factor) remain inferior to that observed in northern Europe (Norway, Scotland), and consequently production costs are higher. This allows profitable aquaculture for a time, but when world production increased, and market prices declined significantly, it became extremely difficult for French enterprises to remain competitive. Consequently, production has not really developed and remains stable at around 1000 tons/year.
Conversely, on the Atlantic or Mediterranean shores of France, temperatures have proved to be too cold for farming successfully the most temperate species of penaeid shrimp (Peneus japonicus) : growth is slow, which makes a marketable size difficult to attain after the short summer months season, not allowing one to benefit from the extremely high price of this product on the French market.
Sea bass and sea bream were introduced in Martinique for cage culture in 1981, by a private French company (AQUAMAR). These species was alleged to grow faster in tropical waters (26–30°C) than in the French Mediterranean (14–24°C). The expected production (500 tons per year) was supposed to be shipped to Europe where market prices were high. The first trials were conducted with fry purchased from French hatcheries, and a hatchery was established to develop local production. The project reached a maximum production of 15 tons (in floating cages), but a series of technical and pathological problems were encountered, including virulent outbreaks of viral disease (picornavirus) affecting fish during the grow-out phase and then during fry and fingerling stages. The owners of the project withdrew in 1986, after bankruptcy (US$ 2 million loss), and the project ended. If some introductions have obviously resulted in positive results and led to important economic benefits (case of salmon in Chile, of the japanese oyster in France for example), many other introductions have led to unexpected problems of this kind. For this reason, any attempt to introduce a new species should be considered very carefully.
: the freshwater prawn (Macrobrachium rosenbergii) in French Guyana
The production of post larvae has been well mastered by French research scientists, and the hatcheries established in the French territories of Guyane and Guadeloupe are fully operational with excellent results. However, the best cost of production attained for the grow-out phase remains extremely high due to local economic factors (price of land, high salary costs). Consequently production costs are much higher than in parallel operations in South East Asia, and the products are not competitive on international markets, including France. Attempts to improve the rearing performances in order to reduce the production costs having failed, and the product remains destined for local consumption only with limited markets (a few tenth of tons) per country, and this production has not developed significantly.
Like all other human activities, aquaculture may have an impact on the surrounding environment. Some exemples of the detrimental effect of aquaculture practices such as intensive industrial farming of trout on river environment or the high concentration of shrimp farms using intensive techniques in mangrove areas are well known. The examples of severe impact of fish cage farming in the sea are less evident. But one may cite the case of hyper-intensive yellowtail farming in Japan, in bays where the water circulation is limited. Thus, any development of a large production over a limited area of the coast line should be examined with caution.
Considering the present status of the reflexion in Jamaica, we do not believe it necessary to engage now in a fully documented analysis of the possible impact of large scale cage culture on the coastal environment, which would remain purely theoretical. It is not to say however that this aspect should be overlooked, but in the contrary should be carefully analysed for any major project of development. We will only stress a few aspects of the impact of cage culture which should be considered by Jamaican authorities and entrepreneurs:
- production of organic matter:
All livestock rearing activities produce organic pollutants, which are released into the environment. When compared to agricultural activities, the effluent of fish farms, and in particular of floating cages, go directly to the water mass, where their impact should be assessed and surveyed. The major components of these effluents are composed of nitrogen and phosphorus, of which only respectively 26% and 18% is “incorporated” in the fish (in the case of salmonids). That is to say that 74% of the ingested nitrogen ingested is released into the environment, compared to 82% of the phosphorus.
Nitrogen is released primarily in a soluble form (60% of the ingested amount), whereas phosphorus is released mainly in suspended solids, a part of which will have a tendency to settle below the cages. These “pollutants” may not have a serious detrimental effect on the surrounding environment, and in the case of oligotrophic waters, they even may be beneficial to the food chain. However, when considering the development of large industrial farms, on a limited surface, this factor should be examined with attention.
Many works have been conducted in northern countries, associated with the development of salmon farming, but very little is known in tropical waters, as the magnitude of cage farming remains limited as yet. At any rate, the impact of farming may vary considerably according to the site : water depth, current and water circulation, and the characteristics of bottom sediments may influence this impact.
- mechanical damage to the sea bottom:
A set of cages has to be anchored on the bottom of the sea in order to operate. In many cases, the use of large anchors, chains or concrete blocks do not affect badly the floor bottom, especially when choosing a muddy or sandy bottom. However, in the case of tropical waters, care should be taken in site selection in order to avoid major damage to the coral reef if any.
- impact of drugs and veterinaryan products
Any animal production at a certain scale has to face disease outbreaks. These lead to the obligatory use of drugs and chemicals to get rid of parasite and bacterial infections. An intensive and uncontrolled use of such products may be detrimental to the environment, either through direct toxicity (i.e the use of organophosphorous compounds to fight crustacean parasitic infestations) or the possible production of pathogens becoming resistant to antibiotics. The use of products should be carefully controlled, like in any other animal production activities, to avoid problems of this kind. Moreover, when available, the use of vaccines to treat the major ubiquitous bacterial infections like vibriosis, should be considered as an alternative to the use of antibiotics.
- disease spreading
Some cases of disease speading are associated with aquaculture development. Concentration of large numbers of individuals, and increasing density are factors which facilitate disease infections. Thus, special care should be taken to limit live fish movements between sites to avoid possible contaminations. Furthermore, extreme concern should be expressed when considering the introduction of a new non indigenous species. Such practices have proved to be highly beneficial to the local economy in many cases (i.e the introduction of the japonese oyster Crassostrea gigas in France, or that of both pacific and atlantic salmon in Chile...). However, some cases of adverse effect on the environment have occured, and much care should be adopted. International institutions, like ICES have promoted a “Code of practice” for such introductions, which is highly recommended to countries considering such practices. They include preliminary disease surveys of the introduced stocks, the restriction of introductions to eggs with the exclusion of adults and juveniles, the use of quarantine facilities etc…
- practical recommendations
The development of cage rearing activities often stimulate concern and possible opposition of resident populations or ecologist groups. The debate preceding the authorisation of a farm to operate can be a good opportunity to bring objective information into a controversial debate. It is thus recommended to establish a “previsional impact study” for large scale operations, including a precise description of the existing environment before the project starts, and to follow carefully the evolution of a possible impact during the upscaling of the operation: biodeposits and changes in vegetal and animal populations below the cages, accumulation of heavy metals in the sediment, modifications of the coral reef. Such programs could be perfectly well conducted by the UWI Department of zoology. Examples of studies carried out on the occasion of large cage-farming projects may be provided.