Mariculture development started in 1972 in Cyprus with the establishment of the Govermental Marine Culture Station at Gastria. However, real development started in 1976, due to the internal political problems of the island, with pond culture of grey mullets in the Akrotiri area. The pond surface area covered 3 × 0.37 ha, and the depth of the ponds was around 2–3 m. Water was hypersaline (range 40–60‰) with temeperatures between 10° and 32°C. Three species of Mugil were stocked at densities of 20 000 fish/ha and intensive management was practised with demand feeding (twice a day) and inorganic fertilisation of the water. The fry used were collected with beach seines during winter time. The production reached 600 kg/ha in 14 months, and poor survival rates were observed. The fastest growing species, M. cephalus ranged between 304 and 548 g followed by M. capito (133–167 g) and M. suratus (51–112 g). However, interest in these species was reported to be low.
One interesting feature for aquaculture development in Cyprus is the presence of Artemia salina in Laraaka Salt Lake in sizeable quantities (150 kg of cysts collected in 1977). Experiments were carried out in the last 5 years on methods of collection, processing, and more recently on decapsulation for use in fish culture projects. Experiments on inoculation of the Akrotiri Salt Lake were undertaken.
Due to the lack of coastal lagoons, intensive cage and pond culture are the only possible choices for fish culture. Cage culture started in 1978 in Paphos harbour (salinity 39‰, temperature 15.5°–27°C). Sea bass culture in cages was tried in 1978 in nylon net cages. The fry, imported from France, were fed on dry pellets twice a day and grew in a year from 1.4 to 168 g. The cages reached a final density of 10 kg/m3 but deformed fish that showed high mortalities were also observed.
Amongst other local species cultured, there is Diplodus sargus. Their fry are collected by use of beach seines in the period from June to August and their growth goes from 0.6 to 55 g in one year. Eels are also being tried in cage culture but conclusive results are not yet available.
Siganids, namely Siganus rivulatus and S. luridus, have been cultured also in preliminary trials, using wild fry. As in other countries it has been noted their good behaviour in cages by keeping them free from fouling algae.
Turtle rearing has also been attempted in the last two years as a means of conserving the species.
The French report covered only finfish and crustaceans. Although mollusc culture is economically more important than finfish and crustacean culture which are still at an experimental and pilot-scale level, this is already an established tradition and the developments from the last Session of COPRAQ are minimal in terms of new techniques.
Extensive aquaculture practices are conducted in coastal lagoons of southern France, and Corsica, covering over 2 500 ha.
The annual production is grossly estimated at 100 tons and the main species in order of importance are: mullet, eel, sea bass, gilthead sea bream and sole.
The operation is similar to that of the “valli” in the Venetian province of Italy, although attempts to rationalize it are being started by the Institut scientifique et technique des pêches maritimes (ISTPM) at Salses-Leucate and by the Centre technique du génie rural, des eaux et des forêts (CTGREF), in Corsica (coastal lagoons of Biguglia, Diane and Urbino) and in the lagoon of Mauggio in Languedoc.
Two species of salmonids, coho salmon, Oncorhynchus kisutch, and rainbow trout Salmo gairdnerii, are farmed in marine waters under intensive culture practices. The Centre national pour l'exploitation des océans (CNEXO) and the CTGREF are the main promoters of this activity.
Due to the high temperatures during summertime in the French coastal waters for these species, the culture period in the sea water is reduced to the months form October-November until March-June.
The initial culture period takes place in fresh water until the rainbow trout reach a weight of 180–200 g (corresponding to an age of 10 months) and coho salmon reach 120–150 g, then they are transferred to cages placed in sea water until they reach a commercial size ranging from 300 to 1 500 g.
Data for these two species are: (a) 50 000 m2 covered for culture in sea water; (b) 10 000 m2 used for initial growth period in fresh water; (c) annual production 100 to 120 tons of trout and 50 tons of coho salmon; (d) juveniles stocked in sea water 150 000 to 200 000 salmon, and from 200 000 to 250 000 rainbow trout.
Another species that has been found suitable for culture in brackishwater environments is the sea bass, Dicentrarchus labrax.
Several groups are interested in the culture of sea bass; amongst these CNEXO has created a pilot station at Palavas-les-Flots with a hatchery and using floating cages for outdoor growth. Two more hatcheries are operated by the Station de biologie marine et lagunaire de Sète and the Groupement agricole d'exploitation en commun - GAEC - Les poissons du soleil.
Pond or cage culture has been used for growing juveniles up to commercial size in several locations of the French Mediterranean coastline. France Aquaculture, a subsidiary company of CNEXO, is making an attempt to build the first integral farm of commercial size in Pinìa, Corsica, and the CTGREF is also attempting the culture of sea bass using thermal effluents at Martigues-Ponteau. The first tons of sea bass from intensive culture were commercialized by the Société Mediterranée Pisciculture in 1978.
Numerical data for this species are: (a) total area on ground 40 000 m2 (not only pond surface area) and 200 to 300 m2 of floating cages; (b) total commercial production estimated between 5 and 7 tons; (c) number of hatchery-produced juveniles (later stocked for outdoor growth) from 800 000 to 1 million.
There is a considerable number of species which have not yet reached the same commercial stage in culture as the species mentioned before, such as penaeid shrimp, sole, eels, gilthead sea bream, turbot, Diplodus sargus, the “rascasse” and the red mullet.
Regarding penaeid shrimp the technical problems linked to their culture have been solved by CNEXO, which has experimented with Panaeus japonicus and P. kerathurus at Palavas. The association, Les Compagnons de Maguelone has also cultured these species.
The main problem with these species is of an economical nature since the production costs are too high to make the operation pay.
For sole the technical problems have been solved and CNEXO has created a pilot plant at Noirmoutier. Eels are being cultured by Aqua Service using residual-heated waters from the nuclear plant of Saint Laurent-des-Eaux.
Regarding the topic chosen for this Session, larval and juvenile feeding, the results of the intersessional work can be summarized as follows:
(a) Finfish
Several teams are involved in research on nutrition of the early larval stages: CNEXO, University of Montpellier and GAEC, Les poissons du soleil. The methods followed are similar and utilise parallel cultures of algae, Tetraselmis sp. used for feeding the rotifer, Brachionus plicatilis, which can also be fed bakers' yeast in place of algae.
Collection of wild sooplankton is still practised, being a cheap and dependable system in certain areas, and it can even be frosen. Artificial diets have been tried, but problems of acceptability by the young fish have been noticed. After the initial days, Artemia salina nauplii are offered to the larvae and apart from wild sooplankton no other replacement has been found. Since availability of canned cyst of A. salina is a growing problem, this point represents a real bottleneck for the development of the industry to a commercial phase, and a replacement has to be found.
(b) Shrimp
For shrimp the Japanese techniques of growing the larvae together with the plankton organisms in the same basin has been abandoned and at present food organisms necessary for the first larval rearing are cultivated separately. A new technique has been developed at C.O.B. (Centre océanologique de Bretagne), which is under the aegis of CNEXO, in order to reduce the amount of live prey needed for the last larval stages. The technique is based on the utilization of fresh fish or mussel meat, finely ground and pulverised in the rearing tanks with addition of alginate powder which, reacting in the water, acts as a binding agent avoiding leaching of nutrients into the water and subsequent contamination. This technique has shown promising results on a laboratory scale. However, as in the case of finfish, the provision of A. salina cysts remains a bottleneck.
Regarding national coordination for development of aquaculture, an interministerial committee was formed in 1978 due to the number of ministries involved (12). This committee has already produced a national plan with inclusion of regional delegates and has also defined a funding policy for development of this sector.
Aquaculture is a rather recent practice in Greece that has expanded through the development of trout culture and, on a lower scale, of common carp culture. For trout culture, around 120 farms exist and a total production of 2 000 tons/year has been reported, while for common carp the figures indicate 10 farms covering 80 ha and a production of 32 tons/year.
Brackishwater and marine aquaculture in Greece are still in their infancy but the prospects are bright.
Regarding mollusc culture the potential of mussel and oyster culture has been studied by the Institute of Oceanographic and Fisheries Research. Natural stocks were singled out and the suspension method was used for the collection of larvas in Thermaïkos Bay. Eighteen farms, which produced 16 tons of Mytilus galloprovincialis, Venus verrucosa, Ostrea edulis and other species, are in operation in the Gulfs of Thermaïkos and Saronikos. The culture of Pecten spp. started in the island of Lesvos with a production of 2 tons/year until now. In the same region a pilot project for the culture of Ostrea edulis using the suspended method started last year. The growth of individuals within 8 months was considerable (more than 8 cm in length).
Interest in penaeid shrimp culture has led to initial experiments of artificial propagation with Penaeus kerathurus as choice species. The purpose of the project is mass production of post-larvae in the laboratory, stocking of suitable areas with them and cultivation of post-larvae in ponds up to marketable size. Stocking of Amurakikos Bay with P. kerathurus post-larvae started last year. This year, post-larvae cultured in two rectangular concrete tanks with a holding capacity of 22 m3, supported with a double bottom system and a sand layer 10 cm thick, increased the initial body weight from 0.08 to 3.2 g in a period of 60 days.
Finfish species are extensively cultured in Greece in brackishwater lagoons. The most important species cultivated in farms (extensive culture) are: mullet (Mugil spp.), gilthead sea bream (Sparus aurata), sea bass (Dicentrarohus labrax) and eel (Anguilla anguilla). This type of mariculture is practised in shallow fenced lagoons and the fish grow up on the natural food available. They are caught on their migration to the sea in traps.
The total area under this type of culture covers 35 000 ha and the yearly production amounts to 2 230 tons. The most important farms are on the following sites:
Amurakikos Gulf on the coast of the Ionian Sea. The lagoons cover an area of 10 000 ha and the annual average yield is 50 kg/ha.
Messolongi area and the Klissova Lagoon on the north coast of Petraikos Gulf. An area of 20 000 ha produces an annual average yield of 55 kg/ha.
Vistonis Lake - Lagos Lagoon on the northeast coast of Greece. The lagoons cover an area of 4 000 ha and the annual average catch is about 80 kg/ha.
Estuaries of Nestos River on the north of the Aegean Sea - a very productive water body of about 1 400 ha. The species Sparus aurata and Mugil spp. are profitable cultures without additional feeding. The production is 200 tons/year.
In addition, collection of elvers from the wild, for stocking in ponds, has been recently started in two small farms at Thermaïkos Gulf, and a project for the cultivation of Mugil cephalus, Sparus aurata and Dicentrarchus labrax has been initiated this year in the Institute of Oceanographic and Fisheries Research.
Also in progress are the experiments for acclimatisation of rainbow trout Salmo gairdnerii to sea water. The aim of these experiments is to identify the most appropriate size of fry to be acclimatised and the best suited diets for their culture in sea water.
For Israel, mariculture is a promising new way of aquaculture development, due mainly to the difficulties in increasing freshwater farming because of the shortage in freshwater supply. In mariculture, where water is not a limiting factor, Israel has the advantage of warmer temperatures than in the countries of Europe which border the Mediterranean, and higher photosynthetic activity resulting in faster growth of the species cultured.
The IOLR Mariculture Laboratory in Elat has been, over the past seven years, the centre of development for Israeli mariculture. It was towards the end of 1972 that work on culture of gilthead sea bream started.
Previously, three years were spent investigating the potential for farming of the local oyster Saccostrea cuculata and the rabbitfish Siganus rivulatus. These initial choices were erroneous due to slow growth and susceptibility to predators and diseases in the case of the oyster, and bad response to captivity in case of the rabbitfish.
The basic idea which guided the sea bream work was to investigate all aspects connected with establishing this organism as a farmed animal. It was felt that an interdisciplinary team, working together at the same site on the same general problem, would achieve the best and fastest results. The different categories of research and development were: nutrition, diseases, reproduction, larval rearing and farming techniques (floating sea cages, brackish and sea water ponds). It should be emphasised that the team did not yield to mounting pressures asking for investigation of additional organisms (different species of fish, oysters, shrimps, lobsters, etc.). It was rationalised that only concentrated effort on one species would bring us to the verge of farming in the shortest time.
After the initial basic work was completed, other species were introduced as part of the polyculture development programme.
The results obtained for sea bream were:
(a) Nutrition
A grow-out diet was developed that enabled the bream to grow at rates which were twice as fast as those in nature.
Basic vitamin requirements were determined.
Weaning diets for the bream larvae (from day 35 on) were developed.
Energy balance in the diet of the sea bream was investigated.
Work on the essential fatty acids is presently under way.
Future work will concentrate on the following problems: finding substitutes for protein sources in the diets (replacing the expensive fish meal); reducing expensive vitamin doses; developing diets for other fish species to enter the system, such as sea bass (Dicentrarchus labrax); developing economical diets for shrimp culture (Panaeus japonicus, P. monodon); developing weaning diets for fish larvae at earliest stages.
(b) Diseases
Three major types of diseases were encountered and investigated:
Parasitological vectors (endo- and ectoparasites)
Bacteriological vectors
Metabolic diseases
Metabolic diseases were investigated together with the nutrition team. These diseases are believed to be connected with deficiencies in the food offered.
The parasitological work involved the study of the appearance, life cycles, epidemics and dynamics of the parasites. Curing techniques were developed. The same approach was applied to the bacterial diseases. This work has been already published.
(c) Reproduction
The controlled reproduction of Sparus aurata has been the subject of the fish breeding team of the Mariculture Laboratory of IOLR in Elat.
The induced spawning study yielded an understanding of the gonadal cycle of this species. This understanding permitted the development of techniques for induced spawning. At present, a technique has been established which forces the sea bream to spawn during five months of the year (two months to each side of the natural spawning season).
Two major approaches were taken:
Endocrinological approach - the intervention in the fish's sex-hormonal pathway by means of hormonal treatment. This approach yielded reproducible techniques for ovulation and spawning of Sparus aurata but has not yet led to a basic understanding of the gonadal maturation. Such basic work is planned for the future, since it is believed that complete understanding of the hormonal control over sexual maturation and spawning processes is vital to the manipulation of fish reproduction.
The practical goal expected to be achieved in the above project is the extension of the spawning season beyond that achieved to date. This will permit commercial hatcheries in the future to supply the farms with fry throughout the year. Another goal is the substitution of the present hormonal agent (HCG) with another hormone. HCG is a large molecule (≃ 50 000 M.wt.) and it is known to evoke an immunological reaction in the fish which neutralizes the hormone. Therefore the hormone cannot be used on one fish more than a few times during the season. This situation is blocking any possibility of breeding and selection work in the future. It is intended to continue the preliminary work which was started in 1977 on the application of LH-RH as the inducing agent.
Environmental approach - inducing sexual maturation and spawning by means of environmental manipulation. It is known that most organisms having one reproductive season a year receive a signal from the environment triggering the sexual cycle. In many species of fish, changes in any one of the parameters - temprature, salinity and photoperiod - may trigger the cycle. Experiments on the two first parameters gave no positive results. A simulation of the natural behaviour of the fish, which leave the lagoons to spawn at sea, was tried. Temperature and salinity conditions in the two environments are very different. At the time of seaward migration, lagoon temperatures are lower and salinity higher than those at sea. It is intended to start an experiment with photoperiodism, combining it with salinity and temperature interaction. The main rationale behind this approach is based on the desire to allow the fish to enter the spawning cycle with the least human intervention. It is believed that the spawned eggs under such conditions will be of better quality, thus leading to the achievement of higher larval survival.
Controlling maturation and spawning by means of environmental manipulation will aid in achieving fish reproduction throughout the year, a very important factor in maintaining a viable industry. The ultimate solution for controlling fish reproduction could be a combination of the two approaches, after a thorough understanding of both of them is reached.
(d) Larval rearing
Rearing the sea bream larvas posed a difficult and challenging problem. It was obvious that until and unless it is solved, the realisation of wide farming will remain an unfulfilled desire. At present, rearing successfully the Sparus larvae, in large numbers and at a reasonable survival rate, is the only major problem left unsolved, though a significant advancement has been achieved. The Laboratory is ready to start a pilot plant for rearing the fish in floating sea cages and/or in ponds (sea and brackish water - see below), but the problem of rearing the Sparus larvas in mass production is still holding progress back. After studying and understanding some of the problems facing the larvae in an artificial setup, it was found that in order to arrive at the goal of high survival rate, a very well controlled rearing facility is needed. Temperature, salinity, light, water quality (from the chemical as well as the physical aspects), water flow, and aeration are some of the parameters defining the physical rearing environment. Such a facility has not yet been built, but should be built and functioning in the 1980/81 breeding season.
In 1975, the first larval rearing season, 250 fish were produced. They were fed mainly on live food (algae, rotifers and artemia) up to the age of 60 days. Since then, many more larvae have been reared, and last season (1979) some 50 000 post-larval fishes were taken out of the hatchery. However, this is still far away from the desired goal. The survival is still very low, and most of the mortality factors at the different larval stages are not understood.
Problems partially solved at present include:
Food chain - A larval feeding regime on which the larvae manage to grow has been established. It is known how to grow the food organisms quite efficiently, in mass cultures.
Incubation techniques - An efficient incubating technique has been established in which, if fertilised eggs are of good quality, over 80 percent hatching is achieved.
Survival rates - The best results so far achieved are 2 to 5 percent survival of hatched larvae. The final density of post-larvae fry is about three fish per litre. As mentioned above, this is not yet satisfactory. The present technique requires tremendous labour and it is far from being economical.
Environmental (tank) conditions - A great effort was put into determining the optimal environmental conditions suitable for larval development. Some tentative conclusions have been reached concerning air flow, water flow and light regimes.
Biological conditions - A good idea of the desired densities of the food organisms in the larval rearing tanks has been obtained and it is known when one food item should start to overlap with the next one as well as the desired larval densities at the different stages. A successful weaning procedure from live to dry food has been determined, though it must be improved.
Since the Laboratory goal was to bring Sparus aurata to the stage of farming at the earliest possible date, a programme for developing farming techniques was launched. It was initiated in the early stages of the project, long before the major problems of nutrition, diseases, reproduction and larval rearing were brought to working solutions. The idea behind this rush programme was to incorporate into the more basic research also problems of a practical nature. The flow of unsolved issues from the farming department to the nutrition, diseases and water quality projects gave immediate directives to the research programme. At present, five years after the farming programme has started, two main methods have been developed by which Sparus aurata can be cultured commercially: farming in floating sea cages and in sea water fish ponds. The possibility of fish farming in brackish water ponds was also investigated.
(a) Floating sea cages - This project was initiated in September 1974. It was conducted for four years in a protected bay, 150 km south of Elat. To summarise the end result of the four years work, a method by which Sparus aurata can be successfully and economically farmed has been developed. The fish grow to market size (250–300 g) in 16 months from hatching, utilising food with a 1:2.5 conversion rate, at a density of 220 fish per cubic metre.
To generalize the work, the experiments were moved into an exposed shore in 1978. There are still numerous technical and biological problems to be solved in this new environment. Present and future work in this subject deals with the adaptation of the technique developed in a protected bay to open sea conditions.
(b) Sea water ponds - This project was initiated in 1975. A series of 8 ponds, 250 m2 each, was built on the premises of the Elat laboratory. The results of the first year were very promising. Yields, when extrapolated to 1 dunam (1 000 m2), were in the vicinity of one ton per year. However, since then, the yields have decreased every year.
Two basic projects concerning the ponds have been carried out: fish farming in sea water ponds (the results are mentioned above) and the ecology of sea water fish ponds. The ecological study, which is still going on, may confirm the hypothesis explaining the decrease in yield. All physical, chemical and biological parameters and their interactions in the ponds were studied. Primary production in the ponds, due to fertilization of the water through fish feeding and intensive solar radiation, may reach 20 tons of organic carbon per year. Most of this material sinks to the bottom of the pond and decays there, mostly anaerobically, releasing into the water toxic compounds such as H2S, CH4, NH4 and others. As the pond gets older, the amount of organic decay increases, and more of these toxic compounds are released into the water column. As a result, the water quality deteriorates, growth rates decrease, and in extreme situations fish mortality occurs. Since the ponds are flushed continuously with fresh sea water to compensate for evaporation and to maintain salinity levels tolerated by the fish, an experiment with oyster growth on the runoff water (see report on oysters below) was started. The preliminary studies of oyster growth are very promising. In future it is intended to start work on cleaning the pond water by circulating it through oyster beds at the rate of the algae average generation time.
It is estimated at present, based on the results in the cage and pond experiments, that it will be possible to maintain a high-density growing fish population in a pond once the water quality is kept at high standards, thus yielding high crops of fish and oysters per unit area, time and effort.
Other species of fish were introduced into the ponds to complement the Sparus aurata: Siganus rivulatus (eats macro-algae); Mugil cephalus (consumes plankton and detritus), and Dicentrarchus labrax, which has very similar qualitits to those of the sea bream.
(c) Brackish water ponds - Since there is a large supply of brackish water of terrestrial origin in the Arava valley (water of 10 ppt: TDS), and since the sea bream is euryhaline, it was decided to try growing the fish in such waters. The idea was based on the fact that these waters have no agricultural use, and that lower salinity may even have an enhancing effect on the fish growth. However, the same problems encountered in the sea water ponds appeared, and even more so, since the brackish water ponds were not flushed at all. Oysters cannot grow in this water, due to its ionic composition which is different from that of sea water. At present, this research and development project is at a deadlock situation. It is intended in the future to utilise this water to compensate for evaporation in sea water ponds, thus reducing significantly the quantities of water needed to be pumped into the ponds in order to maintain the desired level of salinity.
The pond project's by-products were significant: the establishment of a sea water analysis laboratory, and the introduction of the polyculture principle and the concept of landbased mariculture in arid areas situated close to the sea.
Regarding fish culture future plans the following disciplines will be incorporated in the centre's activities: fish genetics, fish behaviour, and a biochemical laboratory to service the nutrition and endocrinological departments.
Early in the pond grow-out work with bream and other organisms, it was evident that rich blooms of phytoplankton were developing in the ponds, fertilized by nutrients excreted by the fish. Experiments were initiated to find a commercial organism which could utilize this otherwise wasted source of food. Of the species examined, the edible oyster was found to be the most promising. One thousand oyster spat (juvenile, just-settled oysters), grown in ponds and outflow troughs, grew faster than any oysters mentioned in the literature, reaching a marketable size of 65 g in 9 months. These oysters were also much fatter and of more regular shape than is generally found in Europe, raising the possibility of catering to a speciality market.
In the second set of experiments, a trough was constructed to receive the outflow from four one-quarter dunam (250 m2) ponds in order to obtain an estimate of the productivities to be expected in such a system. In this trough, 1.3 tons of oysters per dunam of fish pond were produced per year. Small numbers of the more expensive European oyster were also grown successfully. The two major problems associated with trough culture of oysters were: (a) oysters required cleaning every two weeks to remove accumulating faeces, and (b) phytoplankton concentration was very high in the pond water entering the oyster trough, causing the oysters to “wad up and spit out” much of the available food which was then unavailable to downstream oysters. A system has now been developed which reduces the cleaning of oysters from one day per week to about 15 minutes per week, and work in the coming year will be focused on optimizing the concentration of food reaching the oysters. With improved assimilation efficiencies, much higher per-dunam productivities should be possible.
A number of attempts were made to cultivate oysters in brackish water, evaporated to the salinity of sea water. To date, after five trials, no oysters have survived.
(a) Grey mullet (Mugil cephalus)
This species has long been fished in the Mediterranean Sea and Gulf of Suez and to a small extent in the Gulf of Aqaba. It is also farmed in freshwater ponds in Israel. Juveniles are collected in the winter from the sea and stocked together with carp and tilapia. Although it is not a very high-price fish, the grey mullet is worthwhile growing with sparids or other similar fish since it occupies an ecological niche not used by these carnivores, being a detritus feeder. At the same time, it helps to reduce the build-up of anaerobic bottom deposits. Supply of post-larvae from the sea is less than demand, and eventually a mullet breeding programme will have to be initiated. Mullets grown in ponds in Elat with sea bream have shown very rapid growth.
(b) Shrimp (Penaeus semisulcatus and Penaeus japonicus)
Shrimps caught in the Eastern Mediterranean found ready European markets, but from the inception of shrimp fishing in 1973 to 1977, shrimp catches fell from a peak of 102 tons per year to 37 tons per year. Preliminary diet and grow-out experiments were initiated in Elat to obtain a first idea of the needs and growth characteristics of this expensive sea food. Post-larvae were supplied from Tel-Aviv University. It was found that shrimps could be grown to a density of about 125 kg per dunam in earthen ponds using regular fish food. Initial diet experiments showed a number of ways to improve this basic diet for use with shrimps. Best grow-out results to date show that shrimps can reach a commercial size of 25 g in less than six months. This year, a commercially available food is being examined in an attempt to attain standing crops of greater than 125 kg per dunam. In the coming year an organized programme of shrimp breeding and diet evaluation will be started.
(c) Rabbitfish (Siganus sp.)
The rabbitfish is a relatively low-price species found in the Red and Mediterranean Seas. Large quantities of fry are available in nature in season with very little effort. The main market for these fish is in Elat, but a market is developing in northern Israel. The value of this species is in its ability to consume large quantities of macro-algae, leaving pond nutrients available for the growth of micro-algae (phytoplankton) which is in turn food for oysters. Since rabbitfish utilises a source of food in the pond not consumed by sea bream or mullets, the rabbitfish increases the total productivity of the pond. With the present state of the Siganus market, this species will continue to be used only to balance pond productivities.
(d) Sea bass (Dicentrarchus labrax)
This is a high-priced sea fish which can also grow in fresh water. It is reputed to be an aggressive predator on smaller fish. Numbers of these fish have been raised from the egg for the Israel Water Carrier (Mekorot) to be used in their systems as “police fish”, and a number of kibbutsim have also been supplied with this fish for the same purpose. In fresh water culture, tilapia tend to breed in an uncontrolled fashion and juvenile fish compete with and retard the growth of adult fish. The presence of sea bass should eliminate the need for sorting female tilapia out of the ponds by hand or for special species crosses which produce all male fish populations. Sea bass are somewhat more delicate to handle than sea bream and at this point no advantage is seen over bream for mariculture. However, if experiments are successful in using this fish to police fresh water ponds and reservoirs, a small breeding programme could be initiated to supply these needs.
In the last few years, Italy has considerably strengthened research efforts in aquaculture, and production derived from aquaculture has also increased. However, coordination amongst researchers and the production sector has not been effective. The lack of a clear government policy for the development of the sector is in part responsible for this. Nevertheless public investment has not been withheld, resulting in a series of ventures that, although uncoordinated, and thus not reaching the maximum potential, have produced a certain progress.
Italy has developed its mariculture activities mainly along two lines, the first aimed at improving the traditional extensive practices such as the “vallicoltura”, and the second aimed at establishing intensive culture techniques.
In extensive aquaculture the total production including “vallicoltura” and other coastal lagoons is around 6 000 tons/year and the main species harvested are: gilthead sea bream, sea bass, eel, and several species of mullets, which are species that utilize the “valli” and coastal lagoons as feeding grounds since they do not reproduce in this environment.
The culture method has been extensively described in the past and results in average production, for a well-managed “valle”, of about 150 kg/ha/year, but in some cases - due to environmental deterioration - decreases to figures as low as 20 kg/ha/year. In many cases now, natural recruitment is insufficient to cover the seed requirements for proper stocking and artificially produced seed has to be used to compensate, especially in the case of sea bass and gilthead sea bream. While the mullet demand (of about 3.5 million) is normally satisfied, that of sea bass (with a demand of 100 000–150 000) and gilthead sea bream (with a demand of 200 000–300 000 fish) is not.
In order to increase the yield from the “valli”, some projects, combining intensive culture in the first 18–20 months and extensive culture up to an age of 32 months, have been proposed. Initially 18 000 ha will benefit from this plan for improved management aimed at producing 30 000 tons/year.
Another project for the valli of Comacchio, with production of 1 000 tons/year/10 000 ha, has been planned.
The lagoon area around Orbetello produces at present around 400 tons/year/3 000 ha, and another project is being implemented there in order to raise the production of the area to 1 200 tons/year, using seed produced by a hatchery now under construction. This hatchery should produce a million weaned fry per year, and should sell half of its production to farmers while the rest will be stocked in the lagoons.
Southern Italy has also good prospects for this type of aquaculture due mainly to its more favourable climate. On the Ionian coast of Basilicata an eel farm is already covering 104 ha for extensive culture and the production has reached 135 kg/ha/year.
Sturgeon is one of the species that are contemplated for future development and a hatchery for production of one million fry per year will be started in 1980.
Regarding intensive culture, the main species cultured is eel. followed by sea bass and, as soon as techniques for artificial propagation are refined, gilthead sea bream.
In the area of Comacohio a pilot plant has been built with a target production of 200 tons of cel/year and 50 tons of sea bass/year. A more intensive farm for eels is already in operation near Calvisano, for the fattening of elvers and young eels. The production so far obtained reaches 2 000 tons per year, but the potential figure for this farm should be close to 6 000 tons/year.
Again, on the Ionian coast of Basilicata, the same farm mentioned above has 11 ha of ponds for intensive culture of eel and the actual production is reaching 500 tons/year, with a potential to reach 1 000 tons/year.
Gilthead sea bream and sea bass are species with high market value in Italy. For the first one, the scarcity of wild fry and its lack of resistance to cold conditions, limit its production outside the “valli” of the North Adriatic, where, anyway, the figures are reduced to 15–30 kg/ha. The mass production of fingerlings for stocking has not been solved as yet.
In the case of sea bass, a stronger predator than gilthead sea bream, the production from the “valli” is only 10–15 kg/ha, and with a much wider range in size. However, for this species, mass production of fry has been achieved, and programmes for better management are under way. The hatchery of SIRAP (Pellestrina) has reached a level of production of 1.5 million fry.
Another plan for monoculture of this species has been designed by the Centro Ittiologico Valli Venete as follows:
rearing fry up to 8–10 cm size on dry pellettedfood and with addition of Artemia salina nauplii in the very first days;
rearing them up to a size of 120–150 g in concrete tanks of 80–120 m3 or in earthen ponds of 200–400 m2 (depth 1.5 m) at densities of 1–2 kg/m2 in earthen ponds and 4–5 kg in concrete tanks;
rearing in earthen ponds of 500–600 m2 and 2 m deep up to a size of 300–400 g at a density of 2 kg/m2.
As a final point for the production section, it must be mentioned that mussel culture is an important type of culture, reaching annual production figures of 45 000 tons, but unfortunately it has little chance of expansion due to the existing regulations and scarce interest of the public powers.
(a) Mullets
Although the importance of mullet culture is decreasing in Italy due to worsening environmental conditions, the research on nutrition of this species is being continued by the CNR (National Research Council) along two main lines: (i) trophic ecology and (ii) feeding requirements, in order to formulate complete and supplementary diets for intensive culture.
For the first line of research the variables that characterize the trophic value of detrital matter, which constitute the main energy source for mullet, were identified.
Regarding feeding requirements, after studying natural processes of ingestion and digestion, the optimal daily feeding rates in intensive culture were investigated for Mugil chelo and M. auratus. Besides that, the effects of salinity in respect to growth were studied.
Apart from this research on nutritional aspects, experiments on induced breeding and larval rearing have been continued at the municipal hatchery of Orbetello with encouraging results.
(b) Eel
A research programme with the title “Rationalization of intensive eel culture” is being conducted at Comacchio by SIVALCO, with funds of the National Research Council. The objectives of this programme are: evaluation of the efficiency of the traditional fishing methods as well as electrofishing, testing of aeration techniques, study of the composition of sizes in the cultured eels, in order to find behavioural clues and to estimate real food conversion rates, and study of the variations in size and condition of young eels when they arrive at the farms.
This last point is very interesting as it will help to determine the biological and therefore the economical value of batches of young eels that are sold for rearing.
Further lines of research conducted on eels at some universities are the influence of density of culture on sex ratio, as well as genetic dependence.
(c) Sea bass and gilthead sea bream
Research on optimization of the parameters that influence reproduction and larval rearing in sea bass is being continued. Experiments on feeding the larvae from the very first days on artificial food, have yielded encouraging results as far as reduction of cannibalism is concerned.
For gilthead sea bream, research is being continued on the factors that impede mass production of fry and fingerlings in this species. It has been found at the SIRAP farm that the different temperature-salinity conditions influence rates of survival both for embrional development and first larval stages.
Problems with vibriosis have been experienced and are being investigated.
(d) Tuna
In 1978 a programme was started on reproduction of tuna Thunnus thynnus in collaboration with scientists of the Tokyo Fishery University. This joint programme has as its objectives the repopulation of this species both in Japan and in Sicilian seas.
(e) Shrimp
The species which is the subject of research is the local Penaeus kerathurus. This species is being studied mainly at the Laboratory for Biological Exploitation of Lagoons at Lesina.
Research has been conducted on induced breeding both by photoperiod manipulation and eyestalk ablation. Some sinergistic effect of the light has been observed in the induction of maturation started by the ablation of the eyestalk.
In nutrition, four main lines were studied: (i) stomach contents of specimens caught in the wild; (ii) formulation of a complete artificial diet; (iii) formulation of fresh diets made from low value fish products or byproducts; and (iv) research on the influence of polyunsaturated fatty acids ω-3 and ω-6 in penaeid growth.
Some research on pathology of larval and adult stages is being carried out.
The results of these experiments will be applied in a pilot plant that will be located in southern Sicily, consisting of 16 000 m2 of tanks for intensive rearing, and a 2 ha pond for polyculture.
(f) Artemia salina
The Artemia Reference Centre is collaborating with Italian scientists in studying the brine shrimp stock of Margherita di Savoia, which up to now has shown many positive characteristics.
(g) Algae
Since 1974 Gracilaria confervoides has been collected by fishermen in the Lesina Lagoon. The dry product amounts to 100 tons/year at present but once this exploitation is rationalized it is expected to reach 400–500 tons/year. Species like this one are contemplated in the research project “Oceanography and sea-bottoms” of the National Research Council, which is evaluating the algal resources of natural lagoons and man-made salterns of Sicily.
(h) Mollusc culture
Apart from the research that is being conducted on the techniques of mussel depuration, the artificial reproduction of Tapes decussatus has been achieved.
(i) Thermal aquaculture
The ENEL (National Organization for Electric Energy) has started a project for the utilization of waste heat for aquaculture purposes, mainly for P. kerathurus and valued finfish species. Initially this research plant will cover 2 300 m2.
The official report of the Spanish delegation represented by the Instituto Español de Oceanografía (Spanish Institute of Oceanography) was complemented by the report of the Instituto de Investigaciones Pesqueras (Fisheries Research Institute) and both of them are merged in this summary of activities.
At present almost all aquaculture activities on the Mediterranean side and along the southern Atlantic coast (which work with the same species as the Mediterranean laboratories) have been on research or the pilot plant stage. It is very likely that in the very near future, production activities will be started as contracts with parastatal and private companies have already been or are about to be signed.
(a) Crustaceans
Two main species are studied: Penaeus kerathurus and Palaemon serratus. For the first one work is going on at the laboratory of Mar Menor (I.E.O.) and the laboratories of Torre de la Sal and Cadiz (I.I.P.)
It is reported that in the laboratory of Mar Menor (I.E.O.) survival rates up to 65 percent for PL30 have been obtained at densities of 3 500 PL30/m2. For growth tests, post-larvae have been stocked in salterns but the results have been negative.
For the same species, the new Research Station of Torre de la Sal (I.I.P.) has reported 78 percent survival up to PL1 at densities of 2 800 PL1/m2. The production of post-larvae of this species is now limited due to the fact that the cement tanks, recently built at the new station, are undergoing a curing process and therefore the full production potential is not fully utilized. This research station is also testing artificial diets for post-larvae with encouraging results. This year production has been 7 000 post-larvae. As far as the total area covered by the station for culture purposes is concerned, the present figures indicate around 1 500 m2 with a potential for expansion of 15 000 m2. Apart from studies on nutrition, experiments with successful results have been carried out on induced maturation, starting with females with spent gonads, by eyestalk ablation and photoperiod and thermoperiod manipulation.
The Centre of Cadiz (I.I.P.) is also involved in the artificial propagation of P. kerathurus and the post-larvae production varies between 2 000 and 15 000 according to the years. Grow-out experiments have also been performed with this species placing 2 500 specimens in an earthen pond of 700 m2. Growth observed has been 24 kg in 10 months of extensive culture with a final survival of 66 percent.
Regarding the second species, Palaemon serratus, the laboratory of Mar Menor (I.E.O.) has achieved a survival rate of 93 percent for a production of 2 000 PL/m2. However, growth of the postlarvae is reported as not being satisfactory due to cannibalism and bad feed conversion rates.
The Research Station of Torre de la Sal (I.I.P) is also involved in the culture of this species. A total of 6 000 juveniles (70 days old) has been produced at a density of 2 720/m2.
Another crustacean that is receiving attention in Spain is Artemia salina, and the I.I.P. is involved in studies for mass production on a contract with private investors. Studies on the characterization of the different races and their geographical distribution in Spain are also being conducted by the Research Station of Torre de la Sal.
(b) Molluscs
The species which has been the subject of research was the cephalopod Sepia officinalis. Experiments on its potential for culture have been carried out by the Centre of Cadiz (I.I.P.) and the production obtained has been 20 000, 25 000 and 2 300 specimens in 1977, 1978 and 1979 respectively. Positive points for the culture of this species are its fast growth, the possibility to obtain fertilized eggs from the wild and a better acceptance by the market of the small sizes (6–7 cm) which bring the best prices. Against it we can list its aggressive behaviour and difficulties for feeding since it requires moving live pray. High mortalities have been experienced in extensive culture at densities higher than 10 000/ha. Growth observed has ranged from 300 to 400 g in 5 months with a final density of 1 specimen/13 m2. In intensive culture in cement tanks of 8 m3 densities of 5 kg/m2 have been maintained with good growth.
(c) Finfish
The species considered for culture in Spain are: sea bass Dicentrarchus labrax, gilthead sea bream Sparus aurata, sole Solea solea, and mullets Mugil spp.
For sea bass, the laboratory of Mar Menor (I.E.O.) reports a production of 20 000 fingerlings (60 days old) with survival of 20 percent, and experiments are being completed on their feeding up to marketable size using dry artificial diets. For the same species the Research Station of Torre de la Sal reports a production of almost 17 000 fingerlings (67 days old) with a survival up to this stage of 34 percent and a stocking density of 5 600 fingerlings/m3. Different types of hormones are being tested with this species. The I.I.P. Centre of Cadiz has produced 1 500 fingerlings of this species by induced breeding and has carried out experiments in semi-intensive culture in salterns obtaining an average growth of 400 g in 18 months.
For gilthead sea bream, in Spain considered a better species than sea bass, the laboratory of Mar Menor (I.E.O.) reports a production of 30 000 fry (10–15 mm) with densities of 10–16 fry/l. Experiments for weaning these fry on artificial dry diets are being conducted. An agreement has been signed with the National Industry Institute (I.N.I.) for production of 250 000 fry of gilthead sea bream to be reared up to marketable size.
At the Research Station of Torre de la Sal (I.I.P.) 4 000 fry have been obtained (45 days old) with a survival of 11 percent, and the Centre of Cadiz of the same Institute has produced 20 000 fingerlings in 1979. This Centre is collaborating with a private company in the construction of a pilot plant for the production of sea bream fingerlings, and is using earthen ponds, rather than salterns, of several hectares for polyculture experiments with sea base. With this species, growth experiments in extensive culture at densities of 10 000/ha have shown rather slow growth, reaching an average weight of 130 g after 12 months. At lower densities and in polyculture, the sea bream reached 150 g in 8 months with the best specimens weighing 250 g.
Sole is a promising species for culture and is being investigated by the Research Station of Torre de la Sal. In 1979, 24 000 fingerlings (size between 5 and 7 cm) were produced, with an average survival of 81 percent after 30 days (average size 19 mm). The stocking densities were between 6 000 and 10 000 fry/m2 depending on the tanks. From that size they were reared in one year up to a length of 18 cm with a survival of 96 percent. To induce maturation the treatment consisted in a 16-hour photoperiod associated with injections at rising doses of PMSG together with HCG. Once the ovary started hydration, HCG was used alone and the fish spawned after 29 days of treatment.
Mullets are being reared by the laboratory of Mar Menor (I.E.O.), where females of Mugil chelo spawned by hand-stripping, producing 5 500 fry (13 mm) at densities of 5–6 fry/l and with 23 percent survival rate. In the same laboratory M. saliens spawned naturally and 6 400 fry were obtained with a similar survival as M. chelo although at a lower density of 2–4 fry/l.
The techniques employed by the I.I.P. for feeding of larval stages of finfish and crustaceans involve the use of phyto- and zooplankton as initial diets.
For the first, the following species are the most commonly used: Skeletonema costatum, Tetraselmis suecica and Scenedesmus obliquus, while for zooplankton Brachionus plicatilis, Daphnia magna and Artemia salina are the main ones. Research on mass culture of the rotifer Hexarthra fennica, the cladoceran Simocephalus vetulus and of harpacticoid copepods has also been attempted. For rearing of Sepia officinalis the Centre of Cadiz has used Mesopodopsis slaveri, Dianysis bahirensis and Palaemonetes varians.
The feeding rates of B. plicatilis and A. salina for the larval stages of the cultured finfish and crustaceans has been determined. For mass culture of B. plicatilis, containers of 60 l capacity were used and cultured Tetraselmis were given as feed to the rotifers, which reached densities ranging from 150 to 250/ml. This initial rotifer culture was then transferred to conical tanks of 150–250 l volume where they were fed bakers' yeast and rice bran extract. Here they reach densities from 60 to 120 rotifers/ml, and this second stage is then transferred to raceways of 1 200–3 000 l volume where they are again fed Tetraselmis. This tertiary stage is used to feed the larval stages of finfish and crustaceans.
Regarding A. salina, the nauplii are obtained from decapsulated cysts (using sodium hypochloride for decapsulation). Conical tanks and raceways are utilised for rearing the instars, and food is Tetraselmis, bakers' yeast and rice bran. Densities obtained vary between 1 500 and 15 000/l according to size.
Artificial dry diets for feeding of P. kerathurus are also investigated but although improvements are reported, they cannot be considered yet as complete diets. Apart from special locally formulated diets, French and Japanese rations are being tested.
A special pellet, made in Spain, is being tested for feeding sea bass, and the Centre of Cadiz (I.I.P.) is employing a modified trout pellet mixed with ground crab meat for feeding sea bream from the third month. With this diet mortality has been nil.
The initial stages of mariculture development in Yugoslavia were devoted to the preparation of a programme of research by the Yugoslav Mariculture Group. This programme was accepted by industry and related governmental institutions' and then the research projects were started.
The following are the research activities undertaken by the Marine Research Institute of the Adriatic coast in the past intersessional period:
Continuation of research on nutrition of gilthead sea bream, sea bass, mullet and eels at laboratory scale, in cages and in lagoons.
Construction of small hatcheries for artificial propagation of finfish.
Experiments on induced and natural breeding of sea bass have been conducted, and the fry produced are being reared up to marketable size. The results obtained are: after 19.5 months of culture in water temperatures ranging from 10°to 16°C an average length of 241 mm was obtained with an average weight of 196 g, and with a rather variable condition index, ranging from 1.7 to 3.6.
Cage culture of sea bass was started using fry produced by SIRAP in Italy and the weight after 6.5 months of culture was 22 g with a condition index of 1.5 to 2. Water temperature ranged from 18°to 25°C.
Surveys to locate nursery grounds for the finfish species of economic interest were carried out mainly for yellowtail (Seriola spp.) and eels.
Surveys are also conducted to locate optimal areas for mariculture along the coast and, once found, to ensure legal protection.
Regarding future activities and projects, the following can be listed:
Construction of a commercial hatchery for production of sea bass fry to be reared in cages, and the start of trout culture in sea water. In order to make the best possible use of the existing resources (in terms of sites and water quality) fry from hatcheries will be stocked as well as fry collected from the wild (for sea bass and other species such as mullets, eels and gilthead sea bream). Some importation of fry is also envisaged.
Continuation of research on physiology and toxicity for fish culture purposes. In this area of research special attention will be paid to possible pollution of marine environments as a result of eutrophication caused by intensive cultural practices.
