Annex I
SUMMARY REPORT OF THE MISSION'S VISIT TO
COUNTRIES IN THE MEDITERRANEAN REGION

C Y P R U S

The study of the marine aquaculture potential in Cyprus was carried out 14–18 November 1978 by D. Charbonnier, H. Cook, M. Girin, J. Glude and M. Zei.

1. SUPPLY AND DEMAND

1.1 Supply of fisheries products

The per caput fish consumption on the island of Cyprus was listed as 7.0 kg in 1970 when Cyprus landings were 1 395 t and imports 2 050 tons. By 1973, fish landings increased to 1 445 t and imports to 2 325 tons. After, production dropped to 1 185 t and to 930 t in 1975, but has since increased to 1 190 t by 1977. During this three-year period, imports decreased to 1 140 t (in 1974), but subsequently increased to 2 270 t by 1977. Landings and imports since 1974 exclude the northeastern area. Fish landings in this area are currently 55 t, which provides only 400 g per caput.

1.2 Supply of species with aquaculture potential

Table 1 lists species that might have potential for aquaculture, now or in the future, and shows retail prices in 1978.¹

The total production from marine aquaculture in Cyprus at the present time is about one ton of mullet grown in the tanks and ponds at the Boghaz Fish Culture Station.

1.3 Estimated demand

There is a strong demand for marine fish in Cyprus, but the demand in the northeastern part of the island is primarily for low-priced food species, such as mullet. Trout production, which currently is 40 t, could be increased if warranted by local demand. The international market for smoked trout is good, but an industry based on export is said to require consistent production of at least 200 t/year.

It is obvious from the statistics of landings, imports and prices that the demand for fish in Cyprus is not being met by the local supply and that significant increases could be utilized. It is unlikely that the catch of fish from territorial waters could be increased sufficiently to provide needed supplies now or in the future. However, marine fish farming could add significantly to the supply of certain species and could create new job opportunities.

¹ Table 1 was provided by A. Demetropoulos, Director of Fisheries

Table 1
RETAIL PRICE IN CYPRUS OF SOME CULTIVABLE SPECIES DURING 1978

Note: Price varies with season and size of fish

¹ oke = 1 282 g

² £.Cyp. 0.35 = U.S.$ 1.00
£.Cyp. 1.00 = U.S. $ 2.82

2. STATE OF AQUACULTURE

2.1 Commercial ventures

There is no culture of marine species on a commercial basis in Cyprus at present. Prior to 1974, there was one private mullet farm at Syrian Okhori, but it was discontinued after 1974.

2.2 Current research and development activities

The Department of Fisheries is currently conducting studies of sea bass culture in floating net pens, or cages, at the Paphos Station, using fry obtained from France. Although these studies are progressing well, some significant mortality has occurred as a result of malformation of the operculum, which exposes the gills to infection and mechanical damage. The cause is not known and further research is needed.

Studies on the culture of the green and hawksbill turtles are also being conducted at Paphos to determine if turtle stocks can be maintained or expanded by artificial hatching of eggs and return of juveniles to the beach where the eggs were collected before their migration to the sea. There is also a possibility of developing techniques for the culture of turtles to market size in captivity, following the techniques developed at Grand Cayman and other places.

The Boghaz Station, operated by the Department of Fisheries until 1974, is currently used for experimental mullet culture with fry obtained from the wild along the adjacent shoreline. Some other species, such as rabbit fish or spinefoot (Siganus), have also been collected as fry and are being held in tanks with the mullet. According to the resident fisheries biologist, Siganus are especially sensitive to low oxygen, which sometimes occurs during mid-summer nights in tanks that have extensive blooms of phytoplankton. If this problem can be solved, Siganus might be used to keep mullet culture tanks clean as they will feed on the algae attached to the sides and bottoms of the culture tanks.

2.3 Institutional factors

It appears that the Government of Cyprus favours the development of aquaculture, and it is possible that individuals, firms or cooperatives could obtain permits or leases of suitable coastal areas for this purpose. Furthermore, the Government has a programme of loans for the establishment of trout farms and this programme might be expanded to include culture of marine species.

Although foreign investments in agriculture are limited, there appears to be a possibility that the Government of Cyprus might make a separate case for the development of aquaculture. Even so, it is possible for a foreign investor to develop a joint venture with a Cypriot who has a 51 percent share. According to Mr. Demetropoulos, Director, Department of Fisheries, Nicosia, there is much private interest in the development of aquaculture ventures and it seems likely that a proposal with a reasonable chance of financial success would attract the necessary capital.

The expansion of aquaculture in Cyprus will also be facilitated by the good supply of trained technicians and craftsmen available on the island. Furthermore, the infrastructure is well developed, including facilities for transportation and marketing of perishable products, such as fish. Specialized technologies, such as solar water heaters, are available and in use on the island, taking advantage of the excellent climate and abundance of sunshine.

Finally, the tax structure favours aquaculture since essentials, such as fish meal and specialized equipment, can be imported tax free.

3. POTENTIAL FOR AQUACULTURE DEVELOPMENT

3.1 Crustaceans

Cyprus has several advantages for intensive shrimp culture. It has a favourable climate, clean, warm water, mild winters, and some level coastal lands adjacent to the sea. There is an excellent demand for Penaeus kerathurus on the island and in the Mediterranean region generally. Methods for larval culture of this species have been developed in France and Spain and post-larvae could be obtained for initial experiments. Several other species of shrimp might be considered for culture in Cyprus. The Japanese shrimp (Penaeus japonicus) has been grown experimentally in France and post-larvae are available. Penaeus monodon and Metapenaeus ensis grow rapidly and reach a marketable size in a short time. The hatchery technology for these species has been partially developed in Tahiti and The Philippines. All are grown commercially from juvenile to market size in southeast Asia.

In Cyprus, shrimp could be raised in pond culture systems at densities of about 5 shrimp/m² of bottom. Later, when adequate supplies of post-larvae become available from foreign or local hatcheries, shrimp aquaculture could be developed using culture systems, such as raceways with solar heating at densities up to 3 kg/m² of bottom. The product could be sold to local hotels and when the local demand is satisfied, to the export market. Intensive controlled environment systems for shrimp culture are being developed in Mexico for Penaeus stylirostris and P. vannamei, and in Japan for Penaeus japonicus.

Although the main potential in the northeastern area is for the culture of mullet in ponds, there may be potential in the future for combining mullet and shrimp culture to increase the returns of the aquaculture operation. This, of course, is a long-range prospect and would require the development of polyculture systems and a shrimp hatchery.

3.2 Molluscs

The Department of Fisheries (Ministry of Agriculture and Natural Resources) has attempted oyster culture but the results have been discouraging. Although there appears to be no immediate prospects for developing commercial culture of molluscs, the techniques being developed in the Virgin Islands and in Hawaii may have application in the future. In these systems, appropriate species of algae are grown in tanks as food for oysters or clams. If controlled environment systems are used for fish and crustacean culture in Cyprus, the effluent water might be used to grow food for filter-feeding molluscs.

3.3 Fish

Although Cyprus has few shallow coastal lagoons or estuaries, there is a good potential for growing sea bass and sea bream in coastal ponds, or later in tanks or raceways. The demand and prices for these species, as well as for shrimp, are high and the technology for these culture systems is being developed. Initial trials could be made using juveniles from France or Italy and later a hatchery could be built in Cyprus.

Commercial farms for sea bass and sea bream and possibly for shrimp could be established in areas where relatively level land, with suitable characteristics for pond construction, is available close to the sea. In these locations, clean water could be pumped directly from the sea or from salt water wells into ponds. At a later stage, it might become profitable to grow these fish in high-density intensive culture systems using tanks or raceways. Feed supplies should ideally be from local sources, although the high price of these species might even justify use of imported feeds. The domestic market for the product would consist of retail sales to the local population and institutional sales to restaurants. If the local demand can be satisfied, export markets could easily be found for these highly-valued species.

There is good potential to expand mullet production in the coastal area close to the Boghaz station by construction of ponds. This could produce significant quantities needed for local consumption.

Looking further to the future, it would be interesting to work with the rabbit fish (Siganus) and possibly the amberjack (Seriola) or the dolphin fish (Coryphaena). These species have been grown in other parts of the world and they occur here and have high consumer acceptance.

4. PROGRAMMES NEEDED TO EXPAND AQUACULTURE

4.1 Limiting factors

Four factors appear to limit the development of aquaculture in Cyprus:

1. the shortage of fresh water;
2. the lack of a shallow lagoon system that makes extensive aquaculture possible in some other Mediterranean countries;
3. the low productivity of the sea, combined with high salinity and high temperatures, impeding mollusc growth; and
4. the lack of a biological station to replace the Boghaz Fish Culture Station.

4.2 General programme requirements

A research and development station, similar to the one that existed at Boghaz, is needed in the southern part of the island. Plans for such a facility have been prepared by the Department of Fisheries. Although a specific site has not been suggested, it appears that the Paphos area would be satisfactory. Work there should include research, development, pilot-scale testing, and demonstration leading to intensive culture systems applicable in this environment for culture of sea bass, sea bream, marine shrimp and later for rabbit fish (Siganus) and the amberjack (Seriola). Such an installation would provide significant national benefits and could eventually serve as a regional training centre for intensive culture methods.

The existing Boghaz Fish Culture Station could best be used for demonstration of pond culture of mullet. Mullet production at Boghaz could be expanded immediately by the construction of a series of ponds adjacent to the laboratory, fed by means of salt water pumps and using fry collected along the adjacent shoreline. At some time in the future, the mullet culture systems could be expanded to include polyculture with marine shrimp to provide additional income to the fish farmer.

4.3 Recommended projects or actions

4.3.1 Development of a hatchery for shrimp, sea bass and sea bream

Technical assistance would be needed for the design of a pilot-scale hatchery for sea bass and sea bream. Techniques developed in the Mediterranean region and elsewhere for the maturation of shrimp and for the rearing of larvae should be applied in the country. The present state of this technology warrants the establishment of a production-scale hatchery.

4.3.2 Development of polyculture of shrimp and mullet in ponds

The mullet culture system developed at the Boghaz station should be adopted for pond culture in adjacent areas in combination with shrimp to increase profitability.

4.3.3 Development of pond and controlled environment systems for culture of shrimp, sea bass and sea bream

With adequate supplies of hatchery seed, these species could be grown in ponds constructed close to the sea and later in tanks or raceways with temperature control to provide ideal growing conditions all the year round.

Appendix 1

PERSONS INTERVIEWED

Appendix 2

REFERENCES

Demetropoulos, A., 1978 Annual report of the Department of Fisheries and the Cyprus Fisheries. Annu.Rep.Dep.Fish.Cyprus Fish., (1977):41 p.

Demetropoulos, A. and D. Neocleous, 1969 The fishes and crustaceans of Cyprus. Fish.Bull.Dep.Fish.Cyprus, (1):21 p.

Stephanou, D., The status of fish culture in Cyprus. Cyprus Ministry of Agriculture and Natural Resources, Department of Fisheries (in press)

Tal, S., 1964 Survey of fish culture in Cyprus. State of Israel, Ministry for Foreign Affairs, Department for International Cooperation, 8 p.

UNEP, 1978 Report of the expert consultation on aquaculture development in the Mediterranean region, convened by the Government of Greece in cooperation with FAO/GFCM and UNEP. Athens, 14–18 March, 1978. Geneva, UNEP, UNEP/WG.15/5/Rev.1:19 p. (Restricted)

White Fish Authority, 1971 Report on the prospects for developing fish farming in the area of the Akrotiri Salt Lake. Cyprus Ministry of Agriculture and Natural Resources. London, Overseas Development Administration, (Unpubl.rep.M.D.89):28 p.

T U R K E Y

The study of the marine aquaculture potential in Turkey was carried out 7–14 November 1978 by D. Charbonnier, H. Cook, J. Glude, P. Rouzaud and M. Zei.

1. SUPPLY AND DEMAND

1.1 Supply of fisheries products

According to FAO statistics, the total fish catch from marine and inland waters in the country was 155 000 t in 1977. Of this quantity, 80 000 t comprised European anchovy (Engraulis encrasicolus) and 20 000 t of Mediterranean horse mackerel (Trachurus mediterraneus), largely caught in the Black sea.

1.2 Supply of species with aquaculture potential

According to FAO estimates, total landings in the country include 100 t of gilthead sea bream, 2 200 t of mullet, 300 t of sea bass, 200 t of eels, less than 200 t of sole, and about 500 t of shrimp.

Few molluscs are landed in Turkey. Oysters are scarce and are not a well-known or accepted food item. Mussels are found in the Black Sea and the Bosporus and a small fishery for these exists. Some mussels are found in the Sea of Marmara, and in the eastern end of the Mediterranean Sea. According to FAO estimates, total landings of mussels in 1977 were 6 tons.

1.3 Estimated demand

The average per caput consumption of fish was reported to be 5.9 kg/y in 1973. Up to 45 kg/y of fish are consumed along the coast, but negligible quantities in the interior. Fish consumption is expected to increase as the population expands and distribution systems bring more fish to the interior. It is reported that sea bass and sea bream, which fetch about L.T. 80/kg, are to be in high demand and that consumption of mullet, which is sold at about L.T. 40/kg, could double if supplies were available.¹ A moderate market exists for mussels, and a high demand for shrimp.

2. STATE OF AQUACULTURE

2.1 Commercial ventures

The only aquaculture of marine species at this time is lagoon culture. Various species, including sea bass, sea bream, sole, mullet and eel, enter the coastal lagoons in the spring and are retained there by a weir across the entrance channel. After growing throughout the summer, the fish are captured at the weir as they attempt to return to the sea when the temperature decreases in the autumn. All the catch is marketed, including even some undersized fish.

¹ L.T. 26.50 = approx. U.S.$ 1.00

Lagoon fish farms, especially in the Saros Sea and the sea of Marmara, are operated by fishermen's cooperatives. The Government assists the cooperatives by providing up to 60 percent of the cost of capital improvements. Channel dredging, water control, and weir construction are carried out by the State Hydraulics Works agency. Estimated production from coastal lagoon culture includes 60 t of sea bass, 100 t of sea bream, 500 t of mullet, 20 t of sole, and 250 t of eel.

2.2 Current research and development activities

Research and development work relative to aquaculture is conducted by Ege Üniversitesi (Aegean University) at Izmir through the Institute of Hydrobiology in the Faculty of Science, and the Department of Fisheries in the Faculty of Agriculture. Both the Faculty of Science and the Faculty of Agriculture at the University of Ankara, and the Faculty of Science at Istanbul have fishery-related projects. The rearing of sole and shrimp larvae and juveniles is being studied by Ege Üniversitesi, Institute of Hydrobiology. This work will be expanded at the new marine laboratory at Urla, and there are plans to begin experimental culture of sea bass and sea bream.

2.3 Institutional factors

Fisheries are administered by the General Directorate of Fisheries in the Ministry of Food, Agriculture and Livestock, but several other agencies, including the State Planning Organization and the Fisheries Division of the State Hydraulics Works are also involved in projects related to marine fisheries and aquaculture.

Fishermen may group themselves into cooperatives, which are authorized and controlled by Turkish laws. At present, some 9 000 fishermen are organized into about 110 cooperatives. Cooperatives are organized into Fish Producers Cooperative Unions on a regional basis. All the current fish culture in lagoons is conducted by cooperatives, but a number of private individuals and firms are now reported to be interested in developing commercial aquaculture ventures.

3. POTENTIAL FOR AQUACULTURE DEVELOPMENT

3.1 Crustaceans

Substantial quantities of shrimp are landed along the southern Aegean and Mediterranean coasts and there is a strong demand for the product. Climatic, geographical and hydrological conditions in the area appear suitable for shrimp culture. Nevertheless, the latter is only just beginning in the Mediterranean region and testing of its economic viability on a commercial scale is needed before it can be recommended for application in Turkey.

3.2 Molluscs

There are few oysters or clams in the country and a limited market. Mussels are an accepted product, but supplies are low. Mussel farming might be developed in the Black sea, the sea of Marmara, or the northern Aegean Sea, if demand becomes large enough to justify expanded production.

3.3 Fish

There is good potential for extending the traditional lagoon culture system to additional areas, in the Enez area of the Saros Sea. Similar opportunities exist in the sea of Marmara and in the Aegean Sea. There is also good potential for increasing the production and value of the product of traditional lagoon farming by the adoption of valli culture used in Italy. This would require retaining the undersized fish captured in weirs, as they attempt to return to the sea in the autumn, and holding them throughout winter in specially constructed channels or enclosures. During the early spring, the fish would receive supplemental feeding for a short time and then would be released into the lagoons to grow during the summer and to be marketed in the autumn.

Additional opportunities exist for culture of sea bass, sea bream, mullet, sole and, perhaps, eels in ponds. However, full development of these systems would require dependable sources of seed and use of prepared feeds. In general, there are several positive factors that should facilitate marine fish culture in Turkey, such as the availability of suitable sites, high demand for aquaculture products and the existence of well-developed cooperatives adequately assisted by the Government.

4. PROGRAMMES NEEDED TO EXPAND AQUACULTURE

4.1 Limiting factors

Although some research is in progress, there is a real need for more scientific information as a basis for aquaculture. Also, there has been no pilot or commercial scale testing of advanced culture methods to determine their economic viability in the country.

4.2 General programme requirements

An immediate opportunity exists to upgrade traditional lagoon farming to valli culture. This could be accomplished first at the Vakif farm by excavating channels about 3 m deep where the fish could be held over winter to continue rearing during the following year. Over-wintering and growing of undersized mullet, sole, sea bream and sea bass during the second summer would require supplemental feeding in the early spring. Natural foods, such as green crabs, scrap fish and fish wastes should be used first. Some time in the future, however, it may be economical to use locally-produced pelleted feeds.

Undersized sea bass, sea bream and mullet might also be held for further growth in fenced enclosures within the lagoons or in the sea. Also, there is a possibility of using floating net pens or cages, where the water is deep enough.

Natural stocking of lagoons might be enhanced by increasing the number or size of channels connecting with the sea. This would also improve circulation, especially if flow control systems were installed to use some channels as inlets and others as outlets. In some places, fresh water could be added to lagoons in the summer to maintain the salinity at the desired level and also to increase productivity. State Hydraulic Works engineers could design various water control structures needed for aquaculture. The production of lagoons might be increased by supplemental stocking of fry, unless the limits of productivity have been reached by natural stocking. This could be determined by collecting fry in other locations and stocking them in a test lagoon in the spring. Catch records in the autumn would show whether there was an increase in production or whether the fish were stunted.

Coastal lagoons and deep, protected bays along the southern Aegean coast could be used to grow undersized sea bass or sea bream to market size in floating cages. Later, cage culture systems might be adopted.

There is a need to develop a better scientific or technological base for aquaculture. This might be accomplished by several different kinds of actions:

1. Ege Üniversitesi could expand their larval culture of sole and extend this to sea bream and sea bass, building on the knowledge of larval culture systems that has already been developed in France and Italy. It is important to make sure that these systems are applicable under Turkish conditions.

2. Ege Üniversitesi could raise juvenile sea bass, sea bream, sole and, possibly, shrimp in tanks, raceways or ponds at their new laboratory at Urla. This could be the beginning of intensive culture system development.

3. Ege Üniversitesi could also grow juvenile sea bass and sea bream in floating cages in some of the protected bays on the islands off-shore from Urla.

4. The University could test various natural foods in their experimental culture systems. This could improve the knowledge about food requirements of various species and provide a basis for developing satisfactory and economical diets for intensive culture.

5. The University could also study diseases of fish. As culture develops from extensive to intensive systems, diseases are likely to become a problem and, therefore, investigations on these should commence simultaneously.

6. The University might conduct surveys to locate additional sources of fry from the wild that might be used for the stocking of ponds.

4.3 Recommended projects or actions

4.3.1 Development of a National Action Plan to describe projects and actions needed to develop aquaculture.

4.3.2 Development of fish production in lagoons by applying Italian valli culture systems. This might be accomplished in a demonstration fish farm at Vakif in cooperation with the Fish Producers Cooperatives Union.

4.3.3 Development of pond culture systems for mullet, sea bass, sea bream and sole. This might be accomplished at Vakif.

4.3.4 The improvement of scientific knowledge of aquaculture species and technical knowledge of their culture. This could be done at Ege Üniversitesi or other aquatic research centres.

4.3.5 The development of plans for a hatchery and nursery for sea bass, sea bream, sole and shrimp. This might be done at the Urla Marine laboratory of Ege Üniversitesi.

4.3.6 The development of plans for adapting cage systems to the culture of sea bass and sea bream and later testing such systems. This might be done at the Urla Marine laboratory of Ege Üniversitesi.

4.3.7 Training of fish farmers, extension workers, farm managers, processing and marketing personnel, scientists, and engineers.

Appendix 1

PERSONS INTERVIEWED

Appendix 2

REFERENCES

Acara, A., 1959 The northern lagoons at the Sea of Marmara. GFCM Proc.Tech.Pap., (5):235–9

Baird, R.H., 1973 Marine fishery development. Investigation into the possibility of establishing new molluscan commercial fisheries in Turkey, with particular reference to the mussel (Mytilus galloprovincialis) of the Black Sea. A report prepared for the Marine Fishery Development Project. Rome, FAO, FI: SF/DP TUR/548/5:7 p.

FAO, Turkey, 1973 Marine fishery development. Terminal report. Rome, FAO, FI: DP/TUR/70/540:30 p.

FAO/UNDP, 1975 Report to the Government of Turkey on fisheries administration. Based on the work of J.G. Simpson. Rep.FAO/UNDP(TA), (3311):47 p.

Geldiay, R., 1969 A report on the collection of Natantia (Crustacea, Decapoda) along the coast of Turkey from the Eastern Mediterranean to the vicinity of Izmir. Sci.Rep.Fac.Sci.Ege Univ., (74):16 p.

Girin, M., 1977 Rapport de mission en Turquie du 6 au 18 novembre 1977. Brest, CNEXO, C.O.B., 17 p.

G R E E C E

The study of the marine aquaculture potential in Greece was carried out 30 October–6 November 1978 by D. Charbonnier, H. Cook. J. Glude, P. Rouzaud and M. Zei.

1. SUPPLY AND DEMAND

1.1 Supply of fisheries products

According to national production records, the Greek fisheries in the Aegean, Ionian and Mediterranean seas landed a total of 90 000 t in 1977 while production from inland waters amounted to 12 000 tons.

Greece exports about 7 000 t of fishery products, largely eel, shrimp, mussels, cuttlefish, mullet, roe, oysters and sea bream. Oysters from private farms in the vicinity of Thessaloniki are exported to France, Italy, Holland and Belgium.

1.2 Supply of species with aquaculture potential

Estimated landings and production of species with aquaculture potential include 1 000 t of sea bass, 1 100 t of sea bream, 2 500 t of sole, 1 500 t of mullet, 100 t of shrimp, 200 t of oysters and 1 800 t of mussels.

1.3 Estimated demand

Per caput consumption of fishery products in Greece is about 18.5 kg/y with a strong preference for marine species.

Demand varies with species. Mullet has a strong domestic demand at the government-controlled price of Gr.Dr. 110/kg.¹ Small-sized mullet was being sold at Gr.Dr. 80–100/kg and large ones at Gr.Dr. 110/kg in the retail market at Kavala, northern Greece, in October 1978. Mullet is abundant during the autumn harvest period but scarce at other times. It is estimated that annual sales could be doubled if fresh mullet were available over a longer period of time.

Sea bass, sole and sea bream are in high demand, but there is only a limited supply. If supplies were adequate, consumption might be increased several times. The government-controlled price for sea bass and sole is Gr.Dr. 180/kg, but the price in the open market may reach Gr.Dr. 230/kg.

¹ Gr.Dr. 36.50 = approx. U.S.$ 1.00

Eels have a strong export market and it is estimated that at least twice the present landings could be sold. The government-controlled price for eels is Gr.Dr. 225/kg.

Shrimp is in high demand and sells at about Gr.Dr. 300/kg, but the supply is limited.

There is a limited supply of oysters and a moderate supply of mussels. Although the domestic market is limited, there appears to be some export possibilities.

2. STATE OF AQUACULTURE

2.1 Commercial ventures

Fish farms in the country use the lagoon culture system in which young fish migrate into lagoons in the spring and are trapped as they leave in the autumn or winter. The traps or weirs may be more or less advanced in design, but are, in principle, similar to those used elsewhere in the Mediterranean region. Some fish are also caught by gillnetting in the lagoons. This is a primitive system of fish culture as there is no supplemental stocking or feeding. In some places, lagoons are being deepened to two or three metres to allow the fish to survive there through the winter months. This application of the valli culture system used in Italy will permit harvesting of larger fish after an additional summer's growth.

The lagoon fish farms are generally built by the Greek Government and leased to fishermen's cooperatives on condition that they pay 25 percent of the value of their production as tax. This, however, encourages cooperatives to report lower catches than actually obtained. Furthermore, the Government controls prices, which encourages fishermen to sell on the open market.

The total area of the numerous and extensive lagoons, especially those in the Ionian Sea and of the Aegean around Macedonia and Thrace, has not yet been determined. De Angelis (1960) reported that a number of important ones range from 200 to 14 000 ha, and the annual yield from them ranged from 22 to 220 kg/ha.

Recent published yields are lacking, but some production data from four lagoon fish farms (Keramoti, Aghiasma, Eratino and Vassova, having a total area of 1 235 ha, and located west of the river Nestos estuary, northern Greece) have become available through the courtesy of the Ministry of Coordination. The average annual fishery production from this laguna system during the ten-year period 1967/68–1977/78 was 148.2 t, and the average annual value for a nine-year period (1969/70–1978/79) was Gr.Dr. 7 225 800 (approx. U.S.$ 197 900). The annual average production for the ten-year period consisted of mullet (109.3 t), sea bream (16.9 t), eel (11 t), sea bass (4.4 t), crab (1.6 t) fish roe (0.3 t), and others (sole, gobies, mussel and shrimp (4.7 t)).

Estimated annual production from lagoon culture includes 100 t of sea bass, 300 t of sea bream, 1 100 t of mullet, 50 t of sole, and 600 t of eels.

Oysters and mussels are produced by private aquaculture. Mussel farms are located in the Evros river delta, and the Bay of Salamis, while an oyster farm in the estuary of the river Axios reportedly produces 40 t/year.

2.2 Current research and development activities

The Institute of Oceanographic and Fisheries Research (IOKAE) of the Ministry of Coordination at Aghios Kosmos, near Athens, has the responsibility for research and development activities related to fisheries and aquaculture. They conduct applied research to solve problems at the request of other government agencies. In the experimental hatchery of the above Institute, larvae of the shrimp Penaeus kerathurus have been grown to post-larval stage with a survival rate of 40 percent.

Studies of trout nutrition are also in progress in this Institute, and over 20 test diets using local ingredients have been evaluated. These studies have not been extended to marine species. Research and development efforts of IOKAE will be strengthened by a new cooperative UNDP/Unesco project which provides funds for fellowships, consultants and training.

Eel culture was tried by a private company in the vicinity of Thessaloniki in 1976. In a small cement pond of 80 m³, 11 000 young eels, with a total weight of 600 kg, were grown to 3 800 kg during the course of the experiment.

A pilot-scale carp farm, being constructed by a private company near Arta, will include culture of eels, while a private company is said to have plans for building a 78-ha fish farm in the Prefecture of Pieria, southwest of Thessaloniki for the culture of sea bass, sea bream, shrimp and molluscs in ponds.

2.3 Institutional factors

The Aquatic Resources Department of the Ministry of Agriculture is responsible for administration of fisheries and aquaculture. Lagoons are the property of the State, but can be leased to individuals or cooperatives for fish culture. Leases to individuals, for a period of five years, go to the highest bidder and renewal is also subject to bidding. Successful cooperatives can lease space in lagoons for fish culture and can also renew the leases without bidding.

Individuals can lease areas in the open sea for two years for experimental aquaculture. If successful, they can obtain a 15-year lease of that area and can renew it for an additional 15-year period without bidding. This policy is to encourage culture of new species or use of new areas for aquaculture.

Cooperatives received State assistance to develop lagoon fish farms. The State will construct weirs and other structures needed for fish culture on the basis that the cooperative will pay a tax equal to 25 percent of the value of the fish produced.

Although the State can legally operate fish farms, it only does so to maintain an installation when changing from one lessee to another. At the present time, there are about 50 leases for lagoon or marine fish farms, 90 percent to cooperatives and 10 percent to individuals.

The Ministry of Coordinaton is responsible for environmental planning through the National Council for Physical Planning and the Environment. This Ministry also includes the Institute of Oceanographic and Fisheries Research, which has responsibility for research, development and training regarding fisheries and aquaculture.

3. POTENTIAL FOR AQUACULTURE DEVELOPMENT

There is a high potential for aquaculture development in the country because of the excellent marine and brackishwater environment. The occurence of productive shallow lagoons, and protected deep-water bays gives the opportunity for at least two major kinds of aquaculture, namely lagoon farming and fish culture in pens and cages.

The Government is receptive to aquaculture development. Land and water areas are available for fish farming by cooperatives, private firms, or individual fish farmers, and the leasing system encourages new types of aquaculture. Greece also has supplies and materials needed for building and operating fish farms and good highways for transporting the product to market.

Finally, the country has a historical base of lagoon culture developed over a period of more than 30 years and a tradition of growing and handling fish.

3.1 Crustaceans

There is a possibility for development of shrimp (P. kerathurus and perhaps other species) culture in the future. This might start with a combined culture with mullet, as the two species are compatible. At a later stage, this should change to intensive monoculture of shrimp. New methods are being developed for intensive shrimp culture in France, Japan, U.S.A., and some other countries. In the future, this could result in a development of intensive shrimp culture in Greece. Such a system would require supplemental heating during the winter, when the temperatures are too low for shrimp growth.

3.2 Molluscs

There is a good potential for expansion of mussel and oyster culture using the off-bottom methods in those protected bays where algae production is high and the salinity is somewhat lower than the open sea. Traditional methods used in the Mediterranean could be applied in other areas.

There may also be a possibility for shallow-water aquaculture of oysters and mussels in some of the lagoon fish farms where salinity is satisfactory.

3.3 Fish

There is a good potential for expanding production of mullet, sea bass, sea bream, and sole by upgrading the existing lagoon farming to valli culture, applying systems developed in Italy. This would allow undersized fish to grow an additional year before harvesting, and consequently raise the value of the product.

Pond culture of these species, following methods developed and being tested in France, Israel, Italy and Spain, could greatly expand production in the future. However, these systems would require local hatcheries to provide fry of sea bass, sea bream and sole. As methods for producing mullet commercially in hatcheries have not yet been developed, natural sources of fry, occurring at places such as Mesolonghi, could be utilized.

There are also good opportunities to culture various species of fish in floating cages, or in fixed enclosures. Greece has protected and deep-water bays, many of them with rather low productivity. In such areas, fish could be raised in floating cages and the waste products from the fish and the unconsumed food could contribute to the productivity of the area. For such culture systems, a hatchery or source of fry from natural stocks would be required.

4. PROGRAMMES NEEDED TO EXPAND AQUACULTURE

4.1 Limiting factors

More information is required concerning the biology of cultivable species, their nutritional needs, diseases, migrations, growth and cultivation methods. Without such information, companies or individuals embarking on mariculture would have a considerable capital outlay to cover research and development and this might retard or even prevent entry into full production. It would seem obvious that a government venture would be better equipped to undertake such research than private industrial firms.

The second major limiting factor is trained personnel. Training is needed at all levels, including fish farmers, fish farm supervisors and extension specialists. Culture specialists are needed to adapt the technology developed in other areas having similar environmental conditions to those of Greece. Research scientists, engineers and economists are also needed.

4.2 General programme requirements

The existing lagoon farming is a suitable base from which to build a modern mariculture industry. The following steps are suggested:

4.2.1 Improve management procedures to increase the number, size, or value of fish harvested by:

1. Increased stocking of fish by letting more water into the lagoons. This might be accomplished by enlarging existing openings or by creating additional channels. Also, fry from other locations might be collected, grown in nursery ponds, and stocked in lagoons.

2. Holding undersized fish in the lagoons for an additional year by:
   • digging deep channels in the lagoons so the fish can over-winter;
   • using a double-trapping method of harvesting to separate large and small fish, and returning the undersized fish to the lagoon; and
   • restricting the time of fishing at the weir to July, August and September when larger fish migrate from the lagoon, or harvest the larger fish with gill nets in the lagoon during the spring and early summer when prices are higher.

4.2.2 Another scheme is to utilize the lagoon as a nursery to produce small fish for growing to market size in different culture systems. This could include the following procedures:

1. grow juvenile mullet in earthen ponds fertilized to increase productivity;
2. grow sea bream and sea bass in floating cages, fenced enclosures, earthen ponds or raceways. Fish scraps or under-utilized species, such as sardines, crabs or molluscs, supplemented by commercially available fish feeds, might be used for feeding; and
3. hold “green” eels in specially designed facilities and feeding until they reach the black migratory stage.

4.2.3 If the foregoing procedures are undertaken, the fish farmers will gradually develop adequate proficiency for intensive culture of various species. At that time, there will be need for seed produced in hatcheries, processed feeds and disease control procedures. To develop this technology in a timely manner, research in all three areas should be started as soon as possible at the Institute of Oceanography and Fisheries Research in collaboration with the Aquatic Resources Department of the Ministry of Agriculture. This work should emphasize hatchery development for sea bass initially and later for sea bream, sole and shrimp.

4.2.4 The best long-range potential for mariculture would seem to be in the utilization of the numerous protected bays in Greece for culture of fish in floating cages. The development activities described above should lead to this type of culture in a reasonable period of time.

4.3 Recommended projects or actions

4.3.1 An aquaculture development centre should be established to test advanced culture methods and to train government workers who will be extending assistance to fish farmers. The Amvrakikos Gulf would be a suitable location because it has suitable sites for valli culture; pond culture of fish, shrimp and eels; raceway culture of fish and shrimp; floating cage culture of fish and off-bottom culture of oysters and mussels.

The Centre should include an experimental hatchery for sea bass, sea bream, sole and shrimp, with facilities for holding brood stock and nursery facilities for progeny.

Initial efforts should concentrate on upgrading the lagoon farming to valli culture, growing undersized sea bream and sea bass to market size in floating cages or enclosures, and developing improved methods for off-bottom culture of oysters and mussels in the country.

4.3.2 Research at the Institute of Oceanography and Fisheries should be strengthened to provide technical support for aquaculture development. The following are recommended:

1. research on nutrition of sea bream and sea bass. This will require the construction of a suitable facility for feed testing;
2. biological research to determine growth, migration, causes of mortality, ecology and environmental requirements of various species used in aquaculture;
3. surveys to locate sites for collection of fry of mullet or other species and development of suitable methods for collecting, holding and transporting the fry; and
4. identifying causes of mortality and developing diagnostic procedures and control methods for use in aquaculture systems.

Appendix 1

PERSONS INTERVIEWED

Appendix 2

REFERENCES

Anon, 1978 New fish farm planned in Greece. Alieia Fishing (375):333–4

Ananiadis, C.I., 1977 Fish farming development prospects in Greece. Fish Farming Int., 4(3):16–7

De Angelis, R., 1960 Mediterranean brackish water lagoons and their exploitation. Stud.Rev.GFCM, (12):42 p.

Pillay, T.V.R., 1967 A preliminary survey of the lagoon fisheries of the Western Peloponnesus, Greece. FAO Fish.Circ., (108):207–24

Smitherman, R.O., 1976 Evaluation of aquacultural development potentials in Greece. UNDP Report to Government of Greece under UNDP/OPE contract (Ref. GRE/75/005), 23 p. (mimeo)

Tsimenidis, N., N. Kriaris and C.N. Vamvakas, 1971 Preliminary survey in locating areas suitable for aquaculture in Greece. Hellen.Oceanol.Limnol. (Period C), 10:497–8

THE SOCIALIST FEDERAL REPUBLIC OF
Y U G O S L A V I A

The study of the marine aquaculture potential in the Socialist Federal Republic of Yugoslavia was carried out 23–29 November 1978 by D. Charbonnier, H. Cook, J. Glude, P. Rouzaud and M. Zei.

1. SUPPLY AND DEMAND

1.1 Supply of fisheries products

The Yugoslavian fisheries landed 50–60 000 t of marine and inland fish during the last few years from the Adriatic Sea and inland waters. Of these, 27 000 t (1966) to 35 000 t (1976) were marine fish. The export of fish has been negligible, but imports of fish and squid (30 000 t) nearly equal domestic landings of marine species. Domestic landings include pilchard, sprat and anchovies (70%), tunas, mackerels and carangids (10%), hake (3%), and a smaller percent of grey mullet, sea bream, sea bass, soles, red mullet and others. It is not possible to estimate the mariculture production from the statistics.

The price of fish varies according to the species, quality, place and season. During the tourist season, the price of some of the popular varieties may almost be doubled. The peak of sardine fishing in autumn does not have much influence on the prices of other fish. Sea bass and sea bream are approx, U.S.$ 8/kg at retail, while grey mullet is about U.S.$ 5/kg. ¹ Mussels average U.S.$ 0.50/kg at retail, while oysters are 25 cents each (10–12/kg). In comparison, sardines sell at about U.S.$ 1.00/kg.

¹ Y.Din. 18.65 = approx. U.S.$ 1.00

1.2 Supply of species with aquaculture potential

According to FAO statistics, landings in 1977 included 43 t of eels, 39 t of sea bass, 62 t of gilthead bream, 243 t of mullet, 78 t of oysters and 296 t of mussels. Only the oysters and mussels were produced by aquaculture.

1.3 Estimated demand

Although the average consumption per caput in the country is about 3 kg, it is much higher on the Adriatic coast. The demand for demersal (white) fish, such as sea bass, sea bream and mullet, is much greater than for pelagic (blue) fish. The demand is much higher than the supply for mussels and oysters, which are species of interest in mariculture. Mussel consumption could be raised several times by providing a steady supply to tourist centres, and by an efficient promotion of mussels in the urban centres in the interior. The Secretariat for Agriculture in Yugoslavia expects that with the expansion of mariculture, the prices for fish and molluscs would decrease, causing an increase in consumption.

2. STATE OF AQUACULTURE

2.1 Commercial ventures

There is no commercial culture of marine fish or shrimp at present in the country.

Cage culture of marine fish is planned for exploitation on a commercial scale. The Zadar and Rovinj research institutes, working with local industrial groups, propose the development of cage culture of sea bass in floating net pens, in deep protected bays, such as Novigrad, Telascica on Dugi Otok and at Limski Kanal.

Valli culture of mullet is proposed to be done in the lagoons in the delta of Neretva and Bojana, and at Portorož, Pomer, etc., where mullet are now fished. There are also plans to start commercial mullet culture in the abandoned salt pans in Portorož.

The culture of flat oysters and mussels is well developed, particularly in the Bays of Kotor, Ston, Pomer, Limski Kanal and elsewhere on a smaller scale. Estimated oyster production is around 200 t of Ostrea edulis and about 300 t of mussels, largely from Ston and Limski Kanal. Mussels and oysters have been produced for many centuries at Ston, which is still the best centre of production on the eastern Adriatic coast. Various methods are used for the capture of spat and for the culture of flat oysters and mussels. This type of culture is carried out by cooperatives and private farmers.

2.2 Current research and development activities

Basic and applied research is carried out in the marine research centres of Kotor (Station for Marine Biology and Oceanography), Dubrovnik (Biological Institute), Split (Institute for Oceanography and Fisheries), Zadar (Centre for Fish and Economy of the Mediterranean), Rovinj (Centre for Marine Research), and Portorož (Marine Biological Station). Governmental bodies, such as the Council for Research, subsidize about half of the planned basic or applied research of institutes. The rest of their funds must be obtained from industry. Although each research centre is independent and able to set up its own projects, there is a coordinating committee for mariculture research along the Yugoslavian Adriatic coast. This committee reviews the past activities and the future plans once or twice a year, coordinates them and negotiates funding by government or industries.

The aquaculture research carried out by the research institutions might be divided into three types: (i) environmental studies and monitoring of environmental parameters, mainly with regard to pollution; (ii) scientific research with regard to primary production, food chain and biology of fish; and (iii) applied research into food and feeding of fish and technology of breeding mussels, oysters and fish.

Feeding experiments have been undertaken with the amberjack (Seriola dumerilii) at the Dubrovnik Biological Institute, and an attempt has been made to rear mullet in floating net pens in the Portorož area under the supervision of the Marine Biological Station at Portorož.

Environmental studies, particularly with regard to pollution, are carried out in all institutions, except Zadar, under the auspices of the United Nations Environment Programme Mediterranean Pollution Project. Studies of the nutrition of fish larvae, fry and fingerlings, are carried out mainly at Split, but also at Kotor and Rovinj. Applied research on foods and feeding of juvenile fish and technology of breeding mussels, oysters and fish is carried out chiefly at Ston, Zadar, Rovinj and Portorož.

2.3 Institutional factors

The Yugoslavian marine fisheries cover four republics: Montenegro, Bosna-Hercegovina, Croatia and Slovenia. About 83 percent of all the marine production comes from the Republic of Croatia and 15 percent from Slovenia. The republic Secretariat for Agriculture, with their sections (or branches) for fisheries, are concerned with general administration, management, and development of marine fisheries and marine resources. Fishing enterprises, cooperatives, other similar commercial organizations and individuals are rather independent. Within the framework of the federal legislation, the republics and communities have adopted their own specific regulations. The marine fisheries in the public and private sectors do not receive any subsidies from the Government.

3. POTENTIAL FOR AQUACULTURE DEVELOPMENT

3.1 Crustaceans

There is a rather limited potential for shrimp culture in Yugoslavia at present. At some time in the future, it might be possible to produce one crop of shrimp during the summer and to grow a coldwater fish, such as salmon or trout, during the winter when the temperature is too low for shrimp culture. There is also a possibility in the future of using intensive, controlled environment systems in which satisfactory temperatures are maintained throughout the year so that more than one crop can be raised.

3.2 Molluscs

There is an excellent potential for expanding the culture of oysters and mussels in the deep protected bays where the salinity is somewhat lower than in the Adriatic. There are good mussel culture systems in use in some places which could be extended to a number of other areas. There are also many areas where oyster culture could be developed much further than it is at present using traditional or improved systems.

There are important unpolluted areas along the coast of Yugoslavia, such as Ston, a centre for oyster culture, and these areas should be reserved for aquaculture. In the future, food production from the sea will be even more important than it is today and these areas can contribute large quantities of high protein food to the total supply.

3.3 Fish

There is excellent potential for cage culture of sea bass at present and also later when the hatcheries are perfected for sea bream. There are many well protected bays that can be used for this purpose in the central Dalmatian area, at Limski Kanal, and others. There is also some potential for fish culture in shallow lagoons in brackish water, such as Vransko Jezero, and the lagoons in the delta of Neretva and Bojana.

The importance of mariculture development has been well recognized by the government, communities, industry and Institutes in the country. The cooperative efforts between the Institutes and the Community Enterprises can provide a sound basis for the development of aquaculture and rapid application at production level.

Added to these is the occurrence of extensive land and water areas, suitable for fish culture, along the coast. These factors clearly indicate a very considerable potential for the expansion of coastal fish farming.

4. PROGRAMMES NEEDED TO EXPAND AQUACULTURE

4.1 Limiting factors

4.1.1 Although oysters have been cultured in the Bay of Mali Ston since the time of the Roman Empire, there is now a threat that nearby coastal areas will be used for tourist purposes. This could adversely affect oyster and mussel culture because of the danger of sewage pollution.

4.1.2 A second limiting factor is an increase in the mortality rate of the European flat oyster (Ostrea edulis), which has reportedly reached 60–70 percent in some places. This mortality generally occurs during the second summer after the oysters are planted in the parks, but the cause is unknown.

4.1.3 Shells of the oysters grown at Limski Kanal are frequently infested by the polychaete worm Polydora and control methods are needed.

4.1.4 Markets for oysters and mussels in Yugoslavia and abroad are limited, although no marketing difficulties have been experienced at the present level of production. There is a possibility that expanded production might result in an over-supply with a resultant price decrease, unless market development activities are undertaken.

4.1.5 The factors that may limit aquaculture of fish include the lack of hatcheries for sea bass and sea bream. In this respect, the plan of the Community Enterprise at Zadar to purchase sea bass fry from Italy for the first two years, and then begin the construction of a hatchery, is considered sound. The plan at Rovinj, based on experimental work at the Institute, to build a pilot-scale hatchery prior to the construction of a production-scale hatchery is also sound. Over a period of several years, it should be possible to develop a supply of fry that would make it possible to expand fish culture for sea bass, and later expand into culture of sea bream and perhaps other species, as proposed in the five-year plan for marine fisheries in the country.

4.1.6 Another limiting factor is water temperature during the winter, which is below the level required for feeding and growth of sea bass, sea bream and mullet. It will take at least two years, therefore, for these species to reach minimum market size.

4.1.7 Although the demand and market price for sea bass and sea bream is high, there is little experience upon which costs of production in cages or floating net pens can be based; consequently, there is a need to culture sea bass on a pilot scale to evaluate the cost of production as well as to improve the knowledge of growth, mortality and conversion rate of foods.

4.2 General programme requirements

For mollusc culture, studies on oyster pathology are needed. Also, oyster culture methods used in other countries should be tested to see if they can be applied to improve the economics of the operations. Market development studies are needed to introduce the processing of frozen mussels.

The development of cage culture of sea bass should be encouraged. The technology used elsewhere for cage culture should be analyzed to determine its applicability in the country. It is obvious that Yugoslavia needs hatcheries for sea bass and later for sea bream. The locations at Nin and at the entrance to Limski Kanal appear to be good sites for hatcheries. There is also a possibility of mullet culture in ponds or cages, using a natural fry supply first, but when mullet hatcheries are perfected, fry produced by artificial propagation can be used.

Looking further ahead, there may be a potential for rearing the amberjack (Seriola) in cages on the southern coast. Species of this genus are grown in cages in Japan. It would take much research and development however, before a culture system would be ready for commercial application.

Finally, to provide a sound scientific basis for developing aquaculture, it is important to enhance the technical competence in the various Institutes. Aquaculture must be based on scientific knowledge if commercial developments are to be successful. It is important to adopt improved methods developed in other countries, but they should be tested to determine their applicability under local conditions. As aquaculture develops further in the country, it will become necessary to establish institutionalized training of fish farmers. There is no tradition of mariculture except for the farming of mussels and oysters, although Yugoslavia has a long and distinguished tradition in marine science.

4.3 Recommended projects or actions

4.3.1 Hatchery technology

The Community Enterprises at Zadar and Rovinj, with technical assistance of local institutes, are planning the construction of hatcheries to provide seed for commercial culture of sea bass and sea bream in floating cages. The application of knowledge available in other Mediterranean countries could expedite the development of successful hatcheries in Yugoslavia.

The Rovinj project presents a good opportunity to develop a demonstration and training centre. The Centre for Marine Research, “Rudjer Bošković” Institute and MIRNA Fishing and Fish Processing Company plan to build a combined research and production hatchery near Limski Kanal. When operational, this facility could serve as a regional centre for training in hatchery technology. It would be helpful to provide training facilities and hatchery specialists from other countries for short periods during the planning stage, and for longer periods when this hatchery becomes operational. The hatcheries at both Rovinj and Zadar could provide valuable information concerning production costs in relation to market value of the seed.

4.3.2 Cage culture technology

There are good possibilities for culture of sea bass and sea bream in cages in the deep protected bays, canals and inlets of the coast. This type of aquaculture was initiated, on an experimental basis at Portorož, Lim, Novigrad, and others, using fry procured from Italy or produced in Rovinj. Commercial projects to grow sea bass and sea bream to market size in floating cages are planned near Zadar and Rovinj. The culture of sea bass and sea bream in Limski Kanal will provide a good opportunity to develop and test systems for cage culture which might be used in other areas in the Mediterranean region. This would include various cage configurations, anchoring systems, and operational procedures and evaluation of production costs in relation to market prices.

The Rovinj Project could serve as a regional centre for demonstration of cage culture systems and for training in their operation. Technical assistance would be needed for short periods during the planning stage and for longer periods when the fish farm becomes operational. External assistance may be needed later for regional training activities.

4.3.3 Suspended culture of oysters and mussels

Although oyster and mussel culture is well established in the Ston and Limski Kanal areas, there is a definite need for developing and testing more efficient methods. External technical assistance may be required for testing improved farming methods, determining causes of oyster mortality and developing control measures for marketing studies.

Appendix 1

PERSONS INTERVIEWED

Appendix 2

REFERENCES

FAO, 1978 Yearbook of fishery statistics. Catches and landings, 1977. Yearb.Fish.Stat., (44):343 p.

FAO/UN, 1961 Rapport au Gouvernement de la Yougoslavie sur l'ostreiculture et la myticulture. Basé sur le travail de P.E. Lubet. Rep.FAO/UN (PEAT), (1425):20 p.

GFCM, 1978 Statistical bulletin: nominal catches. Bulletin statistique du CGPM: captures nominales, 1966–1976. Stat.Bull.GFCM/Bull.Stat.CGPM, (2):104 p.

Lubet, P.E., 1961 Rapport au Gouvernement de la Yougoslavie sur l'ostreiculture et la myticulture. Rep.FAO/UN(PEAT), (1334):55 p.

Nikolić, M. and I. Stojnić, 1962 A system of oyster culture on floating shellfish parks. Stud.Rev.GFCM/Etud.Rev.CGPM, (18):8 p.

Stjepćević, J., 1974 Ecology of mussel (Mytilus galloprovincialis Lamk.) and oyster (Ostrea edulis L.) in cultures of Boka Kotorska Bay. Stud.Mar.Stn. Mar.Biol.Oceanogr.Kotor, (7):164 p.