The material and equipment requirements of the coastal lagoons are the least demanding, being limited primarily to the structures used for controlling and trapping fish as they enter and leave the lagoons. Traditionally, and still used in some lagoons (e.g., Prokopos, near Patras), fences and traps were of bamboo. Nowadays fences are made from wooden stakes and plastic mesh netting and traps use a mild steel frame covered with the same netting. The stakes are of chestnut (most commonly) or oak, having lives of two and five years respectively. The netting is UV resistant black plastic with a square 10 mm mesh, manufactured in Greece, and generally replaced after two years. the cost of establishing a 1.5 m high fence is estimated at Dr 900/m (Source: Messolonghi fisheries office). The significance of the cost of such fences depends on the length of fence required per hectare of lagoon area; in some of the more seaward lagoons of Messolonghi many kilometres of such fence are used.
In the last seven years improvements have been made to some lagoons, notably those under the responsibility of the Kavala and Preveza fisheries offices. The improvements generally involve providing deeper areas (up to 3 m depth) in the lagoon in the form of channels and/or special overwintering ponds, and the replacement of traditional fences and traps with more modern structures using concrete framework and aluminium screens according to Italian designs; the screens are manufactured in Greece with a high degree of accuracy and finish.
Fresh water fish culture in Greece is reported on by Edwards 1. For the trout farming industry he concludes that whilst most of the equipment and technology presently in use is somewhat outdated, it nevertheless functions satisfactorily; should, however, new units be constructed or old ones modernised, advantage should be taken of modern techniques and designs, specifically the use of fibreglass hatching troughs and trays of the California type in the hatchery, automatic feeders especially at first feeding and in fry production, round tanks of fibre-glass, steel or concrete, where appropriate, for ongrowing, and “monks” of wood, concrete or fibreglass for improved water exchange in earth ponds and concrete tanks. If the trout farming industry develops beyond the present state where small family units producing less than 20 t/year predominate, there will inevitably be a trend towards more efficient installations and labour-saving mechanization of processes such as grading, fish transfer, feeding and harvesting. The largest trout farm in Greece (Gianetas and Co. on the Vaidomadis River) already takes advantage of such technology, using imported Italian machinery.
1 Edwards, D. 1987 Fresh water fish culture in Greece. Rome FAO, FI: DP/GRE/85/002/4, 36 p.
Carp culture techniques are based on those of Israel and Eastern European countries. Hellenic Fish Farms at Varda uses large silo demand feeders (pendulum type) as are used in Israel, and paddle wheel aerators at the warmest times of year; both items of equipment are thought to have been constructed satisfactorily in Greece. As the industry expands requirements for such equipment will increase, as well as for mechanized devices for harvesting, sorting and transporting of fish.
Shellfish cultivation is reported on by Askew 1. Intensive culture of mussels using Italian techniques is presently the main activity. Systems are technically relatively simple, although the installation and maintenance of equipment is one of the principal operational costs. Two suspension methods are used, but both use vertical pergolari tubes as the holding facility. In the first method, used in shallower estuarine waters with good water exchange, the tubes are suspended from frames of metal or wood. In the second method, used in deeper but still sheltered coastal waters, the tubes are hung from long lines. A typical long line consists of two 120 m head ropes running in parallel 1.2–1.7 m apart and supported by 10 equally spaced flotation drums of 230–330 litres capacity. Pergolari is presently imported from Italy and is available at a cost of approximately Dr 10/metre. Final harvesting density averages 10 kg/m of pergolari and if one assumes that a crop is graded and retubed once during a production cycle and that tube is not reused, the actual cost of pergolari per tonne produced would be Dr 1 000–2 000, relatively insignificant given the current market price of DR 200 000/t; should the value drop to the level of other European countries (approximately Dr 70 000/t), however, the cost would become more significant. Long line flotation drums were initially imported from Italy but now there are at least two companies manufacturing their own in Greece from fibreglass and stainless steel (cost Dr 18 000 for a 235 litre drum and Dr 22 000 for a 333 litre drum); cheaper but less satisfactory are 200 litre plastic barrels used in the olive oil and chemical industry, available second-hand or purchasable new. Moorings are generally composed of ropes and concrete blocks.
1 Askew, C. 1987 Shellfish cultivation in Greece. Rome, FAO, FI: DP/GRE/85/002/6 (in preparation)
Mussel culture operations are presently unmechanized. One of the larger long-line companies has a customized workboat on order (from within Greece). Owing to the difficult and arduous nature of the work and the need to handle large tonnages, any significant expansion of the industry will require mechanization. Other mussel farming industries, such as those of Ireland and New Zealand, use purpose-built rafts which have on board all the handling equipment necessary; operations typically carried out are stripping of seed mussels from collector ropes, declumping, grading, filling of tubes, bagging, etc. Owing to the high capital cost of such rafts, one is generally shared between a number of different producers. Spanish-type rope culture is more amenable to mechanization than Italian type pergolari culture, and may have the advantage that the materials can be more easily manufactured in Greece - rope is already available and the tube used is of light cotton (or 66% cotton, 33% synthetic fibre). (The report by Askew gives more details.)
True oyster culture is presently not practised in Greece. However, overexploitation of wild beds and falling catches may increase the attraction of farming. Requirements would be for French type plastic spat collectors, and plastic net “poches” for nursery and ongrowing strapped to steel trestles; ongrowing on ground plots might require the use of plastic mesh “French fences” for prevention of predation. All of these materials are either imported or readily available in Greece.
The subject of marine fish hatcheries in Greece is covered in detail in the report by Berg and Cittolin 1. Owing to the highly specilized nature of such hatcheries, the requirements for materials and equipment are perhaps the most demanding of any aquaculture system. The culture operations that take place in a marine hatchery can be summarized as follows:
1 Berg, L. and G. Cittolin. 1987 Marine fish hatcheries in Greece. Rome, FAO, FI: DP/GRE/85/002/8 (in preparation)
Each of these operations has particular needs in terms of water quality, quantity and temperature, hygiene, light, handling and management, and thus requires a variety of holding facilities, water supply and treatment systems, temperature controls, and layouts. Specialized equipment requirements may be summarized as follows:
The cost of constructing a marine hatchery is estimated to be between Dr 100 and 150 million for every 1 million fry of annual production. This cost may be broken down approximately into four main components as follows (Scott, unpublished data; Berg, pers. comm.):
|Component||% of Capital Cost|
These figures are likely to be influenced primarily by location (cost of site preparation and provision of access), type of building chosen (e.g., prefabricated concrete or simpler greenhouse type structures), and complexity of water intake and supply system.
The total production capacity of the hatcheries present being planned in Greece is said to be 30 million fry per year (see report by Berg and Cittolin). If these hatcheries reach the construction stage then there will be significant requirements in each of the above component supply sectors. By extrapolation, the potential value of goods required in each sector in the next ten years, assuming the above percentages and an average capital cost of Dr 125 × 106 per million fry of annual production, might be as follows:
|Component Sector||Potential Value of Goods Required (Dr × 106)|
These may be classified as follows:
Special equipment requirements for semi-intensive pond systems are similar to those of carp culture in fresh water already described, possibly with the addition of pumps to aid water circulation.
Intensive landbased units depend absolutely on continuous and adequate supply of pumped water, which may be quite considerable (up to 7 000 m3h-1 for a 100 t unit). The principal requirement is therefore for an efficient and flexible pumped water supply system with ample standby power generation capacity in the event of mains failure. Pumps are generally centrifugal and may be submersible. Other specialized equipment may include low pressure, high volume air blowers and associated diffusers for occasional or emergency aeration, oxygen generators and injectors, pneumatic feeding systems and mechanized handling equipment. Holding facilities are typically concrete or butyl rubber lined earth raceways, or fibreglass or steel circular tanks with concrete bases.
Intensive cage culture is likely to hold the most promise in terms of return on capital invested of any potential ongrowing system in Greece, and is the sector in which the most rapid growth is likely to be seen. Cage farms are free from many of the problems faced by land based units, especially in terms of planning and establishment. Cages may be quickly and easily installed and added to progressively as production grows. They have a relatively low capital cost compared to land based systems. A cage system may be broken down into the following main components:
Supplementary equipment includes:
The first cages to be imported into Greece were from the Scottish company Kames Fish Farming Ltd., and it is from their basic “3-tonne cage” that most of the cages in use in Greece today have evolved. The collar is constructed from celcurized softwood, high density polystyrene and high quality hot dipped galvanized steel; it is made up from two walkways packed with polystyrene and joined by two cross beams; two wooden rails surround the collar, the lower for hanging the net, the upper as a working rail. The collar takes a net of 4.6 m × 5.8 m × 5.0 m deep, which has an enclosed water volume of 125 m3. The celcurization process involves treating the wood under pressure at maximum retention with a copper-chrome-arsenic preservative to protect it against marine borers, and the collar has a useful working life of more than five years if properly moored and maintained.
Larger versions of the same basic cage are now starting to appear, having 4 walkways and a net volume of 300 m3. Other cages in use include those with hinged walkway sections raised 0.5 m above water level and supported intermittently by large polystyrene blocks, encased in wood, polythene sheet or hard polyethylene. Such cages tend to be linked together in a complete unit of 12–24. Simple collars composed of 50 mm diameter steel pipe and supported at the corners by buoys are used successfully in sheltered fresh water environments for trout and carp but have not found wide acceptance in the more demanding marine environment.
As the industry grows, and the more sheltered sites are fully developed, larger and stronger cages (e.g., 15 × 15 m) made from high quality galvanized steel are likely to be required for more exposed sites such as may be found in the Gulfs of Amvrakikos, Corinth and Evia.
Nets are manufactured from 18S gauge knotless nylon. Meshes can be square or hexagonal with common sizes being 6, 13 and 18 mm. Presently all such nets have to be imported.
Moorings for a group of ten such cages commonly consist of a 19 mm steel longlink surface chain stretched between two galvanized steel 1 m3 buoys; five cages are attached to each side of the surface chain; from each of the buoys at either end of the unit run 2 mooring legs, each of these composed of 19 mm chain (length = 3 × the water depth) attached to an anchor. The chain used for mooring legs may in certain circumstances be partly replaced by rope. The design and weight of the anchors used depends on seabed conditions and degree of exposure. Moorings are an extremely important aspect of cage installation and are frequently overlooked. Certain essential procedures and precautions must be followed and taken.
Table 2 gives a summary of the principal installation and depreciation costs of a typical Greek marine cage farm with a 50 t/year production (see Appendix C for full details).
Table 2 Summary of Installation and Depreciation Costs for a 50 t/year Cage Farm (See also Appendix C)
|Moorings||1 768 000||256 070|
|Cage collars, etc.||6 700 000||1 340 000|
|Cage nets||2 860 000||954 000|
|Feeding system||1 266 000||437 000|
|Total||12 594 000||2 987 070|
The information given in Appendix C and summarized in Table 2 may be used to extrapolate industry requirements at different future stages of its development. For example, a cage sector producing 5 000 t/year, assuming that it were an average to be made up of farms such as that in the example, might spend each year Dr 95 400 000 (5 000 ÷ 50 × 954 000) on the purchase of replacement cage nets and Dr 134 000 000 on the purchase of replacement cage collars.
All of the sectors discussed in this section have requirements for miscellaneous goods and articles of small equipment, which although often are not significant in terms of cost, are nevertheless essential for correct system functioning. These “small items” include water quality analysis kits, oxygen and pH meters, salinometers, hand nets, oxygen bottles and diffusers, tools, etc.