Previous Page Table of Contents Next Page



The consultant was called upon to make a number of visits to advise on technical aspects of existing and planned projects. The most important aspects of these visits are discussed in this section.


Prokopos is situated approximately 35 km south west of Patras in the Peloponnese. It is a brackish lagoon with a surface area fluctuating between 100 and 400 ha in summer and winter respectively, and is connected with the sea by a 2.4 km canal. It has an average declared production of 25 t/year (50% eels, 45% mullet, 5% bass), thought in practice to be up to 30% greater than this. The lagoon is owned by the state, administered by the Patras fisheries office, and managed by an 18-member cooperative.

The principal interest of this lagoon lies in its having a number of particular features and problems, one or more of which probably affect most lagoons in Greece. These are:

The majority of the problems described above are due to the inability to control the inflowing fresh water. Unless this flow is brought under control, any other improvements made will in the long term be largely worthless due to continued siltation.

The basic steps in the improvement of the lagoon should be:

  1. Construct a canal to divert the fresh water directly to the sea, probably at a point further upstream.

  2. Calculate the water exchange required in the lagoon.

  3. Ensure that the size of the supply canal is sufficient to allow this exchange to take place.

  4. Alter the orientation of the seaward mouth of the canal to prevent siltation.

  5. Install sluice(s) close to the fisheries station to control levels and exchange.

  6. Clear reeds.

  7. Dredge out deeper overwintering areas in the lagoon.

  8. Install a collecting basin at the lagoon exit.

  9. Install new screens and traps.

  10. Consider subdivision of lagoon with net fences to allow better stock management.

  11. Construct (semi-) intensive ponds with pumping system in the swampy area on the lagoon periphery near the station.

The costs of any improvements made must be carefully assessed to ensure that they are proportionate to the likely resulting increase in production. This lagoon is already quite productive compared with most Greek lagoons - probably close to 300 kg ha-1 - and further increases in productivity may be difficult to achieve.

The lagoon is probably unique in possessing such a wide ranging variety of physical, social and legal problems, and as such may provide an interesting subject for a model development.


The Messolonghi fisheries office is promoting a trial using enclosures to demonstrate to local fishery managers the potential for keeping small fish alive for ongrowing. The present policy of removing even the smallest fish from the traps is widespread - one summer fish down to 40 or 50 g average weight are kept for sale, anything less returned to the water usually dead. This practice is highly wasteful and totally needless, and any efforts to promote change must be applauded and supported.

Two enclosures, each of 1 500 m2, have been strongly and adequately constructed using the usual lagoon materials of wooden stakes and black plastic 10 mm netting; they are located in a side channel opening into the main Messolonghi navigation channel, relatively close to the open sea, where there is said to be good water exchange; the maximum and minimum water depths are 0.5 and 0.3 m respectively. It is proposed to stock the enclosures to reach a final stocking density of 1 kg/m2, or 1 500 kg/enclosure (bass and bream). In order to supply the oxygen requirements of such a stock, there would have to be a continual movement of water through the enclosures and a replacement rate of at least 4 times a day. Detailed measurement of water levels and quality parameters over a continuous period of time is essential before high stocking densities are attempted, and a provisional maximum stocking density should be set at 250 kg/enclosure. A further danger of enclosures, particularly in shallow water such as in this case, is the accumulation of waste food and faeces causing deterioration of water quality within the enclosure; feeding practices should be carefully controlled to prevent such accumulations.


Kokala is situated 3 km south of Preveza on the southern and seaward side of the mouth of Amvrakikos Gulf. It is a shallow (average 0.3 m) unproductive lagoon of 30 ha, belonging to the Nomarchia of Aitolias-Akamanias; administration is the responsibility of the Messolonghi fisheries office.

A number of ‘improvements’ have been made to the lagoon and funded by the Nomarchia. The works carried out were:

Unfortunately these works may not be effective for the following reasons (as recounted by the local fishery manager):

This is a distressing situation, bearing in mind the commitment of the Nomarchia to improve the lagoon. It is a prime illustration of how well-intended funds can be largely wasted owing to a failure or breakdown in communication between the funder, the improver and the intended beneficiary.

The commitment of substantial funds to small, potentially unproductive lagoons such as Kokala must be debatable, even if they are well directed. The potential annual income of Kokala if producing 6 t/year (200 kg/ha) would be in the region of Dr 4.2 × 106 (average price of Dr 800/kg). Any improvements made should therefore be in proportion to this income; if it is assumed that the fishery can tolerate an annual depreciation sum of 10% of income and that the life of works carried out is 20 years, then the maximum that can be afforded for improvements is approximately Dr 9.6 × 106. For lagoons already in production, the costs must be balanced against any potential increase in production which is likely to be much smaller than the new production achieved in a previously unused lagoon.


The first site visited at Palio Varka is privately owned. The site is exposed to the prevailing north wind with a fetch of about 10 km. The first cages installed were constructed from discarded 200-litre steel oil drums supporting steel spars and walkways, an often first attempted method of cage construction; these were found inadequate for a number of reasons and have been discarded. The cages presently in use, and supporting a recently imported population of sea bass, are of an articulated, raised walkway design, the principal materials being wood and polystyrene. They were designed by a local naval architect and have been well made; the principal problem lies with the method of attachment of the polystyrene blocks to the walkways - presently steel bands are used, which tend to work loose. However, these cages are not suitable for the exposed nature of the site. The operators are aware of this and are intending to replace them with an imported design.

The second site visited was at Bogonitsa Bay, on the north side of the Gulf, and belonging to the Preveza fisheries office. The cages installed were also constructed by a local naval architect, but following the proven “Kames cage” design. The principal fault in these cages was the underspecification of the corner brackets - although stainless steel, the thickness of the plate used was only 2 mm; it should be at least 6 mm. Another more immediate problem was the means of attachment of the cages to the central mooring chain, the deficiency of which was causing significant abrasion to the wooden cage members. The usual “lug and pin” method of attachment used for this type of cage was omitted and a system of chains, shackles and tyres used instead. It was strongly recommended that all these deficiencies be made good.


The newly created Institute of Marine Biology at the University of Crete is instigating an imaginative and well-planned development programme for aquaculture and is fortunate in possessing an experienced and motivated team of people. Their proposals are for an experimental hatchery and pregrowth unit in Herakleion and for production in cages in Elunda Bay.

The following comments can be made regarding the suitability of Elunda for cages:

The model proposed for the development of cage farming in the bay, e.g., the allocation of concessions 70% to inexperienced local operators, 20% to experienced outside operators, and 10% to the University should, if successfully applied, provide the most rapid transfer of technology to the local operators, who learn by the example provided by the experienced operators; the University research activity acts as a stimulus to new methods and ideas.

A bay in many ways ideally suitable for cages is located 1 km to the east of Elunda on the opposite side of the peninsula; it is sheltered, deep (17–25 m) and would appear from the chart at least to offer good water exchange; it is also separated physically and visually from Elunda which is a very popular tourist resort. This site was not, however, visited.

The programme of the University should be properly supported, offering as it does to investigate many of the potential problems and constraints of intensive mariculture in Greece.


The consultant was asked for advice by the Hellenic Agency for Local Development (ETA) concerning three sites owned either by local communities or municipalities.

One of the functions of ETA is to carry out feasibility studies for local communities and municipalities, and lagoon improvement and aquaculture is one area of their activity. The three sites in question were Lefkas lagoons, Mati Tyrnavou (a spring-fed fresh water lake) and Mavrotopos (potential for marine pond farm). Advice was provided on the first two sites but only the latter could be visited.

The municipality of Alexandroupolis owns 600 ha of low-lying, predominantly sandy land adjacent to the sea, 7 km east of the town. Various proposals have been put forward for aquaculture development on this site, mostly integrated systems with intensive and semi-intensive components. The site has two major constraints:

One solution proposed for the seawater intake consisted of:

  1. A 50–100 m channel excavated in parallel with the shoreline and 20–30 m from it.

  2. This channel connected to the sea at each end by two further channels.

  3. The entrances to these channels to be protected by rock arms.

  4. The pumps to withdraw water from channel (a).

The size of the various components would depend on the volume of water extracted.

Before deciding on strategies for pond development, a detailed soil survey of the site is required, being properly carried out along preset transects and examining the soil profile to a depth of 2 m. Although the site is predominantly sandy, there are areas of silty clay present, notably along the course of the old river bed; the extent and depth of such areas must be evaluated.


This site, being developed by SPEKA in conjunction with a local cooperative as a demonstration centre for a variety of aquaculture systems, has been discussed in detail by a number of other consultants visiting the site. This consultant would add the following comments:


The lagoons at Kavala (notably Keramoti, Agiasma, Eratino and Vasova) have been the subject of extensive improvement in recent years. The reason for this is the good relationship existing between the cooperative members and the local fisheries office, and the honest declaration of catches by the members.

The consultant was asked to advise on the siting of a pregrowth unit for growing hatchery reared fry of 1–2 g up to 30–50 g prior to stocking in lagoons or ongrowing more intensively. All four sites were visited. The most favourable location for a unit appeared to be at the main mouth of Eratino lagoon. Water quality here appeared to be excellent and an intake could be inexpensively located in the area enclosed by the newly constructed traps and screens. The unit could be located close by and discharge into the deep over-wintering pond on the opposite side of the fishery station. Electricity is not presently available, but a supply is shortly to be installed.

Previous Page Top of Page Next Page