The Greek Experience of Artificial Reef

Transcription

1 Journal of Environmental Protection and Ecology 13, No 3A, (2012) The Greek Experience of Artificial Reef Construction and Management D. S. Klaoudatos*, A. Anastasopoulou, C. Papaconstantinou, A. I. Conides Marine ecology Insitute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research, Athens, Greece Abstract. Artificial reefs consist mainly of prefabricated concrete blocks of cubic or cylindrical shape with holes of varying diameter and depth, placed on the sea bed aiming to enrich the marine life of a given area. They provide shelter and facilitate the attraction of several species, thus increasing the commercial and non-commercial fisheries resources of the surrounding area. The suitability of the area of installation is carefully determined and depends on the substrate type, depth, inclination, wave action, a number of physiochemical water column parameters, and vicinity to natural reefs and Posidonia meadows. An artificial reef success largely depends on its acceptance from the local population and stakeholders and mainly from the fishermen. The installation of a new artificial reef usually takes place at an established fishing ground, resulting to the essential need for establishing fisheries management in the area. A successful artificial reef and its rational management will significantly contribute to the socioeconomic development of the area; contribute to the control of the costs of the fishermen and act as a tourist attraction offering considerable opportunities for development. So far no management plan has been elaborated or implemented for any of the 4 artificial reefs operating in Greece. Keywords: artificial reefs, site selection, management plan, Greece. AIMS AND BACKGROUND The aims of the current paper are the description of the present artificial reef construction state and establishment in Greece. One contemporary method of sustainable management of the fisheries resources is the development of marine protected areas (MPAs). The aim of the creation of an MPA is not only limited to the protection of important ecological ecotopes and/or species threatened with extinction, but extends to the protection of fishing, spawning and nursery grounds, thus contributing to fish stocks recovery and increasing fishing productivity 1. It is of no coincidence that the institution of MPAs was incorporated as a management tool both in the new EU regulation (in 2000) relating to the management measures for sustainable use of fisheries resources in * For correspondence. 1647

2 European seas and the corresponding regulation for the Mediterranean Sea (regulation 1967). One form of MPA is the construction of artificial reefs. Artificial reefs are man-made or natural objects placed in selected areas of aquatic environments to provide or improve rough bottom habitat and thereby enhance populations of reef-associated species and the opportunity to harvest some of these species 2. The first artificial reefs on record were made in the early 1800 s in Japan from sticks of bamboo. Since the early 1950 s marine fishery interests have been investigating the use of artificial reefs for manipulation of fish populations. The construction and sustainable management of an artificial reef aims to: enhance habitat for fish and benthic organisms associated with reefs; increase reef biological carrying capacity; enhance biological diversity; increase fish populations, and provide sustainable fishing opportunities. The construction and sustainable management of an artificial reef can ensure an increase of the fishing biomass and production, while at the same time offering considerable protection to a sufficient number of spawners thus ensuring the sustainable management of the fished population. Artificial reefs consist of artificial infrastructures made mainly by concrete blocks with holes of varying diameter and depth, placed on the sea bed in order to enrich the marine life of a given area, providing shelter and facilitating the attraction of several species, aiming to increase abundance, biomass and consequently the fishing production in the vicinity of the installation area. The creation of artificial reefs along with the simultaneous introduction of a MPA where a number of management measures can be implemented, aims to enrich the marine life, increase biodiversity and fisheries resources, facilitate scientific research, increase the awareness of the public for marine life protection and marine environment in general. DISCUSSION Artificial reefs are submerged man-made constructions placed on the sea bed, which enhance the technological-ecological mechanisms or actions of environmental mechanics, substrate aiming to enrich the marine life of a given area providing shelter and facilitating the attraction and concentration of several different species 1. According to a number of authors 3, artificial reefs seem to have a number of functions, such as the increase of biodiversity and the protection of the fishing resources from the trawl net. Apart from these functions artificial reefs are able to induce consecutive biological phenomena such as the reduction of mortality of the fish eggs and the early larval stages, construction of nests or shelters for species which are not highly migratory, attraction and enhancement of the stocks of 1648

3 pelagic fish which find food in the area of the reef, energy recirculation through production of biomass from sedentary species settled on the surface of the reef and finally through protection of the entire ecosystem 4,5. There are, however, scientific views 6 8, which maintain that artificial reefs harm the marine resources, since their only function is the concentration of available biomass and not its actual increase. The productivity of marine life inside and in the vicinity of the reef area increases through three distinct mechanisms: (a) through the extension of the trophic niche of the young individuals; (b) enhancing the niche in which adult individuals live, and (c) by protecting the living territory of the species from fishing and natural mortality. The results of the afore-mentioned mechanisms are the increase of commercial and non-commercial fisheries resources that live in and in the vicinity of the reef. Substantial research has been conducted on the form and materials used for artificial reefs aiming to provide guidelines for the environmental-friendly construction of the reefs and at the same time satisfy the colonising species niche requirements. European scientists spearhead the research on artificial reef building materials. Use of concrete has been accepted by the majority of the European artificial reef constructors 1. The concrete blocks used are prefabricated with a cubic or cylindrical shape, with triangular or circular openings of different size and shape. The use of reused material for artificial reef construction has environmental and financial implications. The use of old tires for artificial reef construction is considered in Europe as chemical and toxic polluters and therefore their use is not favourable. Wrecks are often suggested as artificial reefs, since their use enhances tourist development attracting recreational divers. Until the present day there has been no extensive research regarding wrecks and therefore their true value for use as artificial reefs remains unknown 2. In Greece artificial reefs are composed by reinforced concrete with holes of different size and shape placed on strictly selected spots of the sea bottom (Fig. 1). It is very important to carefully choose the most suitable area for an artificial reef installation where a number of interventions will take place thus amplifying the management of the reef from its users and mainly for the fishermen. It is imperative to avoid transport routs or areas already used by commercial trawlers. Some of the most important criteria for an artificial reef installation are the substrate type, depth, a number of physiochemical parameters, vicinity to natural reefs and protection of certain zones from overfishing

4 Fig. 1. Different elements used for artificial reefs in Greece today 9 (A pyramid blocks; B cement or metal pipes joint together in pyramids; C boulder stacks; D trawl net traps, usually are installed around the reef to protect it from towed gears; E, F perforated cement blocks) In order to maximise the biological development of an artificial reef, it is important to take into account the benthic substrate geomorphology and the water column hydrology in the area where the reef will be established. Criteria for an artificial reef site selection are the following: the distance from natural reefs should not exceed 1.5 km; the reef must be located in the vicinity of the Posidonia sea beds which function as alternative food source for species populating the reef; the reef elements should not be placed on the Posidonia sea beds but in spaces near them; the benthic substrate should have little or no tilt; transparency of the water column should be high; the water depth should be between 25 and 40 m; in case the reef will be used as a fish colony exclusively, the reef elements can be placed in depth of 30 to 40 m; in case the reef will be used as a potential diving park, the reef elements should be placed in approximately 20 m depth; the selected area must be protected by high wave action; access to the reef for coastal fishermen should be easy. One very important factor needs to be taken into account when considering a suitable area for artificial reef construction is the presence of rivers in the vicinity. This factor was apparent by the artificial reef already established in Preveza (north-west Greece) which was established at a short distance from the mouth of the Axerontas river. The result was that during the winter period when the rainfall increases dramatically in the surrounding area, the river outfall transports a large 1650

5 amount of suspended material which is deposited on the reef elements, having a profound effect on the reef health and success 10. Site selection for an artificial reef would take into account the needs of the coastal fishermen and most important a study of the fish migrations, productivity of the area, allocation of natural reefs in the vicinity. The study is comprised by two phases, the preliminary phase, which precedes the artificial reef installation and the scientific monitoring phase that follows the installation. Based on the information obtained by the preliminary phase a decision will be made regarding the installation site, the construction material and the shape of the reef. The extent of an artificial reef can be determined in absolute and relative extent. In absolute extent one has to calculate the expanse, volume, displacement, and productivity, whereas in relative extent the management of the fishing productivity needs to be established in order to fish a certain percentage of its total productivity or biomass. The available funding for the construction and 5-year monitoring are definitely another important factor that will determine its extent and assess its productivity. The benefits from the establishment of an MPA are not immediately portrayed but a certain amount of time is required in order for the marine life to blossom, a fact which includes consecutive colonisation of a number of species and their adjustment in the area. The successful installation and rational management of an artificial reef could contribute to the control of the costs of the fishermen in the surrounding area through the increase of the fishing resources (production increase) and to limiting the distance of the fishing trips to closer fishing grounds. In addition a successful artificial reef will significantly contribute to the socioeconomic development of the area, by creating additional employment and ensuring the current employees. A successfully established artificial reef could be used as a theme park or dive park thus acting as a tourist attraction while at the same time offering considerable opportunities for development of the surrounding area through the creation of specialised services aiming to satisfy the need of the tourist industry (dive centres, selling and renting of diving equipment, etc.) and further expand the current infrastructure (hotels, restaurants, tourist shops, etc.) in order to meet the increasing demand. The success of an artificial reef largely depends on its acceptance from the local population and stakeholders and mainly from the fishermen. An example of high socioeconomic acceptance is the artificial reef that will be constructed in the municipality of Pieria in Litochoro (north Greece), where the local population and mainly the fishermen are very positive with the idea and have facilitated with the preliminary phase of the site selection study, strongly advocating in favour of the reef installation (HCMR, 2009). The opposite has been the case for the artificial reef planned to be established in the municipality of Laconia in Monemvasia (south Greece) where despite the acceptance from the local population the local coastal 1651

6 fishermen strongly oppose the idea of an artificial reef installation, hampering with the preliminary phase of the site selection study, considering its presence as a limiting factor for fishing in their fishing grounds completely disregarding the benefits 1. At present 4 artificial reefs are installed and operate in Greece (Kalymnos, Fanari in Rodopi, Ierissos in Chalkidiki, Preveza) with no specific operational and exploitation plan. The installation of a new artificial reef usually takes place at an established fishing ground, resulting to the essential need for establishing fisheries management in the area. At present there has been no management plan elaborated for any of the artificial reefs operating in Greece and no specific aims have been defined regarding their operation and exploitation, resulting in their abandonment after their initial installation. In Greece today there is no specific policy legislation and no effective tools for coastal area management, with policies aiming at land development control and building regulation and no institutional mechanism to ensure coordination between economic development policies and physical planning 2. Fishing permits to a limited number of coastal fishermen could be issued and in the case of a large reef established in a relatively large distance from the coast free access for a large number of fishermen should be considered. In certain cases where a number of fishing categories are involved in the vicinity of the artificial reef causing conflicts amongst coastal fishermen fishing with different fishing gear, a number of certain management interventions regarding the use of fishing areas are imperative taking into account that increase in fishing effort could cause overfishing. In those instances, the management entity needs to implement a program which will implicate the local managing bodies and the fishermen of the area in an effort to organise an acceptable management system establishing through voluntary and mandatory agreements a common acceptance regarding the daily workforce, number of vessels fishing, fishing gear and techniques and the legal landing size. Nevertheless because artificial reefs can be located in depths from a few meters down to 200 m their management from a technical point of view is difficult. A key question to be addressed to those who plan fisheries management is how to ensure maximum production of biomass and fishing, while protecting a sufficient number of broodstock to ensure sustainable management of the population caught. The reduction in mortality for juvenile fish, the abundance of food and the survival of a large number of broodstock, are factors directly related to the improvement of the performance of a certain population, its biomass increase and production. An important factor that can contribute to ensuring the maximum fishing biomass is the correct establishment and rational management of artificial reefs. An important argument, however, against the artificial reefs is that the protected areas can attract large number of predators which appeared in the same area in small numbers 1652

7 prior to the establishment of the reef. In that case, predation on juveniles of fish will eventually increase applying pressure to a resource which may be valuable. As an example, the artificial reef of Kitros (central-north Greece) is planned to be built in the region of a recognised nursery and reproduction ground of the shrimp Melicertus kerathurus which is a valuable species for the coastal and trawler fishery in the area and for the market. It is known that the population of various predators increase dramatically around artificial reefs due to the high numbers of juveniles and small sized fish attracted there and it is supposed that these predators will also affect the shrimp juveniles many times more than without the reef. The successful deployment and efficient management of an artificial reef can help control costs for fishermen by increasing the biomass of fish (production increase) available in the region and improve the cost efficiency of the fishing activity, usually because the artificial reefs are located near a port, thus reducing oil consumption for travelling between port and fishing grounds as well as the search time within the fishing ground. It also protects coastal fisheries from trawlers fishing illegally (close to the coastline). A management plan should aim to develop and interconnect the benefits of the artificial reef as a marine protected area (MPA) for the local fisheries stocks and at the same time the social and economic exploitation of the reef as means for local tourist development, with minimum investment through the attraction of specialised travels for underwater swimming (dive tourism) in a potential theme or dive artificial reef park. Greece is a well-known tourism destination worldwide. It is recognised as one of the top 10 tourism brand names. Its multi-faceted tourism personality encompasses many tourism special interest forms and activities, including diving. Recreational diving is expanding rapidly in the recent years. Services and dive locations can really surprise both the experienced as well as the novice diver, to create an unforgettable diving experience. The plan could integrate the relative national and European laws and policies. Until today no such plan has been elaborated for any of the 4 artificial reefs operating in Greece (Kos-Kalymnos islands Dodecanese; Fanari Rodopi, north Greece; Ierissos Chalkidiki, north Greece; Preveza western Greece). In addition no specific aims have been defined regarding their operation, while at the same time a complete abandonment of the artificial reefs has been observed after their initial installation. The operational plan could also include guidelines for site selection of artificial reefs and guidelines for the selection of building materials suitable for Greek species which are important emerging issues since there are more artificial reefs planned to be constructed in Greece. A successful case of an established artificial reef management is the Kos- Kalymnos reef (south-east Greece) where the fishermen are the ones protecting, guarding and managing the reef, benefiting from its installation and function. In contrast, the artificial reef established in Preveza (western Greece) is an example 1653

8 of a poorly managed reef where the fishermen are the ones fishing inside the reef area showing complete disrespect for its intended use, not allowing the reef to function properly and offer substantial benefits. CONCLUSIONS While fish populations are constantly reducing in the Aegean Sea and the competition between coastal and medium (trawlers, purse seiners) fishermen is increasing, the protected areas created by the installation of artificial reefs could be a possible solution. The first artificial reef installation in Greece took place during 1999 in the Thracian Sea in the municipality of Rhodopi in Fanari (north Greece), and after 12 years experience indicated a complete success displaying 150% average fish population increase, reaching up to 400% for certain species. The installation of 3 new artificial reefs (Kos-Kalymnos islands Dodecanese, Ierissos Chalkidiki, north Greece, Preveza western Greece) followed with positive results for coastal fishermen. New artificial reefs are planned to be established in other areas of Greece (Pieria, Litochoro north Greece, Laconia, Monemvasia south Greece; Messinia, Kyparissia south Greece; Crete south Greece). A prerequisite for increased fish landings is the existence of a management plan to regulate fishing effort in the region, in other words, control how many boats fishing the area defined by the reef center, how many fish they catch and the appropriate fishing techniques. The creation of protected areas with the establishment of artificial reefs contribute to the resolution of certain problems of fisheries management, at least for certain categories of fishermen, such as inshore, while medium fishermen will benefit in a later stage. A dispute between fisheries biologists (attraction-production debate) is whether artificial reefs renew ecosystems that have been largely damaged by pollution and overfishing, or simply attract existing populations away from their natural habitats, creating concentrations of fish and making them vulnerable to overfishing. Studies have shown that artificial reefs have resulted in a growing population of the species when the environment is the limiting factor and when there are management rules enforced for the control of fishing in the protected area. Designing reefs that attract species appearing occasionally in the region and applying restrictions on fishing can result in the reduction of overfishing of vulnerable species. Eventually, artificial reefs are no substitute for natural ecosystems. They can not replace the establishment of marine parks, which have shown to restore fished populations even if they perform the same economic benefits as artificial reefs. The creation of artificial reefs with the parallel establishment of a protected area aims to enhance marine life, increase biodiversity and fish stocks, improve scientific research, increase public awareness for marine life and marine environ- 1654

9 mental protection. The benefits of establishing such areas are not directly visible but require some time for life to flourish through sequential colonisation of species and their adaptation in the new environment. A successful artificial reef is instrumental for the socio-economic development of the region, creating new jobs and safeguarding existing ones since it can be combined with other activities 11. A reef can also be used as a diving park offering significant opportunities for development of the region through increased tourist attraction creating specialised services (dive schools, dive operators, rental and sale of diving equipment) and expanding existing ones (hotel industry, restaurants, shops, etc.) 12 in order to meet the needs that will arise. REFERENCES 1. HCMR: Final Study for the Implementation of Artificial Reef in the Municipality of Laconia (Peloponese, South Greece) in the Area of Monemvasia. Technical Report (Ed. A. Conides). 2010a (in Greek). 2. HCMR: Feasibility Study on the Construction of an Artificial Reef in the Municipality of Pieria in the Area of Litochoro (North Greece). Technical Report (Ed. A. Conides) (in Greek). 3. G. RELINI, A. PEIRANO, L. TUNESI, L. ORSI RELINI: The Artificial Reef in the Marconi Gulf (Eastern Ligurian Riviera). FAO Fisheries Report, 357, 95 (1986). 4. G. BOMBACE: Note on Experiments in Artificial Reefs in Italy. In: Management of Living Resources in the Mediterranean Coastal Area. Studies and Reviews. General Fisheries Commission for the Mediterranean, 58, 309 (1986). 5. G. BOMBACE, G. FABI, L. FIORENTINI, S. SPERANZA: Analysis of the Efficacy of Artificial Reefs Located in Five Different Areas of the Adriatic Sea. Bulletin of Marine Science, 55 (2 3), 559 (1994). 6. J. J. POLOVINA: Artificial Reefs: Nothing More than Benthic Fish Aggregators. CalCOFI Reports, 30, 32 (1989). 7. R. B. MOFFITT, F. A. PARRISH, J. J. POLOVINA: Community Structure, Biomass and Productivity of Deepwater Artificial Reefs in Hawaii. Bulletin of Marine Science, 44 (2), 616 (1989). 8. J. J. POLOVINA, I. SAKAI: Impacts of Artificial Reefs on Fishery Production in Shimamaki, Japan. Bulletin of Marine Science, 44 (2), 997 (1989). 9. A. CONIDES, D. KLAOUDATOS C. PAPACONSTANTINOU, A. SIAPATIS, S. GLYKOKOK- KALOS, P. BEKAS: Final Study for Implementation of Artificial Reef in the Municipality of Laconia (Peloponese, South Greece) in the Area of Monemvasia. Hellenic Centre for Marine Research, Institute for Marine Biological Resources p. (in Greek). 10. HCMR: Assessment on the Present State of the Artificial Reef in the Coastal Zone of Ionian Sea, Preveza Municipality. Technical Report (Ed. A. Conides). 2010b (in Greek). 11. S. APAK, S. UZUNOGLU, A. F. ACIKGOZ: Mobilising Financial Resources for Sustainable Tourism Industry on the Balkans. J Envir Prot Ecol, 9 (4), 940 (2008). 12. E. G. GULER: Sustainable Tourism in Mediterranean Islands. J Envir Prot Ecol, 7 (4), 880 (2006). Received 19 March 2012 Revised 18 July