PR/74 - USE OF DECOMMISSIONED PLATFORMS IN OPEN SEA TO ENHANCE FISH PRODUCTION ("OFF-SHORE")
- Giovanardi, Istituto Centrale per la Ricerca Applicata al Mare, ICRAM, Loc. Brondolo, 30015 Chioggia (Ve)
Key-words: Decommissioned platforms, off-shore mariculture, remote control, Adriatic sea
This research project, belonging to the Third Triennal Plan of D.G. Fisheries and Acquaculture, intends to find practical solutions which enable to utilize offshore structures, as the methane-extracting platforms of the Adriatic, which, once decommissioned, could constitute a valid logistic support for the settlement of the necessary materials (food, feeding systems, etc.) and of a remote control system for the automatized management of fish culture in submerged cages.
The experimentation, which at present is still going on, intends therefore to set up: the equipments and services in order to develop the control and management system of a pilot plant for fish rearing posizioned in an offshore area, the following experimental trial for a significant period of the whole system and the evaluation of the F.A.D. (Fish Aggregating Devices) of the plant.
After remarkable practical and administrative difficulties we have met to use a decommissioned platform offshore Ravenna, defined from the beginning in agreement with AGIP-ENI, we had to decide to utilize as stationary platform an analogous structure of smaller size which is close to a long-line mussel culture plant belonging to the "Associazione Produttori Pesca " of Cattolica, located about 1.5 miles from the coast at a depth of 11 m.
At the present date (October 1998) an experimental rearing of gilthead (Sparus aurata) in two submerged cages, fixed to a stationary offshore platform outsides Cattolica (Northern Adriatic), is still going on. The system has been designed in order to make self-sufficient for at least two weeks and completely checkable from land the feeding management. Simple cages, of new concept, have been employed, endowed with remarkable elasticity, which have shown to resist unfavourable meteomarine conditions, characteristic of the Northern and Central Adriatic sea.
A fundamental aspect of the proiect has been the realization and the setting-up of the control system. This one is made up of two main units. The first, positioned on the platform, performs different functions: the management of the modules for feeding and for the control of hydrological parameters, the recording of local data, the activation of the control and alarm functions, the interface with the transmission system via radio from and to coast. The second unit, positioned at land, enables the operators to manage the functions which are set up on the platform, namely: the remote control of the feeding system, the management of the alarms, the management of the information recorded for the statistical compilation concerning the amount of the supplied food, the water temperature at the cage level, the interface with the transmission system from and to the plant. The land system is made up of a PC with a monitoring and control software which automatically carries out the supervision of the land system; a radiotransmitter, UHF band, joined to the PC, enables the connection with the system at sea. This one is made up of a control unit and of some modules which carry on the following functions: the automatical food supply, the water temperature recording at the cage level, the energy supply and the data transmission. Even if the experimentation is still on the way, the results we have already obtained confirm the effectiveness of the set up system. In the process of our trial no disadvanteges have turned up (at least until now) to endanger the final result and the introduced settlements have allowed to modulate the system on the basis of the needs come up each time. The project shows the characteristics of a pilote plant therefore remains the need to verify the effectiveness of the adopted solutions transferring them to commercial experiences.
From a general point of view in spite of a great interest which has come out in the last years both at national and international level on the subject of decommissioned offshore structures for mariculture or for other productive and commercial purposes, it has not arrived yet to solve the big problems of normative, economic and practical nature (for example, safety and management responsability, upkeep costs of big size platforms, etc.).
At present our Operative Unit has been following a pilot experience of utilization of submerged and untreated parts of decommissioned offshore steel structures, already colonized by fouling organisms, to relocate them, according to predefined standards, in a close "biologically protected area", situated offshore Ravenna. This is in order to protect and enhance the fauna and flora on those mobile bottoms, with eventual benefits for the fishing areas which are around these artificial structures reconverted in their use destination.
- PR74 
