Innovative submerged cages and mooring systems in off-shore fish-farming installations

In Italy, primarily because of the lack of sheltered marine areas, the improvement in the fish production can be achieved through the installation of off-shore fish-farms utilizing submersible and submerged cages. These cage typologies have been proven to be effective solutions leading, in case of unfavourable sea-conditions, to a reduced risk of damage for the structures as well as a lower level of stress for fishes. In this paper, after a description of two innovative cage prototypes, the mooring systems relative to such cage typologies are described, paying particular attention to the problems related to their installation. Particularly, the design of a submerged cage to be positioned at different depths, ranging between 7 and 40 meters, and the relative mooring system has been carried out with the aim to find environmental conditions suitable to introduce, in the Mediterranean Sea, the farming of the turbot (Psetta maxima). The results of the experiences carried out so far point out the validity of the system employed and show that the environmental conditions found in deep sea waters are suitable for turbot farming in many areas of the Mediterranean sea.