Evaluation of technical and environmental problems in offshore cage culture of the mediterranean gilthead seabreamSparus AurataLinnaeus: 1758

Aim of this study, was firstly to assess the seabed deposition of a fish farming facility located in the Alghero Bay (Western Mediterranean) by using the MERAMOD® particulate waste dispersion model, and evaluate actual scenario and a forthcoming situation represented by an enlargement of the fish farming area. The impact seabed surfaces forecasted by the model increased from 5.6 ha in the actual scenario up to 7.3 ha in the supposed potential condition. The second part of the study aimed to describe the settlement and development of biofouling organisms on cage nets at the above–mentioned farming facility. This was done by investigating different developmental phases of the biofouling communities on net panels inside cages containing big and small gilthead sea bream (Sparus aurata) specimens. The rapid increase of biofouling on all the experimental panels positioned inside fish cages suggests that caged mariculture activities have the potential to provided an enhanced food supply to epibiotic communities. Lastly, the objective of the third part study was to improve the knowledge of the ethological traits of different–sized gilthead sea bream specimens reared in floating cages. With this aim, the most common behavioural patterns of this species were observed during different times of the day and in the presence or absence of food. The results acquired show that the behaviour of fish reared offshore in the Alghero Bay is dramatically affected by the feeding rhythms in captivity.