hypothesis using stable isotope analysis, to examine the feeding ecology of the species in the NWMS, and modelling techniques, to identify the species habitat preferences in the Ligurian Sea and determine how these were influenced by dolphin behaviour. We compared δ13C and δ15N of by-caught and stranded dolphins from the NWMS. Results suggested no consistent dietary differences between the five study areas and revealed possible seasonal variations in the diet. When habitat preferences were studied, we found that striped dolphin in the Ligurian Sea associates with the peripheral coastal area and the oceanic frontal area, both characterised by distinct prey availability. However, the exam of dolphin activity revealed that the species favours the coastal area in terms of feeding behaviour. This affinity is explained by the predictable food concentration. The productivity of the frontal area is however suggested to be an attractive feeding ground but for a migrating component of the Mediterranean population. This study suggests therefore that two components of the striped dolphin population overlap in their range, but partition their habitat and may have specialized in their dietary habitat, supporting the hypothesis of differences in the feeding ecology likely to have driven the striped dolphin population in the NWMS. The occurrence of larger groups in deep waters is related to socializing activities. We suggest this pattern results from the meeting of the resident and the migrating components presumably for mating reasons. Given these results, we highlight the importance of the Ligurian Sea for the species as being a foraging and a possibly breeding ground. Conservation and management of this human-impacted species should also consider the complexity of its Mediterranean population structure.
Sustainable Aquaculture Development.
School of Agricultural Sciences, Department of Ichthyology and Aquatic Environment, University of Thessaly, Fytoko Street, GR38446 Volos, Greece.
Sustainable aquaculture development relates to ecological, biological, economic and institutional sustainability which, in turn, relates to social and cultural issues. Ecological sustainability refers to fundamental task of maintaining or enhancing the resilience and overall health of the ecosystem and maintaining the resource base at levels that do not foreclose future options, whereas biological sustainability is about growth nutrition and health of farmed species. The issue of organic aquaculture should be also addressed.