Study of the Biomass and Spatial Distribution of Deep Pelagic Fish Larvæ of Sicilian Channel in Relationships to the Physical and Chemical Parameters of the Water Column.

Mesopelagic fish represent one of the most important links in the food chain of the marine ecosystem. Their abundance in the Mediterranean sea makes them the most important members of the deep water fauna and a potential resource for future fisheries. The aim of this work is the study of the spatial distribution, composition and biomass of mesopelagic fish larvae species in relationship with the oceanographic parameters of the Sicilian Channel. This area is characterized by different water masses associated with the typical hydro graphic structures of the Channel (Atlantic Ionian Stream-AIS), influencing the presence and distribution of fish species larval stages. Samples were collected during oceanographic surveys, on board of URANIA O/V in years 2005, 2006 and 2007. Distribution maps of the hauls, grouped in clusters, showed similar patterns during all analyzed years. The most common spots we found were located under Pozzallo, Cape Passero and Siracusa, though there were small spots along the central shelf of the western coast. These results would be influenced by the existence of different water masses on the surface, associated with the AIS path and with the hydrographic structures. The occurrence of these species in shelf areas would be associated with the coastal upwelling characterizing the northern part of the study area. In addition, the accumulation of larvae on the south-eastern edge could be related to the strong salinity front off Cape Passero.