Study of sea bottom geo-biofacies associations in relation to spatial distribution of commercial interest fish species through acoustic instruments.

Over the past 20 years, MultiBeam sonar System (MBS) had a remarkable technological development for marine sciences. As a matter of fact, these instruments provide bathymetric, morphological and seafloor composition information. The latter is given by the backscatter, which represents the backscattered wave after it has interacted with the seabed. Depending on how much wave is lost by absorption, snapshots of the bottom are obtained, whose color differences represent different acoustic facies (i.e. grain size, composition or benthic differences). Currently it is possible to study the backscatter of the whole water column, which is useful, for example, to identify fish schools. This PhD research projects aims to characterize the seabed in specific areas of the continental shelf in the Strait of Sicily with the use of acoustic signals from the MBS. Specifically, the following goals are meant to be achieved: Characterization of the study areas from the viewpoint of acoustic facies; study of associations between acoustic facies and distribution. & abundance of some target fish species; recognition of fish schools in the water column by means of multibeam and characterization of their main geometries (i.e. volume and density of the schools).