Sightings of risso’s dolphin (grampus griseus) off the Southern coast of Linosa island (South-Central Mediterranean Sea)

Abstract

Risso’s dolphin distribution, habitat preferences, and site fidelity in the Strait of Sicily are very little known. During three summer seasons of sea surveys, we sighted this species offshore Linosa island in groups of variable numbers of individuals (2-20 with an average of 9.7 ± 7.0 SD). Sightings were located in a small area showing medium depth (average 591 m) and bathymetric features that usually correspond with known habitat preferences of the species. A total of 32 individuals belonging to 4 age classes were photo-identified and 8 of them were re-sighted once over years. This work illustrates for the first time, the presence of the species in the studied area and the results seem to indicate a site fidelity over years.