Risso’s dolphins (Grampus griseus) are relatively large dolphins measuring up to 4m in length. Most distinctive is the blunt head without beak and dark coloration dominated by whitish scars which they accumulate throughout life, making older animals appear almost white.
Risso’s dolphins are distributed worldwide in tropical and temperate seas with preference for deep offshore waters and coastal areas with narrow continental shelves. The Risso’s dolphin is present in the entire Mediterranean Sea and is considered a regular inhabitant, although its abundance throughout the basin is unknown. Within the Mediterranean Sea, the Risso’s dolphin is mostly encountered in deep pelagic waters, in particular over steep shelf slopes and submarine canyons.
Since the 19th century, the Risso’s dolphin has been recorded on numerous occasions in the Adriatic Sea. Regardless of the relatively high numbers of strandings and their presence throughout the Adriatic basin, the Risso’s dolphin was considered as only occasional. This categorisation has been partially revised based on data collected by the 2010 aerial survey that indicated the important presence of this species in the southern part of the Adriatic, in particular in areas with steep slope and depths between 600-900m. The southern Adriatic clearly represents a suitable habitat for the Risso’s dolphin. This is also confirmed by the NETCET 2013 aerial survey.