Impact of cetacean watching vessels on Risso’s dolphins behaviour in the Gulf of Taranto: preliminary information to regulate dolphin watching

Dolphin and whale watching has become worldwide a popular ecotourism activity. However, it can itself be a source of disturbance/stress to animals. Therefore, it is necessary quantify its impacts on cetacean species and possible behavioural responses to interaction between vessels and cetaceans. This study provided first preliminary information of the possible impact of a research vessel on behavioural activity of the Risso’s dolphin recorded in the Gulf of Taranto from April 2019 to September 2020. Information about positive, neutral and responses of Risso’s dolphins to research vessel was collected according focal-group protocol with instantaneous scan-sampling during 60 sightings, for a total of 300 sampling sessions of 3-min. Travelling resulted the most observed activity state (62%) followed by resting (24%), socializing (7%) and feeding (7%). A neutral response were observed in 81.3% of cases, a negative one in 17% of cases and positive in 1.7% of cases. For each activity state recorded, the most observed behavioural response was neutral, followed by negative reaction. Results provided in this study seems to indicate that Risso’s dolphins displayed a neutral response in the most of sightings. However, further studies are necessary to better understand if the presence of whale watching vessels may induce changes, and to what degree, in the essential behaviour of this and other species occurring in the area.