Vessel traffic affects bottlenose dolphin (Tursiops truncatus) behaviour in waters surrounding Lampedusa Island, south Italy

• DOI: 10.1017/s002531541100083x
• Publication Date: 2011-07-22T06:14:46Z
• Authors: Elena Papale; Marta Azzolin; Cristina Giacoma
• Keywords: Archipelago; Bottlenose dolphin; Cetacea

Since 2003, as part of the LIFE project ‘Del.Ta.’ (NAT/IT/000163) a bottlenose dolphin community has been studied in order to assess impact increasing boat traffic Pelagie Archipelago (Sicily, Italy). During summer 2006 and 2008, land-based surveys were carried out at Lampedusa, one Archipelago's Islands, set hours from 6 locations (7 2008) standard weather conditions. Continuous horizon scanning focal group sampling methods used study presence behaviour. Dolphin–boat interactions recorded for each sighting. A total approximately 559 spent monitoring 83 sightings recorded. With regard different types vessels, interaction with sailing boats was always neutral, whereas fast caused interruption all activities avoidance Positive occasionally occurred bottom trawling fishing boats. Interactions when powered engine approached within 200 m predominantly resulted negative reaction dolphins (approximately 70%) behaviour affected terms occurrence patterns. Behavioural analysis showed that animals reduced frequency behaviours related feeding, social relaxing activities. The also increased information-gathering such spyhopping. use Markovian chain models revealed evidence disruptions sub-sequences made up often associated feeding. After departures, rarely restarted their previous activity persistence this effect could have long-term consequences result non-habituation. Sighting duration decreased vessels. possible may be indicated by lower mean sighting highest In view scenario outlined above, local authorities need enforce requirement maintaining distance over away promote regular vessel impacts tourist watching cruises.