A first assessment of operator compliance and dolphin behavioural responses during swim-with-dolphin programs for three species of Delphinids in the Azores

Abstract

The popularity of swim-with wild dolphin programs around the world is fast growing, with the studies required to investigate their impact lagging behind. In the Azores, species targeted include the short-beaked common (Delphinus delphis), the bottlenose (Tursiops truncatus) and the Atlantic spotted dolphin (Stenella frontalis). To evaluate the effects of this activity on local dolphin populations, and thus provide support for management decisions, dolphin response data were collected onboard commercial boats off São Miguel Island between 2013 and 2015. All three species revealed high degree of neutral and avoidance behaviours, and very low approach rates. Tursiops showed higher frequency of neutral responses than Delphinus, while Stenella both avoided and approached more frequently than the other species. When boats intersected the path of dolphin groups, avoidance responses were more likely and the duration of swims was shorter. Swims were also shorter when animals were resting and travelling, and when groups were smaller. The operators generally complied with the legislation, except in respect to the number of swim attempts per dolphin group, which was higher than the legal maximum. Improvement of the current legislation and concurrent reinforcement of controls is essential to avoid detrimental long-term effects of this activity on dolphin populations in the Azores.