The short-term impact of dolphin-watching on the behaviour of bottlenose dolphins (Tursiops truncatus) in western Australia

This paper presents the research findings of interactions between bottlenose dolphins (Tursiops truncatus) and a dolphin-watching Tour Boat in Bunbury (Western Australia). Sixty-four hours of surface behaviour observations were collected with "focal group sampling" assessed over three minute intervals. The study compared behaviour patterns both with and without the presence of the Tour Boat. The results show that the presence of the Tour Boat can influence the duration (time spent) and frequency (number of occurrences) of behavioural states and also the structure of the population. The time spent resting (P<0.05) and feeding (P<0.01) decreased, whereas travelling (P<0.01) increased. The frequency of all the behavioural states increased, in particular travelling, resting (P<0.01) and feeding (P<0.05). The group structure was also influenced (X2 =11.44; P<0.01), as dolphins tend to spread in more groups of fewer animals in the presence of the Tour Boat. The behaviour analysis of the direct reaction of animals in close contact by the Tour Boat showed that dolphins displayed attraction in 20% of cases and were deterred in 28% of cases; for the rest, the response was neutral. The short-term changes in behaviour pattern can be used as an early indicator of potential halt to animal vulnerability in order to assess and recommend appropriate management and conservation strategies especially in regions, such as the Mediterranean Sea, where, for the combination of many disturbance factors, cetacean populations are vulnerable.