|Title||Effects of Tour Boats on the Behaviour of Bottlenose Dolphins: Using Markov Chains to Model Anthropogenic Impacts|
|Publication Type||Journal Article|
|Year of Publication||2003|
|EndNote Rec Number||8742|
Nature-based tourism activities have been developing over the last decade, but it is still difficult to manage these activities sustainably. This sector is increasingly focusing on whales and dolphins in coastal communities, but the exact effects of these tourism activities are unclear. Markov chain modelling may help researchers assess the effects of tourism activities on the behavioural budget of small cetaceans. Matrix models have been used widely in population ecology to provide successful management guidelines. From June 2000 to August 2001, I collected information on the behavioural state of bottlenose dolphin (Tursiops spp.) schools from a population residing in Doubtful Sound, Fiordland, New Zealand. In addition, I recorded the occurrence of boat and dolphin interactions. I then calculated the transition probabilities of passing from one behaviour to another by using a first-order, time-discrete Markov chain model. Behavioural transitions during which a boat-dolphin interaction occurred were compiled in an “impact” chain. All other transitions were tallied in a control chain. I then quantified the effect of boat-dolphin interactions during behavioural transitions by comparing the behavioural transition probabilities of both chains. Socializing and resting behaviours were disrupted by interactions with boats to a level that raises concern. Both the duration of bouts and the total amount of time spent in both these behavioural states were substantially decreased. Dolphins were significantly more likely to be travelling after an interaction with a boat. However, the overall behavioural budget of the population was not significantly affected. Therefore, the bottlenose dolphin population seems to be able to sustain the present level of boat interactions because of its low intensity. More effort is needed to develop prognosis analyses in order to understand how the effect of boat interactions on dolphins changes with variations in intensity.