engleski

Behavioural responses of Bottlenose dolphins, Tursiops Truncatus to boat traffic in the Kvarnerić, North-Eastern Adriatic Sea

The objective of the study was to examine the effects of exposure to boat traffic on the behaviour and respiration of a small, resident bottlenose dolphin population in the Kvarnerić, North-eastern Adriatic Sea. A focal group was followed during boat-based surveys and behavioural data sampled at 3-minute intervals whilst respiration data were collected, by applying a continuous sampling procedure during focal individual follows. The results suggested that boat traffic had a significant impact on the Kvarnerić dolphin behaviour. The behavioural budget in the presence of boats showed a decrease in activities associated with feeding and resting whilst travelling behaviour increased. In terms of behavioural responses, neutral and negative were observed while there were no positive responses of a group. The particular features such as type of boat, propulsion or speed, type of approach, distance from the animals and duration of encounter were important factors in eliciting the behaviour response. Primarly fast and erratically moving vessels caused negative responses, particularly over extended periods of time. Alternatively, neutral responses were mainly associated with fishing boats, slow moving or stationary vessels. Behavioural responses were observed when boats were within a 300m range of the dolphins, becoming accentuated within 100m. Additionally, it was found that dolphins formed tighter groups when within close proximity of the vessels (÷2=39.271 , df=4 , p<0.001). No significant differences in respiration pattern were found when in the presence or absence of boats (W=17.0 , n=6 , p>0.05) but it was shown that dolphins performed longer dives during encounters with speedboats than with other boat types (73.8 sec, SD=39.4 vs. 19.7sec SD=9.5 respectively). The results obtained during this study may play an important role in defining a code of conduct for tourist boats during dolphin encounters within the borders of the recently established „Lošinj Dolphin Reserve“.

behaviour ; bottlenose dolphins ; boats

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