|(übersetzt):||The results of this study show that close boats (<100 m) affect the behaviour of bottlenose dolphins more strongly than boats further away (>100 m). Close boats induced a decrease of feeding, resting and social behaviour. The proportions of high-speed swimming and slow swimming increased. In the presence of close boats, dolphins were observed 6 times more frequently to leap and 3.6 times more frequently to tail-slap than under control conditions an indication of disturbance. Dolphins responded to close boats with evasive manoeuvres similar to techniques used for avoiding predators. With more than two close boats, animals swam approx. 37% faster than without close boats. An energy consumption of 2.93 W kg-1 was calculated. This corresponds to a daily energy demand of 50.6 MJ per dolphin with 200 kg body weight. With boats at close range, the mean power requirement of dolphins was around 15.4% higher than during controls. With close boats, dolphins used a third of their energy budget to avoid boats by swimming at high speed. In the light of these findings, recommendations for dolphin-watching guidelines are given.
|Schlagworte:||Tursiops , dolphin watching, energetic, Energetik, behavior, Verhalten, bottlenose dolphin, Tourismus, whale watching, Delfin