Effects of Whale-Watching Vessels on Adult Male Sperm Whales Off Andenes, Norway

Abstract

This study investigated the effects of whale-watching vessels (WWV) on solitary sperm whales off Andenes in northern Norway. The presence of WWV did not have a significant effect on the duration of the surface and foraging dive periods or on the respiration pattern and dynamics. However, the presence of WWV made sperm whales almost seven times more likely to perform a near-surface event (NSE). NSEs are submersions without fluking for short periods of time that take place during the surface phase. The occurrence of NSEs led to a significant increase of 75% in surface time, which is 6 min more at the surface that were not compensated with longer foraging dives. Additionally, the occurrence of NSEs was associated with changes in the animals' respiration pattern and dynamics. Data collection concerning NSEs and respiration dynamics (both parameters assessed here for the first time) is strongly recommended in future impact studies on this species. NSEs may be indicators of disturbance and are reasonably easy to identify, and thus identifying and better understanding the causes of this behavior have management implications.