Northwest Fisheries Science Center

Cumulative energetic costs of killer whale responses to anthropogenic disturbance

Killer whales respond to anthropogenic activities in a variety of ways, including changes in acoustic behavior, surface behavior, dive behavior, direction of travel, and behavioral activity states. For example, one study demonstrated that Southern Resident killer whales increase the amplitude of the calls in response to vessel noise ( The next link/button will exit from NWFSC web site Holt et al. 2009) and these response have small but measureable energetic consequences in bottlenose dolphins ( The next link/button will exit from NWFSC web site Holt et al. 2015). This study, originally funded by the Office of Naval Research and conducted by Drs. Dawn Noren and Marla Holt along with UC Santa Cruz collaborators, will quantify the cumulative energetic costs of a suite of responses to disturbance from vessels and noise. The cumulative costs are quantified in terms of increased energy expenditure relative to the daily activity budget. The results to date demonstrate that the cumulative change in energy expenditure related to short-lived behavioral and acoustic responses, changes in swim speed, and changes in activity states is negligible to very low. It is apparent, however, that reduced foraging behavior is a ubiquitous response to various sources of anthropogenic disturbance in odontocetes, including Southern Resident killer whales. Extended reduction in energy acquisition as a result of reduced foraging opportunities, rather than small and brief increases in metabolic rate caused by short-lived behavioral reactions, is more likely to affect energy balance, consequently altering body condition and ultimately affecting fitness of individuals.