Large baleen and small toothed whales face greatest energetic consequences from sonar disturbance

Anthropogenic noise is a pervasive and increasing source of disturbance to wildlife. Marine mammals exhibit physiological and behavioral responses to some sound sources, especially naval sonar. The responses can lead to lethal effects, but predicting the population consequences of sublethal impacts requires a more robust understanding of cetacean energetics. Here we show that energetic consequences are greater for small and large cetaceans, compared to intermediate sizes. Costs incurred by avoidance behaviors are more sensitive to lost feeding opportunities than increased energy expenditure associated with fleeing the sound source. Because the relationship between foraging efficiency and body size depends on feeding mode, small particulate feeders (e.g. porpoises) and large filter feeders (e.g. blue whales) face the greatest costs relative to energy requirements. These results fill a gap in the Population Consequences of Disturbance framework by using empirical measurements of baseline cetacean energetics, which will aid in conservation planning for threatened and endangered marine mammals. Furthermore, the model is applicable to other forms of disturbance, such as vessel traffic or seismic exploration, and the scaling approach facilitates assessments for understudied species.