Quantifying northern bottlenose (Hyperoodon ampullatus) and sperm whale (Physeter macrocephalus) acoustic behavioural responses to anthropogenic noise in Baffin Bay-Davis Strait, Canada

Abstract

Militaries are expanding operations in the warming Arctic but aim to minimize impacts on marine mammals. To assess the effects of military sonar on northern bottlenose and sperm whales, controlled exposure experiments were conducted in Baffin Bay–Davis Strait, Canada, during fall 2022 and 2023. Acoustic data were collected using DTAGs (n = 2) and drifting hydrophone buoys (n = 8). Sonar (1.86–2.5 kHz, 1 s, max 176.4 dB re 1 µPa at 1 m), vessel (<4 kHz), echosounder (26–31 kHz), and whale sounds before, during, and after the exposures were recorded. Echolocation clicks and buzzes were analyzed relative to sonar phases and sound exposure levels. Northern bottlenose whales stopped clicking and sperm whales reduced clicking in response to sonar. Both species responded to vessel and echosounder noise and ceased buzzing (resumed >4 h afterwards). These results support the need for proactive military mitigation measures in the Arctic.