Effects of noise from ore carrier shipping on narwhal (Monodon monoceros) during the open water season in the East Canadian Arctic

Abstract

Shipping is increasing in Arctic regions, exposing previously naïve marine mammal populations to underwater shipping-related noise. I assessed the impact of shipping on the acoustic habitat of narwhal (Monodon monoceros) and other local marine fauna. Broadband sound pressure levels (SPL; 10 Hz-25 kHz) under auditory weighing functions were compared between times of ship presence and absence using noise levels from passive acoustic recorders. Effects of ship presence and noise on narwhal behaviour were also analyzed. Broadband SPL were significantly reduced under narwhal hearing scenarios relative to unweighted levels. Narwhal perceived shipping noise at low levels and did not perceive increases until ships were within 5 km. No significant changes in narwhal behaviour were observed when only ships were present. Behavioural changes caused by other stressors were observed. Ship presence frequently occurred along with other stressors, limiting observations of behavior in the presence of ships. Continued monitoring is recommended.