Narwhal acoustic presence in Eclipse Sound, Nunavut: relationships with sea ice and responses to ships

The Arctic Ocean is undergoing rapid sea ice loss and increasing ship traffic, introducing potential stressors for wildlife and challenges for management and conservation. This study examines narwhal (Monodon monoceros) responses to vessels in eastern Eclipse Sound, Nunavut, Canada using underwater acoustic recordings and ship tracking data collected between 2016 and 2021. The effect of ship proximity on detection of narwhal echolocation clicks was analyzed, accounting for environmental and temporal factors affecting detection probability. Narwhal acoustic presence exhibits seasonality, peaking in July and October, and is correlated with low solar angle in both seasons and sea ice concentration during ice formation in October. Our analysis revealed an inverse relationship between ship proximity and narwhal acoustic presence in July and October, most pronounced when ships were within 20 km of the recorder in October. These distances suggest that narwhals react to broadband sound pressure levels well below 120 dB re: 1 µPa and are more sensitive to low-frequency sounds (< 1 kHz) than previously assumed. This study offers region- and population-specific insights into narwhal responses to ships, highlighting the importance of integrating long-term monitoring of wildlife, environmental conditions, and human activities to improve prediction of Arctic marine species' movements and behavior.