Singers of the High Arctic; Seasonal acoustic presence of Spitsbergen bowhead whales (Balaena mysticetus) around Svalbard, Norway

Abstract

Marine mammals throughout the circumpolar Arctic are facing profound levels of environmental change due to climate warming. Among them is the bowhead whale (Balaena mysticetus), an Arctic endemic cetacean that spends its entire life in Arctic waters and lives in tight association with sea ice habitats. The Spitsbergen bowhead whale population resides in the Northeast Atlantic, where they were hunted to near extinction during commercial whaling in the previous centuries. In this study, Passive Acoustic Monitoring (PAM) was used to analyse their seasonal and spatial trends at six different sites around the Svalbard Archipelago, Norway. A total of 47,232 audio files, recorded between 2017 and 2022, were analysed for bowhead whale vocalizations. The analyses focused on data collected between October and May, using a combination of Long-Term Spectral Averages (LTSA’s) and visual/auditory verification. These findings were subsequently correlated to seasonal changes in environmental conditions. Bowhead whale vocalizations were detected at all study sites, but with significant variation between locations as well as some interannual variation. The consistent and high detection rates of singing west and east of Svalbard suggest that these sites may serve as key areas for bowhead whale overwintering and breeding. In contrast, the lower and fluctuating detection rates in the area north of Svalbard suggest that it serves as a movement corridor between regions. Significant positive correlations were found between bowhead whale acoustic activity and high sea ice concentrations, emphasizing their highly ice-affiliated nature. This study provides novel information on the distribution and habitat use of Spitsbergen bowhead whales and raises concern for the recovery of this population in an Arctic that faces rapid sea ice habitat loss.