A large-aperture densely populated coherent hydrophone array system was towed at multiple locations off Norway encompassing regions above and below the Artic Circle during an experiment in spring 2014. Vocalization signals up to 4 kHz from diverse marine mammals species were received over multiple diel cycles at each measurement site off Alesund, Loften, and the Northern Finnmark region of the Norwegian and Barents Seas. Here we compare and contrast the species-dependent marine mammal vocalization temporal and spatial distributions for the three regions. Data from the coherent hydrophone array system are automatically processed to enable signal detections, bearing estimation via beamforming, and time-frequency feature extraction via pitch tracking. Bearing-time trajectories of signal detections after automatic classfication are first extensively verified by visual inspection of select spectrograms. Verified marine mammal vocalization bearing-time trajectories are next localized via the moving array triangulation technique and mapped onto geographic space, including error bounds for range and cross-range estimates. Vocalizations belonging to baleen whale species include fin, humpback and minke, and tooth whale species include sperm and beluga. The species-dependent diel, diurnal and nocturnal call rates, as well as call spatial distributions provide insights into their behavior and interactions in the undersea environment.
Ghosh et al. (2025) studied this question.