Bearded seal (Erignathus barbatus) vocalizations across seasons and habitat types in Svalbard, Norway

Abstract

Male bearded seals (Erignathus barbatus) use vocal displays to attract females and to compete with other males during the mating season. This makes it possible to monitor breeding populations of this species using passive acoustic monitoring (PAM). This study analysed year-round acoustic data records from AURAL instruments in Svalbard (Norway) to investigate seasonal variation in the acoustic presence of male bearded seals and the phenology of different call types (long, step and sweep trills) at three sites representing a variety of habitats with varied ice conditions. Male bearded seals vocalized for an extended period at a drift-ice site (Atwain; January–July) north of Spitsbergen, while the vocal season was shorter at a High Arctic land-fast-ice site (Rijpfjorden; February–June) and shorter yet again at a west-coast site that has undergone dramatic reductions in sea ice cover over the last 1.5 decades (Kongsfjorden; April–June). Generalized Additive Models showed marked seasonal segregation in the use of different trill types at Atwain, where call rates reached 400 per h, with long trills being the most numerous call type. Modest segregation of trill types was seen at Rijpfjorden, where call rates reached 300 per h, and no segregation occurred in Kongsfjorden (peak call rate 80 per h). Sea ice cover was available throughout the vocal season at Atwain and Rijpfjorden, while at Kongsfjorden peak vocal activity (May–June) occurred after the sea ice disappeared. Ongoing climate warming and sea ice reductions will likely increase the incidence of such mismatches and reduce breeding habitat for bearded seals.

The Arctic and the future Arctic? Soundscapes and marine mammal communities on the east and west sides of Svalbard characterized through acoustic data

“…Bearded seal sounds were detected intermittently for four months in Kongsfjorden, while this species was nearly continuously vocally present for almost nine months at M2 (commencing in November). Male bearded seals perform trilling vocalizations to advertise their breeding condition, so the presence of their trill call types is a good proxy for the mating season at a given location (Van Parijs et al, 2001;Llobet et al, 2021). The short vocal season in Kongsfjorden in this study, compared to studies in the 1990s and early 2000's, suggests reduced mating activity in the fjord.…”

“…The spectrogram correlation parameters for the blue whale consisted of a 10 s long down-sweep from 18 to 16 Hz, with a detection contour width of 3 Hz and a 1 s FFT with 75% overlap. For the fin whale, the spectrogram correlation parameter was a 2s down-sweep from 30 to 19 Hz with a contour width of 7 Hz (Ahonen et al, 2021). Due to the presence of low frequency noises from vessels and strumming noise, this automated detection method did not provide enough information for a final acoustic presence determination for these species.…”

“…Some studies have been focused on geophysical sounds (iceberg bubbling, iceberg calving; Glowacki et al, 2018;Mahanty et al, 2020) or species-specific biological sounds (e.g. Van Parijs et al, 2001;de Vincenzi et al, 2019;Llobet et al, 2021), but increasingly there is a need to document noise from anthropogenic sources in the context of the biological community (Ahonen et al, 2017;Ashokan et al, 2020;Madan et al, 2020;Sanjana et al, 2021;Stafford, 2021;Richard et al, 2023).…”

High Arctic “hotspots” for sperm whales (Physeter macrocephalus) off western and northern Svalbard, Norway, revealed by multi-year Passive Acoustic Monitoring (PAM)

“…Daily sea ice data was retrieved from the Norwegian Meteorological Institute 87 for each recording site. Daily ice cover for each location was computed using the same principles as in Llobet et al 88 . Around each mooring location, 1000 random points were created within a 50 km radius.…”

Static Acoustic Monitoring of Harbour (Phoca vitulina) and Grey Seals (Halichoerus grypus) in the Malin Sea: A Revolutionary Approach in Pinniped Conservation

“…Satellite telemetry [23][24][25], aerial and ground surveys [26,27], photo-identification [28,29] and recently, habitat modelling [30][31][32] have been used to identify important breeding, foraging and pupping areas. To a lesser extent, despite its advantages over the previous techniques, underwater acoustic studies have been carried out on different pinniped populations, describing the variety of calls that they produce and their associated behaviours (e.g., Weddell seal Leptonychotes weddellii [33]; grey seal Halichoerus grypus [34]; crabeater seal Lobodon carcinophagus [35]; bearded seal Erignathus barbatus [36]). However, such studies have only been performed close to haul-out sites, paying more attention to the breeding calls of the males (e.g., grey seal [37]; harbour seal Phoca vitulina [38]), and on a short-term basis.…”