Acoustic detections of Arctic marine mammals near Ulukhaktok, Northwest Territories, Canada

Abstract

The Arctic marine environment is changing rapidly through a combination of sea ice loss and increased anthropogenic activity. Given these changes can affect marine animals in a variety of ways, understanding the spatial and temporal distributions of Arctic marine animals is imperative. We use passive acoustic monitoring to examine the presence of marine mammals near Ulukhaktok, Northwest Territories, Canada, from October 2016 to April 2017. We documented bowhead whale (Balaena mysticetus Linnaeus, 1758) and beluga whale (Delphinapterus leucas (Pallas, 1776)) vocalizations later into the autumn than expected, and we recorded bowhead whales in early April. We recorded ringed seal (Pusa hispida (Schreber, 1775)) vocalizations throughout our deployment, with higher vocal activity than in other studies and with peak vocal activity in January. We recorded bearded seals (Erignathus barbatus (Erxleben, 1777)) throughout the deployment, with peak vocal activity in February. We recorded lower bearded seal vocal activity than other studies, and almost no vocal activity near the beginning of the spring breeding season. Both seal species vocalized more when ice concentration was high. These patterns in vocal activity document the presence of each species at this site over autumn and winter and are a useful comparison for future monitoring.

Beluga Vocalizations Decrease in Response to Vessel Traffic in the Mackenzie River Estuary

“…The detector was trained based on marine mammal vocalizations collected in the northeastern Chukchi Sea (Hannay et al, 2013;. The details of this detector and classifier are fully described in Mouy et al (2013), and this detector has been effectively used to classify beluga whale whistles in the western Canadian Arctic (Halliday et al, 2018a(Halliday et al, , 2019. The pulsed call detector was built in Raven Pro, version 1.5 (Bioacoustics Research Program, 2017) using the band limited energy detector with the spectrogram set to a window size of 7000 samples for files with a 96 kHz sample rate and 10 000 samples for files with a 384 kHz sample rate, minimum frequency set to 16 kHz, maximum frequency at 48 kHz, minimum duration at 0.1 s, maximum duration at 2.5 s, minimum separation at 0.05 s, signal-tonoise ratio threshold at 2 dB, block size at 10 s, and hop size at 5 s.…”

Bowhead and beluga whale acoustic detections in the western Beaufort Sea 2008–2018

“…In the 1980s and 1990s, when seasonal sea ice was considerably older, thicker and more extensive for most of the year, bowhead whales migrated out of the Beaufort Sea from late August through October and into the Bering Sea by November [54]. Now, though, bowhead whales are remaining in the Beaufort Sea longer, as evidenced by recent data from the Canadian Beaufort where bowhead whales were detected in late December in 2016 [55], the same year in which they were recorded in our data, just further west, into January 2017. More extreme evidence of this delayed migration includes mid-winter sightings and acoustic detections of bowhead whales in the eastern Canadian Beaufort in 2018-2019 [56].…”

“…More extreme evidence of this delayed migration includes mid-winter sightings and acoustic detections of bowhead whales in the eastern Canadian Beaufort in 2018-2019 [56]. While the seasonal residency of bowheads in the Beaufort seems to be extending with declining sea ice [55][56][57], particularly in the fall, there is less evidence that they are changing their overall distribution. As in the 1980s to early 1990s [28], bowhead whales are still found predominately on the Beaufort Sea shelf suggesting that distance to the coast, and/ or bathymetry is a more important driver of occurrence than distance to sea ice [44,58].…”

Bowhead whales overwinter in the Amundsen Gulf and Eastern Beaufort Sea

“…More specifically, we examined the final date in the autumn and the first date in the spring when a bowhead vocalization was detected. We previously collected and published results from three datasets: Sachs Harbour (71°55.621 0 N, 125°23.447 0 W) in 2015-2016 [30] and Ulukhaktok (70°42.857 0 N, 117°48.020 0 W) in 2016-2017 [31] and 2017-2018 [32]. All three of these acoustic datasets used the same type of acoustic recorder (SM3M) and the same mooring configuration and identical settings as the Ulukhaktok recorder described above, but with a recording duty cycle of one 5-min file recorded every 30 min and +18 dB of gain for the Sachs Harbour recorder.…”