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As a consequence of global warming, sea-ice continues to melt, with prolonged durations of sea-ice absence in regions that are historically covered in pack ice. Warmer ocean temperatures and the loss of sea-ice is altering marine environments, especially in Arctic regions. Arctic marine environments are experiencing seasonal shifts of habitat use as these warmer, ice-free regions become available to many ice avoiding marine mammals, such as the sperm whale.
Sperm whales (Physeter macrocephalus) occur throughout the world’s oceans, including high latitude regions, but are limited to ice-free regions. In 2014, the first record of these toothed-whale species were made in the area of the Pond Inlet (figure A) in the eclipse sound region of Baffin Bay. Another rare sighting was later recorded in 2018 in the same region. These recent, rare sightings have led the authors to hypothesise that sperm whale occurrences are only a recent phenomenon in Eclipse Sound. Baffin Bay is suffering the same fate as many other historically sea-ice covered regions, as it sees longer ice-free periods in recent decades.
In this study, authors combined historical sighting data and acoustic data to visualise sperm whale presence in Baffin Bay. The mean sea-ice concentration (SIC) of the area, since 1901, were analysed to be compared to the acoustic presence of sperm whales near the recording sites. Historical sighting data was compiled from 8 published, open-source datasets of sperm whale occurrences and distribution. Among these, commercial whaling records for sperm whales were accessed through the OBIS database, from the History of Marine Animal Populations (HMAP) dataset and Data Set 04: World Whaling.
Passive acoustic recordings were collected between 2015 to 2019 in the Eclipse Sound region in order to create a timeseries of the presence of sperm whales in the region. This method made use of two types of autonomous, bottom- mounted recording devices that collect passive acoustic recordings named: Song Meter SM2M (SM2M; Wildlife Acoustics, Inc.) and High-frequency Acoustic Recording Package (HARP; Wiggins & Hildebrand, 2007). The former (SM2M) was deployed at the Guys Bight site (red, figure A) with a sampling rate of 192 kHz. The latter (HARPs) were deployed at the Pond Inlet site (blue, figure A) with a sampling rate of 200 kHz. These devices with these sampling rates, are able to detect the high-frequency echolocation clicks of marine mammals, including those of sperm whales.
The results from the collected sighting- and acoustic data show that sperm whales have historically been observed in the Baffin Bay region (figure B), with the most sightings documented in eastern Baffin Bay. The northernmost records of sperm whale sightings were all documented within the last decade. This observation supports the author’s hypothesis that sperm whale presence in Eclipse Sound is a recent phenomenon. The sighting data revealed no other recordings of sperm whales in the Eclipse Sound area, besides the two records in 2014 and 2018, respectively. The acoustic data, however, revealed that sperm whales are present in this region yearly between 2015 and 2019 in the late summer and autumn months. Authors found that there was an increase in sperm whale presence over the 5 year period that the study was conducted and that this increase in presence is closely related to the minimum sea ice concentration of each year.
Posdaljian, N., Soderstjerna, C., Jones, J. M., Solsona-Berga, A., Hildebrand, J. A., Westdal, K., Ootoowak, A. & Baumann-Pickering, S. (2022). Changes in sea ice and range expansion of sperm whales in the eclipse sound region of Baffin Bay, Canada. Global Change Biology, 00:1–11.