Fin whales winter off Svalbard | Polarjournal
Fin whales are the second largest baleen whales. Like other marine mammals, they are sentinels of the current environmental changes. Photo: Julia Hager

Fin whales are regularly observed off Svalbard, especially during the summer months. However, the rapid warming of the Arctic and the resulting change in prey availability appears to be making the waters west of Svalbard increasingly attractive to fin whales, even in the dark season.

An Italian research team recorded more than 16,000 fin whale signals over a seven-year period (2014 – 2020) in Kongsfjorden on the west coast of Spitsbergen using passive acoustic monitoring, where permanently installed hydrophones monitor underwater sounds. The team found that not all fin whales migrate to temperate latitudes to breed and may instead use waters off Svalbard for mating.

The hydrophones were installed at the entrance to Kongsfjorden on the west coast of Svalbard. Map: Papale et al. 2023

The analyses of the recordings showed that fin whales stay off Svalbard throughout the year. In addition, the team found that the songs of fin whales showed different patterns over the years. While the researchers recorded almost exclusively sounds with a frequency of 20 hertz during the months of February to July over the entire seven years, sounds with a frequency of 130 hertz were also detected, especially during the months of October, November and January. They suspect that fin whales either change song patterns over the year, or that individuals from other acoustic populations with different patterns spend the winter off Svalbard.

If the latter hypothesis is correct, it would suggest that fin whales have the flexibility and adaptability to change their migration strategies, the team of authors said in the study published in the journal Nature Scientific Reports. The whales could spend the breeding season in the Arctic one year and migrate south again the next.

According to the author team, because of changing environmental conditions, knowing when and how whales are in Arctic regions is critical for their conservation in the face of climate change.

During the year, fin whales off Svalbard mainly make sounds with a frequency of 20 hertz. Audio and photo: NOAA Fisheries

Fin whales normally spend the summer in high latitudes, where they feed on krill and small pelagic fish, and move to temperate regions in the winter to give birth to their young. Along the west coast of Svalbard, fin whales have been observed as far north as 81.5° N between March and November, with most sightings between June and September.

According to the study, researchers have observed an increase in fin whale sightings in Svalbard’s coastal waters and fjords since 2002. After 2010, the whales shifted poleward as more warm water flowed northward and their prey from the Atlantic also appeared more frequently at high latitudes.

The research team suspects that the increase in water temperature and decrease in sea ice caused by climate change is making the habitat more attractive to fin whales, causing them to postpone their migration.

Julia Hager, PolarJournal

Featured image: Michael Wenger

Link to the study: Papale, E., Pelagatti, M., Pedrazzi, G. et al. Occurrence and patterns of fin whale songs reveal alternative migration strategies in Svalbard Islands, Norway. Sci Rep 13, 4436 (2023).

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