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Bowhead whales likely reproduce beneath the sea ice northwest of Spitsbergen, while using the open water in the eastern Fram Strait as a migration corridor. This conclusion comes from researchers in the Ocean Acoustics Group at the Alfred Wegener Institute, who recorded the calls of bowhead whales using underwater recorders and analysed the records with artificial intelligence. Their study on bowhead whale habitat use in relation to sea-ice cover has now been published in the journal Scientific Reports.
If bowhead whales produce particularly varied and diverse calls in one area, it is very likely that the area is a breeding ground. The species occurs exclusively in the Arctic Ocean and is therefore endemic to this region. Across the vast, partly ice-covered Arctic Ocean, researchers from the Ocean Acoustics Group at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have installed hydrophones that can continuously record underwater sounds. This allows them to document calls of soniferous species in remote regions without being on site and to draw conclusions about the animal’s occurrence and behaviour based on the acoustic data.
A team including first author Marlene Meister has now published a study on the bowhead whale population around Spitsbergen in the journal Scientific Reports. This population was massively hunted during times of commercial whaling, reducing the population from an estimated 33,000 to 65,000 individuals to just a few hundred. Although the Spitsbergen population has been protected since the 1930s, it has so far not shown clear signs of recovery. Bowhead whales are severely threatened by the decline of Arctic sea ice, as it represents an important habitat: here they find abundant prey and protection from hunting orcas. “If the ice disappears, the population will lose a central habitat,” says AWI biologist Marlene Meister. “It is likely not possible for the whales to simply move farther north, as food availability there is very limited.” At the same time, the receding ice is making the Arctic Ocean more accessible to shipping. This in turn increases the risk of habitat pollution from oil and noise, as well as the risk of whales colliding with ships.
To better assess the consequences of this habitat loss, the researchers focused on the occurrence and acoustic behaviour of bowhead whales in areas with different sea ice conditions. “Observations show that the Spitsbergen population frequently occurs in areas covered with sea ice, from the ice edge to several hundred kilometres into the pack ice, where openings in the sea ice serve as breathing holes for the whales,” says Marlene Meister. Accordingly, the Ocean Acoustics Group investigated two contrasting regions in Fram Strait (the waterway between Greenland and Spitsbergen): The first region was located northwest of Spitsbergen in predominantly ice-covered water; here, acoustic recordings from 2022 and 2023 were analyzed. The second region was located in the eastern Fram Strait in open water, where acoustic data from 2012 to 2023 were available. The scientists converted the audio data into spectrograms and evaluated them using artificial intelligence. To do this, they applied an AI image-recognition method trained on spectrograms of bowhead whale calls, which they then used to identify the calls. The team then examined the AI-detected calls in greater detail, with a particular focus on the region northwest of Spitsbergen, where singing occurred between October and April.
The researchers manually divided the recorded bowhead whale singing into individual songs (i.e. sections that were highly similar) and analysed their temporal occurrence in relation to sea ice conditions. In total, twelve different songs were detected northwest of Spitsbergen, each occurring over periods ranging from days to weeks. From October onward, the number of different songs per month increased and peaked in February with eight different songs. “One possible explanation is that more animals were present in the region in February and produced a broader array of songs, which increased overall song diversity. Another possibility is that individual whales sang more diversely in February, potentially gaining a reproductive advantage if females prefer males with more diverse song repertoires.” The increase in song diversity coincided with a regional retreat of sea ice at the boundary of the study region. In December, the recorder was located up to 200 kilometres inside the sea ice , whereas in February, after the ice had receded, it was situated directly at the ice edge. “The close link between song diversity and distance from the ice edge was a surprising result for us,” says Marlene Meister.
In the second, ice-free regiononly calls and no songs were detected. The AWI biologist explains: “Bowhead whales were regularly present in the ice-free eastern Fram Strait, but the reason for their presence there remains unclear. It is possible that the animals are merely passing through the area and call to maintain contact with each other. The fact that we did not detect any songs there also suggests that the eastern Fram Strait is not a breeding ground.” Studies such as the current one contribute to a better understanding of bowhead migration pattern and help to identify key habitats, such as feeding and breeding grounds, so that conservation measures can be as effective as possible.
OPUS – The open portal to underwater soundscapes
The Ocean Acoustics Group has published a wide variety of underwater sounds on its OPUS portal (Open Portal to Underwater Soundscapes: https://opus.aq). OPUS provides easy and open access to long-term soundscape data recorded in the Arctic, Antarctic and elsewhere – from singing whales, calling seals and moving ice masses underwater to anthropogenic noise. Not only researchers, but all ocean enthusiats can dive into the world of underwater sound and listen to the sounds of the oceans here.
Based on these long-term acoustic data, researchers from the Alfred Wegener Institute published a study in JASA Express Letters in October 2025.
The study revealed that the songs of Antarctic fin whales exhibit regional variations. These differences can serve as acoustic markers – enabling different populations of the same species to be distinguished solely based on their acoustic characteristics. These findings could improve the long-term acoustic monitoring of fin whale populations in the Southern Ocean, providing a clearer understanding of their distribution – an important foundation for international management plans aimed at protecting fin whales more effectively in a changing ocean.
Marlene Meister
+49 (0)471 4831-1390
marlene.meister@awi.de
https://doi.org/10.1038/s41598-025-25360-2
https://www.awi.de/en/about-us/service/press.html
Bowhead whales appear to breed under the sea ice northwest of Spitsbergen while using the open water ...
Source: Ocean Acoustics Group
Copyright: Alfred Wegener Institute / Ocean Acoustics Group
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Bowhead whales appear to breed under the sea ice northwest of Spitsbergen while using the open water ...
Source: Ocean Acoustics Group
Copyright: Alfred Wegener Institute / Ocean Acoustics Group
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