Don’t mind if I do: Arctic humpback whales respond to winter foraging opportunities before migration

Lisa Elena Kettemer*, Theresia Ramm, Fredrik Broms, Martin Biuw, Marie-Anne Blanchet, Sophie Bourgeon, Paul Dubourg, Anna C. J. Ellendersen, Mathilde Horaud, Joanna Kershaw, Patrick J. O. Miller, Nils Øien, Logan J. Pallin, Audun H. Rikardsen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Migration patterns are fundamentally linked to the spatio-temporal distributions of prey. How migrating animals can respond to changes in their prey's distribution and abundance remains largely unclear. During the last decade, humpback whales (Megaptera novaeangliae) used specific winter foraging sites in fjords of northern Norway, outside of their main summer foraging season, to feed on herring that started overwintering in the area. We used photographic matching to show that whales sighted during summer in the Barents Sea foraged in northern Norway from late October to February, staying up to three months and showing high inter-annual return rates (up to 82%). The number of identified whales in northern Norway totalled 866 individuals by 2019. Genetic sexing and hormone profiling in both areas demonstrate a female bias in northern Norway and suggest higher proportions of pregnancy in northern Norway. This may indicate that the fjord-based winter feeding is important for pregnant females before migration. Our results suggest that humpback whales can respond to foraging opportunities along their migration pathways, in some cases by continuing their feeding season well into winter. This provides an important reminder to implement dynamic ecosystem management that can account for changes in the spatio-temporal distribution of migrating marine mammals.
Original languageEnglish
JournalRoyal Society Open Science
Issue number9
Early online date6 Sept 2023
Publication statusE-pub ahead of print - 6 Sept 2023


  • Pregnancy rates
  • Stopover
  • Hormone profiling
  • Spatial ecology
  • Migration timing
  • Marine mammals


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