Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2025
Erindi/veggspjald / Talk/poster E39
Höfundar / Authors: 1) Edda Elísabet Magnúsdóttir, 2) Þóra Margrét Bergsveinsdóttir, 3) Hildur Pétursdóttir, 4) Maria Asuncion Borrell Thio, 4) Alex Aguilar, 6) Audun Richardsen, 5) Patrick Miller, 1) Jörundur Svavarsson
Starfsvettvangur / Affiliations: 1) University of Iceland, 2) Uppsala University, 3) Marine and Freshwater Research Institute, 4) University of Barcelona, 5) University of St Andrews, 6) University of Tromsø, The Arctic University of Norway
Kynnir / Presenter: Edda Elísabet Magnúsdóttir
For the last two decades, humpback whales have recovered rapidly after near depletion in the mid-20th century. Traditionally considered to separate breeding and feeding behaviour by season and location, recent evidence shows delayed migration and even overwintering in high latitudes. Males have also been recorded singing – a breeding display – in subarctic and Arctic waters, suggesting a trade-off between growth and reproduction that may have aided recovery. This study examined life history strategies of humpbacks wintering in polar environments. Reproductive hormones were measured across all seasons and stable isotope analysis was used to explore year-round foraging. Preliminary findings indicate seasonal sex ratio shifts where females dominate in summer, males in early winter, while ratios balance from mid-winter to spring. Males with both high and low testosterone levels were observed in winter in the Arctic, indicating a mix of immature and mature males among singers and possible mating opportunities. Heightened progesterone levels, suggesting pregnancy, were detected from mid-summer, peaking before the migration period. Isotopic niches (δ13C and δ15N) were broadest in winter and spring but narrowed in late summer and early winter. Overall, the results provide new insight into how flexible foraging and reproductive strategies may support resilience and continued recovery of humpback whale populations in high-latitude ecosystems.