Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2025
Erindi/veggspjald / Talk/poster V6
Höfundar / Authors: Mélissa Forgues (1,2), Valerie Chosson (2), Sverrir Daniel Halldórsson (2), Christophe Pampoulie (2), Guðjón Már Sigurðsson (2)
Starfsvettvangur / Affiliations: 1. Ecole nationale vétérinaire de Toulouse, 23 chemin des Capelles, 31300 Toulouse, France, 2. Marine and Freshwater Research Institute, Fornubúðir 5, 220 Hafnarfjörður, Iceland
Kynnir / Presenter: Mélissa Forgues
The diet of harbour porpoise (Phocoena Phocoena) is known to be essentially composed of capelin (Mallotus villosus), but the observed changes in environmental conditions (increasing waters temperature and salinity, acidification) have modified the biology, timing of migration and distribution of the Iceland-East Greenland-Jan Mayen capelin stock. The aim of this study was to investigate the impact of these changes on harbour porpoise diet. The stomach contents of seven harbour porpoises bycaught in 2022 and of six harbour porpoises bycaught in 2025 were examined. All the stomachs of the porpoises bycaught west of Iceland (6) contained capelin remains, both in 2022 and 2025. In the stomach contents of the porpoises bycaught north of Iceland (7), capelin was the predominant prey in 2022 (4) too whereas 2025 bycaught porpoises (3) had close to no capelin in their stomachs. These stomachs were either empty or contained Atlantic herring (Clupea harengus). Furthermore, the calculated capelin size, based on the size of the otoliths collected from the stomachs, appears to be smaller than the prey observed in similar stomachs, 30 years ago. Whereas capelin remains the predominant prey of harbour porpoise in west Iceland, there appears to be considerable variation in diet according to location and fluctuating size of fish stocks.