Recent changes in the diet composition of common minke whales (Balaenoptera acutorostrata) in Icelandic waters. A consequence of climate change?

Abstract

The common minke whale (Balaenoptera acutorostrata) is the most abundant mammalian top predator in Icelandic continental shelf waters. Here, an account is given on the first systematic research programme into the feeding ecology of common minke whales in Icelandic waters based on an analysis of minke whale stomach contents data collected in Icelandic waters during 2003–2007. The results show pronounced spatial and temporal variation in the diet. The temporal changes include a decrease in the proportion of sandeel in the diet over the study period and a corresponding increase in herring (Clupea haerengus) and haddock (Melanogrammus aeglefinus), particularly in the southern area. The diet also differed markedly from the previously available, limited data from Icelandic waters with less krill and the cold water species capelin (Mallotus villosus) and more gadoids and herring in the more recent period. These changes in diet composition are consistent with recent changes in the Icelandic continental shelf ecosystem, including increased sea surface and bottom temperatures and changes in distribution and abundance of several fish species, including sandeel (Ammodytidae) and capelin. Although natural fluctuations cannot be ruled out at this stage, these dietary changes, together with decreased abundance in coastal waters, may reflect the responses of minke whales to a changed environment possibly driven by global warming.

Key words:

• Feeding ecology
• minke whale
• global warming

Acknowledgements

Sincere thanks are extended to the captains and crews of the sampling vessels. We also thank the many people involved at various stages of the sampling process and analysis of the stomach contents. In particular we thank our colleagues Inga F. Egilsdóttir, Sverrir D. Halldórsson and Þorvaldur Gunnlaugsson for their contribution.

Editorial responsibility: Geir Ottersen