Fatty acid composition of the blubber and dermis of adult male Atlantic walruses (Odobenus rosmarus rosmarus) in Svalbard, and their potential prey

Abstract

Blubber biopsies were collected from 18 adult male walruses from Svalbard, Norway. The biopsies were taken vertically through the skin and the entire blubber layer down to, but not including, the muscle layer. Fatty acid (FA) compositions of inner blubber, outer blubber and dermis of the walruses and of potential prey organisms were determined. The three layers differed significantly from one another in FA composition. Generally, the inner blubber contained more long-chained monounsaturated, saturated and polyunsaturated FAs, while the outer blubber and dermis contained more short-chained monounsaturated FAs. This stratification is similar to what has been observed in other marine mammal species. However, differences between layers were less pronounced than in most other species, possibly because the extremely thick overlying dermis of walruses provides an insulating shield, which affects the FA composition of the outer blubber. The FA composition of the potential prey organisms was different from that of the blubber of the walruses, although more similar to the inner blubber than to the outer blubber or dermis. FA composition in the inner blubber was not significantly correlated with age (assessed by tusk volume), while the FA composition of the outer blubber and dermis were significantly correlated with age.

Keywords:

• Blubber
• diet
• fatty acids
• stratification
• walrus

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank D. Griffiths, M. A. Fedak, C. Freitas, and H. Eggenfellner for their help in the field, S. A. Olsen, A. Paulino and B. R. Olsen for help and advice in the laboratory, and A. Igesund for his assistance with graphics. This study was supported financially by the Norwegian Research Council, the Norwegian Polar Institute and the University of Bergen.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark