New publication: Dietary variation of killer whales

Dietary variation within and between populations of northeast Atlantic killer whales, Orcinus orca, inferred from 13C and 15N analyses

ANDREW D. FOOTE,1 Institute of Biological and Environmental Sciences, University of Aberdeen,
School of Biological Sciences, Tillydrone Avenue, Aberdeen, AB24 2TZ, United Kingdom, and
Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster
Voldgade 5–7, 1350 Copenhagen K, Denmark;

HEIKE VESTER, Ocean Sounds, Hjellskaeret, 8312
Henningsvaer, Norway, and Cognitive Ethology Lab, German Primate Center, Kellnerweg 4, 37077
Gottingen, Germany, and Max Planck Institute for Dynamics and Self-Organization, Bunsenstraße
10, 37073 G¨ottingen, Germany;

G´ISLI A. V´IKINGSSON, Marine Research Institute, Program for
Whale Research, PO Box 1390, 121 Reykjavık, Iceland;

Mass Spectrometry Facility, SUERC, East Kilbride, G75 0QF, United Kingdom.


Epidermal skin samples from eastern North Atlantic killer whales, Orcinus orca,
were analyzed for carbon and nitrogen stable isotope ratios. From those, comparisons
within a data set of 17 samples collected from Tysfjord, Norway, in November
suggested that diet is relatively specialized during this time period at this location.
There were significant differences between a small set of samples from Iceland
and those collected from Norway, which had all been assigned to the same population
by a previous population genetics study. The results would be consistent
with matrilines feeding on either the Norwegian or Icelandic stocks of Atlantic
herring (Clupea harengus). There was no significant difference within Icelandic samples
between those assigned to the population known to feed upon herring and
those assigned to a population hypothesized to follow Atlantic mackerel (Scomber
scombrus). The greatest differences were between the epidermal samples analyzed in
this study and tooth and bone collagen samples from the North Sea that were analyzed
previously, which also showed significantly more variation in isotopic ratios
than found for skin samples. These differences could reflect differences in turnover
rate, differences in diet-tissue fractionation and discrimination due to the amino
acid composition of the different tissues, and/or greater competition promoting
dietary variation between groups in the North Sea.

2012 by the Society for Marine Mammalogy