This dataset includes the nitrogen and carbon isotopic values from killer whale skin samples (Orcinus orca, n=38), and from herring (Clupea harengus, n=4), lumpfish (Cyclopterus lumpus, n=5) and harbor seal (Phoca vitulina, n=1) muscle samples collected in 2017-2018 in northern Norway. Nitrogen values (d15N) are non-lipid extracted and (d13C) are lipid-extracted.