Bulk stable isotope analysis (SIA) of historical and contemporary squid beaks

Raw data obtained from stable isotope analysis of δ13C and δ15N in beaks of the squids Gonatus fabricii (Lichtenstein, 1818) and Todarodes sagittatus (Lamarck, 1798) (Cephalopoda: Oegopsida), and primary analyses of these data. Squids sampled in the Baffin Bay, Davis Strait and Nordic Seas (1882-2010) and Iceland, Faroe Islands and Ireland (1844-2023), respectively. The beaks either come from the squids caught as bycatch, or from natural history museums, from stomach contents of predators.