Diets of albacore, Thunnus alalunga, and dolphins, Delphinus delphis and Stenella coerulaeoalba, caught in the Northeast Atlantic albacore drift-net fishery: a progress report

Abstract

A comparative dietary study of a community of large oceanic predators has been made possible by the availability of data on gut contents from tunas and other by-catch species sampled during the Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER) fishery department study of the ecological impact of the French tuna drift-net fishery in the Northeast Atlantic. The stomach contents of common (Delphinus delphis) and striped dolphins, (Stenella coerulaeoalba), albacore (Thunnus alalunga) swordfish (Xiphias gladius), wreckfish (Polyprion americanum), blue shark (Prionace glauca), Ray's bream (Brama brama), and other minor species were collected in the summer 1993. This pilot study examined a small number of these samples, paying particular attention to comparisons between the diets of dolphins and tunas, associated versus non-associated in the catches. Besides the problem of by-catch, this set of samples represented a unique opportunity to investigate dietary relationships between co-existing oceanic predators and the ecological position of the dolphins in this community.