Records of Isistius sp. (Elasmobranchii: Squaliformes: Dalatiidae), from the Azores archipelago, inferred by fresh bite marks in dolphins

Abstract

The marine waters around the Azores archipelago have been studied for quite a long time. Deeper areas, however, were historically poorly accessible and only now previously unreported species are recorded regularly. Our monitoring efforts of the Azorean ichthyofauna have recently revealed two cases of indirect evidence of the presence of a cookiecutter shark (Isistius sp.). The evidence, documented photographically, was in the form of explicit bite marks on two dolphins representing two separate species: the Atlantic spotted dolphin, Stenella frontalis (Cuvier, 1829) and the short-beaked common dolphin, Delphinus delphis Linnaeus, 1758. The two dolphins swam close to Terceira Island. No specimens have yet been collected. The shape, and size of the wounds observed suggest that they were inflicted by a cookiecutter shark. The fresh state of the injuries suggests they were sustained recently in the proximity of the Azores.