‘Fatal interaction’: death of a false killer whale by an Indo-Pacific sailfish bill

Abstract

Here we document an exceptional and previously unreported event: the stranding of a false killer whale, Pseudorca crassidens , newborn in northeastern Brazil resulting from a fatal collision with an Indo-Pacific sailfish, Istiophorus platypterus . Detailed necropsy, pathological examination, and genetic identification of the embedded foreign structure demonstrate unequivocally that the trauma was caused by the bill of an Indo-Pacific sailfish. To our knowledge, this represents the first confirmed case of interaction between these two species for the Brazilian coast, and one of the very few documented worldwide, providing valuable insight into the ecological dynamics of pelagic predators in the Southwestern Atlantic. This case also underscores the importance of long-term beach monitoring programmes for detecting unusual biological events and improving our understanding of marine mammal ecology, behaviour, and mortality sources.