Description and identification of beaks of some cephalopod species obtained from shark stomachs in northern Peru

Abstract

Mandibles, or beaks, of cephalopods, have become a useful tool for their identification. These hard structures, in addition to having different morphological characteristics, are composed of chitin, water, proteins and amino acids that allow them to be among the last components digested in the stomach of an organism. This means they can be found in the stomach contents of different marine predators, which helps to understand the ecological relationships that exist in the ecosystem. We analyzed the cephalopod beaks found in the stomach contents of three shark species: Blue sharks, Smooth hammerhead sharks and Shortfin mako sharks that were captured by the artisanal fishing fleets operating from the Peruvian ports of Salaverry (La Libertad), San Jose (Lambayeque), Mancora (Piura) and Zorritos (Tumbes). Beaks of 18 cephalopod species (12 squid species and 6 octopus species) were identified and characterized. In addition, from the lower beaks recovered, an identification key was developed to provide a tool for the identification of cephalopods found in the diet of marine vertebrates in the southeast Pacific Ocean, primarily in Peruvian waters. Finally, this research seeks to contribute to future studies of trophic relationships between prey and predator, particularly those related to top predators. Understanding these relationships will make it possible to establish the bases for fisheries management with an ecosystem approach, with the aim of ensuring the sustainability of hydrobiological resources and their fisheries.