Abstract

Stable isotope composition of marine top predator’s tissues provides insight information of its trophic ecology and migratory behavior. Previous reports have shown that dermal tissues could record longer patterns of hunting and movement. Based on this, the aim of this study was to describe the feeding and migratory habits of the white shark from Guadalupe Island, using stable isotopic analysis of dermis. We considered a small subset of many possible prey taxa that the sharks could have eaten throughout their migration: pinnipeds, squid and tuna. We grouped the data in five focal areas: Gulf of California, Coast of California, Isla Guadalupe, SOFA and Hawaii. We performed a Bayesian mixing model to study the trophic ecology of this top predator. Average isotopic values for dermis tissue of white shark were δ13C (-14.5‰) and δ15N (19.1‰). Corrected white shark dermal mean values to resemble muscle were δ13C (-16.6‰) and δ15N (21.2‰). Mixing model data from dermis showed predation in offshore areas such the SOFA and a main importance of pinnipeds as prey of the white shark in Guadalupe Island. 

Keywords: white shark, feeding habits, stable isotopes, mixing models, Guadalupe Island, Pinnipeds