Stable isotope signatures of whisker and blood serum confirm foraging strategies for female New Zealand sea lions derived from telemetry

Recognizing the individual variability of foraging behaviour of marine predators is important for understanding their role in the marine ecosystem and identifying how species may respond to environmental variability or human impacts. This research examines stable isotope signatures (δC13 and δN15) of blood serum and whiskers from 22 female New Zealand sea lions, Phocarctos hookeri (Gray, 1844) to determine if the isotopic composition of serum reflects foraging strategy and; that serum and proximal whisker growth had similar signatures reflecting that the isotopic composition of whiskers reflects foraging strategy diet. Female NZ sea lions are known to have two distinct foraging strategies (mesopelagic or benthic ecotypes), shown to be habitual within and between years. Females who are known to be mesopelagic foragers have higher overlap and are at greater risk of harmful interactions with fisheries. This research found that the two foraging strategies identified from telemetry are also associated with different δC13 and δN15 isotopic values from blood serum and whiskers. Therefore, stable isotope analysis could be used to determine the proportion of the female population that are likely to be exposed to the detrimental direct and indirect interactions with fisheries.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author