Spatio-temporal variability in trophic ecology of jumbo squid (Dosidicus gigas) in the southeastern Pacific: Insights from isotopic signatures in beaks

Abstract

Jumbo squid (Dosidicus gigas) plays an important role in marine ecosystems throughout the eastern Pacific, but the knowledge of its feeding and migration patterns is limited. In this study, we measured stable isotopic values (δ13C and δ15N) from the edge of lower beak lateral wall to investigate spatio-temporal and trophic ecology of jumbo squid in the southeastern Pacific. The effects of latitude, mantle length and distance to the shelf break (DSB) on isotopic values in normal years (2013 and 2014) and an El Niño year (2015) were evaluated with a generalized additive model. Differences in response curves between the normal and El Nino years revealed a shift of migratory strategy. Compared with normal years, the predicted range of the horizontal migration of jumbo squid became smaller in the El Niño year. The analysis characterized significant differences in the isotopic niche between years and areas. The isotopic niche in the El Niño year was narrower than those in normal years. Our results suggest that the migration and foraging ecology of jumbo squid are substantially influenced by mesoscale oceanic oscillations. The spatio-temporal variability of trophic patterns indicates that substantial migration and foraging plasticity facilitate jumbo squid with a high capability to adapt to environmental volatility.