Spatio-temporal diet variability of the California sea lion Zalophus californianus in the southern California Current Ecosystem

Characterizing predator diets is essential to understanding food web dynamics. We investigated the dietary breadth and variation of California sea lion (CSL) Zalophus californianus at 3 Channel Islands from 1981-2015. Prey species were identified hard parts soft-tissue remains pyrosomes recovered fecal samples, revealing a diverse diet fish cephalopods. Percent frequency occurrence percent split-sample used describe long-term trends, correlations between prey taxa, diversity, similarity. The most common 142 taxa market squid Doryteuthis opalescens , northern anchovy Engraulis mordax shortbelly rockfish Sebastes jordani jack mackerel Trachurus symmetricus Pacific sardine Sardinops sagax hake Merluccius productus Scomber japonicus . Dietary differences observed male female lions, animals different islands seasons. Intra-island 2 locations more similar than inter-island diets. Important inter-annual decadal changes in identified. CSL shifted an anchovy-based 1980s based-diet 1990s 2000s, with other being consumed frequently when consumption those main declined. Prey-switching likely provides flexibility needed dynamic Current Ecosystem, may allow CSLs adapt supply availability driven by climate change.