Contribution of ocean variability to climate-catch models of Pacific sardine

Abstract Small-pelagic fishes are economically and ecologically important as they make up a large proportion of wild-caught fisheries and provide an important link between planktonic organisms and higher trophic level organisms such as piscivorous fishes, squid, seabirds and marine mammals. In the California Current Ecosystem (CCE), the distribution and abundance of Pacific sardine ( Sardinops sagax ) is influenced by both natural climate variability and exploitation. This study uses Generalized Additive Models to evaluate the effects of environmental forcing at multiple spatial scales (i.e. local, regional and basin) on sardine catch recorded at British Columbia (CAN), California (USA) and Bahia Magdalena (MEX). We find that the Pacific Circulation Index, sea surface temperature, upwelling strength, and primary productivity were the most influential factors explaining variability of sardine catch in the northeastern Pacific Ocean. Our CCE-wide analysis shows that regional scale environmental variability best explained catch rates of the Pacific sardine for California and Bahia Magdalena while basin-scale environmental variability did so for catch rates for British Columbia.