Evidence of Temperature-Driven Shifts in Market Squid Doryteuthis opalescens Densities and Distribution in the California Current Ecosystem

Climate change is impacting the abundance and distribution of marine resources. The consequences of these impacts are likely to alter trophic interactions between species within an ecosystem and affect fisheries opportunities for coastal communities. Market squid Doryteuthis opalescens comprise the largest fishery (by volume) in California, USA, and questions persist about whether the changing ocean conditions are leading to an increase in squid abundance in traditional fishing locations as well as marginal habitats in northern areas. To examine this potential phenomenon, we used fisheries-independent survey data collected by the National Marine Fisheries Service between 1998 and 2019 to develop a spatiotemporal model that estimates changes in the squid density from central California to northern Washington. We found a fivefold increase in the squid index of abundance across the entire spatial domain of the surveys during the sampling period, with the largest increases occurring in the Oregon and Washington strata. Although our model demonstrated that encounter rates and squid densities for the surveys increased in warmer and more saline waters, large shifts in squid distribution were only associated with deviations in ocean temperatures that could be characterized as marine heatwaves. This analysis adds to a growing body of work documenting the spatiotemporal response of marine resources to both long-term trends in warming ocean conditions and episodic events, such as marine heatwaves. Furthermore, it demonstrates the need for ecosystem assessment models with the ability to forecast changes in species distribution and abundance at spatiotemporal scales that are relevant for coastal fishing communities.