UC Santa Cruz

Market squid (Doryteuthis opalescens) constitute one of California's largest fisheries by landings and are an essential prey item for numerous top predators in the California Current ecosystem. However, extreme fluctuations in market squid abundance inhibit our ability to forecast local recruitment. We generate a species distribution model for market squid with data from an annual survey to examine the mechanisms behind the variability in their regional abundance and occurrence. Our results indicate juvenile market squid abundance was controlled by local recruitment in connection with sea surface temperature and upwelling dynamics, with finer spatial variability connected to the extent of upwelling dominated regions. Recent changes in these environmental factors also appear to contribute to the recent northward range expansion of market squid. Our spatiotemporally explicit model estimates of juvenile market squid abundance predicted the occurrence and abundance of older market squid in the diet of California sea lions (Zalophus californianus) and California fishery landings with as much skill as regional survey indices, suggesting the models are robust. Collectively, we provide mechanisms driving market squid variability throughout California's waters and an ecosystem assessment of this economically and ecologically critical species.