Environment, krill and squid in the Monterey Bay: from fisheries to life histories and back again

The fishery for market squid in California is extremely valuable and only recently subject to regulations (in that sense, it is one of the last great open-access fisheries on the western coast of North America). We briefly review the history of the fishery for Loligo opalescens, on an annual time scale. Within-season analyses suggest that cohorts of squid persist offshore and move inshore for reproduction throughout the season. In order to predict the timing of inshore movement of squid, we develop a life history model using stochastic dynamic programming. This model allows us to link squid growth and reproduction with environmental factors, particularly, upwelling, temperature, and food abundance, in a consistent Darwinian framework. Using the model, we predict the timing of squid movement inshore in cold and warm environments, and the amount of biomass inshore in weekly intervals. We compare the model predictions with unpublished fishery-dependent data subsampled from landings and discuss the implications of our work for management of the squid fishery.