Abstract

We present the results of a study of the connectivity between Pacific cod spawning and nursery areas, and settlement of Pacific cod in the Gulf of Alaska. This work was conducted to address the hypothesis that spatial and temporal patterns of recruitment are related to variability in connectivity between spawning and nursery areas. To examine this hypothesis, we developed a Lagrangian, biophysical, individual-based model of Pacific cod early life history and dispersal using the Dispersal Model for Early Life Stages (DisMELS) framework. This model is driven by currents and scalars such as temperature from a version of the Regional Oceanographic Model System (ROMS) developed for the Gulf of Alaska. Results of our study show connectivity patterns predicted by the model that agree with our understanding (based on genetic analyses) that there is a high degree of localized retention in Pacific cod. The results indicate that the Shumagin Islands and Prince William Sound regions may serve as important collectors of Pacific cod recruits from upstream spawning areas. We also find correlations between individual-based model outputs and several large-scale climate indicators that appear to show settlement in several important nursery areas, and recruitment overall, are positively affected by slower gyre circulation in the Gulf of Alaska. We hypothesize that this is due to enhancement of retention, settlement in the Shumagin Island region, and reduction of transport of young cod out of the Gulf of Alaska to the southwest.