Should I Stay or Should I Go Now? Simulating Fish Feeding Ecology in the Bering Sea

We use a high spatial resolution model for the Bering Sea (Bering 10K ROMS-NPZD) as a platform to model fish. Growth is based on bioenergetics while foraging is based on dynamic prey fields. Fish prey selection is a function of size based prey preference and prey availability. Fish move horizontally following gradients of potential increase in biomass, the combined effect of potential individual weight gain and predation mortality. Diffusion is added as a constant rate. Habitat selection occurs along gradients towards preferred size and species specific preferred habitat, where the preferred habitat is that where biomass gain is maximized and less crowded. We ran the model with one way feedback (NPZD supplies zooplankton prey fields) and two way feedback (NPZD provides zooplankton prey fields, fish model provides fish predation mortality to zooplankton model). This set up allowed us to quantify how much movement is driven by food availability (or lack thereof), predator avoidance, and diffusion. We show emerging distributions for each type of simulation for two species with different diets: walleye pollock, and Pacific cod, and quantify the amount of habitat in terms of its quality: good (biomass increases), bad (biomass decreases) or neutral (no increase).