Modeling Environmental Effects on Juvenile Brown Shrimp Production in an Estuarine Ecosystem

Brown shrimp (Farfantepenaeus aztecus) are a commercially important fishery species of the northern Gulf of Mexico.   Young shrimp settle in estuarine salt marsh habitats during the juvenile phase of their life history, and processes that occur during their residency affect growth, survival, and recruitment of sub-adults to the fishery. We developed an agent based model that simulates the cumulative effects of temperature, salinity, and access to emergent marsh vegetation on juvenile brown shrimp growth and survival.  Our model is spatially articulate, with three habitat types and three salinity zones; it functions on an hourly time step to track growth and survival of shrimp super-individuals from recruitment into the shallow nursery habitats at 12 mm TL until they reach 70 mm and move into deeper bay water.  We have compared our modeled shrimp production with various abundance and biomass data from fishery independent surveys.  Preliminary analysis shows similarities in seasonal patterns, but annual variability in resource survey data appears higher than our modeled estimates. We are continuing to explore larval recruitment patterns and trophic interactions as possible interacting factors.  Ultimately, we hope to use inter-annual variability in production estimates to reduce uncertainty in the current stock assessment model.