How Complex Are the Population Dynamics of Red Snapper in the Gulf of Mexico?

Complex dynamics in marine populations remain a major challenge for management of marine living resources.  Red snapper (Lutjanus campechanus) is one of the most important commercial and recreational fisheries species in the Gulf of Mexico.  Gulf red snapper has been assessed to be overfished and undergoing overfishing since the late 1980s.  Management of Gulf red snapper has been complicated due to the greatest source of mortality attributed to shrimp trawl bycatch, rather than harvest.  Assessments indicate that reduction of bycatch mortality on juveniles is key to stock recovery.  Despite all efforts to solve the bycatch problems, the stock still remains significantly overfished.  The discrepancy indicates that assessment models may not sufficiently track the dynamics of the species.  Applying nonlinear forecasting models, we analyzed Gulf red snapper time series of landings, biomass, discards and age compositions, and examined dynamical complexity and predictability to develop short term forecasts of stock abundance.  Preliminary results showed that landings tend to be of relatively low dimensionality and high predictability.  Considering the slightly short time series, we further explore the utility of these nonparametric models to examine potential associations between the stock trends of Gulf red snapper and other relevant species, as well as environmental variables.