Up the Ante on Bioeconomic Submodels of Marine Foodwebs:A Data Assimilation-based Approach

While economists have discussed ecosystem-based management and similar concepts, little attention has been devoted to the art modeling. Models of ecosystems or foodwebs that make economic analysis viable should capture as much as possible of system structure and dynamics while balancing biological and ecological detail against dimensionality and model complexity. Relevant models need a strong, empirical content, but data availability may inhibit modeling efforts. Models are bound to be nonlinear, and model and observational uncertainty should be observed. We suggest the data assimilation method ensemble Kalman filtering to improve modeling of ecosystems or foodwebs. To illustrate the method, we model the dynamics of the main, pelagic species in the Norwegian Sea. In order to reduce the parameter dimensionality, the species are modeled to rely on a common carrying capacity. We also take further methodological steps to deal with a still high number of parameters. Our best model captures much of the observed dynamics in the fish stocks, but the estimated model error is moderate.