Representation of multistanza life histories in Ecospace models for spatial organization of ecosystem trophic interaction patterns

The Ecospace model for spatial organization of trophic interactions has seen limited use for evaluation of policies such as marine protected areas, partly because of concern about representing key indicator populations only by spatial biomass distributions. The software has been improved to include spatial representation of age structure for such species, by means of the Ecosim "multistanza" population submodel, which assumes similar diet compositions, predation risk, and vulnerability to fishing over blocks or stanzas of fish ages. A computationally efficient version of Ecospace now preserves the multistanza age structure over spatial habitat and ecosystem biomass maps, evaluating body growth and mortality rates as spatial averages weighted by relative biomass use of each model spatial cell. A more computationally intense version divides each multistanza population into spatial packets (an individual-based model approach) for more precise analysis of how movement patterns and movement histories over mosaics of trophic opportunities and risks affect population performance and variability. The two approaches give surprisingly similar predictions of abundance patterns over both time and space, agreeing well in case-study applications to the Gulf of Mexico and California coast with each other and with nonspatial Ecosim predictions.