A simulation model of carrying capacity for mussel culture in a Norwegian fjord: Role of induced upwelling

Shellfish carrying capacity is determined by the interaction of cultured species with the ecosystem, principally constrained by environmental characteristics, especially food availability. A recent experiment carried out in Lysefjord (SW Norway) has shown that induced upwelling of nutrient-rich deeper water stimulated phytoplankton growth, potentially increasing the carrying capacity for mussel cultivation. With the aim of assisting in development of sustainable mussel culture in Lysefjord, an object-oriented model of aquaculture–environment interactions and mussel carrying capacity was constructed. A multiple box ecosystem model was developed within the visual simulation environment of Simile software allowing explicit coupling between boxes, which represent regions of the fjord. Once the box model was developed and calibrated, subsequent application of PEST (Parameter ESTimation) allowed optimization of different parameters of the model in order to manage mussel production according to carrying capacity criteria. The Simile model and the simultaneous application of PEST allowed several scenarios taking into account different stocking densities, upwelling alternatives, and the creation of new cultivation areas.