Title: A simulation model of carrying capacity for mussel culture in a Norwegian fjord:

26 Shellfish carrying capacity is determined by the interaction of cultured species with the 27 ecosystem, principally constrained by environmental characteristics, especially food 28 availability. A recent experiment carried out in Lysefjord (SW Norway) has shown that 29 induced upwelling of nutrient-rich deeper water stimulated phytoplankton growth, 30 potentially increasing the carrying capacity for mussel cultivation. With the aim of 31 assisting in development of sustainable mussel culture in Lysefjord, an object-oriented 32 model of aquaculture-environment interactions and mussel carrying capacity was 33 constructed. A multiple box ecosystem model was developed within the visual 34 simulation environment of Simile software allowing explicit coupling between boxes, 35 which represent regions of the fjord. Once the box model was developed and calibrated, 36 subsequent application of PEST (Parameter ESTimation) allowed optimization of 37 different parameters of the model in order to manage mussel production according to 38 carrying capacity criteria. The Simile model and the simultaneous application of PEST 39 allowed several scenarios taking into account different stocking densities, upwelling 40 alternatives, and the creation of new cultivation areas. 41 42