Fish simulation culture model (FIS-C): A bioenergetics based model for aquacultural wasteload application

A generic bioenergetics model for chinook salmon was modified to estimate solid wastes from a commercial net-pen aquaculture operation in a Minnesota mine-pit lake. The model was calibrated using data from the operation on growth, ration, and temperature. Multiple simulations were run to form three-dimensional response surfaces for consumption, egestion, excretion and respiration as a function of fish size and water temperature. These formed the basis for the Fish Simulation Culture (FIS-C) Model. Predictions for food consumption and solids load were compared with actual ration levels and sedimentation within the mine-pit lake from 1989 to 1992, and compared well with the general trends of the observed data. However, the actual predictive power of FIS-C was very sensitive to our initial model assumption that aquaculture operations are predicated on maximizing the growth of their stock. FIS-C currently does not account for management decisions electing sub-optimal stock growth, but under these conditions does estimate a worst case loading scenario for the system. The annual phosphorus load to the system predicted by FIS-C was not significantly different from that of the mean of 17 values of annual P-load estimated empirically from the literature. However, FIS-C's estimate of P-loading shows a pronounced seasonal pattern to the annual loading. FIS-C offers substantial benefits to users by estimating seasonal and shorter term food wastage and wasteloads to receiving waters under particular operating conditions. Then, other operational scenarios can be created to examine the effects of changing fish inventory, feeding schedule, food composition, etc., in order to examine the impacts on production, environmental and/or regulatory requirements, prior to costly implementation.