Dynamic modelling of pellet distribution in Atlantic salmon (Salmo salar L.) cages

The model derived in this paper describes the short-term spatial distribution of feed pellets in a cage of Atlantic salmon (Salmo salar L.), under the influence of current, gravity and the presence of fish. The fish are represented with appetite depending on stomach content, and with feeding rates affected by their size distribution. Feed distribution, feed intake by various size classes of the fish population, and feed waste can be simulated during single meals or longer feeding periods under various physical conditions, with different pellet sizes, feeding frequency and pellet release rates, and different fish size distributions. Fish motion is not explicitly modelled. The model is formulated with Atlantic salmon as model species, but it can be adapted to other species that feed on sinking feed particles in the water column. The model has been compared to measured data with respect to feed intake and wastage rate, showing good agreement. Average feed depth during meals is part of the model output, and simulations of the model have indicated that this could be a key factor in detecting the reduction of the fish's appetite and deciding when feeding should be reduced or stopped to minimise feed waste. (C) 2004 Elsevier B.V. All rights reserved.