Modelling how the physical scale of experimental tanks affects salmon growth performance

In this study, we explored the potential of using mathematical models for studying the effects of physical scale of production units on the growth performance of Atlantic salmon (Salmo salar L.). Atlantic salmon are typically produced in large sea cages, but for ethical, practical and economic reasons, most research experiments are performed in tanks or cages of comparatively small volumes, and it is therefore important to consider the representability of small-scale experiments with regard to growth performance. Based on an existing model, we developed a model for estimating the effects of changes in physical scale on salmon growth performance. The model was verified using experimental data obtained from a laboratory study featuring growth experiments in tanks of different sizes, and found able to predict the effects of increasing tank scale. We also used the model in a series of virtual experiment studying how sensitive the scaling effect is towards how (i.e. changing only radius, only depth or both) the volume is scaled. The results from the virtual studies indicate that larger production volumes lead to improved feed ingestion and growth, provided the increase in volume is achieved through horizontal or horizontal plus vertical expansion of the units, but also implies that the nature of the scaling effects depends on other factors such as tank cross section.