Modelling the environmental effects of fish farming in a Norwegian fjord

A coupled 3D physical, chemical and biological ocean model has been applied for a fjord at the western coast of Norway. The main objective of the study has been to investigate and document the environmental effects of fish farming with a particular focus on eutrophication.An environmental impact study with respect to both size (i.e., fish production) and location of the farms has been performed. The experiments showed that increasing the production of fish in each farm resulted in a rather small increase in the primary production, and had no impact on the oxygen level. The locations of the farms were of larger importance. The effect on the primary production was the largest if the fish farms were located quite far inside the fjord. The best localization of the fish farms was found to be near the mouth of the fjord where the water exchange with the coast is the largest.