Summary: | This thesis evaluates the environmental performance of six different fish farming systems. The thesis is part of the network group “Hållbar fiskförsörjning I Stockholms län” (HFFS) which tries to increase the domestic and regional production of fish in Stockholm and move to a more sustainable supply in the Stockholm county. Two of the chosen systems; pangasius from Vietnam and salmon from Norway are delivering a substantial part of the fish consumed in Stockholm today, although they are very different when it comes to system characteristics. One system, arctic char with conventional feed, is produced in a fairly small scale in the north of Sweden, while the three remaining systems are viewed upon as possible options to supply Stockholm with fish in the future. Two of these three systems are fed with Baltic Blend which is a new fish feed developed at SLU, Uppsala. The idea of the new feed is to lower the environmental burden by substituting parts of the fish meal with other protein sources such as mussels and microbes. Two of the Swedish systems are recirculating and land-based (RAS), which is a fairly new but growing fish production system worldwide. The life cycle assessment in this study shows that domestic production of fish not necessarily is environmentally preferable but has the potential to be so if some processes can be performed more efficiently. The greatest improvement potential is found in the production of the new feed ingredients, the grow-out phase and the slaughter and guttering of the fish.
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