Baltic Sea herring fisheries have in recent years attracted considerable media interest in Sweden. The main concerns are deteriorating stock status and lack of herring catches suitable for human consumption. One recurring theme is that the demand of feed raw materials by the Norwegian salmon aquaculture industry is driving the development of increasing volumes destined for fishmeal and oil production. However, it is unclear to which extent Baltic Sea herring is used by the Norwegian salmon industry. This report has the specific objectives to map where Baltic Sea herring ends up, including identification of potential obstacles for full traceability – with the overall aim to identify how different actors may contribute to safeguarding long-term sustainable use of marine resources. Based on data provided by the Danish fishmeal and oil processing industry, it is found that Baltic Sea herring is primarily used for the aquaculture sector, especially the fish oil. However, although some feed and salmonid producers were helpful in providing the requested information, responses varied and only piecemeal information could be obtained on the next step in the value chain, i.e. to which specific species and countries. Although annual sustainability reports are published, efficient, fit-for-purpose extracts on the destination of raw material from a certain stock may be effort-demanding to extract and official data detailing this is at large lacking. The same situation also applies for certified aquaculture. Further, the definitions of ‘sustainable fisheries’ applied in current certification systems are inadequate to fully safeguard use of sustainable marine raw material for certified, farmed seafood. Several actors are however working with improvements, such as a new feed standard for Aquaculture Stewardship Council and updates on internal reporting systems by feed producers. In conclusion, to improve transparency and build consumer trust – and ultimately foster sustainable use – it calls for i) more efficient data management strategies and detailed reporting by feed producers to be able to meet questions raised; and ii) sharper rules for feed ingredients allowed by current aquaculture certification standards and a more distinct difference to non-certified seafood related to sustainability and transparency of marine resource use.