Multi-use realization with offshore wind and low-trophic aquaculture in the North Sea and the Baltic Sea.

Low-trophic aquaculture (LTA) could increase food and nutrition security, and offshore wind could increase energy security. Both activities are thus of high geopolitical importance at the national, European and global levels. As such activities may be combined in the same area, there has been considerable interest in developing multi-use systems for both industries, contributing to a range of UN Sustainable Development Goals (SDGs). In the OLAMUR project, we are developing cases in the Baltic Sea and the North Sea, with offshore wind, combined with cultivation of mussels and seaweeds. The Baltic case is situated at Kriegers Flak, in the Danish sector, and the North Sea case is north of the island of Helgoland in the German sector. At both sites, large scale offshore wind farms have been developed and are now in the production phase. The Baltic case started seaweed cultivation in 2023, and mussel cultivation in 2024, and the German case starts in 2024. A third multi-use case study, in Estonian waters, combines cultivation of seaweeds and mussels with rainbow trout farming. The seafood which is produced will be subject to a range of analyses for nutritional quality, and for contaminants. A databased service system is being developed, to assist policymakers in making knowledge-based decisions, and an extensive Data Management Plan which ensures transparent and standardized data capture from all parts of the project, as well as its interoperability towards European Marine data infrastructures (EMODnet and Copernicus Marine) for project data legacy. Whereas seaweeds will utilize excess nutrients such as nitrates and phosphates, the mussels feed on particles such as microalgae, thus the operations can improve water quality in addition to its production of food and biomass. Seaweeds also capture CO₂ and utilization for carbon capture may be an option. Thus, cultivation of low-trophic organisms, can add to a circular bioeconomy, especially in the over-fertilized regions such as the Baltic Sea and to some extent, the North Sea. Whereas several European projects have aimed at engineering aspects of multi-use, the OLAMUR project aims at the operation of offshore LTA at a semi-commercial level in combination with other industries (offshore wind and fish farming). This constitutes a significant leap forward for the multi-use concepts, enhancing LTA and multi-use, ensuring that valuable marine areas can be used in a more efficient and sustainable way.