We are facing several global crises in the area of climate, biodiversity and food. Blue mussels have great potential to counteract these crises with little or no disadvantages. EU with Green Deal and Farm to fork consider the blue mussel pr oduction as an important tool in the green transition of the food system , although several stakeholders see mussel production as a huge polluter . This presentation will focus on the blue mussel production in Denmar k, challenges related to legislations and permissions, and environmental impact and benefits. To assess environmental impacts, the results from a new study will show how biodiversity, and oxygen consumption is impacted by two mussel farms in poorly circulated water areas and by two mussel farms in good circulated water areas. All four farms in the nutrient-rich Limfjorden in Denmark. The results are used to define recommendations for policy makers based on ecosystem and biomass related considerations.