Food for thought: A realistic perspective on the potential for offshore aquaculture in the Dutch North Sea

•A solid knowledgebase and governance process is required to develop policies for sustainable growth of offshore aquaculture in the North Sea.•Environmental goals largely define maximum sustainable production levels. For seaweed culture this is limited to the scale of several hundred km2.•Definition of realistic ambitions is a process rather than a fixed value and greatly benefits from a ‘learning by doing’ approach.