This paper provides a new discussion of the emerging governance regime for marine and coastal environments. It examines the evolution from a non-statutory to a statutory planning regulatory regime for marine aquaculture in Scotland. Specifically, the definition of development, which underpins the statutory operation of the terrestrial planning system, has been extended to include aquaculture developments within 12 nautical miles of the coast. This effectively expands the geographical territory over which land use planning controls operate in Scotland, and coincides with an emerging interest in the governance, planning and management of the marine environment. Taking into account the various controls put in place over time, the paper identifies the changing state–market–civil relations involved in this shift. Notably, over time, the state has progressively intervened in different ways to correct the perceived market failures associated with aquaculture and its environment. The analysis presented here illustrates the deliberate transition to a statutory planning context through a review of the steps taken by the stakeholders involved to devise a regulatory regime that better serves a contemporary social construction of the public interest. It provides evidence of an explicit attempt within the wider modernisation project to design an appropriate form of governance that is open, participative, accountable, coherent and effective. The paper suggests that the elaboration of such contemporary forms of active mediation remain iterative, partial and dysfunctional and points to an important research agenda to inform the emerging marine environmental planning and governance debates.