This thesis, submitted for the Doctor of Philosophy in Geography and Environment, presents a case study of the development of the UK's market-based management system for oceanic fisheries. Implemented gradually in the years since 1984, the informal nature of the UK's fisheries management system, which has developed through a number of incremental changes and government-industry "gentlemen’s agreements" rather than clear legislative moves, means that few official policy documents (and perhaps consequently, little academic literature) on the subject currently exist. This thesis traces the material and political processes of market formation, looking at the origin of market-based policies in the theories of bioeconomics and wider economic history. It asks what the implicit assumptions of the economic discipline can – and can't – tell us about the impacts and outcomes of market creation, and using a Foucauldian inspired approach to economic performativity, discusses the role of ostensibly descriptive theories in shaping the world around them. Finally, it calls for a greater geographical engagement with marine issues, and proposes an action-research role for geographers in the politics of the sea.