AbstractThis paper contributes to the growing body of literature that engages with ontological scholarship on fisheries management and governance, and more generally, to debates on environmental governance. It argues that fisheries governance is an ontological challenge that raises questions of culture, equity, legitimacy and inclusion/exclusion, requiring more context-sensitive and politically aware fisheries governance approaches. By engaging with the concept of political ontology, and drawing from empirical research carried out in Ireland’s offshore islands, five ontological assumptions are identified that underpin Irish fisheries governance and management policies and practices and categorised as social-historical, ecological, geographical, technocratic and markets-driven. Articulating and examining these assumptions provide insights into why policy objectives aimed at supporting small-scale fisheries and their communities may, in practice, not be effective when they are operationalised within a governance paradigm designed around the realities of large-scale, full-time, highly mobile and more economically productive operators. Despite the efforts of ontologically disobedient islanders, the enactment of these ontological assumptions into the dominant world of fisheries governance inhibits the emergence of possible worlds that would enact Irish island inshore fisheries through island logics. The paper concludes that the squeeze on Ireland’s island inshore fishers is not simply spatial, it is ontological. A dominant fisheries ontology has been created by the interplay of ontological assumptions. This dominant ontology undermines the State’s critical policy to maintain and manage Irish fisheries as a public resource in order to avoid the concentration of fishing opportunities into the hands of large and powerful fishing interests.