Member states of regional intergovernmental organisations exert institutional discursive power by influencing regional narratives and policy frameworks. This influence operates through formal communications that validate specific viewpoints. The effectiveness of such discursive practices is predicated on the organisation's credibility, structure, and regional geopolitics. The interaction between institutional rhetoric and national interests often yields nuanced discursive outcomes, reflecting a synthesis of supranational and state-level priorities. At the centre of interstate dynamics is the pursuit of institutional discursive power, which has become a crucial avenue for states to participate in the creation of international governance guidelines. We consider the institutional discursive power of nations within Regional Fisheries Management Organisations (RFMOs) to see how it impacts the establishment of global fisheries governance systems and order. As intergovernmental organisations, RFMOs have significant influence on global fisheries governance. In order to evaluate and compare the institutional discursive power of different countries within RFMO, this study has developed an evaluation framework and model that includes competitiveness, constructiveness, and influence as its three main dimensions. It does this by drawing on a thorough understanding of the institutional discursive power within RFMO and its formation mechanisms, as well as by integrating theoretical principles from evaluation science.