States have established regional fisheries management organizations (RFMOs) to manage transboundary fish stocks. However, the effectiveness of these bodies has been questioned. Problems with overfishing, illegal, unreported, and unregulated (IUU) fishing, and bycatch remain persistent and difficult to solve. In addition to states however, non-state actors (NSAs) also matter for the governance capacity to sustainably manage transboundary fish stocks. These actors include both non-governmental organizations (NGOs), multinational corporations, business associations, consultancies, and private research organizations. They represent diverse interests and pursue different goals in global governance. They are known to participate in meetings of international organizations and the United Nations, and to form transnational partnerships (together with other actors) to address transboundary environmental problems. However, their participation within global fisheries governance and the consequences of that participation for political outcomes achieved, for example by RFMOs, is not well understood. 

I attempt to fill this gap, by addressing two overarching research questions. First: how and why do non-state actors participate in global fisheries governance, and second: how (and under what conditions) does the participation of these actors shape RFMOs’ effectiveness? In order to analyze the participation and consequences of NSAs, I construct a theoretical framework combining insights from international relations literature on NSAs, transnational partnerships, and international regimes, and from the comparative politics literature on interest groups.

The thesis presents four papers. Paper I studies the conditions for NGO participation across seven RFMOs. It finds that NGO participation is shaped by the RFMOs’ own institutional capacity and competitive pressures from other NSAs from research organizations, but not by changes in target fish stock health. Paper II studies the variation in advocacy strategies used by transnational partnerships to shape IUU fishing policy. It finds that partnerships mainly use inside and service provision strategies, but rarely outside strategies. The variation in strategies is shaped by changes in political opportunity structures, i.e., by an increasingly complex global institutional landscape as well as increasing issue complexity and salience. Paper III focuses on the roles of NGOs in relation to transparency across twelve RFMOs. It finds that NGOs have made repeated requests for procedural transparency, and that several requests have received responses from member states, such as notably, the adoption of observer accreditation rules. NGOs also face several barriers to transparency, as they sometimes are hindered from attending certain sessions and from actively engaging in discussions. These barriers limit the ability of NGOs to develop policy-specific advice and to perform accountability functions, with potential implications for RFMO effectiveness. Paper IV explores the influence of NGOs on the effectiveness of RFMOs to manage sharks, by considering two indictors, i.e., changes in policy outputs and to key actor positions. Strategic venue shopping is found to be an important mechanism for NGOs’ ability to influence RFMO effectiveness. Taken together, the thesis contributes to scholarly debates about the participation and influence of NSAs in sustainability science and international relations literature, and related policy debates about the prospects for achieving sustainable fisheries through an inclusive and ecosystem approach to management.