The private sector can play a prominent role in global ocean governance. Yet, industry stakeholders are diverse, and how specific companies engage with policymakers remains poorly understood. Here, we focus on Western and Central Pacific tuna fisheries, which provide ∼60% of global tuna catch and a critical source of income for developing island states. We identified relationships between companies and governments in international fishery negotiations from 2005 to 2018. Relative industry attendance nearly doubled during this time, and 15 of 158 companies have dominated corporate representation since 2014. Further, industry members outnumbered government policymakers on half of the ten largest delegations, and 70% of island state delegations included foreign companies. Meeting attendees corroborated the influence of industry stakeholders, but this differed across countries. During our study period, management of tuna fisheries improved overall, suggesting that company involvement does not hinder sustainability outcomes and could play a supportive role when agendas are aligned.
