Yellowfin tuna (Thunnus albacares ) is considered a single population in the Western and Central Pacific Ocean (WCPO) for stock assessment purposes (Vincent et al. 2020 and references cited therein). However, there is still uncertainty about the stock structure along the Pacific Ocean (Aguila et al. 2015). Regular stock assessment is developed by the Western and Central Pacific Fisheries Commission (WCPFC) and the same entity sets conservation and management measures for this stock in this region.

The Parties to the Nauru Agreement (PNA) is a regional binding treaty-level instrument to facilitate cooperation in the management of fisheries resources of common interest. The agreement requires the management of straddling/highly migratory fish stocks on a subregion basis through Regional Fisheries Management Organizations (RFMOs), and the WCPFC Convention (the regional fisheries agreement covering the WCPFC convention area). PNA members are simultaneously members of the WCPFC and so, a single management unit is set for PNA-related profiles. The PNA unassociated (free school) fishery was MSC-certified in 2011.