Bigeye is a highly migratory species distributed throughout the tropical and sub-tropical waters of the Pacific, Indian and Atlantic Oceans. For the latest stock assessment performed in 2020 (Ducharme-Barth et al. 2020) a discrete stock unit within the domain of the model area (essentially the WCPO, west of 150ºW) was considered, as in previous assessments. Sensitivity analysis performed in 2015 showed that despite extensive longitudinal movements in the equatorial Pacific, the discrete stock assumption was capable of accurately capturing the dynamics and stock status indicators for WCPO bigeye tuna (Ducharme-Barth et al. 2020, and references cited therein).