Size-specific spatiotemporal dynamics of bigeye tuna (Thunnus obesus) caught by the longline fishery in the eastern Pacific Ocean

•The density of bigeye tuna had large interannual variation across the tropical area of the EPO.•There was spatial segregation by size. Adult fish tend to be distributed in the equatorial area, and smaller fish are distributed in marginal areas.•Spatial restructuring by size in response to El Niño and La Niña was observed.•The trend of relative abundance index by size differed.