Note that there is also poleward transport in the shallow currents at the western edge of each subtropical ocean gyre - known as western boundary currents. (skepticalscience.com)
[Response: The classical (i.e. Stommel) theory of the subtropical gyre requires that the interior equatorward (Sverdrup) transport that takes place everywhere but a narrow strip along the western edge of the basin, precisely balance the poleward transport that takes place in a narrow boundary current along the western edge of the basin. (realclimate.org)