We find that in parameter regimes relevant to the recently observed alternating zonal jets in oceans, the formation of these jets can be explained as due to an arrest of the turbulent inverse-cascade of energy by {\em free} Rossby waves (as opposed to Rossby {\em basin} modes) and a subsequent redirection of that energy into zonal modes. This mechanism, originally studied in the context of alternating jets in Jovian atmospheres and two dimensional turbulence in zonally-periodic configurations survives in spite of the presence of the meridional boundaries in the oceanic context.