OBS_VALUE: Pilotage is mandatory for vessels larger than 500 tonnes in certain ports, including the Port of Lázaro Cárdenas, the largest port in Mexico in terms of cargo tonnage. Furthermore, pilotage service can be provided only by Mexican nationals by birth with a certified professional title. However, the Maritime Authority may allow captains on board of vessels engaged in cabotage on a regular basis to pilot their vessels; consequently, foreign captains on a vessel that has been granted a temporary permit for cabotage might be exempted from the obligation of using local pilots.