The Maine Port Authority consists of a board of directors, referred to in this section as "the board." The board consists of 7 directors who must be broadly representative of the State and must have a background in international trade, marine transportation, finance or economic development. Five directors are appointed by the Governor, each to serve for 4 years. The Commissioner of Transportation serves as an ex officio member of the board and as chair of the board and president. The president of the Maine International Trade Center serves as an ex officio member of the board. The directors shall elect a vice-chair, treasurer and other officers as the board determines necessary. A vacancy must be filled for an unexpired term by the Governor. [2007, c. 134, §4 (RPR).]