Whenever a vacancy occurs in the membership of the board, the governor shall appoint a successor of like qualifications. All appointments made shall be for a term of four years, but no member shall be appointed for more than three successive four-year terms. Each member shall serve until a successor is appointed and qualified. Whenever a vacancy occurs in the membership of the board for any reason other than the expiration of a member’s term of office, the governor shall appoint a successor of like qualifications to fill the unexpired term.