The term of office of the members of the board is four years. The terms expire on January 15 of each year in the rotation which is presently established. Vacancies shall be filled by appointment for the unexpired term. On February 1 of each year the Governor shall designate one of the members of the board to serve as president. The term of office of the members appointed pursuant to subdivision (f) of Section 902 shall commence on January 15, 1976.