The abstracters’ board of examiners shall consist of three members each of whom must be appointed by the governor for a term of six years, with the terms of office so arranged that one term and only one expires on March thirty-first of every odd-numbered year. One member of the board must be an abstracter. Each member of the board shall qualify by taking the oath required of civil officers and holds office until that member’s successor is appointed and qualified. Any vacancy on the board must be filled by appointment by the governor for the unexpired term.