(2) The board by rule may establish reduced license fees for those individuals who engage in pilotage activities on less than a full-time basis. However, in no event shall the fee be less than $50. [1957 c.448 §22; 1963 c.105 §2; 1973 c.832 §68; 1977 c.40 §2; 1979 c.11 §2; 1981 c.88 §9; 1983 c.313 §4; 1985 c.271 §2; 1989 c.293 §2; 1991 c.466 §1; 1991 c.703 §41; 1993 c.796 §9]