Once each biennium, in the odd-numbered year, the executive director shall hold public hearings to hear suggestions from the public on changes in the fishing rules or on any other subject with respect to his duties. Such hearing shall be held in Concord and in Lancaster. Public notice of said hearings shall be published at least twice in 2 newspapers having general circulation throughout the state, and in such other newspapers, magazines, or circulars as the executive director may deem desirable. It shall be the duty of the members of the commission to be in attendance at such hearings. The executive director may in his discretion conduct other public or private hearings throughout the year upon petition of interested parties. At the biennial hearings held at Concord and Lancaster and at other public hearings that the executive director shall hold in accordance with the provisions of this section, any person having any testimony to present which bears upon the power and authority of the executive director under the provisions of this title shall be given full opportunity to be heard, and the executive director shall cause a complete record to be kept of all testimony taken.