Before adopting the Master Map of Ungranted Tideland Boundaries in California and a Description of Ungranted Tideland Boundaries pursuant to Section 6338, the commission shall consider all evidence submitted pursuant to Section 6335. The commission may, in its discretion, and shall, upon the request of the protestant, hold a hearing as to any protest or protests prior to adopting the master map and description. The commission may authorize its executive officer or other officer or employee of the commission to conduct such hearing or hearings at a convenient location selected by the commission within each county where such protested boundary is located. Not less than 30 days before the date set for each hearing, a notice, setting forth the time, place, and nature of such hearing, shall be sent by such officer or employee by certified mail to each protestant whose protest is to be heard at such hearing.