Not later than March 1, 1978, the commission shall prepare and adopt a detailed map for the marsh, on a scale of one inch equals 24,000 inches, which shall show both the primary and secondary management areas, and which the commission shall file with the clerk of the county. Upon the filing of such map with the clerk of the county, no further changes in the boundaries of the marsh or the boundaries of the primary or secondary management areas shall be made without the approval of the Legislature by statute.