If any of the lands or property, the use of which is required for right of way and spoil disposal areas, shall have been leased by the Department of Natural Resources to any individual, firm, or corporation for the cultivation and gathering of oysters, the department is authorized and directed to substitute for such leased areas lying within the rights of way and spoil disposal areas other equal areas lying outside the rights of way and spoil disposal areas which are also suitable for the cultivation and gathering of oysters.