Section 29. The aldermen or city council of a city or the selectmen of a town lying upon coastal waters may, in writing, and upon blanks, supplied by the director, authorize any person to construct weirs, pound nets or fish traps in tidewater in locations where no harbor lines exist and also in locations beyond established harbor lines, within the limits of such city or town, for a term not exceeding five years, upon such conditions and subject to such regulations as the aldermen, city council or the selectmen may impose; but no authority so given shall be valid unless approved in writing as to location and construction by the department and the director, and subject to such conditions as it and he may impose; nor until such authorization, together with such approval, has been filed with the director.
No person shall construct or maintain a weir, pound net or fish trap in the tidewater unless in accordance with this section.