Any master of a vessel or watercraft who shall throw or permit to be thrown any stone, gravel, or other ballast from on board the vessel or watercraft into any of the waters of any bay or harbor of this state or within three miles of the outside bar of any such bay or harbor shall forfeit a sum not less than $500.00 nor more than $2,000.00 for each such offense. One-half of the forfeiture shall be paid to the person who first gives information of the offense to the Board of Pilotage Commissioners and the other half shall be paid to the use of the commissioners of the harbors, respectively, for improvement of navigation. In addition, any such master may be punished by imprisonment for not over three months, in the discretion of the court.