Whoever, being the owner, possessor, harborer or custodian of any dog, allows such dog to be upon the designated swimming or sunbathing area of a state coastal beach strand at any time between May 1 and September 30, inclusive, of any year, except when such dog is on said property on behalf of a law enforcement agency or a blind person, as defined in § 2101 of Title 31, is guilty of a violation and shall be fined not less than $25 nor more than $50. For each subsequent offense, the person shall be fined not less than $50 nor more than $100. “Coastal beach strand” shall mean all that coastal real property between the western base of the dunes and the low water mark except those lands within a municipality which has enacted an ordinance governing the activities of dogs on said real property.