Notices referred to in section 7556 shall be given by erecting and maintaining signboards at least one foot square in at least 2 conspicuous places on the premises, one of them near one of the usual landing places on said island, reading as follows: "All persons are forbidden to shoot or hunt on this island", with the name of the owner, occupant or lessee; or such notice may be given verbally or in writing by the owner, occupant or lessee of the island to any person and shall be binding on the person so notified, whether the signboards herein named are erected and maintained or not. Whoever tears down or in any way defaces or injures any such signboard forfeits $100, to be recovered by the owner, occupant or lessee of such island in a civil action.