"There is, however, no way to enforce this law. One can only monitor whether a person is V-notching the gravid female lobsters by placing an enforcement officer on every boat. V-notching is still de facto voluntary."
The Evolution of the Maine Lobster V-Notch Practice: Cooperation in a Prisoner's Dilemma Game
http://www.ecologyandsociety.org/vol16/iss1/art41/