The right of public access to the shorelines of navigable waters is enshrined in the Magna Carta, on which our law is based. This access extends to the mean HIGH tide line. Greedy landowners can claim anything they want but the public's right to walk on the beach goes back to Roman times. Mr. Beck will probably next claim to own the sky over him as well. He has as much right.
https://en.wikipedia.org/wiki/Public_trust_doctrine