so I recommend to try a bit of kindness and submission first, apologize you meant no harm, tell him you understand his position (don't say he is right until you know for sure and surrender that too if true and it's over), tell him what a beautiful property he has and how you would be proud to own it, talk about him and what he has done....
he is proud of his digs and wants to share it with friends, not fight with enemies, I bet you will find out both of you are good people and just have a difference of opinion that can be easily ironed out if you are willing to try.
and if that doesn't work, send lawyers, guns and money, maybe even hire a hit man to off that sob?
I was about to say WTF!!! what kinda BS talk is that.... until I saw the last line
I'm telling ya... just post the hot spot on a local fishing forum and he'll be overrun with boats in no time. He'll have an aneurism with all the traffic and you can go back to your fishing.