One time I had a guy watching me and following me as I fished there at the park. Instead of me continuing working my way along the shoreline, I turned around and walked back, right up to the guy, held my phone up so the guy could see it and took a couple photos of him and said, "Why the fu-- are you following me? I suggest you stop doing this or you are going to have real problems with me. I have some photos of you and I will call the police which right now are sitting in their car right over there"..I lied. He acted all surprised and muttered a few apologizing words and he continued on his way. People like that don't expect you to confront them and will usually back down or shy away. I don't get mad easily, but when I do, watch out! This probably is not the best approach, but I was trying to have a nice day fishing for bass and had had enough. I don't need some stranger following my every move.