hmm... what we need is one of them old "Bear Scare" tactics. One of us goes up there and starts talking to the people splashing around. Somewhere in the conversation, drop the line "yeah, its real nice here, almost every time i come down here to fish I get to see the bear family that live just across the water"
Works best if you have already put a 'yote caller over the other side of the bank with a bear tape in it..
Drawbacks
1- Talking to the people, major drawback. Most dont want to talk, or are too intoxicated to listen
2- Mention a bear and half the idiots will go looking for it (Darwinism in action)
3- Some people are so dumb it wont work anyhow!