Heres a nice idea
A quote from Bearislander
All this legal talk is fun. But if you want a practical solution turn your stereo speakers toward the water, turn up the volume and put on a CD of bad music and hit "repeat".
I recommend "Pennsylvania Polka" or "Chick Dance" but that "It's a small world" tune from Disney World is a good choice.
They will up anchor by the third repeat.