"Scaring off" has been mostly successful here. We live on our pond. Even so, the flying gangsters are always nearby.
How successful you are depends greatly on your being on-site at your pond, especially in the morning. They can show up at any time but morning seems to be their favorite (at +- dawn).
Every spring I go through the same routine of blasting them when ever I see them. Eventually they get sick of it and go to other waters nearby. They still check in on occasion to see if the noise has abated.
