In an earlier thread a post by Andrew Davis provides sage advice on dealing with herons, maybe all of the hints and tips for controlling all types predator problems could be grouped or maybe made a separate section. We all face similar problems. The information might make a nice Pond Boss article, as well. I have seen a lot of posts about numerous kinds of animal pests.
Norm has an excellent point
"The first step is always to try and modify the habitat to discourage the unwanted species" this is much easier to do when in the pond planning stage.

1/4 & 3/4 acre ponds. A thousand miles from no where and there is no place I want to be...
Dwight Yoakam