Have you tried a mesh net over the pond ?? I had a neighbor who had the same issue here in San Diego with a hawk...he put a mesh net over it and didn't have anymore issues.

Speakin of fish-snatchin-birds...and I apologize for highjackin the thread a bit here...but I was a research diver / assistant for tracking white seabass in Mission Bay and off the the San Diego coast. They had a microchip in them from the hatchery and we would track them using sonic equipment.

Every 1 out of 4 we noticed would end up 2 - 3 miles inland. Couldn't figure out what was goin on, turns out the pelican's would watch us release them then go in for the swoop. So I understand your frustration to some degree....Good luck !!