I had the same thing happen 15 years ago, except I went psycho and caught them in the act, I got a shovel and played whack a coon. They did not come back. 9 hits, on 4 raccoons. Raccoon golf. I like them otherwise
I'm a live trapper these days, but you remove one, another moves right, same with squirrels and other varmits.
I got real good at trapping, but after awhile, the relocation process and the stress you put them under(lost a couple of squirrels) became a hassle and many places, the live trap is illegal. You cannot just relocate them on your schedule, you have to get them out and relocated asap, and on a cold night, they can freeze to death after stressing out. But whacking them with a shovel years ago was not exactly humane either.
I suggest letting nature have it's way, or make the pond deeper and larger, get a good sized outside dog etc. Motion detector set ups can work. Lot of trouble though. Birds can easily pick off fish here also. Herons etc.
But these are nice critters to have visit, you might design things around the nature you have. I keep bonsai and have the squirrels finally trained here (they love to bury nuts in the bonsai pots). It's really hard for them to access the pots now.