How do you get rid of river otters without killing them?

Answer 1

They give birth from March on, so you can't disturb them until they leave.

(besides being cruel and inhumane they will leave the kits behind and you will end up with a smell 10 times worse than rotten fish)

If they are under your house close up all entrances except one. Sprinkle flour around so you can see footprints to make sure they come out.

Toss in a rag saturated with ammonia. (This won't hurt them, but they will want to get away from the smell) You can wait within sight to make sure they come out, or check for footprints. If you are sure they are out, then seal up the last hole.

To prevent them from coming in, or eating your garden use strong smelling spices such as cayenne or garlic power, and human urine. (Sounds gross but it is a predator smell and they get the message)

Answer 2

You should hire a licensed trapper to start with. Then between trapping seasons, I recommend either a chain link fence or 1 inch chicken wire (which is cheaper and more effective) with a single wire on the outside (threaded through an insulator on each post) about 14 - 16 inch above the ground. Connect this single wire to an interrupted pulse fencer (electric fencer used for cattle). This will discourage mink, otter, beaver, marten and muskrat from accessing your pond and eating your fish.