Re: Electric Fence (not for bear)
River otter are smart too. Have friends that had several as pets. Really smart and sort of cunning. Once they figure out a easy source of food, you got problems.
Wild ones figured out how to open crab traps during low tides and would sit on top of the trap while eating the crabs and by catch fish. The traps had rubber straps with a hook holding them shut. Quick bite and just pulled them open. A family of otters can eat quite a few crabs daily. The shift a to wire locking pin resulted in them chewing through the wire on the side of the crab pots. They also would flip the traps in shallow water almost immediately after the traps were baited. Frozen shad and menhaden were great treats. Just bit through the rubber strap holding the bait door closed and free food. Removal of the entire family was the only method my friend found to stop it.
Worked with someone that did lots of work keeping predators from raiding for food in certain areas. They had lots of times where foxes and coons would go through 7 and 9 strand electric fences that were 4 inch spacing between strands. Then would exit the area through the fence again. And fences he build were bull strong and hog tight and very HOT.
A live trap with a can of sardines, then haul it 25 miles away to a river is what I would try. But check with you state wildlife agency first, some areas have harsh fines for trapping without license, and until you know what the law is....better to be safe than sorry. If that doesn't work, the old .22 method as a final response.
Started 9/13, building slowly, not trying the no treatment anymore