i was talkin to a trapper at my girlfriends house, doing the same thing trapping beavers and he told them to shoot them if they see them but that they should really be using higher powerd rifles than a 22 because they can get shot quite a bit and sink to the bottom and still be alive. but he had a special kind of snare that was right at there entrance and just below the water so the dogs wouldnt get caught, and after that they havent seen any.