I have caught otters before with the method that mez explains a bit. Find an acitve beaver dam and locate the slide on the dam. Set a 330 at the BOTTOM of the dam, right where the dam levels off to meet the water. Set the trap upside down (with the trigger pointing up). The water will run over the trap and conceal the trigger, should be maybe an inch or less of the trigger visible above the water. The otter slides down the dam and the trigger nails em on the chin, no way to avoid it. Make sure you have a strong anchor because those buggers are amazingly strong. Also use new, strong traps, they are so fast that they can weezle out the back end of a weak trap. good luck