we have never seen any signs of otters being present, no leftovers laying around or their very specific trail they leave in the winter snow. but we certainly have seen the osprey and eagles coming in, but have never really seen them take a fish. They are very wary. The water is stained brown so they would have somewhat of a problem seeing unless they came to the surface. Makes a person wonder whether its really worth stocking if you cannot find out what happened to the all the rest.