If you have an fish eating birds frequently the pond like herons, kingfishers etc. they may complete a cycle involving the snails that producr unsightly "grubs" in your fish. However your redears should take care of a good many at some point. You may just have to give them time.

I'm not an expert on snails by any means but maybe they are in shallow water for a reason i.e. breeding, warmer water etc.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.