They eat everything that swims and have a serious impact on the lake. Their crap is toxic. Look what they did to Middle Island. It's practically defoliated. Motor up close to it and get a whiff. It stinks! When we were kids we'd run all over that island and goof around in the old lodge. I wouldn't step foot on the place without a haz-mat suit. Nothing a scoped .22 and a few thousand shells wouldn't fix!