If you’re a yellow perch or a walleye, native to the Great Lakes, the last fifty years have been something out of War of the Worlds, Invasion of the Body Snatchers, Earth Girls Are Easy et al. Strange alien species fiercer than their American and Canadian counterparts, like the Eurasian ruffe, have been arriving out of nowhere, taking your food, ruining your habitat. If you’re a smallmouth bass, the distinctly unattractive round goby, pictured below, eats your egg nests. As a result, humans in the area are suffering about $200 million worth of ecological damage every year, a new study says. 
This is a matter of ocean vessels accidentally dragging species from far away into the lakes through their ballast water. A big chunk of the estimated annual loss, $123.6 million, comes from the loss of recreational fishing money—those hobbyists love the bass.
