With the addition of seven new plants and animals, Michigan now bans 40 non-native species. That means they cannot be possessed or transported in Michigan or the rest of the Great Lakes region.

The expanded list is part of a deal reached between the U.S. states and Canadian provinces that border the Great Lakes. Many of the newly banned species are still in Europe and Asia, but the creatures get spread around through ships’ ballast. Tourism, and collectors of exotic plants and animals also contribute to the problem.

“This is step is sort of a very strong measure to prevent these species that are threatening other parts of the world from entering the Great Lakes,” says Nicholas Popoff, a wildlife expert with the state Department of Natural Resources. “All these species collectively are invasive in various parts of the world. So, for example, the stone moroko, it’s like a minnow that’s native to Asia, but it’s hitchhiked to other places in Europe.”

Non-native species can upset the ecological balance in a region because they have no natural predators. Popoff says Michigan already spends billions of dollars to deal with zebra mussels, sea lamprey and other species that have already slipped into the region.