May 12, 2008 — The United States and Canada are trying to figure out how to keep new invasive species out of the St. Lawrence River and the Great Lakes. 185 have already snuck in, costing the region billions of dollars a year. Many hitchhiked in the ballast tanks of foreign ships. Both countries want the public to know they're doing something about the problem. So they invited journalists to the port of Montreal to see how ballast tanks are tested for invasive species. David Sommerstein reports.