Asian carp, an invasive and destructive fish, have spread through the Mississippi, Ohio, Illinois and Missouri rivers. In total, the fish are affecting more than 20 states from Louisiana to South Dakota.
Under the right conditions, it could take as few as a dozen Asian carp to establish a population in the Great Lakes. That's according to a report published this month by scientists in Ontario.
If they're correct, the risk of even just a handful of Asian carp escaping into the Great Lakes could be more significant than officials had planned.
This segment aired on September 23, 2013.