(VA) USA Today - It sounds like science fiction: an alien invasion of Lake Michigan by toddler-sized scum suckers. But around Chicago, the fear is so real that governments have already spent more than $11 million building electronic defenses to zap the invaders and trying to poison them.

The alien is a fish, the Asian carp. The fear is that the voracious plant-eaters could migrate from the Mississippi River basin through a Chicago canal and into the Great Lakes, threatening the habitat of lake fish. The risk, however, is that a going-overboard solution (walling off the canal) will be adopted before the costly new defenses (electrical barriers) are given a chance to work. More