Asian carp have been making their way up the Mississippi River system for years after escaping from fish farms and wastewater treatment ponds in the southern U.S.They’re knocking on the door of the Great Lakes, and a number of people are concerned about what could happen if carp become established in the region.In this five-part series, we’ll take a look at what officials are trying to do to keep the fish out, what might happen if carp get in, and why some people want to turn carp into a business opportunity.