While a $300 million dollar federal effort has kept invasive carp out of the Great Lakes, it appears stymied. Almost all the effort has focused in canals in and near Chicago, but researchers also worry that during floods carp could cross a marshy divide between the Lake Erie watershed and the Wabash River, part of the Mississippi River watershed, where Asian carp have been found, Duffy reports. (To view a larger version of the map below, click on it)
Rutherford said "silver and bighead carp would wreak havoc on the current ecosystem," Duffy writes. Invasive carp could reach 34 percent of the total fish weight, twice the size as gizzard shad, the lake's most common plankton-eating fish. Asian carp would lead to sharp declines in shad and other fish that eat zooplankton and algae "as the carp ate up much of their food. And the impact cascades. These fish, including alewife and shiner, are important food for gamefish like walleye and perch. The model suggests carp could force more than a 10-percent decline in walleye and as much as a 15-percent decline in burbot and rainbow trout."