As the journalist Dan Egan has put it: “Bighead and silver carp don’t just invade ecosystems. They conquer them.” On the Illinois River, Asian carp currently make up almost three-quarters of the fish biomass, and on some waterways the proportion is even higher. The ecological damage, meanwhile, extends beyond fish; black carp, which feed on mollusks, are, it’s feared, pushing already-threatened freshwater mussels over the edge.
