Controlling Invasive Species in the Chicago River
Rivers are often used as symbols of destiny or time, but the Chicago Sanitary and Ship Canal is a different kind of watercourse. It is a straight, industrial trench that represents one of the most ambitious attempts to master the natural world. In the late nineteenth century, Chicago faced a crisis: its waste flowed into the Chicago River and then into Lake Michigan, the city’s source of drinking water. To solve the resulting outbreaks of typhoid and cholera, engineers performed a feat of "the control of nature" by reversing the river’s flow. They dug a massive canal that forced the city’s filth away from the lake and toward the Mississippi River.
This engineering triumph, which required the invention of a whole new suite of earth-moving technologies, effectively rewired the hydrology of two-thirds of the United States. By connecting the Great Lakes basin with the Mississippi River basin, humans opened a portal between two previously distinct aquatic worlds. For decades, the canal was too toxic for most life to survive the journey. However, as water quality improved due to environmental regulations, this man-made highway became a corridor for invasive species.
The most formidable of these invaders are the Asian carp, a group of four species known in China as the "four famous domestic fishes." Each has a specialized talent: grass carp eat aquatic plants, silver and bighead carp filter plankton, and black carp consume mollusks. Ironically, these fish were originally brought to America as a "green" alternative to chemical pesticides. Inspired by the warnings in Rachel Carson’s Silent Spring, biologists imported them to control weeds and algae in ponds. But the fish escaped, and their voracious appetites allowed them to conquer the Mississippi system.
To stop the carp from reaching the Great Lakes, the U.S. Army Corps of Engineers has turned to increasingly complex technological fixes. They have electrified the canal, creating a field of voltage that shocks any fish attempting to swim through. Because no single method is foolproof, they are now designing "disco barriers" that use loud noises and curtains of bubbles to repel the invaders. This is the hallmark of the Anthropocene: a "no-analog" predicament where the only answer to the problems caused by human control is even more control. It is not so much the control of nature as the control of the control of nature.
On the front lines of this battle, contract fishermen like Tracy Seidemann pull thousands of pounds of silver and bighead carp from the water every day. These fish are so numerous that they make up the vast majority of the biomass in some rivers, outcompeting native species and threatening the survival of rare freshwater mussels. They are famous for leaping out of the water at the sound of boat motors, turning a simple river trip into a hazardous gauntlet of flying projectiles. Despite the massive scale of the slaughter, the fish are mostly ground into fertilizer, as Americans remain wary of eating a species they consider a nuisance.
Some entrepreneurs, like Chef Philippe Parola, hope to change this by rebranding the fish as "silverfin" and processing it into gourmet cakes. Yet, the logistics of such a solution highlight the absurdity of our current situation. One such product involves catching fish in Louisiana, shipping them to Vietnam for hand-deboning to remove their complex Y-shaped bones, and then shipping them back to New Orleans to be sold. It is a twenty-thousand-mile journey to solve a problem created by a five-mile canal. Ultimately, we find ourselves in a cycle of intervention that spirals back on itself. We cannot simply undo the past; the cost of re-separating the two drainage basins is measured in billions of dollars. Instead, we are forced to manage a planet that has already been remade.
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