Trash or Treasure?

The silver lining to the Asian carp invasion just might be a better understanding of river biology
Illustration by Dominick Santise

The common carp has a reputation as a bottom dweller that forages through mud for its food — a dirty river animal not fit to be highlighted on a dinner menu.

Its cousin, the Asian carp, has it far worse. They’re big and ugly, an aggressive and invasive species that could eventually wreak havoc on the Great Lakes because of their voracious eating habits.

Asian carp don’t believe in leftovers.

But fish biologists might argue that the Asian carp are elegantly evolved, and that the continued research these fish inspire elevates river biology as a whole.

So could there actually be a silver lining to the pending Asian carp crisis — the one that had the U.S. Army Corps of Engineers working for years on possible solutions, and which now has the ear of U.S. Congress in the form of legislation to stop them from taking over our fair waters?

“They’re amazing fish. [They’ve got] so many abilities, so many things they do well,” says Duane Chapman, a research fish biologist for the U.S. Geological Survey who studies Asian carp.

There’s a reason there are so many of them. Asian carp swim faster than their peers and are highly adaptable. They can survive from the southern United States up to just below the Arctic Circle, thriving in both fresh and saltwater. Young ones can survive in water with low levels of oxygen. All of them can modify the length of their guts to accommodate different types of plankton.

They’re also known to jump violently out of the water when startled, says David Glover, a senior research associate at Ohio State University, as a result of unusually high cortisol levels, making them extremely “skittish” and “stressed out.”

But even this annoying behavior seems to be rooted in its evolutionary prowess. It’s because of a finely tuned inner ear system, which is so sensitive that Asian carp could be described as “super-hearing” fish.

The “skittish” side effect is what Glover speculates led Asian carp to be able to cover so much ground in their daily lives, efficiently finding food like no other and, ultimately, surviving well.

Of course these attributes are what make Asian carp dangerous to the Great Lakes’ ecology because of their potential to decimate food sources. Still, better river science has been the result of extensive research, and that’s positive.

“The amount of new technologies that have come out in the last five years” from studying Asian carp is “phenomenal,” says Marybeth Brey, a postdoctoral fellow at Southern Illinois University who studies the movements of Asian carp.

New technologies include the development of acoustic video to monitor fish in cloudy water, new netting apparatuses to catch evasive swimmers, and a better understanding of how fish secrete their DNA into the environment, giving biologists the ability to home in on any species and track their movement. Scientists are also learning so much more about native fish as they scrutinize Asian carp.

Asian carp ironically made their debut in the U.S. thanks to the federal government which, in the early 1970s, extolled their virtues. They first landed in Arkansas where officials believed they could act as a nonchemical filtration system at water treatment plants. Asian carp are indeed ideal for filtering water because of the sponginess of their gills — another unique attribute — where algae is easily trapped.

“They were brought in to be useful,” says Brian Roth, an assistant professor at Michigan State University in the Department of Fisheries and Wildlife.

Sadly those days are long gone. Once Asian carp escaped into North American rivers, the panic began, and there is legitimate reason for concern should these fish eventually invade the Great Lakes.

“Correcting our historic blunder will be difficult,” U.S. Rep. Candice Miller, R-Mich., wrote in a recent Detroit Free Press op-ed piece, criticizing not Asian carp, but the original decision to connect the Great Lakes to the Mississippi River system through Chicago canals. It’s how Asian carp will finally get here if a plan by the Army Corps of Engineers is not implemented to block off the waterways, Miller warns.

Asian carp still enjoy some measure of love abroad. “Outside the United States, people eat the heck out of these fish,” says Chapman, calling them “the hot dog of China.” They’re a rich and inexpensive source of protein, high in good fatty acids.

But they are super bony compared with the more popular and beloved Great Lakes favorites like bass and walleye. It might be “taboo” to ever favor Asian carp over those varieties, Brey suggests.

For Chapman and other scientists, the love-hate relationship with Asian carp persists. He’s not sure what kind of control methods will prevail, but he remains true to his ever-present research subject.

“I think they’re beautiful fish.”