Chasing the “Blue Whale of Freshwater”


The Eco Youth Reporters pose during their tour of Notre Dame. Photo by Kari Lydersen.

Editor’s Note: The following story was written by a student in our Eco Youth Reporters program, conducted in conjunction with award-winning journalist Kari Lydersen and Michigan State University’s Knight Center for Environmental Journalism. The Eco Youth Reporters program is generously funded by the McCormick Foundation:

“The blue whale of freshwater” – that’s how Chris Jerde, research assistant professor at the University of Notre Dame, describes Asian carp. Among the 185 invasive species in the Great Lakes, Asian carp has been the biggest problem. The various species of Asian carp open their mouths and eat “anything” in their path, as Jerde said, growing up to 100 pounds and leaving everything else behind to starve or just barely survive.

But no one can seem to find Asian carp.

That’s where Jerde’s eDNA test comes in. As Jerde showed us atthe Notre Dame Linked Experimental Ecosystem Facility on a bright, hot, empty yet peaceful spot at St. Patrick’s Park, the eDNA test begins by filtering water through something that looks like a coffee filter. It sorts out the rocks and other things in the water, giving him a pure sample of organic particles. The eDNA test looks for DNA from fish and other organisms that he can trace. You can trace the DNA if an Asian carp has been in the water, even if you can’t physically find the fish.

Even though the first focus is Asian carp, the test can also be used for finding the DNA of other fish, to track other invasive species, or to see how native fish are doing after an invasive species comes in.

Asian carp got close to the Great Lakes by floods in Arkansas where they escaped from fish farms. Asian carp is a man-made problem – “We brought them here,” said Jerde.

Jerde started as a math major who eventually switched to environmental science. He was asked by David Lodge, a biological science professor at the University of Notre Dame, to look into the Asian carp situation. From that day on, his career was changed. “No one knows the future of eDNA,” he said, but he’s confident the eDNA testing technology can in the future be used for species other than Asian carp. Jerde said we’re learning more about Asian carp all the time.

“We’re not trying to annihilate the Asian carp,” he said, “but to manage the species.”

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