Solution for a scourge? University of Minnesota scientist is progressing with carp-killer tool

March 06, 2020

Sam Erickson followed his love of science to outer space one summer during an internship at NASA. He came away fascinated by seeing into deep space by interpreting interaction between matter and infrared radiation.

Now a full-fledged researcher at the University of Minnesota’s College of Biological Sciences, the 25-year-old Alaska native is immersed in something far more earthly: killing carp. His fast-moving genetic engineering project is drawing attention from around the country as a potential tool to stop the spread of invasive carp.

“I want to make a special fish,” Erickson said in a recent interview at Gortner Laboratory in Falcon Heights.

In short, he plans to produce batches of male carp that would destroy the eggs of female carp during spawning season. The modified male fish would spray the eggs as if fertilizing them. But the seminal fluid — thanks to DNA editing — would instead cause the embryonic eggs to biologically self-destruct in a form of birth control that wouldn’t affect other species nor create mutant carp in the wild.


University of Minnesota researcher Sam Erickson works out of three on-campus laboratories in his quest to develop a genetically modified common carp with a feature that destroys eggs of females during the spawning season. He has already developed the modification in tiny zebrafish, shown here in acquariums at one of his labs.

His goal is to achieve the result in a controlled setting using common carp. From there, it will be up to federal regulators and fisheries biologists to decide whether to translate the technology to constrain reproduction of invasive carp in public waters.

“What we’re developing is a tool,” Erickson said. “If we could make this work, it would be a total game-changer.”

Supervised by University of Minnesota assistant professor Michael Smanski, Erickson recently received approval to accelerate his project by hiring a handful of undergraduate assistants. He also traveled last month to Springfield, Ill., to present his research plan to the 2020 Midwest Fish and Wildlife Conference.

“We’re pretty excited about where his project is at,” said Nick Phelps, director of the Minnesota Aquatic Invasive Species Research Center at the U. “Things are sure moving fast. There’s excitement and caution.”

Erickson’s research has received funding from Minnesota’s Environment and Natural Resources Trust Fund. No breeding populations of invasive carp have been detected in Minnesota, but the Department of Natural Resources has confirmed several individual fish captures and the agency has worked to keep the voracious eaters from migrating upstream from the lower Mississippi River. Silver carp, bighead carp and other Asian carps pose a threat to rivers and lakes in the state because they would compete with native species for food and habitat.

Erickson views his birth control project as one possible piece in the university’s integrated Asian carp research approach to keep invasive carp out of state waters. Already the DNR has supported electric barriers and underwater sound and bubble deterrents at key migration points. Another Asian carp-control milestone was closing the Mississippi River lock at Upper St. Anthony Falls in Minneapolis in 2015.

‘Shooting star’

Growing up in Anchorage, Erickson had never heard of Macalester College in St. Paul. But he visited the campus at the urging of a friend and felt like he fit in. He majored in chemistry and worked for a year at 3M in battery technology. But his interests tilted toward the natural world and how to “better live in cooperation with nature,” he said. Erickson met with Smanski about research opportunities at the university and was hired on the spot.

Smanski, one of the university’s top biological engineers, said carp is not an easy organism to work with and Erickson lacked experience in the field. But he hired the young researcher and assigned him to the carp birth control project because he seemed to have a rare blend of determination and intelligence.

“I could tell right away when I was talking to him that he was like a shooting star,” Smanski said. “If you set a problem in front of him, he won’t stop until he solves it … He’s taken this farther than anyone else.”

In two short years, Smanksi said, Erickson has mastered genetic engineering to the point that his research is starting to bear fruit.

With his new complement of research assistants, Erickson aims to clear his project’s first major hurdle sometime this year. The challenge is to model his experiment in minnow-sized freshwater zebrafish. The full genetic code of zebrafish — like common carp — is already known.

Erickson’s task is to make a small change to the DNA sequence of male zebrafish, kind of like inserting a DNA cassette into the fish, he said. During reproduction, the alteration will create lethal overexpression of genes in the embryonic eggs laid by females.

By analogy, Erickson said, the normal mating process is like a symphony with a single conductor turning on genes inside each embryo, Erickson said. But the DNA modification sends in a mess of conductors and the mixed signals destroy each embryo within 24 hours.

“In the lab we have to make sure we’re causing the disruption with no off-target effects,” he said. “If we can do this in zebrafish, we hope to translate it. … They are genetically similar to carp.”

Erickson’s upcoming experimentation with tank-dwelling live carp could be painfully slow because the fish only mate once a year. But he’s working his way around that problem by altering lighting conditions and changing other stimuli in his lab to stagger when batches of fish are ready to reproduce.

The birth control process — projected to be affordable for fisheries managers if it receives approval — is already proven to work in yeast and insects. And Erickson said the same principles of molecular genetics have been used to create an altered, fast-growing version of Atlantic salmon approved for human consumption in the U.S.

“We’re not building a new carp from the bottom up … but it’s kind of a whole new paradigm, so we have to get it done right,” he said.