Bringing those numbers down has taken a comprehensive plan.

A team from the U.S. Fish & Wildlife Service explained the process and its importance to Houghton High School students at the Nara Nature Park Monday morning.

“If we weren’t doing this, our fish population would probably be decimated,” said Michael Williams, who led the presentation along with Isaac Rodriguez, both of the Marquette office.

The students — all juniors and seniors — are in a new environmental science class at the school. Many of them are planning to pursue careers in environmental science policy or outdoor careers, said teacher Sarah Geborkoff. She plans to incorporate outdoor learning and work as often as possible.

Garrett Neese/Daily Mining Gazette Houghton High School students Ellie Helman and Brandon Peterson look at lampreys collected by a U.S. Fish & Wildlife Service team during a field trip to the Nara Nature Park Monday.

Ilya Holden, a 12th-grade student, said the class has been learning about what environmental science entails and how much it impacts the world.

Prior to Monday’s lesson, Holden had uniformly seen lampreys as pests.

“It’s hard to remember that even native lampreys are a part of the ecosystem,” she said. “And so just the fact they really need to be focusing on sea lampreys instead of native lampreys is very interesting.”

The sea lampreys reached the Great Lakes from the Atlantic Ocean in the 1930s. Unlike native lamprey, which either only wound fish or do not feed on them, sea lamprey will kill their prey.

A female sea lamprey will lay about 100,000 eggs. Even with a 90% success rate in killing them, that still leaves 10,000.

“We’re not able to fully control them, we just keep it low enough that it’s not an issue,” Rodriguez said.

One method is a backpack-mounted electroshocker, which Williams demonstrated for students. The shocker deactivates at a certain angle, to prevent researchers from electrocuting themselves with an accidental stumble.

“They’ll come up trying to get out of that electric field,” Rodriguez said. “Then we just sweep them up, put them in a bucket, bring them back and ID them.”

Sea lamprey can be distinguished from native lamprey partly by their dorsal fins — divided, unlike the fin of native lamprey.

Depending on how many sea lamprey the team finds and how big they are, a second team will go out and treat rivers and streams with a lampricide. It is essentially a deworming chemical, which interrupts the lampreys’ aerobic respiration. Native lamprey are also affected. However, it would not impact more advanced fish, Rodriguez said.

Teams go back to the waters every three to five years, about the amount of time lamprey are in their larval stage.

In addition to school events, the U.S. Fish & Wildlife will also go to events like county fairs to educate about lampreys. The more people are aware of what they are doing, the better response they get, Rodriguez said.

“A big part of our job is going on to private landowners’ propeties and getting to stream and river locations,” he said. “We wouldn’t be able to shock where we needed to or treat the rivers like we needed to to keep the sea lamprey population down.”

The Houghton High School students will take what they have learned and mentor fourth-grade students in the classroom and the field.

“Being able to experience it more firsthand is definitely going to make it easier to impart to other people,” Holden said.