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Environmental DNA calculates sturgeon populations in Michigan rivers

Sam Silverbrand, Geneticist with the USFWS, sampling for Lake Sturgeon eDNA in the Sandusky River in 2022. Silverbrand also collected eDNA samples this year for the project.
Northeast Fishery Center
/
U.S Fish and Wildlife Services
Sam Silverbrand, Geneticist with the USFWS, sampling for Lake Sturgeon eDNA in the Sandusky River in 2022. Silverbrand also collected eDNA samples this year for the project.

In May, Alpena’s Fish and Wildlife Conservation Office sent their native species crew to the southern part of the state to help with a large project by the United States Fish and Wildlife Services. The crew was looking for the threatened lake sturgeon fish — but not in the traditional catch-and-release way.

The project utilizes eDNA, or environmental DNA, to detect lake sturgeon populations in a variety of rivers. Some of these rivers are located in Michigan, such as the Detroit and Raisin rivers, while others are in neighboring states, such as the Portage River in Ohio and the Niagara River in New York. The DNA is collected through water samples that eventually make their way to the Northeast Fishery Center located in Lamar, PA.

Meredith Bartron is the project leader for this study. She said they’re collecting this way in hopes of detecting sturgeon populations in areas they previously haven’t been able to.

“A number of the rivers have been surveyed with traditional gear over the last 10 to 15 years,” she said. “But no lake sturgeon were detected (that way). We wanted to use environmental DNA as another way to potentially detect the DNA from lake sturgeon in those rivers.”

Bartron said the benefit of eDNA sampling is that crews don’t have to physically find the fish. Instead, they take water samples which go through a filtration system. The filters pick up anything from fish scales to feces to mammal hair and are sent back to the lab. Once there, she said they use something called molecular markers, which narrows their search to just lake sturgeon DNA as opposed to any other organism’s DNA caught in the process.

Samantha Silverbrand is a geneticist involved in the project, and she goes out into the field to collect every year. She said while the collection itself is not difficult, verifying its validity is.

Sam Silverbrand after collecting eDNA samples in the Salmon River in 2024.
Northeast Fishery Center
/
U.S Fish and Wildlife Services
Sam Silverbrand after collecting eDNA samples in the Salmon River in 2024.

“The tricky part about eDNA is just that you can't actually be sure of where the source is coming from,” she said. “It could be a physical sturgeon in the water or it could be from accidental transport by boaters, by our teams, from dead organisms … It can even be transferred by other organisms that have eaten that sturgeon.”

To prevent this, Silverbrand said the teams look for a “true signal,” and they do this by comparing the eDNA with controlled water samples and with molecular markers. Comparing helps the team sort out what samples are from lake sturgeon and what aren’t, as well as if the samples may be coming from their own boats or true to the area.

In 2023, the study revealed lake sturgeon populations detected in Michigan’s Detroit River and River Raisin. Silverbrand said the 2024 samples are still being reviewed and samples are still being collected until July. Once results are concluded, teams will return to the areas where eDNA was detected to do traditional catch-and-release studies.

“eDNA is a really powerful tool,” Bartron said. “It can be used in conjunction with these traditional fishery sampling techniques to learn more and increase our knowledge about distributions of species and then target where fish might actually be.”

Courtney Boyd is a newsroom intern for WCMU based at The Alpena News
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