The odd-looking, prehistoric paddlefish is making a comeback in Minnesota rivers
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Anthony Sindt and Hannah Anema wait silently in a motorboat on the Minnesota River, listening as the hydrophone they’ve dropped into the water picks up ultrasonic signals. Each ping is almost like a unique barcode, which helps them identify tagged fish.
The Minnesota Department of Natural Resources fisheries specialists are looking for paddlefish— a large, prehistoric boneless river fish species native in Minnesota and throughout the Mississippi River Basin. They prefer backwaters and slow-moving currents.
Paddlefish have been swimming in North American waters since the age of dinosaurs, 125 million years ago.
And they do look like they come from a different time–they have a long paddle-shaped snout called a rostrum, and a huge mouth with no teeth. The rostrum detects zooplankton, their primary food source, which they filter-feed through their large mouths.
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The odd-looking fish can grow to be huge; adult paddlefish can be up to 5-7 feet long, weighing 60-80 pounds. They have a shark-like dorsal fin and smooth skin.
“They have this really cool blue tone to them, and their backs get really dark,” the DNR’s Hannah Anema said. “They actually have what I would almost compare to leopard spots on their gill covers. They’ve got the really cool markings right on their gill plate, and their fins are really a purpley-mauve color.”
The paddlefish are a threatened species here. Their numbers declined over the last century because of overfishing, habitat loss, poor water quality and dams preventing them from migrating upstream to spawn. Paddlefish are a migratory species that may travel hundreds of miles within a year to complete their annual life stages.
The DNR’s Anthony Sindt said paddlefish weren’t being monitored or tracked because they aren’t considered an important sports fish that are prioritized like walleye, pike or bass in Minnesota. He added that paddlefish are also difficult for the DNR to sample in the fisheries.
“So for a long time, it was thought that the paddlefish population may not be very large or as big as it once was,” Sindt said. “But, we don’t necessarily know for sure if that’s true.”
For example, “In the Minnesota River, DNR fisheries staff had only captured one paddlefish in a survey prior to 2016,” Sindt said. But then the DNR funded a three year project to specifically to search for and study paddlefish, their movement and preferred habitat.
“During that three year project, we sampled somewhere around 80 plus paddlefish from the Minnesota River we just didn’t necessarily know existed,” Sindt told MPR, adding that the DNR has uncovered larger communities of paddlefish living in the St. Croix and Mississippi Rivers in recent years too.
Returning through reconnection
It’s unclear whether paddlefish are spawning in Minnesota’s rivers more, if more of the fish are migrating from other places, or both. But, researchers are working to find out and learn more about their behavior.
On a warm and sunny day last week, Anema and Sindt headed out on the Minnesota River in a boat equipped with hydrophones and other high tech gear in search of the elusive paddlefish. Near the Highway 22 bridge, Anema and Sindt check on a stationary receiver. While Anema replaces a battery on the receiver, Sindt uploads the data onto a laptop.
“Any tagged fish or fish with a transmitter implanted in it that swims near this bridge, if it emits the signal while it’s somewhat nearby will pick it up, save the information of the fish number and the specific time,” Sindt said.
“Then we can upload that data and use that from all the receivers throughout the river to better understand movement patterns of different fish species such as paddlefish.”
The Mississippi River Basin is an important corridor for fish migration in the Midwest and connects fish to spawning sites, feeding grounds and winter habitats. It’s from the data picked up from these receivers, Anema said, the DNR has been able to see how far paddlefish have been traveling.
“Just some of the movement coming up from all the way down by pool six, which is in Iowa, just paddlefish caught on our receivers that have traveled up from farther down the Mississippi,” she said. “We’ll pick up a weird tag, like ‘Oh, that might not be our state.’ That’s pretty cool.”
Paddlefish are rare to see, and they’re illegal to catch because of their threatened status. But more anglers have caught paddlefish by accident on this stretch of the Minnesota River near St. Peter. Anema said it’s likely a spot where these fish seem to like to gather, depending on the season.
“Compared to the surrounding parts of the river, it makes a really good pool for a lot of fish to congregate,” she said. “People do really well for fishing this specific stretch quite a bit, which leads to running into these paddlefish that sit around in this area.”
Sindt said improving water quality and growing efforts to remove dams appear to be helping paddlefish thrive.
“We can be hopeful that they will have access to important habitats and potentially help increase their abundance and health of their population in the whole system,” he said. “I know it will do that for other species as well.”
‘A very fascinating creature’
The resurgence of the paddlefish is being embraced by the people of St. Peter.
There’s even a local brewery named after this peculiar underwater behemoth. Paddlefish Brewing Company, near the historic Highway 99 Bridge, pays homage to its namesake with a scrap metal art sculpture hanging in its taproom, and a wall of photos of people holding paddlefish, among other items honoring the prehistoric fish.
Long said when he first laid eyes on a paddlefish, he was hooked.
“This is a wild creature,” he said. “Not the prettiest creature, but it’s a very fascinating creature.”
Long said whenever a customer stops in, their first reaction to the paddlefish seems to be shock, and then it shifts to curiosity. He’s hoping to learn the history of paddlefish in the Minnesota River near St. Peter is a unique connection that draws people to the town.
“I think it’s important as a person living to be in awe and wonder and learning and seeing all the weird and wild things we have not only in the world, but on a micro level, right here in St. Peter,” Long said. “These paddlefish are living right under our feet.”
