Missouri Scientists Listen to Ancient River Giant to Prevent Extinction | KCUR 89.3
Sarah Peper was getting ready to go to church last month when she received an unexpected phone call from a colleague alerting her to a rare occurrence: lake sturgeon were spawning along the banks of the Mississippi River near St. -Louis.
“I dropped what I was doing and went out there as fast as I could,” said Peper, a fisheries biologist with the Missouri Department of Conservation.
A few hundred yards from the towering Melvin Locks and Price Dam in West Alton, five endangered lake sturgeon congregated in the shallows, flapping their tails against the current and releasing grain-sized eggs of pepper.
Peper and his colleagues have studied the species for years, but this was the first time they had seen it breeding in the wild. “We had a little sturgeon spawning party on the shore; we were all so excited,” she said.
The lake sturgeon is an ancient creature that evolved millions of years ago when dinosaurs still roamed the Earth. The species was once common in rivers and lakes from Minnesota to Louisiana, but over the past century overfishing and habitat destruction have driven it to near extinction.
Missouri scientists are now tracking Mississippi’s river giants to understand where they breed and identify critical habitats to protect.
One of the largest freshwater fish in North America, lake sturgeon can weigh over 300 pounds and reach lengths of nearly eight feet, about a foot longer than a king-size .
Nicknamed the “rubber nose,” the lake sturgeon has a scoop-like snout and long, whisker-like organs near its mouth that it uses to hunt snails, crayfish, and other small prey.
Lake sturgeon populations have plummeted in recent decades, prompting nine states to list the species as endangered: Missouri, Illinois, Iowa, Indiana, Ohio, Kentucky, Tennessee, Pennsylvania and Vermont.
A federal court last year order the U.S. Fish and Wildlife Service to determine if lake sturgeon should also be protected under the federal endangered species law by 2024.
The lake sturgeon is a strong swimmer that can travel hundreds of kilometers through rivers and tributaries, but man-made dams have divided its habitat and prevented it from reaching spawning sites.
“In the early 1900s their numbers were already dwindling due to overexploitation, but the changes we made to the river to improve navigation really destroyed a lot of habitat,” Peper said. “When they get a double like that, it’s going to be really difficult for them to recover without help.”
Peper is part of a team of scientists who study the movements of the lake sturgeon before and after its reproduction, essential information for the protection of the species.
Ahead of the spawning season this spring, the group captured a dozen adult lake sturgeon from the Mississippi River and carefully implanted radio transmitters under the silvery skin of their bellies, adding to the hundreds of other lake sturgeon that researchers have marked in previous years.
On a blustery April morning, wildlife biologists and scientists from the Army Corps of Engineers boarded a flat-bottomed speedboat and crossed the Mississippi River near West Alton, dragging a special microphone into the water to listen to the tagged sturgeons.
A few minutes later, the radio receiver turned on as a tagged sturgeon passed under the boat. This fish, Individual 22462, was tagged three years ago in Keokuk, Iowa.
Some tagged fish traveled up to 600 miles in just six months, including a sturgeon that swam as far as Iowa and Ohio before returning to Missouri.
A separate receiver attached to an underwater concrete anchor records any tagged fish that pass nearby. In the past month, the receiver has recorded 25 tagged fish, including 18 lake sturgeon.
The rocky shore of the Mississippi near Melvin Locks and Price Dam is the only known spawning site for lake sturgeon in Missouri. By tracking each sturgeon’s movements during reproduction, the team hopes to identify specific habitats to protect, said Army Corps wildlife biologist Ryan Swearingin.
“Hopefully when we have the right conditions we can help keep this area as hospitable as possible during this spawning period,” Swearingin said.
Because sturgeons prefer specific temperatures and water velocities during spawning, he said, the Corps considered whether to open the dam gates just enough to create the “sweet spot” water velocities for sturgeon spawning.
“We’re trying to use the structure of the dam to give us some sort of advantage,” Swearingin said. “There are a lot of dams upstream, so maybe there is potential where we could do similar management there as well.”
For Peper, the project is part of a much larger effort to bring lake sturgeon back from the brink of extinction. The species has survived cataclysmic events for millions of years, she said, but unless prompt action is taken, it is likely to disappear forever.
“Think of all that has happened in those 150 million years; there was the asteroid that killed the dinosaurs, the continents that crashed and broke apart, the volcanoes and the earthquakes,” she said. “These fish have survived all of this. But they can’t survive us unless we do something about it.
Follow Shahla on Twitter: @shahlafarzan
Copyright 2022 St. Louis Public Radio. For more information, visit St. Louis Public Radio.