Ancient fish, modern problem: How the pallid sturgeon could be a warning for the Missouri River
By Elizabeth Rembert , Food, Energy and Agriculture Reporter Nebraska Public Media, Harvest Public Media
June 12, 2023, 5 a.m. ·
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Every day in the spring and fall when water temperatures are right, a team of scientists meet at a boat ramp off the Platte River in Nebraska. Waders on, they board an airboat and head to the fishing lines they baited with worms the night before.
A graduate student leans forward on the boat, reaching for a line and reeling it in.
“Looks like there’s a fish or two on,” said Mark Pegg, a fisheries ecologist and professor at the University of Nebraska-Lincoln. “Might not be the right fish.”
Plenty of catfish, carp and shovelnose sturgeons took the bait, but that’s not what they’re hoping to find swimming in this tributary of the Missouri River.
They’re looking for the endangered pallid sturgeon, a funny-looking fish with a long snout and humped back, all covered in sandy scales.
Since the age of the dinosaurs, pallid sturgeon have swum in what became the Missouri River. They survived mass extinctions and multiple ice ages.
But populations have plummeted over the last 90 years, as construction to protect against flooding and increase navigability in the Missouri River have impacted the fish’s ability to survive.
In 1933, engineers with the Army Corps started building dams, pushing in river beds and removing miles of slow, calm side streams. It deepened the river and sped up the water’s pace to create a navigation channel for the shipping industry.
The projects largely eliminated the fish’s habitat, and Wayne Nelson-Stastny with the U.S. Fish and Wildlife Service said soon it was rare to catch a young pallid sturgeon.
“What they were capturing was older fish, never anything in the small, young type pallids,” he said. “And so there was a major concern about ‘Are we going to have this population go extinct?’”
It took millions of years of evolution for pallids to reach their efficient form, uniquely suited to the Missouri River, said Nelson-Stastny.
“If you were going to design a fish in an engineering program to adapt to the Missouri River, where you can’t see but you can smell, you can hear, and you have to be able to handle the currents, a pallid sturgeon is what you would design,” he said.
Biologists were worried about what it meant if this fish — so in tune with the river — was struggling.
The pallid sturgeon joined the endangered species list in 1990, and the Corps of Engineers adopted an action plan to rehabilitate the species.
“The Corps is required to address its impacts on the pallid sturgeon,” said Joe Bonneau, a program manager with the agency. “That includes a hatchery and habitat restoration projects on the lower river.”
Chris Hooley is a fish biologist at the Gavins Point National Fish Hatchery in Yankton, South Dakota, where they raise baby pallids from eggs and release them into the river to keep the population going. They also track the fish to learn more about its habits and what it needs to survive in the river.
“This serves as a genetic backup for the pallid sturgeon in the upper Missouri River,” he said. “Field crews go out onto the river, catch the fish and bring them to the hatchery, and we’ll raise their offspring before we release them and tag them for tracking.”
Eventually, biologists want the fish to reproduce naturally and grow in the Missouri, without their help. To do that, scientists think baby pallids need side streams of slow, shallow waters to grow up without getting swept up in a fast current – or a catfish’s mouth.
The Corps of Engineers has re-created those habitats by purchasing land from willing sellers. But changing stretches of the river to benefit endangered species hasn’t been popular. It came to a head after the region saw devastating floods in 2011 and 2019. Farmers blamed the habitat restoration projects for their damaged property.
“I've been in meetings where busloads of people show up and say, ‘My farm is not your laboratory,’” Nelson-Stastny said.
But to Gerald Mestl, who worked in Nebraska Game and Parks for decades, the pallid sturgeon has mistakenly become a scapegoat for larger problems on the river.
“The ecosystem is in trouble on the Missouri River. It's not the pallid sturgeon is in trouble,” he said. “It’s unfortunate that the message is lost. The river’s ecosystem supports a lot more than just the pallid sturgeon.”
Bigger problems on the Missouri
Mestl’s research found that narrowing the river for the navigation industry increased flood heights and frequencies. He said undoing those projects and widening the river could restore habitat for animals like the pallid sturgeon and make more room for flood years.
“Yes, it will cost a lot of money,” Mestl said. “But we will have a system that will meet our needs today and for a long way in the future.”
A future that will likely include more flooding as intense storms occur more often in the region.
Rezaul Mahmood, a climatologist at the University of Nebraska-Lincoln, has studied how storms in the Missouri River basin have changed over the last 70 years.
His research showed extreme precipitation events have gotten worse and more frequent over the years, which signals that increased flooding is likely in the Midwest and Great Plains.
“Our engineered systems are not designed to deal with this,” Mahmood said. “We designed the system based on historical records. But when nature itself changes course, it becomes much more difficult.”
Adapting the river for the future climate reality may require a new balancing act between environment, animals and the people that live along the river and depend on it for farming, navigation, recreation and hydropower.
Luckily, Bonneau said stakeholders already have a blueprint for that teamwork, through the case study of the pallid sturgeon.
“That’s one thing pallid sturgeon are teaching us,” he said. “There are solutions that can address stakeholder needs and the purposes of the river. It takes a lot of effort, good science and teamwork, but we’ve done it on the Missouri River, because of the pallid sturgeon.”
This story is part of NOVA’s Climate Across America initiative with support from the Corporation for Public Broadcastin, and distributed by Harvest Public Media, a collaboration of public media newsrooms in the Midwest. It reports on food systems, agriculture and rural issues.
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