The lake sturgeon is a lumbering giant that makes a living grazing on aquatic invertebrates and mollusks with its tubelike mouth, which protrudes from beneath its nose. With five ridges of armored plates and gray, leathery skin, Acipenser fulvescens is a relic of the dinosaur age. Measured from the tip of its bullet-shaped head to its shark-like tail, an adult lake sturgeon can exceed 7 feet and weigh 100 pounds or more.
Lake sturgeon are to Minnesota's rivers what bison once were to the Great Plains. In the Lake of the Woods region, lake sturgeon provided a reliable source of sustenance for the Ojibwe who lived along the Rainy River. Because of this abundance, early Europeans regarded these Ojibwe as difficult trading partners. But, just as wanton slaughter extirpated bison from the state, overfishing, dams, and pollution nearly wiped out Minnesota's lake sturgeon.
Watch researchers net and tag lake sturgeon to better understand how these fish move in the St. Louis River.
St. Croix River Sturgeon Swim On
It's likely that good water quality helped prevent lake sturgeon from being extirpated in the St. Croix River after European settlement. But rafts of timber floating down the St. Croix River during the logging boom in the 1800s and early 1900s may have also made exploiting lake sturgeon difficult, according to DNR fisheries specialist Joel Stiras.
Whatever combination of factors allowed lake sturgeon to hang on in the St. Croix River, the fish began to receive modest legal protection beginning in 1920 with a Minnesota law that required sturgeon less than 15 pounds to be released. In 1947 the Department of Conservation enacted a daily limit of one sturgeon 30 inches or longer. As decades passed the minimum length for harvest increased, but one sturgeon a day was allowed until 1992, when the creel limit changed to one fish over 50 inches per year during a special fall season. In 2009 the limit was changed to one sturgeon over 60 inches.
Today the lower St. Croix River's sturgeon population is estimated at more than 5,000 fish, based on recapture data from 635 sturgeon tagged by fisheries researchers between 2003 and 2014. The fishery is especially popular with the expanded catch-and-release fishing opportunities, says Stiras, who receives reports from anglers when they catch a tagged fish.
"Some anglers are catching [and releasing] 30 or more sturgeon in a trip," he notes. "Most of the time they are smaller when they catch a lot, but fish over 40 inches are common." And every year it seems some lucky angler hauls in a sturgeon that weighs 100 pounds or more. "We had a biologist sample one like that in the spring of 2015 that was 79 inches long and estimated at 125 pounds," says Stiras.
Population estimates based on tagging are complicated by the fact that lake sturgeon can move great distances, says Stiras. In 2013 the DNR began implanting acoustic transmitters in lake sturgeon in the St. Croix and Mississippi rivers to see where the fish go and when. "We have seen a fair amount of movement between the St. Croix and Mississippi rivers," says Stiras.
By the early 1900s these prehistoric fish were extirpated from the Red River of the North as well as the St. Louis River and the western basin of Lake Superior. The last known native-born lake sturgeon from the upper Minnesota River watershed washed up on the shores of Big Stone Lake in 1938.
But sturgeon recovery work by the Department of Natural Resources in cooperation with neighboring states and tribal and federal resource agencies has achieved some remarkable successes. Thanks to careful fishing regulations, dam removal, and cleaner water, Minnesota's largest fish is returning to waters around the state.
Lake of the Woods Turnaround.
In the early 1800s, commercial fishermen killed lake sturgeon simply because they got caught in nets set for walleye, whitefish, and other species. They tossed sturgeon on shore to rot or dried and piled them up like logs to fuel the furnaces of steamships.
The perception of lake sturgeon among commercial fishermen changed in 1855 when a caviar-producing plant opened in Sandusky, Ohio, creating a market for the fish roe. Lake sturgeon harvest topped 1 million pounds a year at the south end of Lake of the Woods during the late 1800s. In addition to the roe, fish processors began selling sturgeon meat, skin for leather, and isinglass—a gelatinous substance in its swim bladder—for clarifying wine and beer. Over a few decades, the Lake of the Woods sturgeon population dwindled to the point where a commercial fishery ceased to exist.
When commercial fishing ended there, sturgeon populations did not bounce back quickly for several reasons. These slow-growing fish don't reach sexual maturity until about age 20, and may spawn as seldom as once every five years. Recovery of the diminished sturgeon population was also thwarted by pollution. Effluent from paper mills had covered prime spawning areas in the Rainy River. Were it not for the Clean Water Act of 1972, lake sturgeon would have likely disappeared from this border water between the United States and Canada. Regulations forced mills to clean up their act. Cleaner water and careful fishing regulations have allowed for a robust recovery of lake sturgeon in the Rainy River and Lake of the Woods.
St. Louis River Saga.
In the St. Louis River and the western basin of Lake Superior, commercial fishing and pollution brought about the demise of lake sturgeon by about 1900. But in 1979 the Western Lake Superior Sanitary District began treating domestic and industrial wastewater before it entered the river. By the early 1980s, water quality had improved enough to attempt restoring lake sturgeon.
The first sturgeon were reared from eggs taken from Wisconsin's Wolf River in the Lake Michigan watershed. Later, eggs came from a Lake Superior strain of sturgeon. Between 1983 and 2001, a total of 142,000 fingerlings and 728,000 sturgeon fry were released into the St. Louis River. Adult fish were first observed in likely spawning areas in 2007. The DNR began collaborating with Minnesota Power to control flows at the Fond du Lac dam during spring spawning. In 2009 boulders were added below the dam to restore 800 feet of spawning habitat, thanks to a partnership of the DNR, the U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Service, and The Nature Conservancy.
Today resource managers from Minnesota, Wisconsin, the U.S. Fish and Wildlife Service, and the Fond du Lac band continue to gather evidence that this fish population is doing well. Fish are captured via electrofishing each spring when the river's water temperature reaches 50 degrees and adult fish move upstream to spawn. Sturgeon are measured, weighed, and inspected for tags. A piece of fin is also gathered for genetic testing. A small electronic tag is implanted via syringe in each untagged sturgeon, and the fish is released. If researchers catch the fish again, they will scan the tag. This monitoring has shown good growth rates, with some stocked sturgeon exceeding 60 inches.
DNR fisheries biologists also implanted acoustic transmitters in 45 sturgeon captured in the St. Louis River in spring 2016. Another 40 sturgeon will receive them in 2017. The transmitters, which have a battery life of about 10 years, track sturgeon movement by sending out signals that are picked up by receivers in the river and in the estuary near Duluth.
"With that technology we can better evaluate the use of the estuary as well as specific habitat areas that might be important," says DNR area supervisor Deserae Hendrickson.
Still, more evidence of successful spawning must be gathered to determine if the river and its population of stocked fish are healthy enough to establish a naturally reproducing population. "Within the last few years, we've seen only the occasional naturally reproduced fish," says Hendrickson, who hopes test nets will show more young sturgeon in the next five to 10 years.
Waters That Flow North.
In the Red River of the North watershed, overfishing and the construction of dams led to extirpation of lake sturgeon. But since the 1990s, seven of the eight dams in the U.S. portion of the river have been removed or converted into sloping rapids—providing fish passage and spawning habitat for reintroduced lake sturgeon. The DNR is working with the U.S. Army Corps of Engineers to convert the last U.S. dam near Drayton, North Dakota, into rock rapids, according to the DNR's Henry Drewes, who supervises northwestern Minnesota's fisheries.
The last remaining dam on the Red River is near Lockport, Manitoba. Drewes says, "To date, we have restored over 400 miles of river as a free-flowing stream in the state of Minnesota."
Dam removal and modification on the main stem of the Red River and similar projects on tributaries opened the way for reintroduction of sturgeon. Beginning in 1997, the DNR trapped juvenile sturgeon from the Rainy River and relocated them to the Red River. Because both rivers are part of the Hudson Bay drainage, the Rainy fish were the closest genetic match, says Drewes.
In 1999, with help from the U.S. Fish and Wildlife Service, the DNR began purchasing sturgeon eggs from the Rainy River First Nations. DNR hatcheries in Detroit Lakes and the Genoa National Fish Hatchery near La Crosse, Wisconsin, typically raise the sturgeon to fingerling stage before stocking. The DNR and the White Earth and Red Lake Indian nations have released more than 2.6 million sturgeon in the Red River, five tributaries, and seven lakes within the watershed.
Otter Tail Lake, historically home to sturgeon, is one of those lakes. Just downstream, connected via the Otter Tail River, is Deer Lake, where Dave Thompson has owned a resort for 27 years. About a decade ago, he says, his guests began catching sturgeon incidentally at one of the lake's better walleye spots.
Thompson was concerned that guests might run afoul of the law if a conservation officer suspected they were intentionally hooking sturgeon. Until recently it was illegal to target sturgeon anywhere other than the Rainy River and the St. Croix River below Taylors Falls. That restriction was lifted, due in part to Thompson's initiative, notes Drewes. He says the resort owner's questions helped advance formal discussions about a statewide catch-and-release season for sturgeon.
In 2014 a fishing regulation change allowed anglers to practice catch-and-release fishing for sturgeon. Special regulations allow some sturgeon harvest on the Rainy River and the lower St. Croix River, but all fishing for sturgeon is prohibited in Minnesota between April 15 and June 15 to protect spawning fish. The new regulations allow for 10 months of catch-and-release fishing for sturgeon statewide. This change is "an acknowledgement that we have made significant progress in restoring the species in multiple watersheds across the state," says Drewes.
For Thompson the recovery effort has been a rewarding journey. In the early 2000s, he helped stock some fingerlings in Otter Tail Lake. "When I asked how many years it would be before we'd start catching them, I was told, 'Oh you won't be able to catch any in your lifetime,'" he recalls. "Now we're catching fish that are over 50 inches long. This is a phenomenal success story."
Return to Minnesota Headwaters.
In fall 2014 Norm Haukos retired as DNR area fisheries supervisor in Ortonville, but he hopes the legacy of his work will be swimming in Big Stone Lake long after he's gone. Haukos grew up here near the shore of this 26-mile-long lake on the Minnesotan–South Dakota border. As a kid he saw old photographs of giant sturgeon that had been caught in Big Stone Lake, headwaters of the Minnesota River. He wondered if they could ever return. But when he started working as the Ortonville area fisheries supervisor in 2001, Big Stone Lake was too turbid to reintroduce sturgeon.
Work in the early 1980s by the Upper Minnesota Watershed District had set the stage for improved water clarity by modifying the dam at the Whetstone River to reduce the amount of silt flowing into the lake. The district and the Roberts Conservation District in South Dakota along with Citizens for Big Stone Lake told lakeshore residents about ways to reduce phosphorous pollution. The two districts and the lake association also collaborated to help farmers upgrade feedlots and implement practices to reduce soil erosion. Those efforts, in addition to restored wetlands in the watershed and bank stabilization projects, helped to improve the lake's water quality.
Around 2005 "we started seeing more vegetation in the lake," says Haukos. "Water clarity improved, and it got to the point where we thought maybe we could reintroduce sturgeon."
Haukos said other dam removals downstream of the headwaters made a sturgeon reintroduction more likely to be successful. "We realized that if there were going to be sturgeon in the headwaters, there are going to be sturgeon downstream," he says. Some of the dams have been converted into sloping rapids that allow fish passage and provide swift water and clean gravel, which sturgeon need to spawn. "The removal of the dam at Minnesota Falls and the removal of the dams on the Pomme de Terre and Lac qui Parle rivers increased the amount of sturgeon spawning habitat that was out there."
The reintroduction is a collaboration between the Minnesota DNR and South Dakota Game, Fish and Parks. In 2014 the first stocking included 6,500 sturgeon fingerlings. The stocked sturgeon are the progeny of fish that spawn in the Wisconsin River, which, like the Minnesota River, is a tributary of the Mississippi. These fish, reared by the U.S. Fish and Wildlife Service, were the closest genetic match to the sturgeon that once swam in the Minnesota River, explains Haukos.
South Dakota and Minnesota contributed another 7,500 fingerlings in 2015, and 3,600 were released in 2016. In fall 2016, DNR fisheries specialist B.J. Bauer reported that DNR biologists caught 12 sturgeon in test nets. He noted the fish ranged from 17 inches to 24 inches and seemed healthy.
"The initial goal is that we would see 30-inch fish within five years. To have growth like that already, we'll easily do it," says 62-year-old Haukos. "I've still got time to catch a big one."