by CHRIS ROGERS
With a motion akin to milking a cow, Troy LeJeune gently squeezed a trout that lay paralyzed in his arms. “It takes a little finesse, but it’s really easy once you get used to it,” Anna Nelson said. With each squeeze, a stream of bright orange eggs shot out of the fish’s vent and into a collection dish in front of LeJeune. A clove oil solution knocks the trout out for this procedure. Occasionally, LeJeune gently shook the fish to jostle its eggs closer to the vent. When it was all done, he dropped the trout into a tub of salt water, which — believe it or not — helps the freshwater fish recover from being handled, and grabbed the next one.
Nelson and LeJeune work at the Minnesota Department of Natural Resources’ (DNR) Lanesboro Fish Hatchery, and in one morning last week, they and their colleagues collected around 180,000 trout eggs. It is spawning season at the hatchery, and hatchery staff members will collect eggs once a week for the next few weeks, then incubate those eggs, raise the baby fish — called sac fry — and eventually ship them across the state to be stocked at cold-water streams and lakes.
The Lanesboro Fish Hatchery is the largest cold-water hatchery in Minnesota. The majority of the state’s brown trout are produced at the facility, just off the Root River. In a single year, the hatchery will send nearly 760,000 young trout as far as the Twin Cities, the North Shore, and the Boundary Waters, as well as to local creeks and streams. Native brook trout and naturalized brown trout and rainbow trout reproduce enough to support self-sustaining wild populations in some Southeast Minnesota streams, but the DNR stocks trout to help keep up with fishing demand and to maintain populations in streams where sediment and other pollutants have weakened wild trout reproduction.
The Lanesboro hatchery has an unusually abundant supply of clean, cold water that allows it to raise more trout than anywhere else in the state, assistant hatchery supervisor Derrick Casper explained. The hatchery is built at the headwaters of Duschee Creek, where two springs pump out a rush of pure water. “This is the blessing of Lanesboro,” Casper stated. “You get about 6,000 gallons per minute.”
Unlike some Driftless Region springs, which are affected by surface runoff during rain events, the Duschee Creek springs are consistently clean, Casper said. “Even when it’s really flooding and all of that — if it’s a really heavy rainfall, you might see a tiny bit of sediment, but that’s it,” he stated.
Once in the 1980s, the hatchery had a problem with excessive sediment in the spring water, Casper recalled. DNR staff discovered it was caused by a new sinkhole some distance away; the sinkhole was sealed and the water cleared up, Casper explained.
The DNR diverts some of that spring water to hatchery buildings where eggs are incubated in trays, sac fry and fingerlings are fattened up in large tubs, and concrete raceways where the hatchery’s adult brood stock do their part to further their species. Pallets of highly specialized trout food — made from ground-up fish — are shipped in from Utah. How much food the trout need to reach a certain size by a certain date has been refined to an exact science, Nelson said. So, when a DNR fishery in Finland, Minn., orders a particular size of brown trout fingerlings to be delivered in early spring, the Lanesboro hatchery staff know exactly how much to feed the fry in order to hit the target size on delivery day.
“Fish have a very good feed conversion ratio compared to other species,” hatchery supervisor Scott Sindelar said. A 600-pound Holstein steer, for comparison, might have a food-consumed-to-weight-gained ratio of 5:1, according to the University of Minnesota Extension. With fish on the other hand, “Almost all of the feed gets turned into fish biomass,” Sindelar explained. “There’s almost no waste.” That is because, as cold-blooded animals, fish do not have to spend energy on regulating their body temperature, and because they float in water, “They don’t have to fight gravity as much as other animals,” Sindelar said. “And respiration is a lot easier,” he added. “They can pull oxygen out of the water without too much difficulty.” It is enough to make one wonder why any animal would want to live on land.
Hundreds of thousands of fish do produce some waste, however, and the Lanesboro hatchery has something like a mini-sewer plant to handle it all. Before being returned to the creek, water that flows through the hatchery is routed through settling ponds and clarifiers that capture fish-waste solids. Those solids are later applied to fields as manure, and, just like a municipal sewer plant, hatchery staff have to test the water they release back to the creek regularly to make sure it meets the Minnesota Pollution Control Agency’s strict standards.
When the hatchery’s young trout reach fingerling and yearling size, DNR staff load them up in specialized trucks and semi-trailers full of holding tanks bubbling with oxygen to keep the fish healthy during transport. Nelson explained how she must make sure the water the trout are being released into closely matches the temperature of the water they are transported in or the fish can die of shock. Once they adjust the fish to any temperature differences, DNR staff release the little trout to swim off and find insects to eat and quiet pools in which to hide. “We get to see a lot of Minnesota going to stock fish,” Nelson said, adding, “It’s a dream job.”
The Lanesboro Fish Hatchery is open to the public on weekdays from 7 a.m. to 3:30 p.m. For more information, visit www.dnr.state.mn.us/areas/fisheries/lanesboro-hatchery/index.html.