Decked out in waders and battery-powered backpacks, a crew from the Minnesota Department of Natural Resources cut through brush to reach a stream in Wabasha County. The State Fair was approaching, and it was time to catch some fish.

Led by fisheries specialist Eric Sanft and biologist Dan Spence, the group of four were looking for "brookies," or brook trout, in a tributary of the Zumbro River. Spence and another member of the team wore the specialized backpacks, attached to long metal poles that ended in a loop and a trailing bundle of wires. The hardware runs an electrical circuit through the water. The idea was to stun the fish, but not kill.

Spence agreed that the equipment had a "Ghostbusters" look. "It may or may not have been borrowed from work for Halloween," he said. But there were no specters to catch — only the fish that, caught in the current, slowly floated to the surface.

Every year for at least two weeks before the Great Minnesota Get-Together, DNR crews fan out on rivers and streams to help stock the agency's centerpiece pond and aquariums inside its log building. As opening day approaches, they also retrieve truckloads of captive fish, some of which have attended the fair for decades, from a clandestine location that the DNR guards throughout the year.

It's all an effort to put together one of the most popular fair attractions, and one of the few where visitors can actually see wild animals rather than domesticated livestock.

Waist-deep in the chilly trout stream, Sanft and Spence found that a job that might normally have taken an hour stretched through the morning. The stream was full of "young-of-years" — fish that emerged in the spring but were too small to bring to the fair. One of the crew found himself pulled into mud and clambering over the limbs of a fallen tree as he extended the electrical probe to coax trout out of a deepwater pocket.

Eventually, after slowly walking against the current, the team had netted enough mature fish to fill two buckets. These trout were one of the few populations in Minnesota that could not be genetically linked to any known hatchery, meaning their ancestry stretched back to when Minnesota was covered with glaciers.

They were loaded into a specialized tank on the back of a truck, where the water was cooled and continually pumped with oxygen to keep the fish breathing. Not every fish was likely to survive the trip to the fairgrounds — a stowaway white sucker was already floating belly-up by the time it was placed inside.

The reality, Sanft said, is that fish regularly die in the process of catching them or transferring them over to the fair. At times, "it feels counter to like, what our job is," he said. At the same time, the fair displays are a crucial outreach tool for the agency, he said.

Spence added, "People see fish as individuals. When they see a 30-inch walleye die, they freak out, when there's hundreds of thousands of walleyes that size [in the wild]."

A state secret

Many of the fish at the fair are repeat guests, staying the rest of the year in a pond the agency keeps as a closely guarded secret. It's ringed with a barbed wire fence and obscured by brush. For those 50 weeks, through fall, winter and spring, the DNR mostly leaves the state's most famous fish alone, to live and die and, probably, eat each other in the confines of the 1-acre pond.

One lake sturgeon that calls the pond home dates at least to the late 1980s, when it was caught in Lake St. Croix, said TJ DeBates, east metro area fisheries supervisor for the DNR. The fish can live to 100, though fishery managers don't know the exact age of this sturgeon.

If an angler snuck in and managed to land one of the bigger residents of the artificial pond, they could easily notch a state-record catch — though it would be hard to mark in the record books. That doesn't mean people haven't tried. On a recent visit to the pond, which had been drained of all but small rivulets running across the cracked-concrete bottom, Genevieve Furtner pointed to a broken fishing rod sitting on high ground. "We don't know how it got here. We don't know who it's from," she said.

Furtner, the state fish hatchery manager, used to be on call 365 days a year to respond to anything that surveillance cameras around the pond picked up. Once, Furtner walked up to a camera to find that it had been nudged upward, the lens pointed towards the sky. The cameras have since been dismantled, since they only ever seemed to capture birds or rustling grass.

The agency now places floating nets on the pond to block poachers from dropping in a line.

But mostly, the DNR tries to keep the pond as natural as possible. Except for scraping some muck out of the bottom every year, "we let the fish be fish," Furtner said.

Then, every August, the water is drained, and the fish make their annual trip to Falcon Heights.

Homecoming

Moving hundreds of fish into the fair pond itself is a challenging operation — five specialized trucks and two trailers pulled up at various times to drop off fish on Aug. 20 — and above all, it can be stressful for the animals.

The biggest specimens were gently lowered into the pond with little problem. Furtner stood in waders in the water — pumped up from a well that runs about 53 degrees — and took fish after fish, wrapped in a brown mesh cradle. She dipped it under the surface and unzipped the sides to release what she called the state's "river monsters," gar and paddlefish.

"That's a dang nice paddlefish," she said as one of the filter feeders pushed its rounded nose forward through the water. "That's going to be the star of the fair this year."

Not every fish was so lucky. Earlier, someone had forgotten to turn the oxygen on in the tank of a truck holding a group of much smaller fish, meaning the occupants could have asphyxiated on the ride to the fairgrounds. Sanft was there to receive them, dropping them into the water from a net at the end of a long pole. Some lingered, immobile, at the bottom of the pool.

Sanft nudged a small freshwater drum, its silvery stomach shining as it sat on its side. The fish jolted awake, and swam away. "We're lucky we didn't kill all of them," he said.

Not all of the fish would stir. As she chatted with onlookers and assembled media, Furtner waded through the pond and gathered some of the dead fish in a net.

"We all make mistakes," DeBates said later when asked about the dead fish. But he said the agency does its best to keep occupants of the pond comfortable. "Every year I feel like we're doing better, we're taking better care of the fish."

A few days later, on the hottest day of the fair, there was no sign that anything had gone wrong. The brook trout sat in the DNR building in a cooled aquarium coated in condensation. Outside, hundreds of fish whirled through the pond. Despite the sticky weather, visitors ringed the pool to point at paddlefish, walleye, and the massive muskies.

Gus Gustafson, who was wearing a red and white bobber as a dangling earring, peered into the pond with sons Ben, 6, and Wes, 4. Gustafson said the exhibit made it easy to pick out species that might not end up at the end of a line, even though the family goes fishing about once a week.

"What's that one?" Wes asked, pointing to a long, slender fish with a rounded snout.

"A shortnose," Gustafson replied, pointing out the gar species on a DNR poster of Minnesota fish. They lingered a few minutes longer under the bright sun, and then left, saying goodbye until next year.