Wisconsin Department of Natural Resources fisheries specialists have spent much of January and February updating the public on various projects and trends in northeastern Wisconsin.
One of a handful of meetings, held Feb. 3 at the DNR Service Center in Green Bay, focused on trout habitat and population trends in Oconto and Marinette counties.
Tammie Paoli, a DNR fisheries biologist based in Peshtigo, discussed brown and brook trout populations in the South Branch and First South Branch of the Oconto River, which flow through northern Oconto County.
The DNR surveys trout populations in the South Branch west of Mountain every two years.
“We caught more browns the last time we did this in ’24,” she said. “There was a really nice showing of young-of-the-year in that 2- to 3-inch size and lots of different age classes, including one fish that was over 22 inches.”
Besides capturing, measuring and releasing fish, DNR crews also record the number of fish per mile and researchers found a thriving population of browns in the South Branch.
“Brown trout 8 inches or greater actually increased from 2022 to ’24,” Paoli said. “It’s a good trout stream for browns if you can catch them.”
Brook and brown trout are successfully reproducing naturally in the South Branch, but browns have outnumbered brookies since a regulation change that took effect 10 years ago, she said.
“We wanted to expand some additional harvest opportunities for brown trout,” Paoli said. “We changed it in 2016 to the current 8-inch size minimum and a three-fish daily bag limit. We thought that by maybe opening up harvest opportunities, we might be seeing fewer browns (in surveys), but that’s not what happened. The opposite happened.
“Maybe it’s too soon to really know for sure. It’s only been a handful of years that we’ve done this survey since that regulation change, but there might be some other things that are going on. Part of it might be climate change. Brown trout do better in some warmer waters. We just don’t see much for browns in the First South Branch vs. the main South Branch. I can’t explain why.”
The Oconto River and its branches — including the North, South and First North — offers anglers a great trout fishery, according to Paoli.
“Habitat is a huge factor, almost too much habitat in some areas,” she said. “Some of these systems are a bit more resilient against some of the climate issues. We just don’t see the development. National forest land or the Menominee Reservation covers most of the South Branch area. The lower reaches are agriculturally dominated, but even that has changed. There used to be a lot of cattle-watering systems in the South Branch area. Those are a thing of the past because nobody has cows anymore, so we have no reason to worry about grazing.”
The DNR and U.S. Forest Service have worked to make more stretches of the Oconto accessible to anglers. One stretch along the South Branch in the Chequamegon-Nicolet National Forest west of Mountain includes several handicap-accessible wooden fishing piers.
The DNR estimates Oconto and Marinette counties have a combined 1,000 miles of trout streams.
“It’s incredible,” Paoli said. “There’s a map showing all the trout streams of Wisconsin and our area has one of the highest concentrations besides the Driftless Area. It’s incredible because we just don’t see the fishing pressure.”
Northeastern Wisconsin’s streams such as the Oconto and its branches also have long undeveloped stretches.
“National forest land or the Menominee reservation covers most of the South Branch,” Paoli said. “The very lower reaches are agriculture-dominated, but even that has changed. There used to be a lot of cattle-watering systems that the department put in in the South Branch area, but those are a thing of the past. Nobody has cows anymore, so we have no reason to worry about grazing.”
The DNR has also been monitoring trout in a half-mile stretch of the First South Branch just south of County Road W west of Mountain every other year, including last year.
“There is a series of bank coverage that was installed in the late ’80s or early ’90s and they’re getting old,” Paoli said. “The bank covers provide really good habitat. It’s really an awesome sight to survey, but we’re seeing that some of them are starting to fail. There is a plan to do some work on those.”
Crews ended up capturing fewer, but larger, brook trout last year.
“When we look at legal-sized fish — 8 inches or greater — we did see an improvement in our most recent survey,” Paoli said. “It’s certainly something we’re going to have to keep an eye on. Long-term, we’re not seeing anything really jumping out as a big problem.”
