Brad Dokken: Determining the extent of winter fish kills in North Dakota a work in progress, managers say

May 13—Now that the ice is finally off all or most lakes, the extent of winter fish die-offs in North Dakota is coming into focus, fisheries managers say.

In the Game and Fish Department's Northeast Fisheries District, winterkill has been documented in about 10 lakes, including North Golden Lake in Steele County, Harvey Dam and Goose Lake in Wells County and Juanita Lake in Foster County, said Randy Hiltner, Northeast Fisheries District supervisor for Game and Fish in Devils Lake.

Juanita is primarily a pike and perch lake, along with bullheads, carp and white suckers.

"That's one that will winterkill in almost a normal winter, so no surprise," Hiltner said.

Other lakes that winterkill regularly include Niagara Dam, just off U.S. Highway 2 near Niagara, North Dakota, and Buffalo Lake near Esmond, Hiltner says. Winterkill occurs when heavy snow and ice block sunlight, in turn preventing photosynthesis. Die-offs result when oxygen levels diminish to the point where fish can no longer survive.

"The worst part was that when the snow came, it never blew off the lakes," Hiltner said. "It was solid snow cover the whole winter."

Perhaps the most significant fish kill in the Northeast District appears to have occurred on North Golden Lake, Hiltner said. Perch, walleyes, bluegills and pike — in that order — are the predominant gamefish species in North Golden, with perch comprising 25% of the catch and walleyes making up 15% of the catch in a 2022 survey. "A fair number" of those walleyes were longer than 20 inches, and bluegills up to 9 inches were observed in the summer 2022 survey.

In his 30 years with the Game and Fish Department, Hiltner says this is the first time he recalls a winterkill on North Golden, which measures 317.3 acres with a maximum depth of 12.6 feet. He received photos of the fish kill on North Golden from Drew Johnson, the department's district game warden in Finley.

"There were dead bullheads and bluegills and big walleye, perch, so again, that's a significant kill for sure, and we're going to plan on getting over there and netting that to see what's left," Hiltner said. "Whenever the bullheads are dying, you know it's a significant winterkill."

Meanwhile, "lots of dead perch and bullheads" were documented at Harvey Dam, and Northeast District fisheries biologist Todd Caspers observed dead walleyes while driving by the west side of Goose Lake on state Highway 3 en route to a meeting, Hiltner says.

"I've heard some other reports that there's quite a few dead fish at Goose so it's a significant fish kill," Hiltner said. "We'll have to do a follow-up netting survey to see what's left in there."

On the upside, Hiltner said he did hear a report of a northern pike run on the west side of the lake.

"Sometimes that happens, too, where you get a big walleye-perch kill, and then it hardly phases the pike," he said.

The news isn't all bad, though. Red Willow Lake, a popular 151.4-acre fishery northwest of Binford known for pike, walleyes, bluegills, largemouth bass, perch and pure-strain muskies, appears to have "skated by" and avoided a winterkill, Hiltner says.

"I was over there when about half the ice was off, and I didn't see any dead fish," he said. "So, that might be one we got through without a fish kill."

As of this week, at least, Hiltner said he hadn't gotten any die-off reports from fisheries closer to Grand Forks such as Fordville, Larimore, Whitman and Matejcek dams, either.

"I haven't heard anything," he said. "We had a lot of places — we were over there in February, and a lot of places would have decent oxygen like 3 to 4 feet under the ice and then get progressively worse as we went down. We just hope the fish ride up high in the water column and make it through."

All told, Hiltner estimates fish die-offs occurred on "roughly 10" of the district's 45 to 50 lakes, when including fisheries such as Niagara Dam and Buffalo Lake that winterkill regularly.

Just in the past couple of days, adult perch, some of which hadn't yet spawned, were stocked into North Golden Lake, Goose Lake and Harvey Dam as part of efforts to replenish the fisheries.

The perch have come from lakes in the Southeast Fisheries District, Hiltner says.

"They've got some really good perch lakes — some have way too many perch — and (they have) been helping multiple districts to replenish perch populations after the winter kills," Hiltner said.

Statewide, Game and Fish has a list of about 85 lakes with potential fish kills, with die-offs now confirmed in 35 to 40 of those, said Greg Power, fisheries chief for Game and Fish in Bismarck.

The magnitude of those 35 to 40 fish kills remains to be seen, Power said

"I think we'll have a lot firmer feeling about a week from now," he said. "We've done little or any netting ourselves. These are just what we've seen or the public has called in."