Several North Dakota lakes face risk of winter fish die-offs, fisheries managers say

BISMARCK – December’s moist, heavy snow could not have come at a worse time from a fishing standpoint and is now affecting dissolved oxygen ranges in a number of lakes throughout North Dakota, growing the potential for fish die-offs, based on Greg Energy, fisheries chief for the North Dakota Sport and Fish Division in Bismarck.

Winterkill happens when heavy snow blocks daylight from reaching the water, hindering the flexibility of aquatic vegetation to supply oxygen via photosynthesis. As crops die and decay, they will deplete dissolved oxygen ranges to the purpose the place fish can’t survive.

Such occasions are likely to occur step by step, and the complete impression gained’t be identified till the ice goes out, Energy says. Between reviews from anglers and routine dissolved oxygen testing by division workers, Energy says there are at the least 30 lakes of concern already, a quantity he expects will rise to 50 or extra.

“Perhaps excluding excessive southwestern North Dakota, for essentially the most half, our lakes are nonetheless 100% snow-covered, and it’s been that method since December,” Energy stated. “For positive we’ve misplaced just a few already – important or complete winterkill – and that’s ongoing. However ultimately, I am positive we’ll have dozens.”

Shallow, marginal lakes have been hit the toughest, Energy says. By all indications, this will probably be one of many worst years for winterkill in fairly a while, he says.

Low oxygen ranges are also a priority on a number of lakes in northeast North Dakota, stated Randy Hiltner, Northeast District fisheries supervisor for Sport and Fish in Devils Lake. Current testing by Sport and Fish workers discovered low dissolved oxygen ranges in a couple of dozen district lakes, together with North Golden Lake, Goose Lake in Wells County and Pink Willow Lake, Hiltner says.

Historically, none of these three lakes have been prone to winterkill, he stated. Pink Willow had a winterkill in 1994, and Goose Lake had low oxygen two or three winters in the past however didn’t winterkill, Hiltner stated.

“I’m actually hoping that’s the case once more as a result of it’s acquired an actual good walleye inhabitants – some huge fish,” he stated. “And I don’t have something on report for North Golden Lake winterkilling, so that will be form of a shock if it does.”

Different Northeast District lakes in danger are Sykeston Dam, the Heaton Slough Complicated, Harvey Dam, Goose Lake, Buffalo Lake, Finley Dam, Niagara Dam, Battle Lake, Juanita Lake and Island Lake.

A number of the lakes, together with Niagara Dam, have a historical past of winterkill, Hiltner stated. To this point, he says, nobody has known as to report seeing lifeless fish on underwater cameras, though anglers fishing Harvey Dam have reported that a lot of the fish are excessive up within the water column, the place what little dissolved oxygen is left stays.

“That, too, has had a historical past of winterkills and solely being a so-so fishery, however the final two to a few years, walleyes – and significantly huge perch – have performed very well,” stated Energy, the fisheries chief. “It has been a terrific native fishery; now, it is most likely going to go away once more for just a few years.”

Sport and Fish will proceed to observe the lakes for dissolved oxygen ranges all through the winter, Hiltner stated, and attempt to conduct netting surveys as quickly after ice-out as attainable to find out the extent, if any, of winterkill.

“That method, we can provide out data, too,” Hiltner stated. “Anglers will wish to know earlier than fishing will get getting into earnest.”

If there’s a vivid facet to the potential winterkill situation, it’s that North Dakota went into the winter with an all-time excessive variety of fishing lakes, Energy stated.

“You may by no means afford to lose any lakes, however should you’re going to lose them, it’s higher when you’ve got as many as now we have now as in contrast with 20 years in the past,” he stated. “The damage isn’t as unhealthy.”

If winterkill is suspected, Energy says, it’s essential that anglers notify Sport and Fish as quickly because the ice goes off. Usually, water in lakes with depleted oxygen smells like rotten eggs. An abundance of seagulls circling a lake is one other signal of winterkill. Relying on the fishery, the division could possibly alter its stocking plans to speed up restoration of a lake the place die-offs happen, Energy says.

“The earlier we learn about it – we are able to’t be all over the place – so the extra eyes on the market, the higher,” he stated. “Or noses, perhaps.”