Hundreds of fish on a Northern Minnesota lake were found floating belly-up in the water this week, to the shock of people living in that area.

It's happening on Little Cut Foot Sioux Lake northwest of Deer River.

People who visit or live on the lake want to know why so many fish are turning up dead.

Including two anglers, Beau Thunshelle and Jason Johnson, who take a trip to the lake every year.

"Really it's been a tradition for my father-in-law. His family has been camping and fishing here for over 50 years," said Johnson.

They got hooked said Johnson, "so we keep coming back, and really the fishing has been what keeps bringing us back."

On Sunday before they arrived, it was a much different story.

"We had an unfortunate event this year where we kind of had a perfect storm of bad circumstances," said Chris Kavanaugh, the Regional Fisheries Manager at the Minnesota DNR.

About 1,000 dead walleye were found floating in Little Cut Foot Sioux Lake. But the big question 'why' remains.

Kavanaugh explained, "low dissolve oxygen, a high abundance of fish, a change in the wind and we had some mortality of walleyes in our trap net out there."

The Minnesota DNR says the low dissolved oxygen water is due to the long winter and late ice-out, but it was when the wind pushed that low oxygen water into their traps that the DNR noticed something was wrong. 

"And started to notice the fish showing some signs of stress," said Kavanaugh. "Some of those fish had succumbed to that low dissolved oxygen coupled by the crowding."

The DNR does not expect this unprecedented die-off to have any short or long term affects.

He said, "to put that in perspective, in a typical year at Cut Foot we may see over 35,000 walleyes come through the trap."

Anglers can still see the aftermath since the cleanup on Monday

"I saw a couple yesterday floating but not like the ones in the video," said Thunshelle. "But yeah, there's definitely a few floating around back here."

But these anglers aren't letting a couple dead walleye kill their annual trip.

"It's been pretty good action so far," said Johnson.

The DNR wants to make clear that the fish which turned up dead were not "stripped," which is a process done by the DNR to collect walleye eggs during spawning season.

According to Minnesota Department of Natural Resources spokespeople, the die-off is an "unprecedented event" for the lake, but was not due to DNR stripping. Those with the Minnesota DNR say these fish had not yet been stripped of eggs or milt, so it was not a direct result of being handled. 

They add egg stripping operations lasted three days, and ended almost two weeks ago.
 
The DNR says they take the care of these fish very seriously, and monitor them 24 hours a day.