Something fishy is going on at Holter Reservoir.

Hundreds of dead carp are floating in the popular reservoir on the Missouri River between Helena and Great Falls.

Bruce Rich, the fisheries bureau chief for Montana Fish, Wildlife and Parks, said they’re investigating the reason behind the dead carp, but at this point he can only speculate on the cause of their demise. No other fish species seem to be involved.

“We had a crew go out yesterday, including a state fish health specialist, to take samples to see if there’s the possibility that this is a disease-related issue,” Rich said Tuesday. “But what we know so far is we don’t see any obvious signs of mortality.”

The samples have been sent to a lab for analysis, and it’s expected to be at least a week before results are available.

Rich said he wasn’t aware of any similar incidents involving dead carp on the Missouri River reservoir system.

FWP was first contacted about the dead carp Friday, so Rich said he thinks something happened to the fish on Thursday. The fish were found floating in the Gates of the Mountains and American Bar area of the reservoir.

Some of the carp showed signs of trauma, but not all of them did. Rich said it was difficult to believe that they all died from getting run over by boats or that they were shot by people bow-fishing. He added that he has no reason to believe that they found any kind of toxic food source, although he’s not ruling that out either.

And while the water has warmed up in recent weeks, it’s still not hot enough to kill the carp, according to Rich.

FWP plans to leave the dead carp in the water to allow them to decompose and “refertilize” the fishery.

“If this turns into the type of numbers where it might pose a hazard, we might consider doing something, but at this point I don’t think we need to,” Rich said. “My understanding is they’re pretty dispersed; they’re not just in one spot.”

The state agency adds in a press release that although this does not represent an increased risk to human health, people should thoroughly cook any fish they catch.

Nancy Duffy at the Gates of the Mountains boat tour office said their guests are noticing the dead carp in the reservoir, but they’re gone by the time the river starts flowing faster in the canyon. She doesn’t have any problem with them in the water, but added that they pull out dead ones that get too close to their docks.

The dead carp also have an upside, she noted.

“We have a lot of eagles and ospreys diving in the water and having a feast,” Duffy said. “I can see them out the window. That’s the beautiful part of it.”

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Reporter Eve Byron: 447-4076 or eve.byron@helenair.com. Follow Eve on Twitter @IR_EveByron.


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