Chronic wasting disease in deer spreads to more North Dakota hunting units |  State & Regional

Chronic wasting disease in deer spreads to more North Dakota hunting units | State & Regional

Chronic wasting disease in western North Dakota deer appears to be spreading from two directions, and state wildlife officials are hoping to stem the tides before they meet in the middle.

That might not be possible, but at the very least “we hope that’s decades away,” said Charlie Bahnson, wildlife veterinarian with the state Game and Fish Department.

Linking landowners and hunters in areas of highest concern could be key to slowing the spread of the disease.

“Hunter access is a big tool that we’re working on developing,” Bahnson said.

Twenty-six deer killed by hunters last fall positive for the fatal disease that tested the nervous system in deer and also in elk and moose. Fourteen of the cases were from hunting unit 3F2 in the south central part of the state, and eight were from 3A1 in the northwest corner.

That’s not surprising — two-thirds of the 70 documented CWD cases in the state since the first detection 13 years ago have been in 3F2, and one-fifth have been in 3A1. The cluster in south central North Dakota might have started with a deer that wandered in from South Dakota, where CWD is more established, and the cases in northwest North Dakota likely came from Saskatchewan, where the disease also is more prevalent.

People are also reading…

But surveillance from North Dakota’s hunting season last fall also documented a second CWD case in Unit 3B1, to the south of 3A1, along with single cases in three units to the north and east of 3F2. The cases in 3D1, 3E2 and 3C are the first confirmed in those three units.







charlie bahnson.jpg

Charlie Bahnson, wildlife veterinarian with the North Dakota Game and Fish Department


PROVIDED, ND GAME & FISH DEPT.


North and south

Confirming a single case in a unit between the south central and northwest parts of the state “is not the end of the world,” Bahnson said.

“When you see localized pockets of CWD, you kind of expect to see a slow increase out from those areas, and that’s probably what we’re seeing in those three new units,” he said.

But eight hunting units now have confirmed CWD cases, and Bahnson said it’s likely that the northward and southward progression of the disease will continue. What the department hopes to do is keep infection rates below levels at which they reach a “tipping” point and the disease begins having an impact on deer population levels.

“It’s maybe more of a termites-before-a-house-fire type of thing — this slow increase of a problem from year to year, until all of a sudden you have a major problem,” Bahnson said.

Game and Fish has long had baiting bans and carcass transportation restrictions in place aimed at slowing the spread of the disease, with violations carrying a $200 fine. The agency also is now studying ways to link landowners with hunters to increase the deer harvest in areas of higher disease prevalence.

“So far, the discussions and effort toward access have primarily involved a core area of ​​3F2,” Bahnson said. “The last few years of surveillance have started to show a small portion of 3A1 that warrants this same attention. We’ll likely start making contacts up there in the next year.”

Stemming the tide

CWD has been an issue in North America for years. It’s been detected in wild deer, elk or moose in 24 states, as well as in Saskatchewan and Alberta north of the Canada border, according to the US Geological Survey’s National Wildlife Health Center.

North Dakota was considered CWD-free until 2009, when the first case was confirmed in 3F2. Officials confirmed one or two cases in the state just about every year after until 2018, when three were detected. That was followed by 12 cases in 2019 and 18 cases in 2020, and the 26 during the 2021 hunting season. The notable increases in recent years means the disease could be on the verge of accelerated growth in the state.

“A single positive deer, they’re kind of a symbol to be on guard,” Bahnson said. “The next step we get concerned about is when you find positive deer year after year.

“We’re kind of in that Phase Two in two different areas of the state,” he said, referring to the south central and northwest units.

Infection rates become concerning when they reach 5-10%, because “this means you are getting close to the point at which you can expect large annual increases in infection rates,” Bahnson said. The infection rate in mule deer in the northwest jumped from about 2% in 2020 to 7% in 2021, he said. It’s around 5% for mule deer in the south central unit.

Those rates are still relatively low when compared with other states where they’ve reached 30-60% in some areas. Rates that high are something North Dakota’s Game and Fish Department “is hoping to put way into the future or prevent entirely,” Bahnson said.

The infection rates at which CWD begins affecting deer population levels aren’t exact.

“Every population can sustain some level of added mortality, but eventually the disease reaches an infection rate that outpaces the population’s ability to compensate,” Bahnson said. “Some studies in Western states have found this to be at 25-35%, whereas Eastern states with higher deer productivity can probably sustain a higher infection rate.”

Any significant acceleration in the spread of CWD would impact an industry that contributes tens of millions of dollars to North Dakota’s economy annually. Deer populations already have been impacted in recent years by a loss of habitat due to oil development and changes in farming practices, three straight harsh winters beginning in 2009, and a significant outbreak of epizootic hemorrhagic disease last year. But the 72,200 deer licenses made available to hunters last year was the highest level in a decade.

Game and Fish hopes to keep the license numbers up, and to get more hunters to take part in the CWD surveillance program. Participation around 10% in focused units typically gives the department a sufficient sample size for testing, according to Bahnson.

Just under 5% of hunters last fall participated in those units. In south central North Dakota — where Bahnson said hunters are “more engaged” due to the higher prevalence of the disease — participation in 3F2 dropped from 9.5% in 2020 to 8.5% in 2021.

“That is a little discouraging,” Bahnson said.

For more information on CWD, go to https://gf.nd.gov/wildlife/diseases/cwd/faq.

Reach Blake Nicholson at 701-250-8266 or [email protected]

.

Leave a Reply

%d bloggers like this: