Elk may ultimately not be as susceptible to chronic wasting disease as researchers previously thought, according to a decadelong study published recently.
Some elk carry a gene that either delays the onset of the illness or possibly stops symptoms altogether, said Terry Kreeger, retired veterinarian for the Wyoming Game and Fish Department.
Kreeger co-authored the paper published recently in the online journal Ecosphere, with results that could have implications for Wyoming’s winter elk feeding grounds.
The gene does not mean elk are immune to the disease, he said. If it spreads across the state, elk will die. But according to the model the researchers produced, Wyoming’s populations will recover in the long term.
“Like all living things, you and I are alive today because sometime in our past an ancestor had good genes to overcome a disease, and it dominated,” he said. “This model gives a little bit of hope that even if we did fail in our best efforts to combat the disease, even in the end, we will come out OK.”
The results are welcome news for Game and Fish Department officials dealing with the disease’s possible slow march westward toward Wyoming’s feeding grounds.
Conservationists say the study poses more questions than it gives answers about the immediate health of Wyoming’s herds.
The study started 12 years ago when Game and Fish’s Sybille Research and Visitor Center received 39 elk from the National Elk Refuge in Jackson.
The elk stayed at the research station in relatively close quarters known to carry chronic wasting disease, a nonliving protein that inhabits the ground.
“It was the maximum exposure to the disease that any elk would see in the wild,” Kreeger said. “We would watch the elk and see how long they live.”
The work was intended to mimic a worst-case scenario on an elk feeding ground, he said. While chronic wasting disease has not yet reached the western side of Wyoming, it is moving closer.
The disease causes animals to become skinnier, lose mental capability and eventually die.
At the research center, some of the animals died relatively quickly. Others lived four or five years, and one cow elk is still alive, 12 years later.
Kreeger and the other researchers already knew that elk have three forms of one gene. What they didn’t know was how it would play out in a real-world scenario.
They found that the first form causes elk to be most susceptible to the disease. The second allows them to live about twice as long, and the third form, while rare, may never kill the elk.
Researchers coupled the Sybille Research Center data with long-term models projecting birth rates and concluded that eventually, within 100 years and with reduced hunting, elk herds would recover.
“The animals that live longer produce more calves. The calves will produce more calves who carry the disease-resistant gene,” Kreeger said. “Over time, the resistant genes tend to dominate in the population, and the population starts to increase with animals.”
Wyoming’s Game and Fish Department, which manages 22 of the state’s 23 elk feeding grounds, is updating its chronic wasting disease plan for the state, said Brian Nesvik, head of the Game and Fish Department’s wildlife division.
The plan addresses herd monitoring and may begin to deal with possibilities such as immediate removal of a carcass to help prevent the spread of the disease, or continued removal of elk that show acute signs of the disease, he said. This study will be another factor.
“Bottom line is does it mean anything tomorrow for major changes on how we do feedgrounds or look at how we monitor CWD in the state? Probably not in the near term,” he said. “But it certainly gives managers and our veterinarians a new piece of research to consider when they are planning.”
The feeding grounds started about 100 years ago. They exist now largely to keep elk separated from cattle, preventing the spread of brucellosis, a disease that causes some calves to abort in cattle. Feeding grounds also prevent damage to private property and increase hunting opportunities, Nesvik said.
Those opposed to feeding grounds have long worried about the possibility of chronic wasting disease infecting the areas.
Lloyd Dorsey, program associate for the Greater Yellowstone Coalition, said the study only further shows the serious impacts of disease on feeding grounds. Elk herds would be reduced in the short term by about two-thirds if hunting continues at current rates, according to the study.
“And that is if indeed their assumption of genotype selection plays out,” he said. “How could that possibly be interpreted as a benefit for Wyoming?”
If hunting is reduced to only elk with antlers, herds would still decline but would start to recover within about 100 years, the study continued.
Nesvik said the study gives the department some hope that herds wouldn’t be wiped out by the disease.
“I would never say it’s not concerning, because it is, but this study certainly gives us some hope,” Nesvik said. “Or some good, scientific basis to believe that it wouldn’t have detrimental long-term population-level impacts.”