The study finds that hunting can be an effective form of disease control when enacted consistently at high levels over many years.
BOZEMAN, Mont. — Hunting greater numbers of male deer can slow the spread of chronic wasting disease, a lethal wildlife disease, according to a new study by the U.S. Geological Survey and the Wyoming Game and Fish Department.
Chronic wasting disease is caused by a misfolded protein called a prion, and infection leads to neurological problems, starvation, and eventually, death. The disease affects animals in the deer family, including deer, elk and moose. Chronic wasting disease is 100% lethal and highly contagious. It has rapidly spread across the U.S. since it was first discovered in the 1960s. It is now found in at least six countries, four Canadian provinces and 35 U.S. states.
Chronic wasting disease outbreaks are a serious concern for wildlife managers because members of the deer family are economically, culturally and ecologically important. The disease has been implicated in declines of deer and elk in several states, including in Wyoming mule deer herds where the number of animals infected can exceed 50%. The disease spreads easily through the environment from infected deer droppings, urine and saliva, and there are no vaccines or treatments, making it difficult to control. One potential tool is hunting, which might reduce the number of infected animals within a population and slow down the spread of the disease. Many states are now working to increase hunting levels in an effort to slow the spread of disease. However, hunting-based strategies are not always effective and can be controversial. Despite the interest in this management tool, there is still little real-world evidence of its effectiveness.
The study’s authors examined chronic wasting disease trends in 10 different mule deer herds across central and eastern Wyoming, which varied in hunting pressure. They analyzed 20 years of data gathered by Wyoming Game and Fish Department to understand whether increasing hunting pressure was effective at controlling the disease.
“We found that harvesting a high proportion of the adult males in the herd – around 40% every year for 20 years, is expected to keep chronic wasting disease infections at low numbers,” said Wynne Moss, lead author and USGS scientist. If this high level of hunting pressure is applied consistently (over 20 years), less than 5% of the males on average are expected to be infected. On the other hand, a lower level of hunting pressure, such as 20% of adult males harvested per year, would result in a much higher prevalence of around 30% infected.
The study also showed that harvesting a high number of males over a shorter period – 3 years in a row — still slowed the rate of disease spread within a population but was not as effective as harvesting high numbers over a multiple decades.
“Our results suggest that the use of hunting is a promising, scientifically supported way to manage chronic wasting disease; however, it is important to note that this approach is more likely to slow the disease down than eradicate it,” said Paul Cross, co-author on the study and USGS scientist. “This study provides important evidence about the effects of hunting on wildlife disease management for deer.”
The paper was published January 21 in Ecological Applications.
Learn more about chronic wasting disease.
