Mandatory sampling for chronic wasting disease during hunting season was a success

Although chronic wasting disease once again made headlines across the world in recent months, Colorado Parks and Wildlife staff has been studying the disease over the past 40 years, gaining valuable knowledge about the prevalence of the fatal neurological disease and its effects on deer, elk and moose.

CWD, which is caused by abnormal proteins called prions, attacks the immune system and brain of infected animals causing them to display erratic, abnormal behavior. For the next two to three years after contracting CWD, the infected animal becomes emaciated, eventually wasting away due to starvation.

“Recent, sensational headlines likening effected animals to ‘zombies’ are unfortunate and a bit disappointing,” said Michael Miller, senior wildlife veterinarian for CPW. “The reality is these animals are just very sick—there’s nothing scary or supernatural about it. This is a disease that’s been around for quite some time and it will likely persist for the foreseeable future. Hopefully we can begin making more steady progress on learning how to reduce its prevalence and lessen its effects.”

This disease has been an issue that CPW staff and hunters have been talking about for years. The Colorado Parks and Wildlife Commission heard a presentation on CWD in free-ranging deer and the results of the 2017 mandatory sampling during the recent meeting in Denver.

“CWD and wildlife disease is huge problem that we will continue to face. We need to continue working on management options and we need all of our partners to participate in this process,” said Bob Broscheid, director of CPW. Without hunters, CPW would have a harder time collecting the information needed to assess the health of Colorado’s herds.

For some time CPW has been relying primarily on voluntary submission from hunters to help monitor the disease; but in recent years participation levels have dropped off significantly. During the 2017 hunting season, the agency enacted a mandatory sampling for mule deer bucks in 19 high priority game management units. The mandatory sampling focused on male deer harvested because all of the targeted units had buck licenses available. Mandatory sampling resulted in a 10-times higher submission rate in the targeted units compared to the previous year’s voluntary rate. Based on this success, different units will be targeted for the 2018 big game season.

Monitoring has shown that adult male deer have the highest infection rate in herds statewide, which is why CPW focused on this as the most reliable indicator for tracking prevalence trends over time. The 2017 sampling results show that CWD is stable or has declined in areas where adaptive management practices have been in place for years. The rate of infection in other areas has increased.

“We have a problem in some herds, but we are not facing a crisis,” said Matt Eckert, terrestrial programs supervisor for CPW. “The health of our wildlife is our primary concern and we must take management actions now to protect these animals for the long term.”

Colorado is fortunate to have some of the leading researchers and biologists on the subject working for the agency. CPW staff also have a long history of studying and managing mule deer, dating back to the agency’s origins. Staff, hunters and community members conducted an extensive public engagement process to address declines in mule deer, which resulted in the West Slope Mule Deer Strategy. Adopted by the Parks and Wildlife Commission in December 2014, the strategy outlines disease monitoring as a priority focus for the agency.

CPW staff provided recommendations for the Commission to consider, but stressed that any management strategy needs to be done methodically and with public engagement. Where warranted, efforts to control CWD will be most successful with support from communities, landowners, sportsmen and sportswomen to ensure long-term success in managing and suppressing the prevalence of the disease.

“I applaud our staff on their proactive measures to protect wildlife,” said Alex Zipp, Parks and Wildlife Commissioner. “We need to continue to foster collaboration and encourage more people, organizations and agencies to get involved.”

This will be an evolving process as CPW works to consider and test a variety of adaptive management strategies. The involvement of CPW staff and our public will be critical to our success as we work to manage CWD in Colorado.

For more information about Chronic Wasting Disease visit the CPW website http://cpw.state.co.us/learn/Pages/ResearchCWD.aspx.