With CWD rates static, practice of culling deer and elk will stop

With CWD rates static, practice of culling deer and elk will stop

Tuesday, March 14, 2006

With statewide infection rates of chronic wasting disease in big game not showing much change a half-decade after the Colorado Division of Wildlife began killing infected deer and elk, the practice will stop.

The infection rate of deer continues to be anywhere from less than 1 percent up to 10 percent of the local populations, with the heaviest infections on the Front Range in whats known as the endemic area.

Meanwhile, elk show markedly lower signs of infection, from less than 1 to about 2.6 percent of the local population. Most of the CWD occurring in elk is found in the northwestern quarter of the state.

The DOW has made the decision to halt culling of suspected CWD-infected animals a half-decade after the treatment was considered the easiest way to stop the disease from spreading to wild animals and domestic livestock.

However, subsequent outbreaks of the disease along with its continued presence in well-known hot spots has convinced wildlife managers, at least for now, that culling isnt the way to control CWD.

"Our results (from culling operations) are really ambiguous," said Mike Miller, state veterinarian for the DOW and a well-respected CWD researcher. "For every place where (disease) prevalency went down in our treated areas you could find another example where the prevalence was higher in an area we had culled than in a control (unculled) area."

Miller said the culling programs showed "no clear evidence of any kind of beneficial affect" on CWD control.

"If and when we re-institute culling, the work will be under a different framework," said Miller, citing a "lack of consistency" in how culling was done. "We gave it a good effort and at the time it was the responsible thing to do."

Other states, including Wisconsin, will continue their culling efforts.

The DOW did its first culling in the spring of 2002, said DOW culling coordinator Fred Quarterone. Most of the culling was done in mule deer herds along the Front Range, particularly in an area in north-central Colorado where the disease is thought to have existed for nearly 30 years.

The only culling done on the Western Slope, and the only culling that involved elk, was conducted in March of that year on and around the Motherwell Ranch south of Hayden.

When three wild mule deer were discovered to be infected with the disease at the Motherwell Ranch, DOW employees killed 1,033 deer within a five-mile radius of the ranch. Of those, 10 tested positive for the disease, a less-than-1-percent infection rate.

None of the 135 wild elk also killed yielded positive results.

Quarterone said the DOW has killed about 200 deer each of the past several years, all on the Front Range.

Studies by the DOW indicate that from 2002 to 2005, 18 of the states 55 deer Data Analysis Units (composed of one or more game management units) reported at least one case of chronic wasting disease and 11 of the 46 elk DAUs saw at least one case.

Hunters have been asked, and at times required, to submit the heads of deer or elk they killed to the DOW for testing. After initially getting some good response from hunters, recent years have shown a sharp decline in submissions.

Its not clear whether hunters are weary of turning in submissions or, because the occurrence of CWD is relatively rare, if they simply believe CWD isnt anything to worry about.

Whatever the cause, the lack of samples leads to an inability on the part of the DOW to follow the development of CWD.

"The vast majority of animals are not infected with chronic wasting disease," Miller said. "But I wish I knew what is was that motivates people to stop turning (samples) in. Its our best way of tracking the disease."