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State stops culling herds of deer, elk Animals won't be killed to contain spread of CWD By Todd
Hartman, Rocky Mountain News The Colorado Division of Wildlife is giving up on the controversial practice of killing deer and elk to help contain the spread of chronic wasting disease. The decision is a sharp reversal from policy adopted during the height of fears over the fatal brain- rotting ailment, when it appeared that Colorado's multimillion-dollar hunting economy might be decimated. The agency's lead scientist on CWD and an early proponent of culling, Mike Miller, said data collected over the years don't show that thinning herds has had any significant effect on the rate of the disease in the wild. "We're not afraid to acknowledge that some of the things we had tried aren't working as well as we'd hoped," Miller said. "It's never fun. I would be much more comfortable to sit here telling you what does work." Since 2001, Division of Wildlife officials culled roughly 2,300 animals on both sides of the Continental Divide in hopes of containing initial outbreaks or reducing populations in "hot spots" where prevalence of the disease was highest. That's a small fraction of the roughly 100,000 deer and elk killed by hunters annually in recent years. Even so, the technique drew sharp criticism from animal activists, some elected officials and some scientists who questioned whether killing what for the most part were healthy animals was a realistic way to slow or stop the spread of the dreaded disease. But the method had the strong support of others, including Gov. Bill Owens, who championed the effort in the spring of 2002 at a dramatic press conference to announce that the disease had been discovered on the Western Slope. Then, Owens backed what he called an "aggressive policy," saying the future of the state's hunting economy was at stake. The emphasis on culling also came at a time when the public was raising questions about whether CWD, a cousin of mad cow disease, could cross over and strike humans consuming venison. At the time, a human version of mad cow disease had killed more than 120 in England and Europe who had eaten meat from infected cattle. To this day, there's no proven case of a human contracting CWD, or any of its variants, through consumption of an infected deer or elk. Colorado's approach was also mimicked by wildlife agencies in several states, including Nebraska, South Dakota and Wisconsin, which looked to the experience of Miller and the Division of Wildlife for answers on how to deal with CWD as it was discovered within their borders. In fact, some states, particularly Wisconsin, went far beyond Colorado's methods, expanding hunting seasons, doling out licenses and encouraging the public to participate in a massive reduction of herds in infected areas. In hindsight, Miller said, division officials hoped that by culling they could reduce the spread of the disease both within Colorado, and to areas outside the state. Even some computer models backed the notion, predicting in certain scenarios that CWD, if left unchecked, could cut deeply into deer herds. "If we have an opportunity to keep it from spreading, shouldn't we do so?" Miller said of the thinking at the time. "A big part of our motivation was to keep it off the Western Slope. It was real nice idea that was probably 10, 15 or 20 years too late." In fact, Miller now believes, CWD was already established at a level that probably made trying to limit it through targeted culling unrealistic. "The whole tenor these days is considerably different than it was a few years ago," Miller said. "In Colorado we're resigned to the fact that the disease is much more widespread; we are going to have to live with it." But the news isn't entirely bad. CWD has never taken down vast numbers of deer as once feared. In fact, in the most infected pockets of the state, the rate of disease among deer is about 10 percent, not much different than it's been for several years. The agency will continue to test animal heads voluntarily submitted by hunters. Miller, however, is cautious about assuming that infection rates won't increase. In some areas, rates of infection are climbing, although not dramatically, he said. He wants many more years of data before drawing any firm conclusions. "It's like walking into a two-hour movie and watching one minute of it and trying to figure out the plot," he said. The division's scientists concluded culling wasn't making much difference after comparing 16 areas where biologists had targeted deer for population reductions to 16 nearby areas where they did nothing. "What you'd want to see is, ideally, an increase in prevalence (of CWD) where we weren't doing anything, and a decline where we were," Miller said. "And that's not the pattern we saw consistently." One prominent critic of the culling approach has been retired University of Colorado biology professor Charles Southwick, who has argued that culling might actually exacerbate the spread of CWD. That's based on his view that clearing deer out of a "hot spot" just opens the door for more deer to come in and contract the disease from the environment, where research suggests the agents behind the disease can subsist in soil and feces. In addition, Southwick has argued, it might be that most deer and elk have a natural resistance to CWD. By killing off mostly healthy populations, the division might be reducing the creatures that have that resistance, under his view. "On the whole, I'm very pleased with the decision" to stop culling, Southwick said, calling DOW's analysis of its data "an excellent study." Two other states that have used state-operated culling as a tactic to fight CWD, Nebraska and Wisconsin, plan to continue. Even so, both states depend far more on extra hunting licenses and longer seasons to keep deer populations down in hopes of reducing the spread of the illness. "That's certainly part of the strategy," said Bob Manwell, a spokesman for Wisconsin's Department of Natural Resources. "By concentrating most heavily in the area of highest prevalence, we can hopefully reduce the amount of disease that spreads out from that area." In Nebraska, wildlife biologist Todd Nordeen said state workers will cull animals in limited instances when new hot spots are found. But as in Colorado, the more aggressive state-run culling campaigns have slowed down since initial fears four to five years ago that the disease could do more damage than it has. CWD by the numbers 2001 Year Colorado Division of Wildlife began shooting deer and elk to contain the spread of chronic wasting disease 1,700 Approximate number of deer and elk culled in northeastern Colorado, ranging from Boulder County into Larimer County and points east. 600 Approximate number of deer and elk culled in northwestern Colorado in the area around Craig. 10% Typical rate of infection of deer in the state's "hot spots" for CWD. 1% Typical rate of infection for elk in infected areas.
hartmant@RockyMountainNews.com or 303-892-5048 Copyright 2006, Rocky Mountain News. All Rights Reserved. URL: http://www.rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_4578846,00.html |