A View on Wildlife: Minnesota DNR Needs to Rethink its Deer-disease Strategy
Duluth News Tribune
Opinion
Apr 19, 2017 at 12:08 a.m.
Recently, news outlets in Minnesota carried reports about a deadly deer disease called chronic wasting disease, or CWD. It's a concern to hunters because, while long-incubating, it has no cure, and it very commonly hastens an animal's demise. Other states haven't been able to stop its spread, despite aggressive measures.
The state Department of Natural Resources, in response, has started its own aggressive steps. But from a scientist whose research focuses on CWD, I say the most practical response may be more hands-off.
No one is sure of the exact origin of CWD, but it was first reported at a Colorado State University research facility in the late 1960s. CWD was first found in the wild in the 1980s, also in Colorado.
Since then, CWD has been found at sites far removed from the original endemic area; sometimes probable links can be made between these sites through animal or carcass movement, but more often these new appearances left both scientists and wildlife professionals scratching their heads.
The finding of CWD in Minnesota is one such case, though likely represents the expansion of the disease westward from wild deer in Wisconsin.
The DNR has begun a sharpshooting program in certain areas known to have CWD. This very well may be a misplaced effort of the DNR and its use of taxpayer dollars. Both Illinois and Wisconsin spent millions on sharpshooting; and between the states, results have been equivocal. In both cases, CWD has gained ground - exploding in Wisconsin and increasing more insidiously in Illinois.
Even if the DNR could shoot all the deer in an area - unlikely and costly to attempt - chronic wasting disease persists in the environment, and deer in surrounding areas quickly would fill the void.
Because state agencies generally test less than 1 percent of their deer populations for CWD per year, and the tests used are not capable of identifying every positive animal, the disease easily has spread undetected. As an example, it was found in an elk in Arkansas last year for the first time, despite more than a decade of passive and, frankly, limited testing. When authorities subsequently increased their testing in nearby areas, they ended up finding it in over 200 animals.
So why haven't we yet seen sharp declines in deer and elk populations where CWD is prevalent? There are a number of reasons, the most important being that deer at least are a very hardy species and can actively sustain population sizes as long as environmental conditions are good - despite their shortened life expectancy once infected. Further, over time, we can expect the genetics of deer populations to change. Those deer with genes that make them more resistant to CWD should outcompete those that do not. Over time, resistance will be in balance with disease prevalence and populations would be expected to persist and, in most cases, thrive. Sharpshooters, unlike the disease, are unbiased in their selection and inadvertently may remove resistant animals along with more susceptible ones.
Apart from employing sharpshooters, the DNR also is looking to add restrictions to private deer and elk farms that may breed these animals for meat, antlers, or to supply private hunting preserves. As with sharpshooting, this effort would be fruitless and may hinder our understanding and management of the disease.
Deer and elk farms already conduct mandatory testing for chronic wasting disease and are regulated as to fencing, the transfer of animals, and importation. In some cases, farmed deer and elk represent the majority of animals tested in a county. Animals get radio-frequency identification chips, and their movement between facilities is tracked. If CWD is detected, quarantine procedures are put in place. Adding new regulations won't stop a disease that has been traversing through the woods for years.
So what should the DNR do? A passive approach may be practical. After spending millions on aggressive CWD responses, Wisconsin changed to a more passive strategy. So far, hunting quality does not appear to be affected, based on hunter response surveys.
Instead the state should spend resources conducting more intense testing for CWD to better define where it may be found and predict where it may show up next.
It should also fund research into understanding CWD resistance. While it may be impractical to attempt to control the breeding of wild animals, deer and elk farmers do have this capability. Since CWD is a prion disease related to mad cow and Creutzfeldt-Jakob disease, with many things in common with Alzheimer's disease, the research could have a range of applications that also help human medicine and agriculture.
No one likes finding chronic wasting disease, but we have to ensure we make the most out of our response to this challenge, learning from lessons presented in years past.
Nicholas J. Haley is a professor of microbiology and immunology at Midwestern University's campus in Glendale, Ariz.
