The Basics of Chronic Wasting Disease – Part 4
Pursue The Outdoors 06.21.11
To read part three of this article, click here.
Responsible Deer Management
For several years I have been writing about what I call “Responsible Deer Management” and why and how it should be practiced by many states in the Upper Midwest. I’ve written about how deer management policies like “Maximum Sustainable Yield” which promotes the idea of “maintaining the breeding population” of the deer herd “at the highest level that the habitat and landowners will tolerate” (MN Department of Natural Resources publication) often results in deer herds that are not socially balanced between sexes and age classes and deer populations that are at or above the carrying capacity of the habitat, which may lead to physical stress and malnutrition of the deer, and can result in the increased risk of the spread of disease in the herd and death to many of the animals. Although CWD is not prevalent in many of the states of the Upper Midwest, the fact that CWD has been found in Illinois, Minnesota and Wisconsin, and the size of the deer herds in those and neighboring states, makes it highly possible that CWD may spread throughout the Upper Midwest in future years.
The threat of infectious diseases spreading through deer and elk herds is one reason why some hunters and game managers have been asking for changes in wildlife management policies in some states, or areas of some states, in recent years. While some state game agencies have been managing their deer and elk herds for increased and/or maximum numbers of animals, some hunters and game managers in those states would like to see deer herds managed for more evenly balanced sex ratios, and for herds that are more in line with the carrying capacity of the habitat. The threat of the spread of CWD may now cause game managers in several states to reassess how they manage the deer and elk herds in their areas.
What Can Wildlife Managers Do?
Game managers in each state must assess the potential for the spread of CWD in their areas, and the impact of CWD on their deer and elk herds, based on the carrying capacity of the habitat, the number of animals per square mile, the impact on hunting, and the present and long term management goals for the deer and elk herds. Where deer or elk herds are below the carrying capacity of the habitat, or where there are low numbers of animals per square mile (as in some western states), the threat of CWD may be lower and the importance to management practices may be less of a factor than in areas where herd numbers are at or above carrying capacity, where there are high numbers of animals per square mile or where male to female ratios may be out of balance (as in some mid-western and eastern states).
Management Policies
In areas where herd numbers are below carrying capacity, or where the number of animals per square mile is low, the threat of the spread of CWD may be low and there may be no need to do anything more than monitor the herds by routinely for evidence of CWD. In areas where deer herd numbers are above carrying capacity of the habitat, where the number of animals per square mile is high or where the male to female ratio of the herd is out of balance, the threat of the spread of CWD may be high and there may be the need to reduce herd numbers by increasing the number of antlerless permits to reduce yearly population increases, or, in cases where the number of animals per square mile is extremely high, there may be the need for special hunts or eradication programs to reduce herd numbers before infected animals have a chance to spread CWD to a large portion of the herd.
Testing and Surveillance
Game managers in each state should conduct tests on deer harvested by hunters, and on any dead deer that are found, to determine if CWD is present in their herds, and determine the extent of the spread and the possible number of infected deer in their herds. They should also implement a program to eliminate CWD from farmed elk and deer similar to the one proposed by the US Department of Agriculture’s (USDA) Animal and Plant Health Inspection Services (APHIS).
The provisions of this program proposed by APHIS will include fencing requirements, animal identification, herd inventory, surveillance of deaths in animals over 16 months of age and herd certification with increased status (relaxing movement restrictions for animals from non-infected herds) based on the number of years of surveillance without the evidence of diseases including CWD. Additions to any herd will have to be from herds with the same or a higher degree of status. Animals that test positive for CWD will be identified by the use of approved tests performed by APHIS’ National Veterinary Services Laboratory (NVSL) or and NVSL approved laboratory.
Under this plan, CWD positive herds would be depopulated or quarantined. Animals from an infected herd that have come in contact with animals from a second herd would be removed from the second herd, or they would be euthanized. Animals from the both herds would then be quarantined and put under surveillance. If an animal in either herd tests positive, the entire herd would be treated as positive. All euthanized animals would also be tested for diseases.
Baiting, Feeding and Minerals
Because of the uncertainties about how CWD is spread, and how CWD may impact deer and elk herds, State wildlife agencies must be aggressive in how they manage their deer. Since the most likely means of transmission of CWD is from one animal to another through direct contact, or through contact with infected soil or other surfaces, wildlife managers and hunters should both be aware of the fact that the more deer come into contact with each other, the more likely it is that CWD will be spread. In the off chance that baiting and feeding of deer may lead to the spread of CWD, both of these practices should be banned. When it comes to the spread of infectious diseases, especially one as deadly as CWD, it is far better to be safe than to be sorry.
Although at least one animal nutritionist (who subscribes to the copper deficiency hypothesis) suggests that hunters do not need to stop supplying minerals to deer (because supplying minerals leads to healthier deer), the risk of the spread of CWD (where deer congregate at mineral sites) far outweighs the benefits of supplying mineral supplements to the deer. If hunters and wildlife admirers want to provide supplemental nutrition for deer, they should do it through habitat improvement and food plots, where the spread of CWD is less likely to occur.
What Can Commercial Game Farmers Do?
The USDA strongly urges deer and elk farmers to enroll in State CWD surveillance and control programs. Game farmers should notify the appropriate authorities of any sick or dead elk and deer in their herds. They should only purchase, trade or acquire deer and elk from farms that have been enrolled in State programs or are otherwise known not to have been exposed to CWD. As a result of the threat of CWD, the numbers of sales, and the prices, of live deer and elk, has dropped significantly in the last year. But, once the government surveillance and testing programs are in place; and deer and elk herds are certified free of CWD, the restrictions on the sale of deer and elk should be relaxed, and prices should rise.
Because copper deficiencies in the diet of ruminants may result in deer and elk being more susceptible to CWD, game farmers may want to make sure their animals receive sufficient amounts of copper in their diets. Game farmers may also want to consider double-fencing their enclosures, to keep animals from outside the enclosures from coming into direct contact with and infecting animals inside the enclosures.
To continue on to part five of this article, click here.
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