And for those that don't want to open the CPW CWD Response Plan report, here's the red meat from it....
VIII. Management Actions and Recommendations to Control CWD Prevalence
A. Reduce Population or Density
If the 5% prevalence threshold for adult males is met or exceeded in a herd, the CWD management response may be to reduce the population or density of animals in specific areas. If this management action is selected, herd managers will strive to reduce population to the lower end of the population objective range identified in the Herd Management Plan. Since the population objective range has already been approved through a public process, a formal public process will not be conducted when managers implement a CWD management response. Hunter harvest will be the primary tool used to reach the bottom of the range.
The rate at which the herd is reduced will be determined by the herd managers, though managers will strive to reduce the population to the lower end of the HMP population objective range and reduce prevalence to below the 5% threshold for adult males within 10 years. When prevalence exceeds 10%, it is recommended that herds are aggressively reduced during the years between the first and second round of mandatory testing for that herd.
Treatments prescribed to reduce or maintain prevalence should go into effect the year following mandatory testing. That same herd will be retested under mandatory testing within a 5-year window according to the 15-year CWD Monitoring Plan. If changes to prevalence have not occurred then the intensity of the prescription may be increased. If the population has reached the bottom of the objective range set in the HMP and CWD prevalence is still above the 5% threshold, CPW will consider revision of the HMP objectives through a CPW Commission-approved HMP revision. The following list of tactics will be considered as possible treatments for reducing population or density and may be expanded over time: Increase female and/or either sex hunting licenses.
Increase harvest in later seasons or high prevalence areas. 24
Increase opportunities for harvest, such as increasing access, the availability of PLO licenses, hunting on open spaces, and new special hunts for youth, R3 and new hunter programs.
Increase harvest by creating a Special Hunting Season for Disease Management in Big Game.
Increase harvest through targeted population reductions not related to hunter harvest. In areas where hunters are not able to access herds, CPW will consider the use of focused herd reduction measures as a last resort.
Increase harvest through enhanced cooperation with municipalities, local governments, federal lands management agencies, HOAs, private landowners and Tribal leadership; establish CWD management programs to reduce CWD on open spaces and landscapes where hunting is currently not utilized as a tool.
Increase hunter access of all types through specialized strategies or programs.
B. Reduce Male/Female Ratio
If the 5% prevalence threshold for adult males is met or exceeded in a herd, the CWD management response may be to reduce the ratio of males to females. If this management action is selected, herd managers will strive to reduce male:female ratio to no lower than the lower end of the sex ratio objective range identified in the Herd Management Plan. Since the sex ratio objective range has already been approved through a public process, a formal public process will not be conducted when managers implement a CWD management response. Hunter harvest will be the primary tool used to reach the lower end of the range.
This management action is expected to be commonly used for deer because adult male deer typically have twice the infection rate as adult females. Reducing the segment of the herd with the highest prevalence should effectively reduce prevalence in the short term. Based on an evaluation in 2018 of all Colorado deer herds that have classification data for at least 2 of the last 3 years, 73% (32 out of 44) have observed sex ratios that exceed the top of their respective HMP sex ratio objective range. This statistic does include several HMPs that have not been updated in many years and current management approaches do not match the outdated HMP objectives; these outdated plans are scheduled for revision.
Another consideration with reducing the male:female ratio is that positive CWD detections in harvested males generally increase in later seasons closer to, and during, the rut. This is because mature males have higher prevalence than younger males and mature males make up a larger proportion of the harvest in later seasons. Focusing hunter harvest of adult male deer during the rut and late seasons may increase the efficiency in removing infected animals from the herd. The rate at which the sex ratio is reduced will be determined by the herd managers, though managers should strive to reduce the sex ratio to the lower end of the HMP sex ratio objective range and reduce prevalence to below the 5% threshold for adult males within 10 years. When prevalence exceeds 10%, it is recommended that the sex ratio is aggressively 25 reduced during the years between the first and second round of mandatory testing for that herd.
Treatments prescribed to reduce or maintain prevalence should go into effect the year following mandatory testing. That same herd will be retested under mandatory testing within a 5-year window according to the 15-year Monitoring Plan. If changes to prevalence have not occurred then the intensity of the prescription may be increased. If the sex ratio has reached the bottom of the objective range set in the HMP and CWD prevalence is still above the 5% threshold, CPW will consider revision of the HMP objectives to lower the sex ratio objective range. The following list of tactics will be considered as possible treatments for reducing the sex ratio:
Increase male hunting licenses.
Increase male harvest in later seasons or in high prevalence areas.
Shift male harvest from early seasons to later seasons in high prevalence areas.
Adjust hunt codes to focus harvest in specific areas. Eliminate float groups to better control hunter pressure across seasons.
Increase opportunities for male harvest, such as changing male licenses from List A to List B, increasing the availability of PLO licenses, hunting on open spaces, and creating new special hunts for youth, R3 and new hunter programs.
Increase male harvest through enhanced cooperation with municipalities, local governments, federal lands management agencies, HOAs, private landowners and Tribal leadership; establish CWD management programs to reduce CWD on open spaces and landscapes where hunting is currently not utilized as a tool.
Increase male harvest by creating a Special Hunting Season for Disease Management in Big Game.
C. Change Age Structure
Colorado data has shown that at current prevalence rates, the age classes of deer most likely to be infected are 4-6 year old males. Without changing the population or sex ratio, managers could change a herd’s age structure to reduce the number of 4-6 year-old males and increase the number of 1-3 year-old males. The following list of tactics will be considered as possible treatments to change the age structure:
Shift male harvest from early seasons to later seasons in high prevalence areas.
Eliminate float groups to better control hunter pressure across seasons.
Revise the HMP to lower the sex ratio objective to lower the age structure of the herd.
Increase opportunities for male harvest, such as changing male licenses from List A to List B, increasing the availability of PLO licenses, hunting on open spaces where hunting is not currently utilized as a tool, and creating new special hunts for youth, R3 and new hunter programs. 26
Increase licenses and establish an antler point restriction. However, antler point restrictions create an additional regulation to enforce, they assume harvest of adult males will increase, and they may create a surge of younger males entering the mature age classes after a few years of implementation. If deer behavior changes and males become more nocturnal, reduction in population or sex ratio may still be necessary.
D. Maximize Ability to Remove Diseased Animals at the Smallest Scales Possible (hot spots)
CWD-positive animals are not uniformly distributed in a herd or over land area. Of great value to managers is an understanding of how CWD-positive animals are distributed at the smallest scale possible. This is because the most effective way to reduce CWD prevalence is to expeditiously remove concentrations of infected animals. CPW currently requires hunters to report the location of harvest and often obtains GPS locations when collecting CWD samples from hunters. Harvest locations are matched with CWD test results to map all of the positive animals harvested and determine where hot spots occur. For herds that include large geographic areas, prevalence estimates may be heavily influenced by high prevalence found in a few hot spots. Targeted management actions would help achieve the CWD management objective of maximizing the impact on CWD while minimizing the impact on herds.
