Conservation Northwest supports new bighorn sheep protections on Washington Department of Fish and Wildlife managed lands 

Conservation Northwest supports new bighorn sheep protections on Washington Department of Fish and Wildlife managed lands 

Conservation Northwest / Jan 13, 2023 /

A new WDFW rule change prohibits domestic sheep and goat use in several wildlife area units to minimize deadly disease transmission

Bighorn sheep in Washington need distance from domestic sheep and goats–two known disease vectors of Mycoplasma ovipneumoniae bacteria. Photo: WDFW.

Last fall, the Washington Department of Fish and Wildlife (WDFW) proposed a rule change to limit domestic sheep and pack goat use within numerous wildlife area units.

This change is meant to better protect bighorn sheep from Mycoplasma ovipneumoniae (Movi)—a bacteria known to cause widespread death and lower lamb survival rates within bighorn sheep herds.

A public comment period and public hearing followed to get feedback on the rule change. Conservation Northwest weighed in support of the changes, providing science-backed comments advocating to minimize the tangible disease risk that domestic sheep and goats pose to wild bighorn populations.

WDFW officially adopted the rule change in early January. The new rule change will start in February 2023, and will be coupled with education, signage and enforcement. This rule prohibits domestic sheep and pack goats (known vectors of disease transmission) in specific WDFW wildlife area units where bighorn sheep reside.

Staff from our Wildlife-Recreation Coexistence and Sagelands Heritage programs submitted a comment letter in November to support the rule change to best protect the future of bighorn sheep in Washington. Read their comments below.

November 30, 2022 

Washington Department of Fish and Wildlife
ATTN: Wildlife Program 
P.O. Box 43200 
Olympia, WA 98504-3200 

Dear Wildlife Program Staff,

Conservation Northwest (CNW) is providing this written comment to support the Washington Department of Fish & Wildlife’s rule change addressed in CR-102 to implement the newly proposed WAC 220-500-045. This rule change is necessary to protect our state’s vulnerable bighorn sheep population on WDFW owned land by reducing the risk of transmission of the deadly Mycoplasma ovipneumoniae. We support this rule proposal as a means for WDFW to fulfill its central mission of preserving, protecting, and perpetuating the state’s fish, wildlife, and ecosystems. 

CNW has an over 30-year history of successfully leveraging funding and public support to protect, connect, and restore habitat and wildlife in the Pacific Northwest. We represent more than 17,000 supporters dedicated to conservation in our state. Our success is largely owed to our practical adherence to science and policy and commitment to collaboratively work with managers, scientists, Tribes, user groups, industry, and other stakeholders to develop and implement durable conservation plans, projects and solutions. CNW’s Sagelands Heritage Program focuses on protecting central Washington’s shrub-steppe wildlife and habitat and has specifically engaged in bighorn sheep conservation efforts over the past decade.  

This rule proposal is reflective of the fact that domestic sheep and goats commonly carry these disease-causing organisms (Martin 1996, Gilmour and Gilmour 1989) and can pose serious risk to bighorn sheep. This vector of respiratory transmission has long been suspected and has significant scientific evidence. Lawrence et. al. in 2010 documented conclusively in the Journal of Wildlife Diseases that a microorganism tagged with a florescent marker and exposed to a domestic sheep was transferred to wild bighorn individuals with a simple contact through a fence. Additionally, a population of sheep at the National Bison Range in Montana were being sampled for research when a respiratory disease outbreak occurred in 2016-2017 that caused an estimated 85% decline in the local bighorn sheep population. Besser et al. (2021) published this research in Ecology and Evolution documenting the one single genetic strain found in all the bighorn mortalities originated from a single domestic flock. This outbreak occurred despite proactive management actions undertaken to reduce risk of disease and increase resilience in this population (Besser, 2021).  

While not every outbreak of pneumonia in wild sheep have confirmed contact with domestic sheep or goats, there is significant scientific evidence that shows that association between these species poses a significant threat to the continued conservation and restoration of wild sheep populations. 

Mycoplasma ovipneumoniae has a long history of adversely impacting the bighorn sheep populations here in Washington as well. From 2009 to 2013, hundreds of wild bighorns from the Tieton and Umtanum herds in Yakima and Kittitas counties were wiped out by the bacteria. Past incidents and the pattern of disease exposure is confirmation that the status quo cannot continue, especially considering the precarious baseline of Washington’s wild sheep population today. While there is a place for pack goats and domestic sheep access on public lands in Washington, it should not be where the remaining 1,700 wild bighorn reside. It only takes one unfortunate instance of disease transmission to have a consequential impact on bighorn sheep numbers, that will take years, if not decades, to recover from. 

CNW sees this proposal as an opportunity to raise awareness about bighorn conservation and for WDFW to continue its work to proactively reduce transmission of Mycoplasma ovipneumoniae. We support the accompaniment of a strong education and engagement effort that includes effective on-site signage, proliferation of information online, and on-the-ground partnerships with domestic sheep and goat owners and users. In the future, we will support incentives for domestic animal owners to test and vaccinate sheep and goats, or other explicit means for better adherence to rules meant to protect bighorn sheep. 

Bighorn sheep are an iconic species here in Washington and elsewhere across the West, and they face real challenges to survival and recovery from small, isolated populations in our state and disease. While there is a place for domestic sheep and pack goats in our landscapes, it is not where wild bighorn sheep reside. WAC 220-500-045 is a necessary rule change to more effectively curb the risk of losing this vital species. 

Thank you for giving us this opportunity to comment on this wildlife protection effort.  


Keith Watson 
Sagelands Heritage Program Conservation Associate 

Kurt Hellmann 
Wildlife-Recreation Coexistence Program Lead 

Besser, T. E., Cassirer, E. F., Lisk, A., Nelson, D., Manlove, K. R. Cross, P. C. Hogg, J. T. (2021). Natural history of a bighorn sheep pneumonia epizootic: Source of infection, course of disease, and pathogen clearance. Ecology and Evolution 11:14366-14382. 

Gilmour, N. J., Gilmour, J. S., (1989). Pasteurellosis of sheep. In: Adlam, C., Rutter, J.M. (Eds.), Pasteurella and Pasteurellosis. Academic Press, London, pp. 223–254. 

Lawrence, P. K., Sudarvili, S., Dassanayake, R. S., Herndon, C. H., Knowles, D. P. (2010). Transmission of Mannhemia haemolytica from Domestic Sheep To Bighorn Sheep Unequivocal Demonstration With Green Fluorescent Protein-Tagged Organisms. Journal of Wildlife Diseases. 46(3): 706-717. 

Martin, W. B. (1996). Respiratory Infections of Sheep. Comparative Immunology, Microbiology and Infectious Diseases. 19(3): 171-179.

Learn more about bighorn sheep and our Sagelands Heritage Program on our webpages.