Author: Wild Sheep Society of BC
The Wild Sheep Society of BC along with our project partners continue to support the Fraser River test and Remove Project. Mycoplasma Ovipneumoniae, a respiratory disease is currently affecting the California bighorn sheep along the Fraser River. Current science suggests the bacteria Mycoplasma ovipneumoniae (M.ovi) is the single most important pathogen implicated in pneumonia related die-offs of wild sheep and is considered the largest threat to wild sheep in North America.
Given the history of domestic sheep on the Fraser extends at least to the early 1900s,
Fraser River bighorns have likely been exposed to M.ovi in the past. Some northern herds were used as source stock for translocations to the USA in the 1950s and 60s and the numbers of sheep recorded by the early to mid-1990s were the highest ever recorded. At that time, there were more than 2,400 sheep along the Fraser River north of Lillooet. In the mid to late 1990s, Fraser River bighorn sheep appeared to have experienced a pneumonia-related die-off with persistent pneumonia observed in juveniles for years afterward. Sheep declines occurred in all areas and that pattern has continued.
In 2020 there were approximately 800 sheep in the same area, approximately a 70% decline. Since 2000, the provincial animal health laboratory has had the ability to test live and dead animal tissues for Mollicutes, and more specifically for M.ovi, and research has confirmed that M.ovi is a primary causal agent of pneumonia in bighorn sheep.
The implementation of the Fraser River Disease Mitigation Program supported by the Wild Sheep Society of BC alongside our partner Wild Sheep Foundation, consists of two key phases. Phase 1, health sampling to document the distribution of M.ovi along the Fraser River and Phase 2, test and remove treatments and treatment effectiveness monitoring.
This project is scheduled over a ten-year period and we just concluded our sixth year of treatment. Over the winter of 2023/24 sixty-four bighorn sheep were captured at Big Bar and the Chasm area.
Since the inception of the project, we have tested over 600 Bighorn Sheep. We are seeing significantly increased lamb recruitment in the treated areas which indicates that wild sheep populations have likely been cleared of m.ovi and we anticipate significant growth in these herds moving forward. Out latest data shows a post treatment lamb recruitment of 47 lambs per 100 ewes compared to a pre-treatment lamb recruitment of 13 lambs per 100 ewes.
However, there is significant work to complete on this project in the remaining four years with a budget of 2.43 million dollars over the life span of the project. Our vision is to restore the struggling California Bighorns on the Fraser River to their historic carrying capacity of over 2400 wild sheep.
It is through the collaborative supportive of the following organizations who have provided funding, that makes this project possible: The Wild Sheep Society of BC, Wild Sheep Foundation, Canadian Wildlife Capture, Wild Sheep Foundation Mid-West Chapter, Abbottsford Fish and Game Club, Habitat Conservation Trust Foundation, Guide-Outfitters Association of BC, and the province’s Together for Wildlife program.
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