In 2013 the Chasm bighorn sheep herd experienced a decline from approximately 100 to 25. Co-mingling with domestic sheep was directly observed on a farm within their home range and further validated through a GPS collaring project. Health sampling as part of the collaring project determined that two out of four Chasm bighorns had been exposed to Mycoplasma ovipneumoniae (referred to as Movi) antibodies that were detected in blood serum samples.
Decline of Chasm bighorn sheep due to Mycoplasma ovipneumoniae (Movi)
Movi is a respiratory pathogen originating in domestic sheep that invades the bighorn sheep lungs and predisposes affected animals to polymicrobial pneumonia. Since the 2013 decline, lamb recruitment within the Chasm population has been poor. The domestic sheep on the farm where contact was suspected have now been sold and no domestic stock remain. This population estimate has been stable to declining for five years. Aerial and ground counts estimate the current Chasm bighorn population is comprised of 17 ewes and young rams.
Following a peak in surveyed populations in the early 1990s, the Fraser River bighorn meta population has declined by over 50% with the current estimated number of bighorns at 500. Aerial surveys from 2019 noted that herds on the west side of the Fraser River within management unit 3-32 had declined by 16% just since the last survey in 2016. Poor lamb recruitment is widespread throughout the study area. In 2011, in response to reports of sick lambs within the Pavilion herd near Lillooet, health samples were acquired and confirmed that sheep were carrying Movi.
B.C. Sheep Separation Working Group and Wild Sheep Society’s “Save our Sheep” campaign
In response to the Chasm die-off in 2013, a B.C. Sheep Separation Working Group was established with representatives of the Wild Sheep Society of B.C., Foundation of Wild Sheep, B.C. Sheep Federation, B.C. Wildlife Federation, the Ministry of Agriculture, and the Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Over time there have been many improvements from the science perspective in terms of literature reviews, sampling protocols, disease assessments, and treatment trials. However, the development of a ‘policy/regulation options paper’ by the Ministry of Agriculture, originally scheduled for 2015, has not been acted upon. It is the lack of action that has prompted the Wild Sheep Society of B.C. to launch their “Save our Sheep” campaign asking for support of British Columbians to save the Chasm bighorn sheep herds in B.C.
Please join the B.C. Wildlife Federation in supporting this campaign. Visit the Wild Sheep Society’s campaign website now and learn how you can take action: https://www.wildsheepsociety.com/help/