According to the North Dakota Game and Fish Department, the 2017 bighorn sheep population survey shows a decrease.
"The decline in the 2017 count reflects the spread of bacterial pneumonia to three previously unaffected herds and consequently the adult and lamb mortalities that followed," said Brett Wiedmann big-game biologist, on North Dakota Game and Fish's website.
In a survey taken in March, there is an 11 percent decrease in population from 2016, with a minimum of 265 bighorn sheep. This is also a 9 percent decrease within a five-year average.
Wiedmann said 2017 count was the lowest since 2006.
Biologists counted 91 rams, 149 ewes and 25 lambs in their survey. There were also 20 bighorns in the North Unit of Theodore Roosevelt National Park.
"Fortunately, adult mortality was low in previously affected herds, and lamb survival improved as well, which could indicate those herds initially exposed to the deadly pathogens in 2014 are beginning to recover," Wiedmann said. "The next few years will be important in determining if the state's population shows signs of recovering from the disease outbreak, or if the pathogens are likely to persist and cause a long-term population decline."
In the northern Badlands, there was a 10 percent decline from 2016 and for the southern Badlands, the population declined 21 percent.
Game and Fish Department biologists count and classify all bighorn sheep in late summer, then recount lambs the next March because they will approach one year of age, to determine additions.
Dr. Dan Grove, department veterinarian, said that 20 adult bighorns were tested for deadly pathogens last winter, but results are still pending. He said animals continue to die from pneumonia but at a much slower rate.
The bighorn sheep hunting season is tentatively scheduled to open in 2018, unless there is a significant number of deaths from bacterial pneumonia. The status of the bighorn sheep season will be determined Sept. 1, after the summer population survey is done. The application to be able to get a bighorn sheep license was due March 28.
Game and Fish issued five licenses in 2017 and all hunters were successful at harvesting a ram.