This is the first fall in many years North Dakota has not had a bighorn sheep hunting season.

Even though the number of licenses always has been low, typically ranging from three to six a year over the past two decades, interest always is high, with the odds of receiving one of these once-in-a-lifetime licenses about 1 in 2,000, plus or minus a few hundred.

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While the North Dakota Game and Fish Department did not open a hunting season in 2015, there was considerable interest in the summer bighorn sheep survey, as it would indicate how much a disease outbreak last summer had affected the population this year. That disease outbreak, verified as pneumonia, killed more than 30 sheep before the onset of winter.

Each summer, Game and Fish biologists count and classify all bighorn sheep, a process that takes nearly six weeks as biologists locate each bighorn herd in the Badlands by tracking radio-marked animals from an airplane. Once a herd is located from the air, biologists hike on the ground to observe each group from a distance with spotting scopes and binoculars.

Biologists then complete the annual survey by recounting lambs in March to determine recruitment-or lambs that survive their first North Dakota winter.

This fall's survey showed that despite the ongoing pneumonia event, North Dakota's bighorn population increased a modest 6 percent from last year, primarily due to good lamb survival and recruitment.

Game and Fish biologist Brett Wiedmann said the survey indicated a minimum of 304 bighorn sheep, which included 87 rams, 159 ewes and 58 lambs. The department's survey does not include about 30 bighorn sheep that live in the North Unit of Theodore Roosevelt National Park.

This year's slight increase can be attributed to better-than-expected lamb recruitment from 2014, Wiedmann said.

Before the summer survey, biologists had not documented any bighorn sheep deaths related to pneumonia since January, but during the latter part of the survey, they did observe sheep that were showing clinical signs of the disease.

Wiedmann said the bighorns showing symptoms of disease this summer were from the same herds that were most affected last year.

"Unfortunately, these are three of our core herds in the northern Badlands, so we'll have to once again closely monitor the impacts of pneumonia, as many adults and lambs showing signs of disease in August likely will not survive the winter," he said.

Those herds in the northern Badlands that were not affected by last summer's die-off appeared healthy again this summer and achieved high female-to-lamb ratios.

Dr. Dan Grove, Game and Fish wildlife veterinarian, said it is too early to tell the severity.

"Since summer 2014, mortalities have not yet been catastrophic," Grove said. "However, the outbreak is ongoing, and we detected a virulent strain of bacteria last year that was collected from both dead and live-sampled bighorns. Consequently, the recurrence of pneumonia this summer may be more apparent when females and lambs are recounted next March."

In addition, Game and Fish has documented a couple of sheep deaths over the past few weeks since the survey was completed.

Only time will tell how long or how much the presence of pneumonia will affect the state's bighorn herd, but that certainly will factor into decisions on whether to hold hunting seasons in the near future.