From the Bureau of Land Management:

The Bureau of Land Management (BLM), Carson City, Sierra Front Field Office has approved a pilot project to treat wild horses that reside near the Fish Springs community, approximately 10 miles south of the Pine Nut Herd Management Area, with fertility control porcine zona pellucide (PZP).

“Last year BLM held three public workshops seeking alternative methods of controlling this wild horse population rather than removal,” said Leon Thomas, Sierra Front Field Manager. “This pilot project was developed with input from several local wild horse groups as the result of those meetings.”

Over the next two weeks individuals from the Return to Freedom Wild Horse Preservation Campaign will be darting mares with PZP. A follow up shot will be needed in approximately 30 days. The mares will be monitored to determine whether this treatment has lowered the population growth rate. If successful, the program may be continued in 2015 and in other areas of the Pine Nut Mountains.

From the Bureau of Land Management