The state of Montana and the National Park Service say they will collect information for a possible new plan to manage bison herds at Yellowstone National Park.

The herds have long been subject to slaughter over concerns they could spread disease to livestock in Montana.

The park service and the state said Friday they will prepare an environmental impact statement on a plan before soliciting public comment. The goal is to replace a bison management plan adopted in 2000.

Officials are trying to conserve a viable wild population of Yellowstone bison while reducing the risk of brucellosis transmission to livestock.

About half of Yellowstone's 4,600 bison test positive for the disease, which causes pregnant animals to abort their young.