The National Park Service will use skilled shooters, capture and other methods to reduce the Grand Canyon's bison population by more than half.

The agency gave final approval this month to the effort to bring the number of bison to around 200 within three to five years.

Park officials say the massive animals are damaging natural and cultural resources. The NPS is concerned about water, plants, soil, and other park qualities.

Up to 600 roam the Grand Canyon's far northern reaches and the adjacent forest. The first herd of 100 animals was introduced to the area in the early 1900s. The NPS worries the heard could grow to up to 1,500 animals within 10 years.

Volunteer shooters would be selected through a lottery and have to prove they're proficient with firearms and physically fit. Much of the work would be done on foot.

The bison meat would be given to volunteers, tribes and food banks.

A team is expected to develop guidelines later this year. Read more specifics here.

The Associated Press contributed to this report.