BOISE, Idaho (AP) — There are too many wild horses on public lands, a federal official said Wednesday, and potential solutions include new sterilization methods, aggressive adoption efforts and holding more horses in corrals.

Acting Wild Horse and Burro Program Division Chief Bruce Rittenhouse of the U.S. Bureau of Land Management said the nearly 90,000 wild horses in 10 Western states are more than three times appropriate levels. Officials estimate that up to 18,000 foals are born each year.

“We know that we are in a challenge right now with this program,” Rittenhouse said.

Wild horses are generally viewed as iconic symbols of the West, but officials say they have few predators and quickly overpopulate what rangelands can support. Officials also say they consume food on rangelands used for raising cattle and can cause problems for native wildlife.

“There is limited forage and range and habitat and water for all of the organisms out there,” said advisory board member Celeste Carlisle during a break in the meeting. “It’s easy for (wild horses) to exceed their own carrying capacity because they reproduce quickly.”

As a result, another 50,000 wild horses are being held in corrals at a cost of $50 million annually, which is more than half of the Bureau of Land Management’s budget for its Wild Horse and Bureau Program.

The advisory board is tasked with making recommendations to the Bureau of Land Management and U.S. Forest Service regarding management of wild horses and burros, which the federal agencies can accept or reject.

Most wild horses roam Bureau of Land Management land, and that agency is in the process of preparing a report requested by Congress examining fertility control, the cost of holding horses, and the potential euthanasia of healthy horses, Rittenhouse said. He said it wasn’t yet clear what the final report might look like when it comes out in August.

Currently, only sick or injured horses are euthanized, and Congress prohibits the sale of wild horses for slaughter.

John Ruhs, director of the  Bureau of Land Management in Idaho, said a return to sending wild horses to slaughter, a standard practice much of last century, wasn’t likely.

“I don’t think that’s the answer,” he said. “I think we have a different society and a different mindset of how we look at those animals.”

Under federal law, wild horses are managed in what are called Herd Management Areas. There are 177 such areas in the U.S. West covering 50,000 square miles (130,000 square kilometers).