BILLINGS, Mont. - Wildlife officials have divvied up how many grizzly bears could be killed by hunters in the Yellowstone region of Wyoming, Montana and Idaho as the states seek control of a species shielded from hunting for the past 40 years, according to documents obtained by the Associated Press.

The region's grizzlies currently are under federal protection, but that could change in coming months, turning control over to the states. A draft agreement detailing the states' plans for the animals was obtained by The Associated Press.

The agreement puts no limits on grizzly bear hunting outside a 19,300-square mile management zone centred on Yellowstone National Park. Inside the zone, which includes wilderness and forest lands adjacent to the park, hunters in Wyoming would get a 58 per cent share of the harvest, a reflection that it's home to the bulk of the region's bears. Montana would get 34 per cent and Idaho 8 per cent.

The management zone has an estimated 717 bears. There is no estimate for how many live just outside the area, although biologists say the number is increasing as grizzly bears expand into new habitat.

Wildlife advocates say the bear population remains too small to withstand much hunting. That's a particular concern given the large numbers of bears already dying, including during surprise run-ins with hunters and after livestock depredations that prompt officials to trap and kill problem bears.

In 2015, at least 59 Yellowstone-area grizzlies were believed to have been killed or trapped and removed by government agencies. That's the most since the animal was given protection under the Endangered Species Act in 1975.

Despite the deaths, state officials say the grizzly population has recovered from excessive hunting and trapping that exterminated grizzlies across most of the U.S. in the early 1900s. The officials have increased pressure on U.S. Fish and Wildlife Director Dan Ashe in recent months to revoke the animal's threatened status.

Directors of the states' wildlife agencies told Ashe in a Dec. 4 letter that such a step was long overdue.

"It is critically important that we capitalize on our tremendous progress and proceeding with a long overdue delisting" of bears from the threatened species list, the directors wrote. It was signed by Idaho Fish and Game Director Virgil Moore, Montana Fish, Wildlife and Parks Director Jeff Hagener and Wyoming Game and Fish Director Scott Talbott.

Montana wildlife activist Louisa Wilcox says the states' push for hunting ignores the many bears already dying due to other causes.

"You're not even hunting them and you have this ongoing pile-up of dead bears," Wilcox said. "Adding a hunt will drive down the population. It's exactly the wrong thing to do."

State officials said bear hunts would be conservative and need approval from wildlife commissioners following a public comment period. The size of each harvest would be on a sliding scale. More hunting would be possible when the population tops 675 bears, and hunting would be largely barred if that figure falls below 600 animals.

"We're definitely not talking about a large number. We're not talking hundreds or anywhere near that," said Wyoming Game and Fish spokesman Renny MacKay.

A decision on whether protections should be lifted is due in early 2016, according to the U.S. Fish and Wildlife Service. Barring a successful court challenge, it would take approximately a year for such a rule to go into effect.