YELLOWSTONE NATIONAL PARK , Montana ( CNN ) -- The gray wolf was officially removed from the Endangered Species Act 's `` threatened '' list Friday after three decades -- a decision that has stoked controversy among environmentalists and ranchers . Federal officials estimate there are 1,500 gray wolves in Yellowstone National Park . It means the wolves can be shot and killed once they step out of Yellowstone National Park as soon as the affected states establish a hunting season . However , state Fish and Wildlife officials can shoot the animals whenever they deem the wolves to be a problem . The government delisted the wolves -- which were eliminated from Yellowstone decades ago before being reintroduced in the 1990s -- because they are now thriving in the park that is dominated by bison , elk and bighorn sheep . `` They 're back here in the Northern Rockies ; they 're back here in Yellowstone , '' said Doug Smith , a biologist for the National Park Service in Yellowstone . `` That 's something to celebrate given their history of human hatred . '' But not everyone is happy about the animal being removed from the endangered list . Conservationists believe hundreds of gray wolves straying from Yellowstone in search of prey could soon be killed by hunters and ranchers . Watch rancher say no wolf is `` sacred '' » . `` We 're not ready to pop the champagne corks and have a party , '' said Doug Honnold , the managing attorney for Earthjustice , a non-profit environmental law firm based in Oakland , California , that has threatened to sue the government . `` My biggest fear is we 're going to go backwards instead of forwards . '' It would n't be the first time . In the early 20th century , wolves were the targets of a massive government extermination campaign . `` It 's harder to find an animal more persecuted than wolves . ... We did wolf extermination with a vengeance , '' said Smith . But attitudes began to change in the 1980s . Elk and bison populations increased dramatically because there was no natural predator to keep their numbers in check . In 1995 , Smith led a team to bring wolves back to the Rocky Mountain landscape . They transplanted dozens of wolves to Yellowstone from Canada . See photos of Yellowstone 's animals » . The project has been regarded as an overwhelming success . There are now more than 1,500 wolves across Wyoming , Idaho and Montana , according to the government . That number convinced federal wildlife officials to remove them from the endangered species list . Federal officials require each of the three states to maintain a population of 100 wolves , meaning a total of 300 wolves across all three states . The states have actually pledged to keep the population higher than that , at a rate of 150 wolves per state . `` We did a thorough analysis , '' said Ed Bangs , the wolf recovery coordinator for the U.S . Fish and Wildlife Service . `` The consensus [ for recovery ] is a population of 300 wolves and 30 breeding pairs . '' He added , `` The wolf population is fully recovered . We have more wolves than we ever predicted and we have fewer problems than we ever predicted . '' Earthjustice says that 's not nearly enough to ensure a viable population and they want to stop the delisting . `` We 're going to have hundreds of wolves die needlessly , '' said Honnold . But many ranchers in the region just do n't understand the fuss about the animals . They have complained for years that the wolves eat their livestock . `` There 's nothing about a wolf that 's sacred , '' said Bruce Malcolm , a cattle rancher and Republican member of Montana 's House of Representatives . He said he 's lost nearly two dozen cows to the wolves in recent years . `` I would have preferred that they never came here , '' he said . If there 's a winner with the controversy , it 's Yellowstone . The wolves have pushed up attendance by more than a 100,000 visitors per year , according to a park study . Smith , who has dedicated his life to the wolves , is philosophical about the debate . `` No one says living with wolves is easy , '' said Smith . `` Living with wolves is a compromise . '' E-mail to a friend .
Gray wolves officially no longer considered endangered . Environmentalists fear hundreds of wolves could soon be killed by ranchers . Rancher tells CNN the animals threaten his way of life . Comment: