TRAVERSE CITY, Mich. — Managers are leaning toward relocating as many as 30 gray wolves to Isle Royale National Park from the mainland to restore an iconic predator species on the verge of disappearing from the Lake Superior island chain, according to a federal report released Friday.

Other options include taking up to 15 wolves to the wilderness park in the short term and adding others over 20 years, or doing nothing immediately while keeping the door open for replenishing their numbers later. Also under consideration is simply letting nature take its course. That probably would doom the Lake Superior park’s wolf population, which has plummeted in recent years and now consists of just two inbred survivors.

The population totaled 24 as recently as 2009.

The choices are outlined in a draft environmental impact report crafted by National Park Service scientists, other staffers and outside consultants. Administrators will make a decision after a 90-day comment period that ends March 15, Isle Royale Superintendent Phyllis Green said.

Wolves have a relatively short history on Isle Royale, where other species such as caribou and lynx lived for considerably longer periods before dying out. Scientists believe the first wolves arrived in the late 1940s, having traversed the frozen lake surface 15 miles or more from Minnesota or the Canadian province of Ontario.

Yet visitors are enthralled when an elusive wolf darts across a backwoods trail or a distant howl breaks the silence of a starry night. Many campers have argued passionately for maintaining their presence — even if it means tinkering with nature, which wilderness purists frown upon. The wolves, along with the island’s abundant moose, are also the subjects of the world’s longest-running biological study of a predator-prey relationship in a closed environment.

Officials said the wolves’ popularity, while important, won’t be the deciding factor. Nor can their fate be considered in a vacuum. Managers must determine how best to care for the island’s overall health as climate change introduces new uncertainties about the future of its plants and animals, said Nancy Finley, natural resources director for the park service’s Central region.

“If it was the last wolf on Earth, it might be a different situation,” Finley said. “But in this case, it’s about managing a unique island ecosystem and determining the role the wolf has in that ecosystem, and how it plays out over time.”

The wolf population has averaged in the low 20s, divided among several packs. They have staked out territories in different sections of the 45-mile-long park, which includes a main island and hundreds of little ones.

Scientists believe other wolves occasionally have wandered over during cold winters, helping refresh the gene pool. Even so, inbreeding has caused health problems, which likely worsened as a warming climate enabled ice bridges to form less frequently. That underscores the need for intervention if the wolves are to be saved, the report said.

Meanwhile, moose numbers are rising steadily and exceed 1,200. Without a predator to keep them in check, they could damage the island’s trees and have periodic population crashes.

Of the four options in the report, the park service’s tentative preference is for capturing 20-30 wolves on the mainland and taking them to Isle Royale by aircraft or boat within three years. Additional wolves could be supplied for the next two years in the event of an unexpected setback, such as a significant die-off among the new arrivals.

That approach would provide the quickest benefit to the park’s natural systems and limit the human disturbance that wolf relocation would cause, as opposed to the alternative of starting with six to 15 wolves and bringing more later.

But officials will keep an open mind and could decide differently after hearing from the public, Green said.

“We have to go beyond loving wolves to understand their complexities … how they function in the wild and their relationship with the ecosystem around them,” she said.

Rolf Peterson, a retired Michigan Tech University biologist who has studied the park’s wolves and moose since 1970, said he was pleased the park service appeared to endorse wolf recovery and “getting paws on the ground” quickly, but was puzzled that its preferred option rules out relocating wolves to the island after five years.

“That ties your hands if things unravel in year eight or year 12,” he said.

The National Parks Conservation Association, a nonprofit advocacy group, also supports wolf relocation, said Christine Goepfert, senior program manager for the Midwest.

“It’s really important to have an apex predator, a species at the top of the food chain,” she said.