Kim Kozlowski

The Detroit News

The wolves on Isle Royale are almost gone.

Two wolves remained on the desolate island this winter, down from three last season, while the island’s growing moose population is estimated at 1,300, according to one of the co-principal investigators of the longest, continuous predator-prey studies in the world.

The official 2015-16 wolves and moose study, now in its 58th year, is being reviewed by the National Park Service since the island is a national park. It is expected to be released at the end of this week or early next week.

But according to professor Rolf Peterson of Michigan Technological University, the annual winter tracking of gray wolves showed that only two remain, estimated at 6 and 8 years old, respectively.

“So they probably won’t last too many more years,” Peterson said.

That, he warned, means the island’s moose population is likely to keep growing unchecked. The island had about 500 moose in 2009 and 1,250 a year ago, while the wolf population peaked at 50 in 1980.

“As we have been stating for several years, wolf predation has been virtually absent for several years, now five years,” Peterson said. “In the absence of limitation by wolves, the moose population is rapidly increasing, and there is concern that moose browsing may do long-term damage to the forests of Isle Royale.”

The wolves, which have survived by preying on Isle Royale moose, have offered scientists at Michigan Tech an unprecedented opportunity to study a predator-prey system on an isolated island for more than half a century. The study has captivated the public, captured the attention of scientists around the world and put the Upper Peninsula university on the map.

Peterson and other scientists have lobbied to bring more wolves onto the island to rejuvenate the remaining few.

Others have argued the human intervention would interfere with the natural population of the wolves and moose.

Ultimately, what happens on Isle Royale is up to the park service, which is conducting an environmental assessment of the island, with a decision expected in late 2017.

Options include no intervention, introducing wolves as a one-time event over a defined period of time and bringing wolves as often as needed over a 20-year period, according to an online newsletter from the park service.

“The potential absence of wolves raises concerns about possible effects to Isle Royale’s current ecosystem, including effects to both the moose population and Isle Royale’s forest/vegetation communities,” the newsletter said. “The revised purpose of the plan, therefore, is to determine whether and how to bring wolves to Isle Royale National Park to function as the apex predator in the near term within a changing and dynamic island ecosystem.”

The park service has sought public input as to how to manage the moose and wolves of the island over the next two decades.

During the comment period last year, the park service received comments from individuals in all 50 states, the District of Columbia and 19 countries.

kkozlowski@detroitnews.com