DULUTH - The National Park Service is getting closer to announcing its final decision on reintroducing wolves to Isle Royale National Park, and it couldn't come a minute too soon.

Wolf researchers for Michigan Technological University say the island may be down to its very last wolf based on analysis of trail camera data gathered over the summer and through September.

"We were able to document only one on a trail camera," said Michigan Tech researcher Rolf Peterson. "It's still possible that there are two."

It's not that having the final two wolves would matter much anymore because the pair was unable to produce viable offspring. The last two, a male and his daughter/mate, produced pups that didn't survive, likely because they were inbred.

John Vucetich, another Michigan Tech researcher who studies wolves and moose on the island with Peterson, said it's very plausible there is only one wolf remaining but that the difference is only an issue for people who are watching the wolves' plight.

"Biologically it really hasn't mattered for about five years. That's when they (the island's wolves) were last biologically viable," Vucetich said.

Wolf numbers have crashed from 24 in 2009 to just the pair earlier this year - a 7-year-old female and 9-year-old male - as inbreeding spurred genetic defects that have crippled the wolves' ability to survive and reproduce.

As wolves decline moose numbers on the island have skyrocketed, from 1,300 in 2016 to 1,600 in 2017, and researchers say that number continues to increase. A new population survey will be conducted in January with results released in April.

It's because of that unhealthy predator-prey balance that the National Park Service decided one year ago to intervene and bring new wolves to the island. Isle Royale officials held public input sessions earlier this year and then sorted through nearly 5,000 public comments on the proposal before submitting their final plan to Washington month ago.

A decision was expected by year's end but it's not clear now if that will happen. Mark Romanski, natural resource division chief for the park, said the final document remains under review by U.S. Interior Department/National Park Service officials in Washington.

"We don't know exactly when that process will conclude," Romanski said, adding that he expects a decision "fairly soon."

In addition to the Park Service's "draft preferred alternative" of introducing up to 30 wolves immediately to bolster the population, the Park Service considered a no-action alternative and a slower reintroduction, starting with just six to 15 wolves and waiting to see what happened.

Some people had suggested that the Park Service stay out of the situation and let the island's wolves run their course, saying the definition of federal wilderness is an area not impacted by human action. But others say the problems wolves face - including climate change and vastly diminished Lake Superior ice cover, which makes it less likely for new wolves to come to the island - show humans already are having an impact.

The 45-mile-long, 143,000-acre island is located about 15 miles off Minnesota's North Shore.

Moose came to the island around 1900, peaking at 2,445 in 1995 and hitting bottom at just 385 in 2007. Wolves are relatively new to the island, having crossed the ice in 1949. Their numbers reached a high of 50 in 1980, and 24 wolves roamed the island as recently as 2009.

Climate change, spurring fewer years of ice bridges between the island and the mainland, has reduced the number of new wolves venturing to the island and reduced the pack's genetic diversity.

The 59-year Michigan Tech effort is the longest running predator-prey study in the world.