ISLE ROYALE — There are only three wolves remaining on Isle Royale as the study on the interaction between wolves and moose approaches a crossroad.

The study began more than 50 years ago, and put wolves and moose on a relatively isolated island and see how they interact. For a while, both populations did well as researchers studied the relationship between predators and their prey. But, as the wolf population dwindled genetic inbreeding began to take its toll.

“For many, many years that the wolves have been there, they’ve mitigated those inbreeding problems by wolves, occasionally, crossing an ice bridge from the mainland to the island and when they crossed that ice bridge, those wolves would bring with them their genes and they’d reproduce with the native wolves on Isle Royale and that mitigates the inbreeding problems,” MTU said Associate Professor of Wildlife Ecology John Vucetich.

There have been fewer ice bridges in recent decades so new genes have not been introduced. Even with the cold winters of the last couple of years, wolves that have crossed the ice to visit the island have not stayed. There are now only three wolves on Isle Royale, with more than 1,200 moose.

The National Park Service will need to make a decision soon on what to do with the study but Vucetich sees three options. One is to conduct genetic rescue by introducing new wolves into the mix, or introduce new wolves only if the current population becomes extinct.

The third choice is to do nothing, but with a runaway moose population on an isolated island, that may not be feasible. “The ecosystem health depends vitally on the presence of top predators wherever there are large ungulates, and we know that in so many places where large ungulates have been left to their own devices without predators, they ruin the forest,” said Vucetich. “They cause great harm to the forest, harm that is not easily undone.”

Until such a decision is made, the study will continue as long as at least one wolf is alive on Isle Royale.