Matt Dyer, a prominent legal aid lawyer from Maine, was with seven other people as part of a Sierra Club hiking trip to Torngat Mountains National Park when he was attacked by the bear.
Peter Deering, with Parks Canada, said the bear managed to pass a portable electrical fence and drag Dyer from his tent at around 1:30 a.m. AT.
Dyer was mauled by the bear, but was dropped after the other group members fired flares to scare the bear off.
Jason Halal, marketing manager for the Sierra Club's national outings program, said Dyer suffered bite wounds and broken bones, but is recovering.
Dyer is in an intensive care unit, but in stable condition, at Montreal General Hospital. No one else in the group was injured.
Parks Canada advises visitors of the park to hire an armed Inuit polar bear guard through the Nunatsiavut base camp set up in the park during their visit, but it is not required. Dyer's group did not hire a bear guard.
Deering said this is an issue Parks Canada is currently looking at.