A research team is trying to determine why muskrat populations are on the decline in the Mackenzie Delta.

Jeremy Brammer, a PhD student at McGill University, is one of the researchers conducting the four-year study. He's collecting carcasses of muskrats and the animals that eat the rodent.

"The goal of that component of the program is to address how much are red fox, how much are mink and otters eating muskrats?" Brammer says.

It's possible that warmer winters are attracting the predators to the Arctic.

James Rogers

'In the 80s when I used to trap, I was getting 200 rats a day,' says trapper James Rogers. (David Thurton/CBC)

"Otters are becoming more numerous and being observed more frequently further North. This is what's being reported to me by trappers," he says.

Trapper James Rogers says he's seen a big decline in muskrats in the last few years, and he's witnessed otters attacking the animals.

"In the 80s when I used to trap, I was getting 200 rats a day," Rogers says. "Those were the good years."

The study, which started in 2014, is a partnership with the community of Old Crow, Yukon. It's funded by the Gwich'in Renewable Resource Board, the local Renewable Resource Council and Environment Canada.

In addition to studying carcasses, the researchers will also use satellite imagery and aerial surveys this summer.

Brammer's team will present their work at Inuvik's Aurora Research Institute at 7 p.m. tonight.