People in the northern Yukon community of Old Crow likely won't be allowed to fish for chum salmon this fall — unless this year's salmon run picks up in the next week or two.

The federal Department of Fisheries and Oceans imposed a two-week moratorium on chum salmon fishing on the Porcupine River, starting at noon PT Monday.

That two-week period encompasses the bulk of the chum salmon run, and DFO officials say the closure will remain in place unless the run improves dramatically.

"People are prepared for this closure. It's something that we're becoming sadly used to," Shel Graupe, director of natural resources with the Vuntut Gwitchin First Nation in Old Crow, told CBC News on Monday.

Graupe said most members of the First Nation have already captured other types of fish for the winter, so they are just hoping scientists can explain what's going on with this year's chum run.

'Really quite puzzling'

The run was supposed to be strong this year, but a high number of salmon deaths has meant there were less than half the normal number of fish counted along the Porcupine River from the Bering Sea to Old Crow.

"The chum run is looking terrible this year, and it's really quite puzzling," Graupe said.

"We don't know what exactly is going on, but we do know that something is going on, or a combination of things, most likely in the marine environment."

The problem could very well be related to the oceans, said Sandy Johnston, DFO's chief stock assessor in the Yukon.

"That's what appears to have happened," Johnston said.

"We'll do the final, I guess, post-season analysis once we get all the numbers in, but at this point, the run isn't looking very strong."

By contrast, the chinook salmon run on the Yukon River was strong this summer, to the point where the federal government lifted fishing restrictions there.