It's been a slow summer for commercial fishers in the Northwest Territories, who have netted less than half of last year's catch.

The lower numbers are partially due to forest fires, according to Jason Grabowski with the Winnipeg-based Freshwater Fish Marketing Corporation, which buys, processes and markets all freshwater fish caught for commercial sale in Manitoba, Alberta, and the Northwest Territories. 

According to a report conducted by the United States Department of Agriculture in September 2012, wildfires can affect the quality of the water as well as the channels in a stream. 

Bull Trout

The Freshwater Fish Marketing Corporation says fish haven't moved into the Mackenzie River yet, and that's where most commercial fishers are waiting to get their catch. (Province of Alberta)

"If a severe fire burns near or across a stream, water temperature can increase substantially," the report read. "Dissolution of smoke, ash, and volatile compounds can alter pH concentrations of trace metals, nutrients, and other chemical constituents in stream."

The report says that can affect what's growing in the body of water, which is often what fish eat. It also says warmer water temperatures can affect where fish swim, which could be different from where fishermen in the Northwest Territories are looking. 

Grabowski says a late ice break-up on the rivers has also affected the season. 

"They haven't had their run yet from the Mackenzie," Grabowski said. "So a lot of guys are waiting around the Mackenzie for the fish to start moving, but they really haven't. Last year, it started the third week of July — and that was late."

Grabowski says fishers have netted 111,000 kilograms of fish so far. Last year, they caught 275,000 kilograms. 

He says fishermen are considering working into the winter.