4,000 square kilometers of land burned near Sambaa K’e. What does that mean for fish?

After a wildfire swept through the forest around Kakisa, NWT, in 2014, Lloyd Chicot began noticing changes in the lake: the pike were thickening and the pelicans were moving in.

Chicot, the head of Ka’a’gee Tu First Nation, attributes the change partly to climate change and partly to the fire’s runoff, which released nutrients and debris into the lake.

“Right after the fire, there was a lot of burnt driftwood and things like that,” he recalls.

Seagulls, once a common sight, dwindled in number to make way for fish-devouring pelicans.

The changes in that community are a glimpse into how wildfires can affect the ecology of the areas they burn.

Changes can be quite small, like those in Kakisa. But Kevin Timoney, a senior ecologist at Treeline Ecological Research in Alberta, says wildfires can also have major impacts, especially in peat bogs, such as those around Sambaa K’e.

The wildfire currently threatening Sambaa K’e has consumed more than 4,000 square kilometers of land south of that community and is burning in both the NWT and BC. The community of nearly 100 people was evacuated on May 31. Residents are still awaiting word on when they can go home, or whether the fire will overtake their small community.

The fire is also affecting the community’s main food source: Sambaa K’e Lake, also known as Trout Lake.

Satellite images from Tuesday show the northeastern arm of the fire approaching the edge of the lake. Sambaa K’e gets its water from that lake and many people live off the fish there.

Timoney, who studies how contaminants affect bodies of water, said one of the most immediate dangers to the lake could be a spike in mercury levels.

That’s because mercury lives in all the peat soil and vegetation around the lake — and can get trapped on smoke particles and make its way into the water, where it becomes toxic.

“Once it gets into the lake, it’s very difficult to remove it,” he explained, adding that it could build up in the food chain and be a long-term problem for anyone wanting to eat fish from the lake .

“Whether that succeeds depends strongly on the nature of the fire: how deep it burns in the peat, the direction of the wind, how erodible the soil is.”

Mercury is already present in that lake. In 2016 the NWT government issued notices to limit the consumption of larger walleye and lake trout in that lake due to higher than recommended levels of mercury.

The NWT Government keeps a list of lakes and rivers where announcements have been made about fish consumption. Lake Kakisa is not among them, although Lake Tathlina to the south has a warning for pike and walleye, which contain more mercury than recommended.

In an email, the NWT Department of Environment and Climate Change said it has an “extensive monitoring network” to watch for contaminants such as mercury from fires.

“Especially in Sambaa K’e, there are several water quality monitoring sites managed by the NWT-wide community-based monitoring program,” spokesman Mike Westwick wrote in an email.

Timoney said that kind of monitoring is key to making sure communities know if their fish are safe to eat after a wildfire.

He said changes in fish like Kakisa saw – with pike getting fatter – carry dangers because contaminants often live in the oily parts of fish.

Westwick pointed to several initiatives that track water quality, including projects that specifically monitor heavy metals such as mercury.

That includes a project led by the Dehcho First Nation and a Wilfrid Laurier University researcher that has been going on for more than a decade.