As wildfires worsen, wild salmon take a hit

Salmon have long adapted to wildfires by spawning in parts of rivers untouched by the fires. But the extreme wildfires engulfing B.C. and western North America are leaving fewer islands of habitat intact, making it impossible for the fish to lay their eggs.

Now, wild salmon are facing a growing threat from the proliferation of hotter, larger fires, and fisheries experts warn more needs to be done to ensure they aren't wiped out.

"We're seeing major wildfires burning huge tracts of ecosystems and completely changing the landscape — and while those ecosystems will recover, salmon need to live in those streams," explained Jason Hwang, chief program officer and vice president of the Pacific Salmon Foundation.

Because salmon always return to the same stream to spawn roughly every four years, even a few seasons of being unable to lay their eggs might mean the fish will never return to those streams. That impact is compounded by a suite of other threats like dangerously warm water, habitat degradation, disease and overfishing that have sent over half of the salmon populations in B.C. into some state of decline.

Since 1986, thousands of fires have burned more than 7.7 million hectares (an area the size of Czechia) within salmon-bearing watersheds in British Columbia and Yukon.

"We can't just say, well, the ecosystem will recover in 20, or 40, or 80 years because in the meantime, the salmon are showing up in conditions that are completely inhospitable," Hwang said.

It is a problem government agencies, First Nations and other organizations responsible for managing the region's post-fire recovery need to address — and fast, he said. To help the process, the organization recently published a so-called "playbook" that compiles dozens of salmon habitat restoration techniques to help officials protect the species from being annihilated by wildfires.

The idea for the document came in the wake of a massive 2017 fire near Quesnel, B.C., when a local salmon restoration group reached out to Hwang to see how they could help ensure post-fire restoration efforts protected salmon. Although there was plenty of research about how best to restore salmon habitat after disruptions like urban development or forestry, nothing brought that research to bear on wildfire recovery, Hwang said.

For instance, stream banks that have been heavily burned are susceptible to intense erosion when it rains. The eroding sediment can then clog up key spawning habitat with silt for years, he said. But researchers have found that applying a layer of straw mulch on top of the soil before it rains can drastically reduce erosion and protect the stream from dangerous levels of silting.

With climate change poised to exacerbate the number of large, intense wildfires in decades to come, Hwang said compiling existing information about how to help salmon thrive could be useful to people trying to restore burned land. The goal is not to tell people what they should do; the intent is to help them decide how best to include salmon in their restoration work.

For John DeGange, who manages wildfire recovery and issues impacting the landscape in northern B.C.'s Omineca region for the B.C. government, the information contained within the playbook helps enhance the "holistic" process of restoring the land after a wildfire.

He says the biggest consideration when it comes to protecting salmon is knowing where they spawn. That helps him decide which parts of freshly-burned watersheds are prioritized in restoration efforts, hopefully protecting the fish from dying out entirely. With limited funding and huge areas of the province burned, prioritizing key areas is particularly important, he said.

"I'm in the north — there's fewer of us around to do the work, but there are a lot of wildfires out there and a lot of work needs to be done," he said.

The kind of severe wildfires that have scorched B.C. in recent years are only going to become more common as the climate crisis worsens, Hwang said. While reducing our greenhouse gas emissions to address the crisis is key, the survival of salmon depends on ensuring their populations last long enough for a return to more normal conditions — if we can reduce our emissions.

"We can't look at salmon that are coming back every year or trying to live as juveniles in their stream and just hope that they make it," he said. "The idea that we're trying to convey is we can do things that will help reduce the negative effects and ideally accelerate recovery — and where we can, we should."