BC Salmon Group Recommendations for Salmon Habitat Destroyed by Wildfires

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The Pacific Salmon Foundation recently published a list of possible human actions to restore salmon habitat damaged by the devastating 2023 wildfire season in British Columbia.

With “larger, more intense and more frequent” wildfires predicted for the future, the Pacific Salmon Foundation is concerned about the habitat of British Columbia’s wild salmon and the watersheds on which the fish species depend.

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“Individual fires have … devastated entire watersheds on a scale and intensity that suggest a potential shift in disturbance patterns experienced in the 20th century,” according to the Foundation’s Playbook to Guide Landscape Recovery Strategies and Priorities for Salmon Habitat Following Major Wildfires.

“The resulting soil changes and loss of vegetation combine to affect river flows and temperatures, channel morphology and water quality, and these effects threaten to push some salmon populations beyond their capacity to adapt,” the guide says. “This is particularly true for those populations that are already ‘at risk’ and limited by factors exacerbated by wildfires.”

The playbook is a compilation of best practices that provide guidance on how to better integrate salmon following wildfire devastation, with approaches to improving their habitat and accelerating the recovery of salmon habitat destroyed by wildfires.

Some of these measures are direct, such as removing blockages that prevent fish from migrating upstream. Another is an engineered debris basin that controls the discharge and collection of sediment in a stream after this natural process has been disrupted by a wildfire.

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Other approaches are not expected to have their full effect for another five or six decades, but their importance is emphasized because of the long-term benefits to the environment on which salmon depend.

These include replanting trees to stabilize erosion and human analogs of beaver dams to mimic structures the animals would build in a floodplain. Structures such as weirs, rock steps, intentional log jams and placed boulders to control river flow can improve river conditions, the restoration strategy says.

Jim Lane, Uu-a-thluk program manager for the Nuu-chah-nulth Tribal Council on Vancouver Island, says the impacts of wildfires on salmon habitat vary by location.

“At the landscape level, fire is the biggest disturbance,” Lane said, referring to how wildfires have affected Vancouver Island. “But overall, it doesn’t happen that often.”

One of the first concerns, Lane said, is how quickly the fire is spreading and whether the fire is next to a small stream or a large lake.

“You don’t have to worry about temperature issues in a big lake, but you probably would in a stream,” Lane said. “If it’s right there, it would probably cause some temperature stress.”

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He notes that temperature stress also depends on water flow and existing water temperature.

“If you have a fire along the shoreline of Sproat Lake, where (there are) no real streams coming in, it’s not going to do much to the lake,” Lane said. “Along a bunch of small streams that are all carrying fish, then they could have some negative impacts.”

Lane added that when the understory, the layer of vegetation beneath the main canopy of a forest, is removed, it can destabilize the surface soil. During rains, material can wash into streams, which can be a problem for fish in the area.

Alexandra Mehl is a reporter for the Local Journalism Initiative at Ha-Shilth-Sa, published in Port Alberni by the Nuu-chah-nulth Tribal Council. The Local Journalism Initiative is funded by the Canadian government.

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