Dean River, BRITISH COLUMBIA
Banking on Salmon DNA in B.C.
On British Columbia’s Central Coast, rivers like the Dean host unique races of wild steelhead coveted by anglers, while regional wild Chinook, sockeye, and chum salmon runs sustain ecosystems and local communities.
This is where Wild Salmon Center is partnering with Coastal Rivers Conservancy, First Nations, Simon Fraser University, and the Department of Fisheries and Oceans to build a game-changing genetic library—one that can help both salmon and the communities they support.
Over the next few years, this library will house DNA samples from hundreds of genetically distinct Pacific Northwest wild salmon runs, including key stocks from the Skeena and the Dean. Central Coast samples were collected this past fall by a team including WSC, CRC, and the Nuxalk Nation, with more field research planned in the coming years.
This tool will help salmon managers and First Nations answer a critical question: what fish are caught in B.C.’s commercial fisheries? Because most of the province’s salmon fisheries are “mixed stock”—in coastal marine zones where multiple runs mingle during their homeward migration—fishers can accidentally overharvest depressed or at-risk populations.
Ultimately, says WSC Science Director Matt Sloat, the library will help map each run’s migration timing and route. Samples collected from these mixed-stock fisheries can be matched with the library to determine what populations are moving through a fishery, where, and when. This knowledge could then inform selective fishing guidelines in areas where salmon populations co-migrate, to allow vulnerable runs safe passage.
The DNA library reflects a new understanding of wild salmon’s amazing ability to adapt to changing conditions. Even geographically close salmon populations can be genetically distinct, evolved for specific conditions. When fishers and salmon managers use the library to inform where and when to avoid vulnerable runs, fisheries can be fine-tuned to save that genetic diversity. The goal, a healthy “portfolio effect,” can pay off the same way this strategy works in the financial world: by spreading risk across many categories.
“Managers have to balance conservation goals with important fisheries,” says Dr. Sloat. “Knowing more about each stock in a salmon portfolio can help support better fisheries and also work to recover endangered salmon runs.”
Below: WSC’s Matt Sloat and Charles Saunders of the Nuxalk Nation collecting samples on the Dean River (Scott Carlson). Bottom: BC and Alaska glaciers (Alamy). Top: Dean River (Jeremy Koreski).
What Glacier Melt Means for Salmon
A new study from WSC Science Director Matt Sloat and a team of Pacific salmon experts finds that 85 percent of North America’s salmon watersheds have at least some glacier coverage—and that 80 percent of that cover will be lost by 2100.
Disappearing glaciers, combined with other climate effects, will leave some North Pacific salmon systems more vulnerable to heat and drought. But retreating ice will also likely create thousands of miles of salmon habitat.
Salmon are hardy and adaptable, with a long history dating back to the Miocene, with its warmer temperatures and higher seas. Wild salmon’s genetic diversity expresses itself in a range of behaviors, including the fraction of salmon that “stray”—e.g., seek out new spawning rivers instead of returning to where they were born.
Because glacier melt will open potential new habitat, salmon managers must think ahead, says study lead author Kara Pitman of British Columbia’s Simon Fraser University.
“We recommend they consider the future state of salmon, how habitat might change,” says Pitman. “That means integrating longer-term predictive modeling for glacier retreat.”
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