A new study at the University of Alaska Fairbanks (UAF) College of Fisheries and Ocean Sciences has confirmed that salmon are spawning in an Arctic Ocean watershed, suggesting that at least some salmon species could be expanding to new territory due to climate change.
Researchers found about 100 chum salmon in the Anaktuvuk and Itkillik rivers on Alaska’s North Slope. Both rivers flow into the Colville River, which empties into the Arctic Ocean.
All the fish caught by researchers in mid-September 2023 were either actively spawning or had finished spawning at sites where groundwater appeared to be flowing to the surface, said Jeff Richardson, communications manager for the college. Similar conditions have supported chum salmon reproduction throughout their typical range.
Westley said the discovery of these fish aligns with a hypothesis that salmon are being pushed north as their traditional habitat changes. Many established salmon populations, including some in California, are declining due to climate change.
“Throughout most parts of the salmon’s range, things have gotten too warm and they’re starting to blink off,” Westley said. “In the Arctic, the water is getting warm enough and they’re starting to blink on.”
He credited a December 2022 workshop hosted by Alaska Sea Grant, to discuss increasing numbers of salmon being observed in the Arctic Ocean, for shaping the goals of this research project.
The workshop helped steer researchers toward the Colville River watershed, some 60 miles southwest of Prudhoe Bay, on Alaska’s North Slope. The research team included UAF’s Westley, fisheries professor Andy Seitz, graduate students Lindley and Joe Spencer, and research assistant Julia McMahon, along with University of Washington ecologist Andrew Berdahl.
While salmon are well known for spawning before they die in the same river where they hatched. Outliers to that pattern exist. At times, they shift to new habitat that is more hospitable, Westley said.
“Straying is part of the biological story of salmon — it’s what they do,” he remarked. “It’s a fundamental part of their biology and evolution. In the Arctic, we can see it playing out before our eyes.”
It’s still unknown whether attempts by salmon to reproduce in the region have been successful. Researchers placed temperature sensors in some of the chum salmon nests to determine whether the rivers completely freeze during the winter, destroying any developing embryos. A return trip is planned in fall 2024 to look for smolt or a new wave of spawning adults.