New research suggests that the rapid transformation of the Pacific Arctic may benefit some species more than others, and that pink salmon may be one of those beneficiaries.
Study leader Ed Farley, a NOAA Fisheries biologist at the Alaska Fisheries Science Center, says their research suggests that warming temperatures are increasing freshwater habitat and improving early marine survival of pink salmon in the northern Bering Sea.
Arctic residents living near the Chukchi and Beaufort seas have noticed an increase in pink salmon in their subsistence nets for the past decade, and more adult pink salmon are being found as well in subsistence nets as far east as the Canadian Beaufort region, Farley said.
“It is likely that these adult pink salmon are straying north during this period of warmer summer ocean temperatures,” Farley said. “What we do not know yet is if the freshwater streams in the high Arctic are warm enough to support successful spawning.”
Still, he added, “we believe the results from the northern Bering Sea region suggest that as the ocean and freshwater systems warm, pink salmon are becoming more successful. Given this result, it is likely that if warming continues in the high Arctic, pink salmon could begin to successfully spawn in those freshwater systems.”
The study itself provides findings of value for commercial and subsistence fisheries, and fishing communities preparing for the future.
“Subsistence harvesters would like to know what foods may be available to them now and into the future,” he said.
In Arctic subsistence diets, fish are some of the most commonly eaten foods, added Todd Sformo, a biologist at the North Slope Borough Department of Wildlife Management and coauthor of the study.
“In the past on the North Slope, salmon have been used for dog food and even considered nuisance fish when interfering with preferred species such as aanaakliq or broad whitefish in the inland rivers,” Sforno said, “Recently there seems to be a change both qualitatively and quantitatively in the use of salmon as a main dish and for smoking.”
“While this research is further south than the waters surrounding the North Slope, it is a beginning of our attempt to account for potential change in subsistence fishing,” he said.
Pink salmon are the most abundant salmon species in the North Pacific Ocean, and over the last decade their numbers have increased there.
With the dramatic loss of sea ice, the ecosystem is transforming, Farley said.
“Seabirds have shifted from fish-eating species to plankton-eating species,” he said. “Fish such as walleye Pollock and Pacific cod are moving north in large numbers. And we are seeing big changes in salmon populations.”
“We think pink salmon are moving north, seeking new territory as the population grows in the south,” Farley said. “Until now, cold temperatures in freshwater rivers and streams were believed to limit pink salmon spawning in northern regions. As the region warms, more areas may open for spawning Thee is also evidence that warmer sea temperatures benefit juvenile pink salmon early marine growth.”
Still there are many unknowns, including what competition for food sources may develop as more pink salmon come into Arctic waters.
Juvenile pink salmon feed on a combination of zooplankton and small fishes. How increased abundance of juvenile pinks will impact other fish through potential competitive interaction remains an unknown.
“We are working on modeling growth rate potential for juvenile pink and chum salmon in this area,” Farley said. “Previous models suggest growth rate for juvenile chum salmon increases during periods of warmer sea temperatures. There are a lot of unknowns on competition among fish species in the northern Bering Sea as the recent warming has seen an increase in adult Pacific co and walleye Pollock into the region too.”
“To date the most exciting thing about this study was being able to link our survey data to changes in ecosystems and climate to see how fish respond to shifts,” Farley said.
The study connected pink salmon dynamics from juvenile abundance to adult returns, something that had not been done previously in this region,
“Conditions in those environments are key to our understanding of pink salmon production dynamics in this region” Farley said. “And conditions under climate change may benefit pink salmon in the Pacific Arctic.”
