Dramatic increases in the melting of Alaska’s massive glaciers in the midst of global warming reflect a silver lining for wild salmon, but once the melting has concluded, such benefits will likely not be realized, according to Peter Westley, a fisheries researcher at the University of Alaska Fairbanks.
Westley highlighted recent work led by colleagues at Simon Fraser University that quantified the rich bounty of salmon habitat currently hidden, but soon to be revealed, by rapidly melting glaciers.
The current rate of melting glaciers in Alaska is much higher than salmon have experienced in a long, long time, said Westley of UAF’s Salmonid Evolutionary Ecology & Conservation (SEEC) Lab.
Currently, glaciers are helping cool the waters and create new habitat for wild salmon, but eventually they’ll disappear and then the cooling of the water will change, he said.
“If glaciers melt and retreat and produce good habitat, but the ocean is too warm or too full of salmon the benefits won’t be realized,” Westley explained.
Still, he said he’s optimistic that researchers can find ways to adapt salmon management for the continuation of the state’s very popular and robust salmon fisheries.
Retreating glaciers are creating a lot of salmon habitat by creating new streams, he said. All of these streams currently have no fish in them, but salmon will stray into them as time goes by, he said, noting that wild salmon in Cook Inlet are all descended from strays that didn’t come home. The Fox River at the head of Kachemak Bay in Homer, for example, was founded by subsiding glaciers and colonized by straying salmon.
Salmon are renowned for their ability to find a way back to their natal streams to spawn. Still, some individual fish stray and colonize new habitats, providing a hedge against catastrophic habitat change at natal streams impacted by climate, social interactions and human disturbance. As noted on the SEEC lab website, the straying of hatchery produced salmon in Alaska and the Pacific Northwest is also a major conservation challenge and members of the SEEC Lab are working to understand causes and consequences of straying in both applied and fundamental contexts.
Members of SEEC work at the intersection of ecology and evolution to address conservation problems toward a goal of sustaining connections between salmon, people and places. They study the homing and straying of wild salmon, their collective behavior and how they are adapting in a changing world, as well as related invasion biology, which poses a threat to native biodiversity and ecosystems.
The melting glaciers were the theme of a recent show at the Pratt Museum in Homer, Alaska, where renown oil painter David Rosenthal, of Cordova. Rosenthal said he hoped that his exhibit of art science and history would go on to many other locations in the Lower 48 states to clarify for many people the changes in the glacial landscape when the ice age is ending.
The full academic paper on glacier retreat creating new Pacific salmon habitat in western North America is available at https://www.nature.com/articles/s41467-021-26897-2.