According to research, more than 6,150 kilometers of new salmon habitat might be produced by glaciers retreating in the Pacific highlands of western North America by 2100.
More than 46,000 glaciers in southern British Columbia and south-central Alaska have been "peeled back the ice" so scientists can see how much potential salmon habitat is produced when the underlying bedrock is revealed and fresh streams flow through the landscape. Researchers revealed that with modest temperature increases, glaciers might disclose potential new Pacific salmon habitat approximately comparable to the length of the Mississippi River (6,275 km).
Low-gradient streams (less than 10% slope) connecting to the ocean with receding glaciers at their headwaters are desirable for salmon in this situation. 315 glaciers were found to meet these standards by the researchers.
Nature Communications published their findings (December 7, 2021), led by researchers from Simon Fraser University (Canada) and the University of Birmingham (UK).
Researchers at Simon Fraser University's spatial analyst Dr. Kara Pitman said they expect most new salmon habitats to be found in Alaska and the transboundary area, where immense coastal glaciers persist. A 27 percent increase in salmon-accessible habitat is expected in the Gulf of Alaska sub-region by 2100.
"Once the conditions in the newly constructed streams have stabilized, salmon may swiftly populate these places. It's a frequent misunderstanding that all salmon return to the streams where they were born. The majority do, but some may wander, migrating into other streams to breed, and if circumstances are suitable, the population can quickly grow."
For nearly three decades, co-author Professor Alexander Milner of the University of Birmingham has studied glacier retreat and salmon populations in southeast Alaska. In the late 1970s, his team worked on Stonefly Creek in Glacier Bay, where glacier retreat exposed a new stream, and he says:
"After glacier retreat generates ideal spawning habitat in the new stream. For example, in only ten years, pink salmon spawning populations in Stonefly Creek expanded from a few dozen to almost 5,000. Other species, including Coho and Sockeye salmon, were often found in the stream, particularly if there was a lake nearby."
According to the study team, a new habitat may benefit salmon in some areas, but climate change will continue to be a severe problem for certain species.
Dr. Pitman adds that "on the one hand, this quantity of additional salmon habitat will create local chances for certain salmon populations."
"On the other hand, climate change and other human factors continue to jeopardize salmon survival—through warmer rivers, changes in stream flows, and horrible ocean conditions. ". "Climate change necessitates a shift in perspective. We can't only safeguard animals' existing habitat; we also have to think about what habitats they'll require in the future."
Pitman, K.J., Moore, J.W., Huss, M., et al. Glacier retreat creating new Pacific salmon habitat in western North America. Nat Commun 12, 6816 (2021). https://doi.org/10.1038/s41467-021-26897-2