A study of potential new Pacific salmon habitat in western North America as a result of glacial retreat through the year 2100 poses benefits to salmon, but also warns of the need for forward-looking management decision making and conservation planning.
The study, published recently in the journal Nature, projects that by the year 2100 glacier retreat will create 6,146 kilometers (3,818 miles) of new streams accessible for colonization by Pacific salmon, of which 1,930 km (1,200 miles) have potential for spawning and juvenile rearing within 18 sub-regions.
“With climate change, the distribution of habitat of salmon in the future is probably going to be different than the distribution for salmon now, because of changes in temperature and precipitation which affect stream flow,” said Daniel Schindler, who researches causes and consequences of ecosystem dynamics at the University of Washington’s School of Aquatic and Fishery Sciences in Seattle.
“We show that the loss of glaciers opens up salmon opportunities in the future,” Schindler, who participated in the study, said. “That is particularly important for Southeast Alaska. Western Alaska doesn’t have as many glaciers to disappear and create new habitat.”
In Southeast Alaska, headwaters of many of those rivers are still under ice and that habitat is disappearing quickly because of climate change.
“What we did was forecast how these watersheds will look in the future under warmer climate,” Schindler said. “As watersheds open up, those streams will be colonized by fish, insects, algae. We see that fish like salmon will establish within a decade of them opening up, mostly in coastal locations, but it shows ice currently prevents fish from going into those streams.”
About two-thirds of the effects of humans on the Earth’s climate system is on heat stored in the water in the ocean and that heat is released into the atmosphere, Schindler said, adding that salmon encounter that climate change in the ocean and in fresh water because the ocean heat has an effect on the atmosphere, which affects precipitation.
The study warns that forecasting the location of emerging salmon habitat is imperative because while such climate change may present opportunities for salmon it also creates prospects for large-scale resource extraction industries such as mining, which have potential to degrade these emerging salmon habitats.
The research, funded by the Gordon and Becky Moore Foundation, identified 315 retreating glaciers at headwaters of present-day streams that will create salmon-accessible streams assuming a 10% stream gradient threshold for upstream salmon migration, plus 603 glaciers assuming a 15% stream gradient threshold.
Gains in salmon habitat, even one kilometer of stream, can produce 500 to 1,500 juvenile coho salmon, researchers note. Thus, with hundreds to thousands of kilometers of new habitat being created from glacier retreat, there’s potential to produce hundreds of thousands to millions of additional juvenile salmon, depending on the species, according to the study.