Climate change: Melting glaciers could create new habitats for Pacific salmon

Melting glaciers in western North America could create new habitats for Pacific salmon over the next century, a modelling study in Nature Communications suggests.

Migratory Pacific salmon are one group of species whose abundances have dramatically shifted in response to changing climate patterns, however, the warming of Arctic and subarctic streams, in combination with glacier retreat, could create potential new habitats for salmon. Previous work has observed the colonization of newly de-glaciated streams by salmon, but predicting future shifts in salmon habitat across regions has been difficult.

Kara Pitman and colleagues modelled glacier retreat under different climate change scenarios. Using this model, they generated a synthetic stream network for a 623,000 km2 region of western North America to quantify emerging streams created by glacier retreat, which they combined with stream gradient-based salmon habitat models. By 2100, the authors project that approximately 6,000 km of new streams will be accessible to Pacific salmon and, of this newly accessible habitat, nearly 2,000 km will be suitable for spawning and juvenile rearing. The authors note that glacier retreat is only one consequence of climate change and other climate-induced effects such as ocean heat waves, sea-level rise and extreme flood events could all cause widespread declines in salmon abundance.

Glacier retreat also creates new prospects for industries such as mining, which can degrade salmon habitat. Understanding the timing and location of emerging salmon habitat is critical to informing conservation planning and to avoid degradation of future salmon habitat, the authors conclude.