Melting glaciers may produce thousands of kilometers of new Pacific
salmon habitat

Date:
December 7, 2021
Source:
University of Birmingham
Summary:
Retreating glaciers in the Pacific mountains of western North
America could produce around 6,150 kilometers of new Pacific salmon
habitat by the year 2100, according to a new study.



FULL STORY ========================================================================== Retreating glaciers in the Pacific mountains of western North America
could produce around 6,150 kilometers of new Pacific salmon habitat by
the year 2100, according to a new study.


========================================================================== Scientists have 'peeled back the ice' from 46,000 glaciers between
southern British Columbia and south-central Alaska to look at how much potential salmon habitat would be created when underlying bedrock is
exposed and new streams flow over the landscape.

Modeling glacier retreat under different climate change scenarios,
researchers discovered that, under a moderate temperature increase,
the glaciers could reveal potential new Pacific salmon habitat nearly
equal to the length of the Mississippi River (6,275 km).

Desirable for salmon, in this case, means low-gradient streams (less
than 10% incline) connected to the ocean with retreating glaciers at
their headwaters.

The team discovered that 315 of the glaciers examined met this criteria.

The international team, led by researchers at Simon Fraser University
(Canada) with University of Birmingham (UK) and other organisations,
published their findings today in Nature Communications.

Lead author, Simon Fraser University spatial analyst Dr. Kara Pitman
comments: "We predict that most of the emerging salmon habitat will occur
in Alaska and the transboundary region, at the British Columbia?Alaska
border, where large coastal glaciers still exist. The Gulf of Alaska
sub-region is predicted to see the most gains -- a 27% increase in salmon-accessible habitat by 2100.

"Once conditions stabilise in the newly-formed streams, salmon can
colonise these areas quite quickly. It's a common misconception that
all salmon return home to the streams they were born in. Most do,
but some individuals will stray -- migrating into new streams to spawn
and, if conditions are favorable, the population can increase rapidly." Co-author Professor Alexander Milner from the University of Birmingham
has researched glacial retreat and salmon populations in southeast
Alaska for over three decades. His team have worked on Stonefly Creek in Glacier Bay where glacier retreat reveal a new stream in the late 1970s
and he comments "Colonization by salmon can occur relatively quickly
after glacial retreat creates favourable spawning habitat in the new
stream. For example, Stonefly Creek was colonised within 10 years by pink salmon that grew rapidly to more than 5,000 spawners. Other species also colonised including Coho and Sockeye salmon, especially where a lake is associated with the stream" The researchers caution that while the newly created habitat is a positive for salmon in some locations; overall,
climate change still poses grave challenges for some salmon populations.

"On one hand, this amount of new salmon habitat will provide local opportunities for some salmon populations," says Dr. Pitman. "On the
other hand, climate change and other human impacts continue to threaten
salmon survival -- via warming rivers, changes in stream flows, and poor
ocean conditions.

"Climate change means we increasingly need to look to the
future. We can't just protect current-day habitat for species but
need to consider what habitats they might rely on in the future." ========================================================================== Story Source: Materials provided by University_of_Birmingham. Note:
Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2021/12/211207152605.htm

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