Climate Change Could Affect Southeast Salmon Habitat

Map based on the latest climate change research shows a projected average annual temperature increase of 6.1 degrees Fahrenheit by 2080 which could mean more rain and less snowfall for Southeast Alaska and western British Columbia. Courtesy Colin Shanley/The Nature Conservancy.

Researchers expect that salmon productivity could shift in Southeast Alaska streams over the next 70 years as temperatures rise and rainfall increases because of climate change.

Projections suggest that the average annual temperature for Southeast Alaska and western British Columbia coast would increase 6.1 degrees to just under 44 degrees Fahrenheit in the year 2080. Precipitation in the form of rain could increase over twenty inches to a total of 145 inches, while snowfall could drop about 30% to about 30 inches a year.

“There could be some serious differences,” said Michael Goldstein of the U.S. Forest Service.

Goldstein was among a group of researchers who briefed attendees on the unpublished research at the recent Southeast Alaska Watershed Symposium in Juneau. A similar presentation on the impacts of climate change was made during the recent Al-Can Summit organized by the Juneau World Affairs Council.

Goldstein said the changes in temperature and precipitation would not be uniform throughout the entire Southeast Alaska and western British Columbia area.

So, temperature and precipitation had the greatest change in the northern mainland and the least change in the southern island provinces. Precipitation as snow had the greatest change in the southern mainland and the least change in the outer coast.”

It could mean warmer and drier extended summers, and warmer and wetter winters.

By 2080, Juneau could be like Prince Rupert. Projected average of 45 degrees Fahrenheit or thereabouts is similar to the average temperature of May 2013. I was looking around the internet and Alabama has an average winter temperature of 45 degrees as well.”

Returning spawning salmon near Salmon Creek in 2013. Photo by Greg Culley

The projections were presented in conjunction with separate research and modeling done by Colin Shanley, a planner and analyst with The Nature Conservancy in Juneau, in his effort to identify salmon habitat ranging from the most vulnerable to the most resilient.

This is watershed-based analysis. Not a cell-based analysis or estuary-based analysis. Basically, watershed area, monthly precipitation both present and predicted from the present climate model, same thing for monthly temperature, watershed elevation, percent lakes, and percent glaciers as well.”

Dr. Sanjay Pyare, associate professor of geography and environmental science at University of Alaska Southeast, said that climate change could play a crucial role in altering stream temperatures and episodic discharges from nearby glaciers and the ice field.

“If you look at the overall discharge coming out of an area like Southeast Alaska and northern British Columbia annually compared to a place like the Mississippi River Basin, it’s actually something like two times the overall freshwater discharge,” Pyare said. “Obviously, it has a lower land mass overall. So, there’s a lot of water coming down the pipes in a place like Southeast Alaska.”

Watersheds that are predominately glacial-fed may, for example, have their peak discharge in mid-summer with colder water. Snow- or rain-fed watersheds may have two discharge peaks in the spring and early fall.



Matt Miller is a reporter at KTOO in Juneau.

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