During summer, salmon rely on glacial melt for cool water. What happens when the glaciers disappear?
Glaciers are disappearing as the climate warms. And as they melt away, endangered salmon might follow.
Salmon thrive in cool water. When the water gets too warm, it stresses fish, reduces their growth, affects reproduction, and increases disease.
Hood: “For salmon, glaciers can be important because during periods of the summer where you have warm air temperatures and it’s dry, if you have a glacier, the stream temperature is going to stay cool because the glacier can release melt water into the stream.”
That’s Eran Hood of the University of Alaska Southeast.
Hood: “If you take a glacier out of the watershed, then during the summer, when you have a warm dry period, you don’t have this reservoir releasing cool water into the stream.”
Water that is too warm for fish is considered polluted under the federal Clean Water Act. So lowering water temperatures is a priority in streams with threatened fish like chinook salmon.
Taking steps like increasing shade along stream banks will help. But as global temperatures continue to rise and these vast glaciers disappear, keeping streams the right temperature for salmon will be more difficult than ever.
Reporting credit: ChavoBart Digital Media. Image graphic: Art by Sharon Cummings.