Artificially Cooling Rivers Could Protect Fish From Climate Change
By Alejandro de la GarzaOctober 23, 2023 12:07 PM EDT
In the midst of a heat wave in Nova Scotia, Canada, this July, humans sought out air conditioning and shelter in the shade. Fish in the Wrights River, meanwhile, converged on what patches of deeper, cooler water they could find, like holes in the streambed out of the sun’s glare. One of those areas of relief, though, hadn’t occurred naturally. It had been created by humans pumping cold water from a nearby well into the overheated stream. Cold-loving fish, like Atlantic salmon, flocked to this stretch of water in droves.
Researchers had devised the setup as part of an experiment to test a potential method for helping Atlantic salmon survive rising water temperatures caused by climate change. Like humans, the fish thrive at a certain temperature range, ideally between about 43°F and 72°F. Spending too much time in water above about 82°F can be lethal. Freshwater rivers and streams like the Wrights are critical to maintaining salmon populations—it’s where young Atlantic salmon grow through their initial life stages before heading towards the ocean; and it’s where they return as adults to spawn. Worries are growing that, due to climate change, these rivers are getting too hot for the fish to survive. In the U.S. Northeast, just a few rivers on the Gulf of Maine still support Atlantic salmon populations—the species’s range once extended as far south as the Long Island Sound. In Canada, meanwhile, populations in some southern rivers have crashed as rising temperatures take their toll