Wednesday November 15, 2023

Hatch Magazine

Scientists artificially refrigerated a salmon stream in Nova Scotia during last summer’s record heat wave. Hundreds of migratory and river-dwelling fish basked in the cold-water flows pumped into the river from a nearby groundwater well. The addition of cold water to the Wrights River was part of a Dalhousie University study conducted to determine if adding colder water to streams that become dangerously warm for trout and salmon during prolonged heat waves can help keep the fragile fish alive. Results, biologists say, were encouraging.

It’s no secret that coldwater-dependent fish like trout and salmon seek out thermal refuge when water gets too warm to comfortably survive. According to the study’s author, Kathryn Smith, a PhD candidate at the Centre for Water Resources at the university in Halifax, climate change is exacerbating the impacts that periods of hot weather have on coldwater rivers.

Nevertheless, questions remained about the likelihood of wild fish using a human-induced plume of cold water to seek thermal refuge. During a nasty July heatwave last summer, Smith and her colleagues got their answer.

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