Atlantic salmon can adapt to warmer waters

Populations of Atlantic salmon have a surprisingly good capacity to adjust to warmer temperatures that are being seen with climate change, scientists have found.
Scientists at the University of Oslo and University of British Columbia addressed questions around how climate change might affect salmon species distribution and abundance.
Scientists studied wild salmon from two European rivers.
They compared a cold-water population from Norway's northern Alta River, where water temperatures have not exceeded 18 degrees Celsius for 30 years, with warm-water populations from France's Dordogne River, located 3,000 kilometres south, where annual water temperatures regularly exceed 20 degrees Celsius.
Eggs from both populations were hatched at the University of Oslo, where they were raised at 12 or 20 degrees Celsius. Despite substantially different natural environments, both populations had remarkably similar capabilities when warmed.

When reared at 12 degrees Celsius temperatures, salmon from both populations developed cardiac arrhythmias at 21 to 23 degrees Celsius, after a maximum heart rate of 150 beats per minute.

But those raised at 20 degrees Celsius developed cardiac arrhythmias at a surprising 27.5 degrees Celsius, after the heart reached 200 beats per minute.
Researchers found that increasing the fish's acclimation temperature by 8 degrees Celsius raised temperature tolerance by 6 degrees Celsius.
"The results are surprising. A fish faced with uncomfortably warm temperatures might relocate or even die if it is too extreme. Here we have evidence for warm acclimation of a commercially and culturally important fish species," researchers said.

The study was published in the journal Nature Communications.