Can Pacific Salmon Adapt to Climate Change?

by Emil Morhardt

Chinook (king) salmon deposit their eggs in the cobbles of Pacific Coast streambeds, where they, and the subsequent developing juveniles spend months before heading out to sea. Some of these streams can get quite warm by salmon standards, and more than one major run has been heavily depleted by temperatures higher than 24 °C which seems to be generally lethal to this species. As global warming progresses we can expect more salmon streams to reach this temperature, so an important question is whether these fish have either the developmental plasticity or the genetic variability that will allow them to adapt. Muñoz et al. (2015) crossbred 16 wild chinook salmon caught at Canada’s Quinsam River Hatchery so as to get 64 different genotypes, then reared half of them at the hatchery ambient water temperatures and the other half at temperatures 4 °C higher. They then looked to see if cardiac function, the apparent limiting factor in high temperature mortality, was shifted to higher temperatures. Continue reading