Climate Change Stunting Growth of B.C. Pink Salmon Right from Birth

High concentrations of carbon dioxide in freshwater are seriously impeding the growth of pink salmon and affecting survival rates, starting right from birth.

A new study conducted by a research team from UBC found that the risks of ocean acidification, which is caused by high concentrations of carbon dioxide and climate change, on marine species have been studied extensively, but the impact on freshwater acidification is still widely untapped.

“Most of the work on acidification has been in the ocean, yet 40 per cent of all fish are freshwater. We need to think about how carbon dioxide is affecting freshwater species,” said Colin Brauner, a professor in the Department of Zoology at UBC. “We found that freshwater acidification affects pink salmon and may impact their ability to survive and ultimately return to their freshwater spawning grounds.”

The study looked into how baby salmon respond to fresh and ocean water with the levels of carbon dioxide expected 100 years in the future.

Researchers monitored the salmon for ten weeks, from before they hatched to after they would migrate to ocean water.

From their efforts, researchers found that salmon beginning their lives in fresh water with high levels of carbon dioxide were smaller, and their ability to smell the water was reduced. Their ability to smell is an essential component to their well-being, as it allows the salmon to return to their spawning ground at the end of the life cycle. In addition, their sense of smell allows salmon to sense and respond to danger.

Moreover, researchers found that the affected salmon were less able to use oxygen to exercise, which is likely to hurt their ability to find food, evade predators, and migrate.

“The increase in carbon dioxide in water is actually quite small from a chemistry perspective so we didn’t expect to see so many effects,” said Michelle Ou, a former master’s student who is the lead author of the study. “The growth, physiology and behavior of these developing pink salmon are very much influenced by these small changes.”

Measuring the oxygen consumption of developing pink salmon. (Photo Credit: Michelle Ou.)

Brauner and Ou worked with pink salmon for their study because it is the most abundant salmon species on the West Coast, and of high economic and ecological importance. Pink salmon enter the ocean at the smallest size of all Pacific salmon, and consequently are the most likely of species to feel the effect of aquatic acidification.

Pink salmon largely populate the Fraser River, moving in massive schools throughout B.C.’s Southern Interior.

The study was published in the Nature Climate Change journal.

Photo Credit: Fisheries and Oceans Canada.