Pink Salmon Risks a Double Threat of Acidification

By Alister Doyle, Reuters

Pink salmon in the Pacific Ocean face a double threat of acidification linked to greenhouse gas emissions since it slows their early growth in rivers and disrupts the chemistry of seawater.

Pink salmon in stream with juvenile salmonids in Bear Creek, Alaska.
Credit: Kentaro Yasui/Alaska USFWS/flickr

Impacts have in the past been more studied in the seas than in fresh water. But the Canadian study found that acidification of rivers could make young pink salmon, the most abundant type in the Pacific, smaller and more vulnerable to predators by dampening their ability to smell danger.

Damage done by acidification “in fresh water in pink salmon could occur in all other salmonids”, Colin Brauner, a co-author at the University of British Columbia, told Reuters. The findings were published in the journal Nature Climate Change.

Carbon dioxide, the main greenhouse gas caused by burning fossil fuels, reacts with water to produce a weak acid. That especially threatens creatures ranging from oysters to lobsters which find it harder to build protective shells.

An international study in 2013 said acidification of the oceans was happening at the fastest pace for 55 million years, because of human greenhouse gas emissions.

In the Canadian experiments, pink salmon grew on average to only about 32 mm (1.26 inches) after 10 weeks, when raised in waters with roughly double current carbon dioxide concentrations, shorter than the 34 mm (1.34 inches) in waters with current levels.

The young fish also weighed less and appeared less able to smell danger. Brauner said it was too early to say if the disruptions would last into adulthood and mean smaller commercial catches.

Scientists say is unclear how far salmon, and other marine life, may adapt or evolve in future generations to cope with rising levels of carbon dioxide.

Editing by Andrew Roche