Salmon are losing their sense of smell. Thanks, carbon emissions

Salmon are starting to lose their sense of smell and their fear of predators, according to research from federal and university scientists in Seattle.

Their preliminary work, presented in May at a symposium on ocean acidification at the University of Washington, documents yet another way carbon dioxide emissions are messing with the world's oceans.

Chase Williams, a postdoc at the University of Washington, said changing ocean chemistry is making it harder for salmon to smell danger. Salmon use smell to navigate, to hunt and to avoid predators.

"They can smell predators themselves,” Williams said. "They can also smell a compound that’s released when a predator is eating one of their schooling mates.”

“In normal conditions, they would avoid the scent of danger,” he said.

But thanks to decades of carbon dioxide emissions from fossil-fuel use and deforestation, conditions aren’t normal anymore. In addition to trapping heat in sea and sky, the added CO2 has changed the chemistry of the oceans, making them more acidic.

In laboratory tanks, as scientists cranked up the carbon dioxide, turning the water more acidic, young salmon stopped avoiding the scent of predation. The UW and National Oceanic and Atmospheric Administration researchers had added a compound that damaged salmon skin exudes as a warning signal to nearby fish whenever one member of a school is attacked.

Conditions as acidic as coho in this experiment faced are not common yet in the world's oceans, but some places, including Puget Sound's Hood Canal and upwelling zones off the Northwest coast, do experience them occasionally.

Seawater is already acidic enough at times in Northwest waters to harm oysters' ability to form shells.

Scientists have found fishes' senses of smell stymied by ocean acidification in other parts of the world. This is the first time they’ve found it in salmon.

"Pretty much all fishes have that acidification-sensitive neurological pathway," ocean ecologist Francis Chan of Oregon State University said in an email. "Now that will probably get played out differently depending on species, but the results that are being reported suggest that more and not fewer fishes face challenges from acidification."

Salmon begin their lives in freshwater, where the measure of acidity can vary widely day to day. Williams said the results seem to show that the fishes lose their ability to adapt to different acidity levels when they migrate to the ocean.

Budget cuts to science

If the Trump administration gets its way, we wouldn't see findings like this so much, but not because the White House wants to stop the carbon pollution behind the problems scientists are documenting.

The Trump budget would slash funding for ocean and climate research, including eliminating funding for a NOAA program called Sea Grant, which funded about half of Williams' study of salmon on acid.

Sea Grant funds research aimed at helping coastal communities, including things like ocean chemistry and workplace safety aboard fishing boats.

“It has wide ramifications if you cut off funding, not just for pointy-headed scientists doing lab work,” Williams said.

The remainder of support for Williams' study came from the state-funded Washington Ocean Acidification Center at the University of Washington.

Co-director Terrie Klinger said the state legislature has eliminated the center's funding for biological studies, though funding for basic monitoring and forecasting of ocean acidity is likely to continue.

"This leaves us unable to continue critical studies on salmon response to ocean acidification and unable to begin research on the association between ocean acidification and harmful algal blooms," Klinger said in an email.

A study presented by William Cochlan of San Francisco State University at the UW symposium found that harmful algae, which shut down crab and clam fisheries up and down the West Coast in 2015, become more toxic when exposed to acidified seawater.

At a recent press conference, White House budget chief Mick Mulvaney said the Trump administration's proposed budget takes aim at spending related to climate science.

"Do we target it? Sure. Does it mean that we are anti-science? Absolutely not," Mulvaney said. "We're simply trying to get things back in order."

Mulvaney said the Obama administration spent too much on climate science. He said Trump's budget puts taxpayers first.

White House budgets are just proposals: Congress decides how Uncle Sam spends taxpayers' money.

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