Carbon emissions are making the oceans more acidic. That’s long been known to harm shellfish, but new research shows more acidic water could take a toll on salmon, as well.
“We want to have a future on the water, but we need our fish out there to do it,” says Amy Grondin, a commercial salmon fisher who trolls for chinook and coho off the coasts of Washington and southeast Alaska. That’s why Grondin is partnering with researchers to learn more about what more acidic oceans could mean for those species. “Fishermen really do know a lot,” she explains. “We’re on the water 24/7 observing.”
So far, the news has not been good.
Researchers have found that the more acidic water expected in coming decades can damage salmon’s sense of smell. Salmon depend on their sense of smell to avoid predators, find food and mates, and make their way back to their spawning grounds.
And the more acidic water is also hard on copepods, which are eaten by the herring, anchovies, smelt, and krill eaten by salmon.
Animals that live in Alaskan waters are particularly vulnerable because that water is already relatively acidic.
That said, “it’s not total doom and gloom with respect to how fish respond to elevated CO2,” says Chase Williams, a University of Washington researcher. He says fish that live in the deepest ocean, such as black cod and deep-dwelling rockfish, “seem to be more resilient to the effects of elevated CO2.”
Nonetheless, Grondin says the fishing industry should act now to help avoid more disastrous effects down the road.
“We can’t change the engines that we have on our boat,” she says. “I have to run it off diesel. But we can be efficient in other parts of our life: how you’re delivering your fish, how the packaging you’re buying is made, how you heat your home or the place where you process your fish.”
Grondin also advocates for a new kind of fisheries management. “Right now, when we’re doing our management, we’re only looking at the commercial species that are mattering to us and our pocketbooks and our plates,” she explains. “We don’t look at what they’re eating.”
Grondin says it’s important to take how all species are doing into account when deciding how many fish to catch.