Alaska's Resilient Crabs Not Immune to Rapidly Acidifying Seas

Fishermen have found fortune and adventure in the frigid waters of the Bering Sea. But ocean acidification caused by carbon emissions has begun to alter the chemistry of the North Pacific, posing threat for Alaska's crabs. PBS NewsHour's Ray Suarez reports in collaboration with the Pulitzer Center on Crisis Reporting and The Seattle Times.


GWEN IFILL: Finally tonight, it's north to Alaska for the first of three reports on climate change in the Arctic region.

Our story was produced for the NewsHour by The Seattle Times, in partnership with the Pulitzer Center on Crisis Reporting. The Times team has just published a multi-platform look at the fallout from increased acid levels in the ocean.

Ray Suarez narrates part one of our series, called Arctic Thaw.

RAY SUAREZ: For decades, fishermen like Kale Garcia have come to Alaska to seek their fortunes in one of the world's most productive marine systems, the vast frigid waters of the Bering Sea.

KALE GARCIA, crab fisherman: here's something very powerful about being out in the ocean. And no matter how big your boat is, it just gets -- it gets very, very small out there.

RAY SUAREZ: And of all the seafood treasures chased by fishing boat captains like Garcia, none has come to symbolize Alaska's adventurous spirit quite like crab fishing.

KALE GARCIA: It was like a sport for me. But it was like an adrenalin sport. And it was -- like any adrenalin sport, you wanted more of it.

RAY SUAREZ: Alaska's Bering Sea crab fishery is one of the most storied industries in the world, known for great risks and great rewards.

But the same ocean waters that spawned this industry may prove its undoing. New research suggests the chemistry of the North Pacific is changing in ways that pose serious trouble for Alaska's two signature crab species, red king crab and snow crab, the culprit, ocean acidification caused by carbon dioxide emissions.

Scientists like Jeremy Mathis with the National Oceanic and Atmospheric Administration have found the oceans have grown 30 percent more acidic just since the beginning of the Industrial Revolution. And that's not the only problem. As carbon dioxide changes the sea's chemistry, it also robs the water of important minerals that marine creatures need to grow, especially creatures with shells.

JEREMY MATHIS, National Oceanic and Atmospheric Administration: Anything in the ocean that builds a shell, whether it's a crustacean like a crab, or a coral reef, need a certain amount of dissolved minerals that naturally exist in the ocean in order to build and maintain those shells. But as ocean acidification happens, it reduces the amount of those minerals that are available for those organisms.

RAY SUAREZ: So oceanographers like Mathis have been teaming up with biologists and fishing experts to better predict how acidification will affect important species like Alaska's crab. Crabs generally are quite resilient, so when researchers exposed baby red king crab to sea chemistry conditions expected later this century, scientists were not expecting much.

Instead, the results raised concerns about the future for red king crab and snow crab, which live in similar environments and may respond in similar ways.

JEREMY MATHIS: And, unfortunately, what they found is there was a significant increase in mortality rates, a loss in growth rate, a loss in calcification, how quickly the crab was able to build their shell. The crab didn't do as well under these ocean acidification conditions.

RAY SUAREZ: The findings were a troubling surprise, says crab expert Andre Punt, a professor at the University of Washington's School of Aquatic and Fisheries Sciences.

ANDRE PUNT, University of Washington School of Aquatic and Fisheries Sciences: Essentially, all the crab died within the first 200 days. So, if they are dying very rapidly in the first 200 days, obviously they're not going to make it to be fishable size.

RAY SUAREZ: That was just the beginning. When Mathis, who makes his living sampling sea chemistry, analyzed ocean conditions off Alaska, he found it changing far faster than expected.

JEREMY MATHIS: And what is really alarming about that study is that we thought we were exposing these crabs to future scenarios which may have been 50 or a hundred years from now, when, in fact, our recent work in the Bering Sea has shown that those conditions exist today. So this is a real thing that is happening right now today, not some future condition that they're going to experience some time later on.

RAY SUAREZ: There's no indication yet that crab in the wild are dying more rapidly. Sea chemistry for the moment is only bad at times of the year when crab aren't particularly vulnerable.

But the waters are growing more corrosive every year. It's also possible that crab might find a way to accommodate these changes in chemistry.

ANDRE PUNT: One of the key things we don't know is how crab will adapt to the future. So it's not unreasonable to assume, for example, that they might move, that, you know, some form of rapid evolution will occur, that they may become somewhat more robust. We don't know that.

RAY SUAREZ: Ultimately, for crab, it may be a race against time.

JEREMY MATHIS: Are they going to be able to adapt, or are these levels of carbon dioxide going to rise so quickly that, from an evolutionary standpoint, that there's just no way they can keep up?

RAY SUAREZ: And with so many of Alaska's crab captains and crew members based in the Pacific Northwest, the industry already has had a front-row seat for the kind of devastation ocean acidification can bring. Acidification in recent years has wiped out billions of oysters in Washington and Oregon, a half-century or more sooner than anyone predicted.

For crab fishermen like Brett Robinson, captain of the Arctic Hunter, the stakes couldn't be higher.

BRETT ROBINSON, crab fisherman: This is definitely something to worry about. All of us, we talk about it. I always just kind of thought, oh, the Bering -- it's not happening in the Bering Sea. I just -- I haven't seen this study. But obviously it is happening in the Bering Sea. I don't know. It's scary as hell. Something has to get figured out. I don't know.

RAY SUAREZ: His boss, Jim Stone, co-owner of the Arctic Hunter and president of an industry trade group, has followed the research closely and is trying to remain optimistic.

JIM STONE, The Arctic Hunter: We're scared to death, but we have heard a lot of horror stories before, been hearing them for years, and we all have, you know? Crabbing is our bread and butter. So, to me, yes, it would be a huge blow to the state to lose king crab due to whatever reason, ocean acidification or other.

Longtime crabber Kale Garcia agrees.

KALE GARCIA: I think it would be devastating. I mean, I know it would be devastating for me. A lot of people that are involved in the industry, it's something that they have been in forever. People like that don't plan an exit strategy out of the fishery. You know, there is no exit strategy. It's like, this is what we do. You know, we fish.

RAY SUAREZ: And, of course, crab won't be the only species affected by changes in ocean chemistry. With researchers studying how acidification could disrupt the marine food web or change the behavior of many important fish, Alaska's fishing community is increasingly resigned to a new reality. Ocean acidification will almost certainly be an extremely disruptive force for years to come.