Ocean Acidification: A Grim Reaper For Wild Shellfish Stocks?

This is the fourth in a four-part series on shellfish and ocean acidification produced by Shady Grove Oliver at KBBI-Homer. You can hear Part 1, Part 2 and Part 3 on the web.

Kachemak Bay - Photo by Shady Grove Oliver/KBBI
Kachemak Bay – Photo by Shady Grove Oliver/KBBI

According to a recent NOAA study, Alaskan shellfish hatcheries risk becoming unsustainable by 2040 because of ocean acidification. Over the last week, we’ve heard how a hatchery in Oregon is dealing with changes in ocean chemistry and about groundbreaking genetic research on shellfish adaptability. But the big questions still remain- how far-reaching will the effects be and can we mitigate them before it’s too late?

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Throughout this discussion, there’s been an elephant in the room. Wild stocks. Do wild coastal shellfish face the same 25 year end date that Alaskan hatcheries do?

“Yeah, I mean, I think that’s the million dollar question right there. Can organisms evolve quickly enough to compensate for that change?”

Gretchen Hofmann is a leading scientist in the field of genetic adaptability.

She’s found that certain strains of organisms do selectively favor the trait of acid tolerance from generation to generation.

“You know, if you look into the literature in other systems, you can find examples where rapid evolution has occurred. So, the answer for biology and living things is yes. But…”

The answer for specific breeds of living things is…we don’t really know yet.

That’s a concern for Alaskans, who have relied on particular types of clams and other shellfish for generations as a food source.

Jeremy Mathis is a NOAA oceanographer who worked on the study at the Alutiiq Pride Shellfish Hatchery in Seward.

“The measurements we made in the hatchery does cause some alarm for the natural environments because it’s the same water we’re seeing in the hatchery that’s all up and down the coast,” says Mathis.

Jeff Hetrick is the owner of Alutiiq Pride. Like many local residents, he’s noticed a serious decline in certain shellfish populations in southcentral Alaska.

“Oh absolutely. I don’t think that we’re going to lose the wild stocks, you’ve basically lost the wild stocks. They’re really hard to come by. It’s difficult for us to even get the brood stock to produce in the hatchery. There’s a razor clam issue that people are aware of on the peninsula. But, especially in lower Cook Inlet and the Homer area, littleneck clams, butter clams, cockles, they’re hard to find. There’s been a decline now for the past decade,” says Hetrick.

Hofmann says some of the urchin divers she works with on the California coast have noticed similar years with very poor harvest numbers. She says there haven’t been enough studies to make a definite correlation with acidification yet, but it’s something scientists and locals are thinking about.

“It’s a pretty big concern, you know, because some of the things we learn about invertebrate biology is that, just the simple first beginning step of fertilization is pH sensitive. So, right there, if you have a species that has the sperm-egg interaction being affected by acidification, then right off the bat, no matter how many adults you have, you have fewer progeny going forward and therefore, really bad recruitment years,” says Hofmann.

“So, what we need to do now, is take our monitoring systems that we’ve installed in the hatchery and expand those out into these natural sites, so that we’re getting that same level of monitoring, that same level of environmental intelligence, so that we can answer that question,” says Mathis.

NOAA’s Pacific Marine Environment Lab in Seattle and the University of Alaska Fairbanks are doing just that. Not only do they plan to expand hatchery research to another site, possibly Ketchikan or Homer, they are also partnering for a new study.

Wiley Evans, is heading out this week with a team of scientists to survey acidification parameters from Dixon Entrance in southern Southeast all the way to Kodiak Island.

“We’re doing measurements both continuously, as the ship’s moving from surface seawater flowing through the vessel, sort of in the same way that we are making measurements at Alutiiq Pride. And we’re also going to be making measurements at specific places where we profile the entire water column from the surface down to the bottom,” says Evans.

When that team disembarks in Kodiak, they’ll still leave some of their equipment on board to continue bringing in data on a different mission that will go up to the Bering Sea, over to Dutch Harbor, and back to Seattle.

Evans says they’re hoping to get a more comprehensive picture of current ocean conditions, so they can make more educated decisions on how to deal with acidification in the future. A future that could look much worse than today, says Hofmann.

“I think it’s a pretty big problem if you stand back and look at it for what it is,” says Hofmann.

It is a complex problem with regional factors that exacerbate it. In places like Alaska, carbon emissions speed up CO2-rich glacial melt. In places like Washington, Oregon, and California that are subject to seasonal upwelling, the newer top layer of oxygenated water now has more CO2 to begin with, so it can’t as efficiently counteract the deeper, older, CO2-rich water that comes to the surface.

On top of that, scientists have estimated that that water coming up is 30-50 years old, so from the 1960s-1980s. Imagine that many years from now when today’s water is what’s below the surface.

“We can’t get complacent and say well, we’ve done enough, it’s time to move on to the next crisis. This is something we have to keep right at the forefront and make sure that people understand that while we’ve learned a lot in the past few years, we’ve still got a long way to go in terms of understanding the long term implications of ocean acidification,” says Mathis.

Mathis says that’s why it’s crucial to do the work now, to salvage and protect what we can of the marine ecosystem for 2, 10, or 25 years down the line.