Many of us think of seaweed as a nuisance. The slimy, sometimes smelly, stuff that clogs fishermen’s nets, gets tangled around our ankles in the ocean, and washes up unwanted on the beach. Even its name — sea-weed — implies something undesirable.
And yet, as we first reported this spring, increasing numbers of fishermen, scientists, and foodies in the country are starting to look at seaweed very differently. As a promising source of food, jobs and help cleaning ocean waters. With rising global populations and limited space to expand agriculture on land, they are turning to the sea — and its “weeds” — as a new frontier.
Bren Smith: Welcome aboard.
Lesley Stahl: Thank you.
Growing Seaweed
It’s not often you get a ride to visit a farm on a boat. But we were on-board with Bren Smith, the nation’s leading advocate for a whole new type of farming — ocean farming. We joined him on a cold day in December, the time of year he heads out to his version of fields to plant his staple crop, a type of seaweed called sugar kelp.
Bren Smith: Here it is.
Lesley Stahl: This is the farm? I can’t see anything. (LAUGH)
Bren Smith: The whole idea is it’s down under the water. So, see the white buoys?
Lesley Stahl: Yes.
Bren Smith: That’s the edges of the farm.
Lesley Stahl: And the black ones?
Bren Smith: Black buoys are holding up a horizontal rope below the surface. So it’s rows– kinda rows of crops. So this is the seed.
He showed us what looked like a tube covered in fuzz.
Lesley Stahl: Is that kelp?
Bren Smith: Yeah, these are the baby plants, they’re about two millimeters. And these are gonna– gonna grow to 15, 18 feet by the spring. It’s one of the fastest growing plants on earth.
And unlike all those plants that grow in earth, seaweed doesn’t need fertilizer, or freshwater. It’s what’s called a zero-input crop.
Bren Smith: So now we’re just gonna unravel it.
Just attach the string it grows on to rope and suspend it eight feet under water.
Lesley Stahl: And that’s it, huh?
Bren Smith: That’s it.
In five or six months, that fuzz will look like this. This was some of his crop last year. Smith began leasing the right to farm this 20-acre plot of water in 2012 from the state of Connecticut. His was the first commercial seaweed farm in the state. Now there are nine, with a half dozen more in the works.
Bren Smith: We hope you know, in 10, 20 years, there are thousands of farmers doing this. We think it’s the future, the time to move out in the ocean and luckily we can do it the right way.
Smith spent most of his life working the oceans in what he now considers the wrong way — on industrial fishing boats, going after lobster, tuna, and cod.
Bren Smith: We were tearing up whole ecosystems with our trawls, fishing in illegal waters, and just really chasing fewer and fewer fish further and further out to sea.
Lesley Stahl: And you didn’t think about–
Bren Smith: No.
Lesley Stahl: –the idea that you were depleting the population of fish?
Bren Smith: The oceans just seemed boundless.
Boundless, and bountiful.
Bren Smith: The sense of meaning of helping feed my country — you know, fishermen– there’s some jobs, you know, coal– coal workers, farmers, I think steelworkers, and– and fishermen where, you know, they’re jobs that are soul-filling. You know, they’re jobs that we write, and sing songs about. And I just, I wanted that life. And it’s– I still do.
But that life was increasingly in peril. Cod stocks crashed due to overfishing, and after Smith reinvented himself cultivating oysters in Long Island Sound, Hurricanes Irene and Sandy hit, destroying his crop two years in a row.
Dr. Charlie Yarish: Bren was really on the verge of bankruptcy.
Searching for a new career on the water, he sought advice from Charlie Yarish, a professor of marine biology whose lab at the University of Connecticut studies some of the thousands of different types of seaweeds.
Dr. Charlie Yarish: But there’s only 20 globally that are actually farmed.
Lesley Stahl: They’re not all edible?
Dr. Charlie Yarish: No, they’re not all edible. Some of ’em actually are quite toxic.
It was Yarish who suggested Smith consider sugar kelp, a local seaweed that gets planted after hurricane season is over, has a mild taste, and can also be used as animal feed and fertilizer.
Lesley Stahl: Seaweed for you, was the lightbulb?
Bren Smith: Yeah, yeah.
Lesley Stahl: The eureka moment.
Bren Smith: We can create jobs here. We– we can protect and improve the environment. We don’t have to make this choice–
Smith now operates one of the largest seaweed hatcheries in the country, with tanks full of developing kelp spores, and a processing room that comes alive in spring when he and his team bring in the harvest and get it ready for sale. Blanched in 170-degree water, kelp turns a vivid green and can then be sold fresh or frozen, sometimes in the form of noodles. Smith’s customers include Google for their cafeteria, Yale University, and several restaurants and wholesalers. He has sold out the last four years.
But at this kelp farm across the country in the waters outside Seattle, producing food is almost beside the point. This is a test farm, where Betsy Peabody of the Puget Sound Restoration Fund and a team of scientists are doing an experiment to see whether seaweed can help fight the growing problem of ocean acidification — caused mainly by increasing carbon dioxide levels in the seas.
Betsy Peabody: Roughly 25% of CO2 in the atmosphere is being absorbed into oceans.
Lesley Stahl: And that is what we’re getting from fossil fuels?
Betsy Peabody: From both carbon emissions, from deforestation, and I think initially people thought, “Well, thank goodness the oceans are taking up some of that carbon dioxide.” But then, scientists started to document that, in fact, when that carbon dioxide goes into the ocean, it causes chemical changes.
Changes like increasing the water’s acidity, as documented in the U.S. government’s 2017 climate science special report. The excess CO2 causes “a decrease of carbonate ions… Which many marine species use to build their shells and skeletons.” Worldwide, “ocean surface waters have become 30% more acidic over the last 150 years.” And in the Pacific Northwest, the problem is compounded by currents that bring more carbon-rich waters to the surface. And that’s where seaweed comes in.
Dr. Charlie Yarish: Kelp take up carbon dioxide like any plant does, and it just so happens it lives in the water. There are winners and losers in ocean acidification. Organisms that produce carbonate shells like shellfish, they’re a loser. They can’t handle the lower PH. They can’t deposit as much calcium in their shells. On the other hand, when seaweeds like kelp, they actually pick up that carbon dioxide because now it’s easier for them to do photosynthesis.
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