We Can Feed the World with Kelp Forests
Kelp grown by Thimble Island Ocean Farm. Photo courtesy of GreenWave.


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We Can Feed the World with Kelp Forests

With just under four acres of ocean, kelp farmers can average about 200,000 pounds of mussels and 500 pounds of dried kelp each year.

Kelp farmer Bren Smith has a vision: 100,000 ocean farms dotting coastlines across the globe, surrounded by conservation zones. In each acre, 25 tons of kelp and 250,000 shellfish can be grown. A network of these farms totaling the size of Washington state, he says, can feed the planet.

"You'll have a range of institutional buyers including hospitals and universities," he says. "And then a range of social entrepreneurs developing innovations products like biofuels, hamburgers, or feeds."

Thimble Island, Oysters, Bren Smith

Bren Smith. Photo courtesy of GreenWave.

Bren Smith is the founder of Thimble Island Ocean Farm in Long Island Sound and GreenWave, an organization that works with start-up kelp farmers around the world. He believes that ocean farming is the new farming model of the future.

"Climate change has completely changed the dinner plate," he says. "Our food system is slowly getting pushed out to sea. With kelp farms, we're going zero inputs. No fresh water, no fertilizer, no feed, no arid land."

Thimble Island, Oysters, Bren Smith

Photo courtesy of GreenWave. Illustration by Stephanie Stroud.

Unlike mono-aquaculture operations, these ocean farms don't require any inputs and encourage a variety of species to grow jointly with one another. Also known as 3-D ocean farming, kelp farming utilizes the entire water column. The kelp is grown on lines in open water. Shellfish like oysters and clams are stacked below the kelp. The water is monitored for pollution on a regular basis.

The products not only provide food, but ecological benefits. Bivalves are especially great at filtering water; an adult oyster, for example, cleans up to 50 gallons of water per day. Kelp, one of the fastest growing plants in the world, absorbs nitrogen, phosphorous, and carbon dioxide from the sea. It soaks up five times more carbon than land-based plants; it also serves as an artificial reef, attracting more than 150 species of aquatic life.

"The kelp that we grow, all native species, sends spores out to nature and creates new kelp farms in the wild. We're rebuilding ecosystems; we're restoring the ocean with our farms," he says.


The practice of farming kelp for food isn't new. Seaweed farming began in Japan in the 17th century.

It is, however, relatively new to the United States. The first open-water kelp farm started in 2006 in the Gulf of Maine.

Thimble Island, Oysters, Bren Smith

Oysters harvested by Thimble Island. Photo courtesy of GreenWave. Photo courtesy of GreenWave.

Today, Smith says he has people from 40 countries and every coastal state in North America requesting information on kelp farms.

"We have young, land-based farmers screaming to us, wanting to start their own farms because they can't afford land," he says. "I call it the nail salon model of the sea. There are minimal capital and skill requirements."

It's a budding movement that's largely taking place on the Atlantic coast. It's attractive because it's cheap; Smith estimates that a kelp farm can be launched with just $20,000 and a boat.

At Casco Bay in Portland, Maine, kelp farmer Matthew Moretti gives me a tour of his facilities. I am surprised at how minimalistic it is; there's a barge, a small boat, and a warehouse. The tour is over in less than 15 minutes.

"That's it," he says.

Moretti is the owner of Bangs Island Mussels, one of the largest mussel-growing operations in Maine. His father was one of the first people to get into offshore mussel farming in Maine. Six years ago, they started their own mussel farm. A couple years later, they expanded to kelp.


Matthew Moretti of Bangs Island Mussels hauls in a line of kelp. Photo by Jenny Rebecca Nelson. Photo by Jenny Rebecca Nelson.

"We're creating a multi-trophic system," Moretti, who went to school for marine biology, says. "It's zero-waste and the mussels, which are filter feeders, clean the water around them. This is the most sustainable way of growing food that I can think of."


The actual farm is a mile out into the ocean, and even that doesn't take up that much space. Mussels are grown on ten rafts measuring 40 by 40 feet. Kelp is grown on lines, marked by buoys on the water. With just under four acres of ocean, Moretti averages about 200,000 pounds of mussels and 500 pounds of dried kelp each year.

He says he plans on adding scallops to his portfolio soon.

But for both Moretti and Smith, the main hurdle isn't growing kelp; it's getting their products onto the dinner plates of Americans.

"People are still new to it. It's not a part of the traditional American diet," Moretti says. "That's one of the reasons why we focus on restaurant customers. We don't sell direct to consumers."


Photo by Jenny Rebecca Nelson. Photo courtesy of GreenWave.

He's partnered with local chefs to create kelp ice coffee and ice cream. Smith recommends kelp in noodle form, barbecued with parsnips and breadcrumbs. Kelp, he says, is just the tip of the iceberg when it comes to ocean plants, of which there are more than 10,000 edible varieties.

"One of the things I've realized while I've been doing this is that seaweeds are not seafood. They're vegetables," he says. "Kelp is just the gateway drug. There are ocean plants that we have never seen before or tasted."

If we can expand our diet, he stresses, we can feed our planet and save it as well.

"The new face of environmentalism isn't just saving the environment," Smith says. "It's figuring out a new kind of economy where we're both protecting and restoring the environment while lifting people out of poverty. We should be creating new opportunities and new jobs while feeding the planet. With kelp, this is our chance to do food the right way."