Cove by cove, scientists, divers and volunteers are hauling up urchins to protect kelp.

By Raymond Zhong Photographs and Video by Glenna Gordon, The New York Times

Raymond Zhong and Glenna Gordon scuba dived with scientists and urchin-smashing volunteers to report this article

From the bluffs, you might have mistaken the little brown heads poking out of the ocean this month for seals, hundreds of them, gathered for a morning conclave. In fact, they were something almost as surprising: bulb upon glistening bulb of kelp, more of it than this cove in Northern California had seen in years.

Beneath the milky water, the kelp’s ropelike stems stood in thickets dense enough to snag the valve on a scuba tank. The parade of long, luxuriant blades, streaming out of each bulb like wavy tresses, made diving these waters feel a bit like touring a hairdressers’ convention.

A decade ago, the coastline north of San Francisco was the site of one of the most horrific deforestations ever recorded. More than 90 percent of the towering, majestic kelp forests, across 200 miles of glittering shore, were dead and gone in years. Felled by freakishly warm ocean water.

Sea creatures starved in droves, notably abalones, the giant mollusks prized for their buttery flesh. At the same time, a mysterious sickness was killing off another denizen of the kelp forests, the mighty, many-limbed sunflower sea star. Without these predators around, sea urchins ran amok, gorging on the kelp that remained and turning the reefs into spiky purple wastelands.

Today, acre by acre, beach by beach, efforts to undo the ruin are bearing early fruit. Or, rather, fronds.

At Portuguese Beach in Mendocino County, scientists are planting kelp seedlings and hiring divers to haul up urchins by the ton. As a result, kelp cover this year is 10 times what it was at its low point in 2023.

A few miles up the road, at Caspar Cove, state authorities are allowing recreational divers simply to smash urchins to bits with hammers and picks. The payoff? The kelp canopy there is nine times its area in 2020.

These and other pockets of recovery are small, scattered. Their success is hardly assured; another marine heat wave could set them back. But they are a crucial first step, scientists say. If enough kelp can be nurtured in these oases, then over time they might reseed more of the coast.

“We’re planting the garden,” said Tristin Anoush McHugh, who leads kelp restoration for the Nature Conservancy. “Let’s see what shows up.”

Bull kelp off the coast of Van Damme State Park, Calif., this month.

Pulling up urchin traps in Noyo Harbor; A kettlebell weighs down a rope module for growing kelp

The Nature Conservancy uses drone surveys to monitor kelp growth.

Kelp forests grow along a third of the world’s coasts, and the threats to them from ocean warming, pollution, overfishing and other stressors are growing in nearly every region. “In a lot of different places, the environments will never be as suitable for kelp forest as they used to be,” said Thomas Wernberg, a professor of marine botany at the University of Western Australia.

That raises big questions about how much any restoration project can hope to achieve, and how long it may need to last. “When are you done, if ever?” he said.

Diving at Portuguese Beach shows what it looks like to begin.

The Nature Conservancy and its partners have been planting baby kelp here, on simple rope modules that suspend the juveniles out of hungry urchins’ reach — nine modules last year, 60 this year. Come fall, the kelp is mature and can blast out trillions of spores, sowing seeds to grow the following year.

Already, the new kelp is helping the ecosystem show glimpses of its former self. During a recent dive, a plump sunflower sea star, about as wide as a dessert plate, with 15 or so chubby arms, was nestled between the rocks beneath one of the modules. Five other sunflower stars have been reported here so far this year.

Even so, you don’t have to swim very far to see parts of the reef that are still absolutely blanketed by urchins, like an invasion of purple alien pompoms.

To defend the kelp at Portuguese Beach, commercial divers have dredged up 41 tons of urchins over the past two years, mostly by hand. At Caspar Cove, volunteers have smashed up 16 tons since 2020. Both methods of pest control are laborious, and it’s unclear who would pay commercial divers to keep doing it year after year, to say nothing of enlisting more divers and expanding to more of the coast.

Culling urchins in Caspar Cove. Divers have dredged up tons of the spiny creatures, which graze on kelp.

KelpFest attendees collected urchins during low tide at Elk Beach.

Purple urchins in a tide pool at Mendocino Headlands State Park.

“There’s only 15 doing this work, and you need 1,500,” said Jon Holcomb, 80, a veteran diver.

One way to fund restoration would be to find something useful to do with all the urchins that are removed. Right now, many are composted or ground into gravel. But the Nature Conservancy and other groups have explored all manner of more-lucrative products that could be made from them, including dyes, filaments for 3-D printing, even leather. (Purple urchins generally aren’t valuable as seafood because they produce smaller gonads, which are those custardy golden lobes that go on sushi, than their red cousins.)

One promising product is countertops. A start-up, Primitives Biodesign, is developing a kind of urchin-shell marble, one that Virj Kan, the company’s chief executive, hopes will be strong but lightweight compared with natural stone. A single countertop could use up the urchins that would cover a tennis-court-size area of seafloor, Ms. Kan said. Primitives is aiming to deliver its first units next summer.

Jon Holcomb is a semi-retired urchin diver.

KelpFest, a community celebration of all things seaweed, took place in Mendocino County this month.

The urchin-ranching lab at the Noyo Center Marine Field Station in Fort Bragg.

The Kashia Band of Pomo Indians, a tribe in Sonoma County, is hoping the rewards from its restoration efforts will come from bringing back a cherished traditional food source.

Along a curl of ancestral coast called Shell Beach, the tribe and its partners are rehabilitating the kelp groves in order to reintroduce abalones there and rebuild the creature’s populations. They’ve hired commercial divers to clear out more than 50 tons of urchins in the past two years. But the tribe is also training its own divers, both to put a “tribal eye” on the work and to help keep it going for the long haul, said Nina Hapner, who leads the tribe’s environmental department.

“We’re all planting seeds and knowing we’re not going to see the full growth of the seeds that we plant,” said Atlas Elliott, 22, a Kashia diver. “But we know there’s going to be growth. We’re making our contributions. We’re watering our plants. We’re feeding our people. We’re doing what we need to do.”

Raymond Zhong reports on climate and environmental issues for The Times.

A Berkeley-based company is crafting materials that will help save California kelp forests.

By Krista Simmons, Sunset Magazine

If you’re a surfer or avid tidepooler, you likely have been irked by the reality of a sea urchin prick. But there’s more reason to dislike these little purple pincushions, which have taken over kelp forest beds and helped cause the endangerment of bull and giant kelp along the coast. Though they are indeed native to the area, purple urchin populations have proliferated, causing an imbalance in Northern California marine ecosystems. A West Coast-based design company out of Berkeley, California, called Primitives Biodesign is finding creative ways to combat that through their creation of Urchinite—a biomarble made of mineralized sea urchin shells that’s designed to support both marine restoration and architectural design.

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Primitives has also done work in the compostable packaging space, but their project involving urchin is arguably their most unique yet. Their stunning shades of lavender and grey tiles are crafted from biocalcites, which are a naturally occurring marine mineral found in purple sea urchin shells. Purple urchins, or strongylocentrotus purpuratus, are harvested from targeted restoration sites where kelp forests have been severely damaged, and then crafted into tiles using a proprietary process that’s the result of a unique collaboration between with marine scientists, urchin divers, and conservation groups.

Working in partnership with the Nature Conservancy, experienced scuba divers harvest purple urchins at kelp restoration sites where outbreaks have been particularly detrimental. They’re then brought into the lab, where they’re mineralized and cultured with a bio-based binder material, resulting in a durable, marble-like stone material called biomarble. It’s then finished and graded by a team of engineers. The company says that for every 50 units of biomarble, 1.1 acres are cleared of purple urchins. The hope is that this will enable kelp forests to eventually regrow and the delicate ecosystem that resides within them to rebound.

“Urchinite has a glacial cool tactility with a rich granular texture and variegated shades of light and dark hues that are entirely derived from natural purple sea urchin shells,” says Primitives Bioesign CEO Virj Kan. “Its color palette spans from soft foamstone ivory tones and thistle hues to smokey wisteria and amethyst umber—colors resonant to oceanic hues in a rocky coastline filled with soft pearlescence, purple sea urchin, and mussel shell.”

The resulting, one-of-a-kind material is more durable than natural marble and limestone, and strikingly beautiful too. Kan says that its architectural and design applications are endless—think countertops, wall coverings, flooring, furniture, and decor. What’s more is that these organic beauties have more than just a great story, they’re made from regenerative materials that contribute to the continued health of marine ecosystems for generations to come.

Kelp rests on the rocks during low tide, left, along the coast in Sea Ranch in Mendocino County. Kelp forests along the Northern California coast have nearly disappeared, leaving the seafloor covered in urchins, such as the one seen at right.

Jessica Christian/S.F. Chronicle

By Olivia Cruz Mayeda, SF Chronicle

Joe Lee surfaced from Mendocino Bay grasping a pearl. It was the 1800s, and a lush forest of kelp swayed beneath him, home to sea urchins and abalone — one of which had transformed a bit of grit into the treasure he held in his hand.

That pearl is still in Lee’s family, and looks much the same as it did more than a century ago. But the kelp forests along the Northern California coast have, of course, nearly disappeared, leaving the seafloor covered in purple urchins in an unprecedented devastation of an ecosystem, and the adjacent fishing industry. The Asian American communities that once thrived off those kelp forests have also changed, searching for new ways to live off the ocean that has sustained them for more than a century.

When Lee found his pearl in the 1880s, he also built a wooden temple to Kwan Tai, the Taoist god of abundance, integrity and longevity. It sits in what used to be Mendocino’s Chinatown, facing south toward the inlet where Big River flows into Mendocino Bay. 

Earlier this year, Lee’s great-granddaughter, Lorraine Hee-Chorley, 72, opened the temple doors, which students in the community’s Chinese New Year parade still enter to receive traditional blessings. Hot sunlight flooded onto an altar adorned with offerings of citrus, which looked out on the ocean where Hee-Chorley’s family foraged for abalone and pearlescent shells that they would sell to tourists in town.

“In this bay, there used to be tons of bull kelp,” Hee-Chorley said, looking out onto the water from the temple’s porch. “But it’s not there. It’s just not there.”

Local historian and Chinese fisherman descendant Lorraine Hee-Chorley, left, opens the doors of the Temple of Kwan Tai, built by her great-grandfather in 1854 in Mendocino. A picture from the late 1800s, right, shows Hee-Chorley’s great-grandfather Joe Lee and her grandmother Yip Lee.

Photos by Jessica Christian/S.F. Chronicle

In its stead are blankets of those spiky purple urchins covering the seafloor. But now, a Bay Area scientist believes she’s found a way to turn the scourge of these urchins into a profit point by using them as literal building blocks. And some of the people working with her are the Asian American fishermen who have spent decades making a living off of the ocean.

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In January, Mickey Kitahara swayed with the morning tide at the bottom of the Albion Cove, about 10 miles south of where Lee found his pearl in the 1880s. He returns to this spot every month to remove purple urchins encroaching on vulnerable kelp fronds with his bare hands. He knows it’s an uphill battle, but he feels he has to do his part to rehabilitate the Northern California coastline — while also supporting his family.

“Those purples in here, they just consume every inch they can, stacked right next to each other on a reef, and don’t leave room for anything else,” he said.

A month later, Mickey, 42, and his father Mike, 75, stood on a metal dock in Albion, tending to their urchining equipment. On either side of the brawny duo were white boats with blue trim. At the bow of Mickey’s boat, a yellow hose encircled itself like a snake. 

Mickey Kitahara on his boat, which he uses for sea urchin diving. In the early 20th century, Kitahara’s great-grandparents were part of a thriving abalone fishery built by Japanese immigrants.

Jessica Christian/S.F. Chronicle

About 35 years ago, roughly the lifespan of an abalone, a 6-year-old Mickey was learning to breathe through a hose just like it in the hot tub outside his Japanese American family’s house in Albion. That was when Mike was making more than $100,000 a year diving off the side of his boat for urchins and abalone. He was carrying on a family legacy that began in Monterey’s fishery, where his grandmother, Takako Kitahara, had shucked abalone on Cannery Row — and lost one of her fingertips to a blade. He passed that legacy to Mickey by gifting him a boat on his son’s 22nd birthday. It was one of about 40 that filled the Albion estuary at the time. 

Mike Kitahara participates in a sea urchin harvest, left, in San Diego in 1977. Kitahara’s wife Susy, right, holds large sea urchins during a dive near Santa Rosa Island, off the coast of Santa Barbara, in 1977.

Photos courtesy of Mike Kitahara

On a gray morning in 2015, Mickey was christening his new urchin fishing license alongside his dad. “Oh man, you’re in for it,” he remembered a diver on a passing boat saying as Mickey cracked open his first catch of the day to find the shells, once plump and egg yolk-orange with roe, empty.

“The quality got so bad you couldn’t sell ’em,” Mike said, looking on as Mickey stepped onto his boat.

Since Mike began diving for urchins in the ’70s, the number of commercial divers in the area has shrunk 90%, he said. The number of urchin processors in Fort Bragg, which used to employ around 30 people each, has halved. Today, the estuary where Mike and Mickey dock their boats sees only around a dozen on a busy day.

“It’s sad to see that a lot of these boats that have been passed down for generations go into disrepair or get scrapped,” Mickey said. “Maybe it belonged to somebody’s grandfather that was passed down to his son and passed down to his son.” 

LEFT: Divers Mickey Kitahara, right, and his father, Mike Kitahara, with boats they use to dive for sea urchins. RIGHT: Their latest docking area is on the Albion River in Mendocino County.

Photos by Jessica Christian/S.F. Chronicle

In the early 20th century, Mickey’s great-grandparents were part of a thriving abalone fishery built by Japanese immigrants like them. Before the U.S. government incarcerated the Kitaharas’ ancestors and 120,000 other Japanese people during WWII, they made up a large chunk of California’s fishing community, including 80% of the fishermen in Monterey, said anthropologist Sandy Lydon. When they returned, the state had seized their boats and barred all “Japanese aliens” from receiving fishing licenses, which they later reinstated. The Japanese community never recovered. Mickey’s great-grandfather, who had previously sold fishing nets, became a gardener.

Eighty years later, Mickey was doing a bit of underwater gardening, filling his nets with unmarketable urchins. He looked at his watch, which counted down the minutes to when he would surface for a break from loading urchins into his basket. Bare, whitewashed rock and droves of zombified urchin husks surrounded him on the seafloor. But in the areas Mickey has been clearing for the past four years, a few patches of kelp stalks fanned out into fronds at the surface.

Since 2021, local kelp restoration projects like the Waterman’s Alliance, Reef Check and the Nature Conservancy have relied on divers like Mickey to do an inverted version of what he was raised to do: collect urchins and then throw them away like piles of dry leaves.

Near the Albion River Bridge in Mendocino County is a kelp restoration project run by the Nature Conservancy.

Jessica Christian/S.F. Chronicle

“The idea is to get these areas to grow kelp, and then as the spores are released we can clear the area to allow for the kelp to grow without as much pressure from those purple urchins,” he said. Still, it was meditative, “like raking leaves in your yard.” 

Now, kelp restoration, too, is under threat. 

In February, the National Oceanic and Atmospheric Administration for Pacific Ocean restoration fired more than 1,000 employees and is slated to close three of its California offices, including ones dedicated to marine protection and fisheries. NOAA helps fund the projects that hire Mickey, so losing that support is a “real fear,” he said as bouquets of kelp bobbed on the bay.

“If it would not be enough to survive, I would need to switch things up and go find a different avenue to bring in some income,” he said.

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The luster of Joe Lee’s pearl, the protective spikes of the urchins collected by Mickey Katahara and even the bone of Takako Kitathara’s severed fingertip have something in common: Each contains calcium carbonate. The substance is also the main component of marble, which is how Virj Kan hopes to help the kelp forest and a Northern California community built on the ocean.

Two years ago, Kan was in Mendocino after earning her masters from the Massachusetts Institute of Technology in biomaterials, hoping she could lend her science background to the kelp crisis. While there she met up with a burly, tanned man outside an urchin processing plant in Fort Bragg who had just culled 400 pounds of purple urchins, which he loaded off his truck in buckets and barrels. It was Mickey Kitahara. Usually, he dumps them into a large bin, which might be repurposed into fertilizer or may just sit there indefinitely, he said. This time, he handed them off to Kan, a scientist.

Scientist and artist Virj Kan in her research residency and lab in Berkeley, where she creates marble from sea urchins. As California kelp disappears, Kan is working with divers to create an economic incentive for culling overpopulated sea urchins from Mendocino. Right, Kan holds a marble tile she created.

Photos by Jessica Christian/S.F. Chronicle

Virj Kan holds a sea urchin in her Berkeley lab. Kan creates marble from urchins, the sales of which she hopes will increase demand for urchin removal and kelp restoration.

Jessica Christian/S.F. Chronicle

“She was going to make tiles or something,” Mickey remembered.

In March, an urchin husk sat on the counter of Kan’s home in Berkeley, a Victorian mansion built for a sea captain now owned by Stochastic Labs, a nonprofit that incubates entrepreneurs. Beakers and flasks perched on a gas stove behind Kan as she held up a small tile variegated with shades of dark and light purple.

“There’s a lot of people studying the kelp forest, a lot of people that are helping to remove the urchins to bring the kelp back, but there’s a missing link, which is, ‘What’s the market?’” she said.

In April, Kan launched Urchinite, a marble synthesized from pulverized, calcium carbonate-rich urchins, whose sales she hopes will increase demand for urchin removal and kelp restoration.

An Urchinite countertop measuring 40 square feet — and costing between $1,600 to $7,200, depending on its design — would restore 0.06 of an acre of seafloor, Kan said. 

The 12 acres within the Nature Conservancy’s purview in Mendocino would translate to roughly 200 countertops.

Kelp rests on the rocks during low tide along the coast of Sea Ranch in Mendocino County in February.

Jessica Christian/S.F. Chronicle

Back in Mendocino in May, Mickey looked at the renderings of Urchinite countertops and tables on his phone. 

“I could see myself interested in a countertop,” he said. “That would be beautiful.” 

Mickey was feeling more optimistic than usual. Tomatoes were growing in his yard and bits of baby kelp were appearing out on the ocean in little balls Mickey calls “lollipops.”

“It is a hopeful time of year,” he said. 

At least once a day, though, Mickey thinks about “Plan B”: what he’ll do if the fisheries don’t come back, funding dries up and efforts like Kan’s don’t pan out enough to keep him diving.

“Some of the guys that have been doing it as long as my dad say the urchin industry is over,” he said. “I honestly don’t know.”

By Primitives Biodesign

Berkeley, CA — Primitives, a biodesign and materials innovation company, is announcing the launch of MARBLIS, a new architectural surfaces brand and its debut innovation, Urchinite™ the world’s first architectural surface made from sea urchins. Urchinite represents a breakthrough in material science and ecological design: a biomarble engineered not just for beauty and durability, but for environmental repair.

While native to California, purple sea urchins have become a symbol of underwater imbalance,  stripping once-thriving kelp forest ecosystems down to sea urchin deserts. Under normal conditions, sea urchins commonly shelter in rocky crevices and feed on drift kelp that settles on the seafloor. With heat waves and loss of key predators, purple urchin populations have surged by up to 1,000% in some areas. Over the last decade, more than 96% of Northern California’s kelp has vanished, leading to biodiversity loss and economic strain across coastal communities. Uni from sea urchins have a reputation as a fine dining delicacy, but unfortunately eating them is insufficient since most have little to no roe.

Marine Ecosystem Before & After Vibrant, healthy kelp forest (left) and sea urchin barren (right). Images: Andrew b Stowe (left) andThe Nature Conservancy, Ralph Pace (right).

Primitives offers a tangible solution to reduce overpopulation of purple urchins - transforming this marine nuisance into a high quality, one-of-a-kind biomarble that helps to restore balance beneath the waves. Developed in partnership with The Nature Conservancy, Primitives integrates material innovation with environmental action by supporting the regrowth of kelp forests vital to carbon sequestration, fisheries, and marine biodiversity. Working in collaboration with marine scientists and commercial divers, purple urchins are harvested at targeted kelp restoration areas. Every 50 units of Urchinite biomarble produced has the potential to clear 1.1 acres of purple urchins, enabling kelp forests to regrow and marine biodiversity to rebound. This measurable ecological benefit puts Urchinite in a category of its own -  where each surface is traceable to a marine restoration event.  

“With Urchinite, we’re not just designing a product, we’re designing a material interface that bridges land and sea - where the construction of a dining table triggers the rewilding of a habitat.”

— Virj Kan, CEO at Primitives. 

Close up of Urchinite biomarble sample. Image by Primitives Bio.

Drawing on over a decade of biomaterials technology expertise, the Primitives team developed a patent-pending process to transform sea urchins into engineered biomarble, a new material inspired by one of the world’s most revered stones. Urchinite is made from biocalcite, a naturally occurring marine mineral found in sea urchin shells. It is formed by integrating this mineral into a biobased binder, resulting in a durable, marble-like stone material called a biomarble. As the first product in this emerging category of biocalcite surfaces, Urchinite is leading the next evolution in the engineered stone industry.

MARBLIS Urchinite™ is designed to be more durable in performance than natural marble and limestone, making them ideal for interior and architectural applications such as countertops, wall coverings, flooring, furniture, and decor. For architects and designers, it offers a bio-based material with no VOCs or silica, that is produced locally with low-embodied carbon. For homeowners and builders, Urchinite is a chance to incorporate local regenerative materials into bespoke environments that impart enduring value and oceanic beauty, while playing a key role in promoting the healing and recovery of coastal marine life. 

Once deemed a "zombie" nuisance, the purple sea urchin is now being reimagined as a symbol of recovery and transformation. Urchinite is the culmination of years of research, blending cutting edge materials science, biodesign innovation, and precision engineering into a product that is as high-performing as it is meaningful and beautiful. Urchinite represents a next-generation approach to blue economy innovation, where climate mitigation and habitat regeneration are supported through market-based solutions.

Available now for custom orders and project partnerships.

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ABOUT PRIMITIVES
Primitives is a biodesign company that develops advanced materials to solve the planet’s most critical environmental challenges. Through cutting-edge materials science, innovative design, and systems engineering, Primitives is reshaping the materials economy into a platform for nature and ecosystem restoration. Working in partnership with leading non-profits, governments, industry, research organizations, cultural institutions, and regional communities, Primitives is building towards a future where — nature speaks, and systems listen. Its consumer-facing architectural surfaces brand, MARBLIS™ brings this vision to the built environment and introduces a new class of stone surfaces called biocalcite, engineered to support ecosystem repair and design performance. Its debut innovation, Urchinite™ is the world's first bio marble made from sea urchins, designed to restore kelp forests and regenerate marine biodiversity.