Kelp Farming in California

By Sia Agarwal

Swaying in the waves along the California coast in dazzling arrays of jewel greens and yellows is kelp, the spotlight organism of the environmental movement. Secured by holdfasts on the rocky sea floor, kelp stalks as tall as 175 feet have thrived off the shores of California for thousands of years.

Kelp forests are vibrant ecosystems that pump oxygen into California’s coastal waters, absorb carbon, and are considered the tropical rainforests of the ocean because of the biodiversity they harbor. San Francisco boasts its own local kelp ecosystem: the Sonoma-Mendocino bull kelp forest, which is home to organisms such as sea otters, sea stars, crustaceans, and sea lions.

However, kelp forests are shrinking in size around the world due to coastal development, pollution, and especially climate change. Marine heatwaves become more frequent as oceans warm, and beginning in 2014, a particularly intense marine heatwave— nicknamed “the blob” by scientists—swept through California’s coastal waters.

Warm waters are an ideal condition for purple sea urchins, which are voracious feeders of kelp. Higher temperatures also make sea-stars—important predators of purple urchins—more susceptible to disease. At the same time as the marine heatwave, “a disease, whether it was a viral or bacterial disease, spread and really reduced the abundances of many sea star species, including one which is very critical in those Northern kelp forests, called the sunflower sea star,” said Scott Hamilton, a fish ecology and kelp restoration researcher at Moss Landing Marine Laboratories. With populations left unchecked, purple sea urchins eat through entire kelp forests, leaving behind barrens. For thousands of kilometers, sea urchins carpet the sea floor after having devoured a kelp forest.

The decline of the world’s kelp forests means the loss of an economic resource, a carbon sink, and one of the world’s most productive ecosystems. In order to save the kelp forests, California’s kelp forest restoration movement spans research labs, businesses, conservation organizations, and more.

At Moss Landing Marine Laboratories (MLML), Dr. Scott Hamilton and Dr. Michael Graham are developing techniques to restore Northern California’s bull kelp forests by growing kelp in the lab. “We are trying to develop techniques to culture bull kelp in the laboratory in large land-based aquaculture tanks where we can complete the lifecycle,” said Dr. Hamilton. This technique can be used for a variety of kelp species which can be useful for preserving marine biodiversity.

“The challenge for us was to try to figure out how we can culture in the laboratory in tanks something that tends to grow thirty, forty feet deep,” explained Hamilton. “We came up with a process to modify the kelp, which is the bonsai kelp idea. In the laboratory, we were able to develop a perpetual spore bank, which is keeping populations going over multiple generations in the laboratory through a tumble-culture process.”

The MLML research team works with The Nature Conservancy and sea urchin divers to implement their kelp restoration methods. “Those collaborations are critical. We couldn’t have done the work without them… especially to do the urchin removal that needed to happen. Reef Check California … has been doing kelp restoration work in collaboration with commercial urchin divers at the site that we work at and a number of other sites,” said Dr. Hamilton, underscoring the advantages of collaboration between researchers and industry for kelp forests’ preservation. “Our work couldn’t have really happened without them.”

Another prong of the kelp restoration movement is kelp farming: the cultivation of kelp where part of or the entire life cycle of the organism is controlled,

Along the West Coast, companies such as Daybreak Seaweed grow kelp that can be used in kitchens and restaurants. Other businesses, such as Primary Ocean, sell kelp as biofuel, fertilizer, animal feed, bioplastic, and other sustainable products.

Further north in Alaska where access to nutritional food is difficult, seaweed and food security are linked; the Alaska Food Policy Council has recommended the increase of in-state food products, such as kelp. A superfood, kelp contains disease-preventing antioxidants, and alginates, which flush out toxins from the body. Kelp farming has the potential to provide economic welfare and nutrition to the state and its people.

To farm kelp, reproductive spores are grown in networks of ropes strung between buoys, creating a farm in the ocean. Once the kelp has reached a certain height, the ropes are hoisted from the ocean, and the kelp is harvested. A farm in New Haven, Connecticut is growing kelp and shellfish at the same time on vertical ropes that span the length of the water column.

“It’s not that difficult to grow [seaweed]. Kelp needs nutrients, sunlight, and good water temperature,” said Dr. Jackson Gross, an aquaculture specialist at UC Davis. Dr. Gross researches solutions for aquaculture systems, including seaweed farms. He explains that the challenge in kelp farming lies in harvesting the large amounts of kelp and finding a market for it.

In California, kelp farming faces a few barriers. State environmental regulations make it a long process to obtain a permit to establish a kelp farm. The review process for a farm can be expensive, ranging from $25,000 to $500,000, and applicants take the risk of not being approved by the end of it. California’s coastal waters, specifically the three miles from shore under state control, are coveted by different sectors from recreation to commercial fishing to military interests, making it difficult to find a place to put a kelp farm.

Additionally, the shape of California’s coastline adds to the challenge of anchoring a kelp farm along the coast.

It’s difficult to grow these types of systems because we don’t have a lot of protected areas. We don’t have sheltered areas like in Alaska or Maine where it’s flat and easy to work in,” explains Dr. Gross, positing that future systems could be large, floating structures away from the coast.

As an alternative, wild kelp harvesting is the practice of collecting kelp that is not maintained under a permanent agricultural/cultivation plot. In Sonoma County, Heidi Herrmann runs Strong Arm Farm, a company that sells hand harvested kelp varieties to chefs and grocery stores. Along with a team of five to ten people in the months of June and July, Heidi harvests kombu and nori, collecting around 200 pounds of kelp per day.

Before her team gets to work along the shore, Heidi instructs the group on how to cut the kelp sustainably. “It’s usually in an area called the meristem tissue where the cells regenerate. When we make our cut with our scissor, it’s still able to grow out about a foot a month,” said Heidi. “It is rewarding to see regrowth happen when I go out to sites some months later.” Kelp harvesters can contribute as much to an ecosystem as they benefit from it. By cutting at the correct site, Heidi and other harvesters enable the kelp to regrow at amazing rates, which allows the organism to capture more carbon. A 2020 study by researchers at the University of Western Australia discovered that Australian kelp forests capture 1.3-2.8 teragrams of carbon every year. This accounts for 3% of global blue carbon, which is the amount of carbon sequestered by the world’s marine ecosystems.

Proponents of kelp farming argue that the practice is a great example of how we can sustainably interact with the ocean in a way that provides us protection against climate change. “We’re enabling that plant to put on more growth and consume more carbon,” Heidi explains. “It’s rewarding to play that key role in intercepting [the kelp’s] life stage but in a way that enables it to still fulfill its natural process, but also gain food and nutrition out of it just from the knowledge of where to cut [the kelp] and when,” Heidi explains. Alongside running her business, Heidi conducts public educational tours through Forage SF on the Sonoma Coast from May to August in which people can learn about kelp harvesting by engaging with the natural ecosystem.

“We go down to the beach as a group and talk about ecology, nutrition, and how to use kelp in the kitchen,” said Heidi. “People share recipe ideas and take home about ten pounds of their harvested kelp.” Dates for Heidi’s tours are typically published in early spring on the Forage SF website.

In addition to its importance as an economic good, kelp holds cultural significance for indigenous communities along the West Coast. Kelp farming and harvesting is ingrained in these communities’ past and ongoing lifestyles. For example, the Haida people, a Pacific Northwest tribe, uses bull kelp as food. Kelp forests are also the fishing grounds for other food products utilized by the community. In another nation, the Coast Salish, there are shared stories about kelp: One Samish myth is about a girl, Ko-kwahl-alwoot, who marries a man from the ocean in order to provide a connection between the land and the sea for her people. As she lives in the sea for longer, she slowly transforms into a more ocean-like being, but the strands of her hair appearing on the shore (the bull kelp) tell her family that she continues to provide the resources of the seas.

Biologically, economically, and culturally important, kelp forests are a unique ecosystem. They present a chance to incorporate sustainability into the state’s economy. Opportunities such as Heidi’s educational tours can help individuals understand the role they play in preserving local ecosystems.

“It’s healthy for us to integrate all those choices in that moment when we are harvesting our food,” said Heidi. “It’s not a place we’re commonly in. I see people processing new feelings or thoughts that they’re being confronted with — a new trust, autonomy, role that they have put themselves in. To me, that’s empowering, and with education, they are more equipped to make a better decision about sustainable food practices.”

The power of citizens in ecological restoration has added great value to the movement. “Advocating for resources and support from our government officials and resource management is critical,” said Dr. Hamilton. “That is why there has been a fair amount of funding directed at this issue because the public has been concerned about these critical ecosystems.” Activists argue that public knowledge of the importance of our kelp forests is vital to the effort to restore them. The different facets of the kelp effort work to understand how humans can interact with the environment with balance, caution, and care. By conserving the kelp forests, scientists, activists, and environmentalists aim to provide hope for the Earth’s future.