Everything is connected.

When a wasting disease began decimating the sunflower sea star population along California’s coastline in 2013, sea urchins — a main food source of sea stars — took over. Unusual ocean warming beginning in 2014 combined with “urchin barrens” on the ocean floor — which suffocated the nutrient cycle — have reduced cold-water-loving kelp forests in Northern California by more than 95%.

Torre Polizzi, who studied marine biology at Cal Poly Humboldt, has joined collaborators on a project to restore bull kelp and other declining algae species to Humboldt Bay and bolster a depressed economy by creating a market for the harvest.

As a grad student, Polizzi helped survey the bull kelp die-off in 2015.

After graduating, he and his partner launched Sunken Seaweed in the Port of San Diego, moving the operation in 2022 to establish California’s first commercial seaweed farm and helping to forge government, NGO, business and academic partnerships.

In July, the California Ocean Science Trust, the Humboldt Bay Harbor District, Cal Poly Humboldt, Sunken Seaweed and Hog Island Oyster Co. (one of Polizzi’s customers) hosted a tour of a land- and sea-based seaweed cultivation project the partners hope will be a cornerstone of both the growing local aquaculture sector and restoring the ecological balance of the bay.

“Probably some of you don’t realize, but you have been using seaweed in your everyday life,” Cal Poly Humboldt’s fisheries biology professor Rafael Cuevas Uribe told a group of about 30 guests, including federal, state and local government officials, before the group embarked on a harbor boat tour of the seaweed farm and hatchery.

“It could be on the toothpaste that you use, the ice cream that you eat, your cosmetics.”

While seaweed farming is the fastest- growing sector of American aquaculture — predominantly taking place in the Pacific Northwest, New England and Alaska — domestic production still accounts for only a small fraction of the global market.

“This is a net-positive industry,” Uribe said.

Seaweed is a carbon sink (absorbing more carbon that it releases), reduces ocean acidification, and is an extractive species, removing excess nutrients in the water such as nitrogen and phosphorous, he said.

Combined algae species produce around 50% of the Earth’s oxygen, provide marine habitat and shoreline protection, and studies have shown certain seaweeds as a livestock supplement reduce methane expulsion, Uribe said.

Partners in Slime

Down at the docks, Humboldt Bay Harbor, Recreation and Conservation District Executive Director Chris Mikkelsen handed out life jackets.

Mikkelsen’s agency also hands out the permits for seaweed harvesting and other aquaculture projects in the bay, which is one of two main oyster-producing regions in the state.

Rethinking and retooling that permitting process is a key component of a vision for Humboldt Bay that included small-scale, sustainable, low-trophic (the lowest part of the food web) aquaculture.

“The challenge is that these are state tidelands lease areas,” Mikkelsen said as the harbor boats got underway.” “A lot of these areas are several acres. For example, one of the sites is about 6.6 acres.”

Permitting and planning for such a large area, including meeting federal requirements like surveys dictated by the National Marine Fisheries Service’s California Eelgrass Mitigation Policy, would prove too daunting for small-scale startups, he said.

“We were able to break the 6.6-acre area up into smaller areas,” Mikkelsen said. “So, we have a 1-acre farm. We have a .6-acre farm.”

“The district went out and did all of the permitting, did the EIR (environmental impact report), wrote the mitigation reporting plan, wrote the initial culture descriptions for the various farm cultivations (each type of seaweed requires its own permit) and allowed people, instead of having to go out and permit 21 acres at a cost of ($25,000) to $50,000, the district was able to cover all those costs and then share those costs proportionately in these smaller lease areas.”

The next challenge, Mikkelsen said, is to make entry for new farmers both attainable and scalable as they hopefully succeed.

An option on the front burner is creating an Aquaculture Innovation Center.

“It’s something that this community is totally dedicated to,” he said. “We’re trying to figure out how we would subsidize that.”

Hog Island Oyster Co. operates several restaurants in the San Francisco Bay area and oyster farms in Tomales Bay and Humboldt Bay. The latter is California’s first permitted oyster shellfish hatchery.

The site is also home to Sunken Seaweed’s land-based operations, including tanks for producing dulse and other seaweed species besides the bull kelp growing on lines of rope in open water, and a laboratory retrofitted from a recycled storage container.

“It takes about three months for seaweed to go from 2 millimeters to about 10- to 14 feet,” Polizzi said as the two boats visited Sunken Seaweed’s open-water farm en route to the Hog Island facility.

“It’s one of the fastest-growing plants — it’s not a plant, mind you, it’s an alga — but plants in the world. We’re not using any fresh water, obviously. No fertilizers, no herbicides. When you think of the applications of what seaweed farming can be — you can make bioplastics out of seaweed without using miles of corn. You can do that with seaweed right in the ocean and not take any natural resources. It’s extraordinarily valuable for food, obviously, pharmaceuticals — those are the higher-tiered markets.”

Location and Infrastructure

“There’s a lot of seaweed farms set up in Alaska or being set up in Washington, Oregon, a few here in California,” Polizzi said. “But there is a serious bottleneck in the agricultural processing capability to do that. Humboldt’s really well suited in terms of where it is in proximity to markets and where there’s already affordable warehouse space that’s already doing this kind of stuff for the whole West Coast. We really could be a hub here.”

Low-trophic agriculture includes oysters, plants, mussels, seaweed and fish, depending upon the species, Polizzi said.

Norwegian-based Nordic Aquafarms is developing a land-based fish farm in Humboldt Bay, which the company said is close to the largest market for yellowtail kingfish outside of Japan. The proposal is for five buildings totaling more than 750,000 square feet and featuring a 4.8 megawatt solar panel array on the rooftops.

“Everybody’s on board with Nordic Aqua Farms now, that is a recirculating land-based fish farm that is going to be right there where that old pulp mill is,” Polizzi said, gesturing to a compound of rundown structures port of the moving vessel. “They’re taking all that down. They’re going to be putting up a huge building and producing sustainable fish there. And people are on board with that because of the species and the level of engineering ….”

Polizzi is hopeful that he and other seaweed farmers, perhaps those trained incubator-farm style through the yet-to-be-created Aquaculture Innovation Center, can take advantage of some of that recirculating seawater necessary for cultivating certain species of seaweed, as he is currently doing at the Hog Island Oyster Co. facility.

“Where we’re at with the Aquaculture Innovation Center is myself along with a small handful of board members have started a nonprofit that will be located alongside Nordic,” Polizzi said. “Nordic is going to be pumping 12 million gallons of seawater a day, and 2 million gallons of seawater is going to be unused. So that’s going to be funneled into, hopefully, our Aquaculture Innovation Center. And a big part of that is business development over there, so, providing space to experiment and have businesses getting started here. There’s a lot of models like that around the country — there’s one in Maine, there’s one in Florida, there’s one in Hawaii — that do that exact thing for aquaculture.”

The entire peninsula was once home to the timber and logging industry, he said.

Now that the industry is largely on its way out in the region, he said, it’s time to consider other uses that will benefit both the environment and the economy.

“And aquaculture is an amazing story on bringing back to life land and area that is extremely valuable.”

“Humboldt Bay is one of the cleanest bays in the entire state of California,” said Polizzi, a fixture at local farmers markets, where he said his presence is as much about educating the public as it is about selling his products.

“I moved my commercial operations to Humboldt Bay for a very specific reason. One, it’s pre-permitted for seaweed farming. Two, the water is very clean. You need clean water and affordable space to do this. There’s few places right now in California that hit those two criteria.”