On Monday morning at Hog Island Oyster Company, bags of fresh oysters were hauled from the back of a flatbed truck, revealing a layer of leftover seaweed drying in the summer sun. Terry Sawyer, the company’s co-founder, pointed enthusiastically as he identified the edible algae species, ulva, commonly known as sea lettuce. It’s a tasty seaweed that, until recently, was illegal to harvest from the oyster racks and other equipment that it naturally grows on in the bay. But last week, the California Fish and Game Commission unanimously approved amendments to Hog Island’s lease to permit the harvest and sale of all macroalgal species that naturally occur on aquaculture gear. Mr. Sawyer said this change took almost two years. “The approval would provide a beneficial use of this volunteer macroalgae after its removal that under current restrictions and regardless of the species requires wasteful disposal on land when gear is cleaned,” said Randy Lovell, the state aquaculture director with the Department of Fish and Wildlife. Hog Island will start harvesting seaweed this month, with plans to process the product in-house and integrate it into menus at its various restaurants. Mr. Sawyer said the company has been curious about the seaweed growing on their racks for decades, but because Pacific herring are known to spawn on macroalgae in Tomales Bay, it was illegal to harvest it. The company must periodically remove the seaweed from its equipment and compost it, so Mr. Sawyer said monitoring for herring spawn was already part of normal operations to ensure roe isn’t disturbed during algae removal. The conditions of the amended lease require that the company harvest between May 1 and Oct. 31 to avoid the spawning season, which takes place from November to April. Hog Island has been farming oysters in Tomales Bay since 1992, and the company excited to expand their operation to culture edible seaweed. The amended lease authorizes them to harvest four types of native edible seaweed growing on their gear: nori, ogo, dulse and sea lettuce. Mr. Sawyer views seaweed as a sustainable food source representative of his goal to achieve climate resiliency. “We take something that is a challenge, a problem or a waste product and we try to figure out how to eat it,” Mr. Sawyer said. Seaweed is known to remove carbon from the atmosphere, and environmental groups are looking at how farming it can address climate change. A 2021 Sierra Club report cited studies showing that wild seaweed can sequester around 173 million tons of carbon annually. The report notes, however, that for seaweed to sequester carbon, the plants must be sunk 1,000 meters deep, where they decay rather than returning to the surface to rejoin the carbon cycle. Other research has suggested that seaweed actually releases carbon. In Hog Island’s case, using seaweed that would otherwise be a waste product may be more sustainable than composting, which releases methane. Regardless, Mr. Sawyer said he’s excited to use a product that doesn’t require any food or freshwater to grow. He said seaweed represents the company’s goal to have a small carbon footprint and inspire people to eat food that connects them to place. “That’s our job: connecting people to where their food is coming from,” he said.