Sonoma Coast low tide reveals previously buried treasures

Seaweed harvesting is something I’d never seriously contemplated, akin to collecting quenelle spoons or harvesting gulls’ eggs: niche and unnecessary. But integral to excitedly looking forward to each season is harvesting what’s available at its peak moment, understanding when that occurs in the calendar, finding the secret spots and rich patches, and fully appreciating the gifts Nature bestows. Seaweed fits these criteria, but in truth, my experience was limited to fish wrapped in nori sheets, and the often muculent salads of wakame, hijiki and red dulse in middling Japanese restaurants, or occasionally in the homes of hippie friends who slip it into their cooking without much mention.

Ethnocentric appetence aside, seaweed’s briny jolt never fails to reset my palate with an explosion of savory umami, one of the five basic tastes, while utterly nourishing the body. More nutritious than land-based plants and high in protein, seaweeds are one of the richest sources of minerals we ingest vegetally, with varying amounts of magnesium, calcium for teeth and bones, sodium, potassium, iodine for thyroid function, iron to mule oxygen to the cells, zinc, vitamin A to support eyes, B1, B2, B6, niacin, vitamin C for the immune system, pantothenic acid, and folic acid. There are trace amounts of vitamin B12 in seaweed, which seldom occurs in land vegetables, and many varieties contain anti-microbial agents to help fight disease. The miso icing on this kelp cake? Seaweed is low-cal and virtually fat-free. And with this morning’s rare, negative low tide following a full moon, as predicted by the National Oceanic and Atmospheric Administration (NOAA), the Pacific is a veritable pick-your-own seaweed farm of slimy red, green and brown jewels.

First daylight filtered wearily through a chilly Sonoma Coast fog, its thick silence an amplifier for the bark of a seal or the exhale of a migrating whale. Wrapped in heavy layers of flannel and an old pair of battered boots, I treated myself to a mug of steaming jasmine green tea and a cigarette of smoldering green bud, hands down my favorite breakfast. But it would be a light meal, as I would require my wits for the day ahead; seaweed harvesting is not for the faint of focus or weak-kneed.

Peering over the cliff to the rocky beach below calls to mind a tenant of permaculture: life is amplified on the edge, where there is a confluence of valuable and diverse microcosms, where plants and animals work together within a sustainable system rather than as single elements. There is no more of an edge than where land meets sea, and where seaweed is a source of life for many different species.

Rich in vitamins and minerals essential for brain development, seaweeds are thought to have played a key role in humankind’s evolution. Archaeologists and marine ecologists Jon M. Erlandson, Michael H. Graham, Bruce J. Bourque, Debra Corbett, James A. Estes and Robert S. Steneck surmise, in an article entitled ‘The Kelp Highway Hypothesis: Marine Ecology, the Coastal Migration Theory, and the Peopling of the Americas’, (The Journal of Island and Coastal Archaeology), kelp forests may have played a role in facilitating the movement of maritime peoples from Asia to the Americas near the end of the Pleistocene, some 14,000 years ago. Then, as now, extensive and highly productive kelp forest ecosystems of the Pacific Rim support seafood and resources relied upon by coastal peoples.

Indeed, the ocean’s edge vibrates with the different tribes of people who have harvested there before me. But to reach the edge, we had to scramble down a gargantuan cliff to the beach. Not having a mountain goat’s footing or cocksuredness, I find it a slog to reach some of the more remote beaches on California’s northern coast, and at times my hike was on all fours, petrified of a tumble.

Seaweed is an alga, a title bestowed on marine plants living in Earth’s fresh and salt waters. Unlike land-based plants, seaweed does not have true roots, stems, leaves, flowers, or a vascular system. Like plants, however, seaweed utilizes chlorophyll for photosynthesis. The three varieties of seaweed (red, green and brown) are determined by their pigments, which dictate how close to surface sunlight each need to live in order to thrive.

Bladderwrack seaweed

The smallest seaweeds are indiscernible to the eye, while the most grand, the underwater forests of kelp, are anchored dozens of feet down on the ocean’s floor, and their leaves, known as blades, play host to an entire world of other algae, fish, crustaceans, bivalves, seabirds, and marine mammals, such as otters and seals. Forests of kelp and other seaweeds grow off California’s rough and rocky coastline, the turbidity adding oxygen to the clear, nutrient-rich waters, which encourages growth. These algae are harvested for use in cosmetics, animal feed, pharmaceuticals and fertilizers, and their compounds extracted to thicken foods such as ice creams and salad dressings.

Seaweed consumption is a dietary staple for many cultures, its farming life-sustaining for centuries. The oceans cover more than 70% of our planet, and as we move into the uncertain future of a changing environment with fewer and fewer natural resources, and more than seven billion mouths to feed, seaweed will inevitably play a more central role on our tables. Remarkably, seaweed cultivation requires neither fertilizer nor fresh water. It’s worth noting here that nearly half of all the fresh water used in the United States goes to raising animals for food (The Food Revolution by John Robbins), and more than 2,400 gallons of water are needed to produce 1 pound of meat (Water Inputs in California Food Production by Marcia Kreith).

The green is good slogan applies to more than just tea and pot. NOAA writes that many seaweeds, including kelp, thrive in the acidifying oceans, which distressingly describes our waters. Seaweeds take up CO2 and nutrients from their environment, improving water quality as they grow by drawing down levels of dissolved acid along with nitrogen and phosphorus. Seaweeds also give off oxygen, which can help with dead zones. NOAA concludes that the combination may result in seaweed farms acting as protective “halos” that mitigate acidification and pollution locally while creating habitat for marine species. Further studies by The World Bank conclude seaweed farming helpful to preserving coral reefs, while research in the Philippines found it may play a role in increasing production of herbivorous fish and shellfish.

Seaweed harvesting

Seaweed cultivation is laborious and done mostly by hand, with seedlings planted on lines submerged in the ocean. David Maxwell Braun of National Geographic Society writes in Ocean Views that more than 25 million metric tons of seaweeds are farmed globally each year, offering sustainable employment in emerging economies, as well as providing new opportunities for fisherman trolling increasingly depleted seas. China produces over half of the world’s seaweed harvest, and countries such Indonesia, Republic of Korea, Philippines, Japan, Ireland and Canada have thriving seaweed economies. The global seaweed haul is worth more than $6 billion, exceeding the world’s value of lemon and lime crops.

But our aims were far more modest on this gray morning, focused on recreational harvest for our table, which in California means a daily bag limit of 10 pounds wet weight of sea algae taken from the Pacific anywhere except Marine Protected Areas (MPA). The negative low tide, which is relative to mean sea level, occurs maybe 20 times annually, leaving tide pools exposed and massive boulders bare of sea, their glimmering shoulders dripping with rubbery aquatic gems.

Once feet were firmly planted on the beach far below, we glanced up to see dozens of monarch butterflies gleefully blanketing the purple phalluses of pride of Madiera plants rooting the cliffs. Heart rate returning to normal, we joined the lithe and agile Heidi Herrmann, proprietor of Strong Arm Farm in Sonoma ( Heidi forages for sea vegetables in season, selling a variety of dried seaweeds around the country. She also leads informed expeditions, anointing the unenlightened with sea tangles and saltwater.

Heidi Herrmann of Strong Arm Farm harvesting seaweed

Seaweeds are comprised of different structures. If the aquatic plant is rooted to rocks or the seabed or other seaweeds, they attach with a connector called a holdfast, which anchors the plant, but does not feed it. Rather, the algae absorb food through their blades, many only one cell thick. These cell walls are rich in sugars to help them bend and not break in swells. Seaweeds not anchored merely float, often spreading their life-giving properties around the world.

Algae grow in response to day length, with the quality and quantity of light needed similar to that of land plants. Many seaweeds are perennial, dying back in the winter months to bloom again from the same holdfast in early summer into early autumn. This window is peak time to harvest seaweed, while it’s thick and ripe and nutrient dense, and before reproduction coats the blades in spores and eggs, or becomes bedraggled by winter storms.

We waded out calf-deep into the rocky outcroppings, salt spray from the surf licking lips and fluttering eyelashes. The moon waning, I tiptoed through the tide pools, not wanting to disturb the vibrant pink starfish, their fat arms left mercilessly exposed by the low tide. Once again on all fours, I struggled across the rocks, made slick and slimy from the various seaweeds and grasses. Focusing my harvesting knife on the sides of rocks, away from possible sneaker waves, I methodically filled my basket. The sun peeked out from behind the curtain of fog, a wizard changing the colors of the frothy waters from gray-blue to green, turquoise, and aquamarine, like the veined stone in a ring from Arizona.

We cut the fronds halfway down and well above the holdfast as instructed, only harvesting those seaweeds in abundance. Unlike foraging for mushrooms, there are no toxic North American seaweeds found in the Pacific, but some are more delectable than others. Harvesting, however, must be done in clean ocean waters (freshwater seaweed is often poisonous) and far from the possibility of pollution. When ocean waters are contaminated, the seaweed turns neon colors and should be completely avoided.

As pelicans soared in formation, an army of bills riding the thermals, we harvested from the intertidal zone, the area above water at low tide and underwater at high tide. But more interestingly, we also foraged the subtidal zone, the area usually submerged and only exposed during extreme low tides following a full moon. The subtidal zone is home to a great diversity of plants and animals, such as Kombu (Laminaria), a silky perennial seaweed with an umami taste that thickens soups and helps make beans more digestible. It’s also credited with reducing blood cholesterol and hypertension. On the same rocks, we also harvested Wakame (Undaria pinnatifida), an annual kelp loaded with calcium and used in seaweed salads.

Grapestone or Turkish washcloth (Mastocarpus papillatus) is a perennial red alga found on rocks in the mid-to-high intertidal area. When dried, its rough surface is used to exfoliate skin in the tub. We were introduced to the unfortunately named Bladder Chain Kelp (Stephanocystis osmundacea), a perennial brown alga found on rocks in low intertidal to subtidal areas. The bladders are pneumatocysts, which provide buoyancy to the seaweed so it’s able to float close to surface sunlight. The bladders pop in the mouth like a salty kid’s candy and make a dynamite pickle.

Grapestone or Turkish Washcloth seaweed

The prolific Sea Lettuce (Ulva species), which aptly reflects its bland name, is an annual green alga residing on rocks, mollusks, wood, and other algae throughout intertidal and subtidal areas. It can be eaten fresh with rice wine vinegar or dried with sesame seeds.

Finally, we harvested several wet pounds of Nori (Porphyra), the kale of the ocean, and one of the world’s more valuable aquaculture crops. An annual red algae, nori can be found on rocks and human-made structures throughout the intertidal and upper subtidal area. One of the most delicious seaweeds, it can be toasted and added to foods like a salty spice.

At Heidi’s recommendation, we also plucked several Feather Boas (Egregia menziesii) from the beach, adding them to our haul to be wrapped around the base of our citrus trees, adding valuable minerals to the soils as they decompose, a Liberace adornment for the Kaffir lime and Meyer lemon.

Feather Boa seaweed

Straightening from my hunched pose, caked with sand and flecks of algae, sneakers long removed, I gazed up at the mountains covered in conifer and cow. In the swelling ocean before us were the bobbing, shiny pates of seals, the pencil legs of Great Blue Herons and Snowy Egrets, an occasional spout from a humpback whale. Dozens of black ducks, wings scraping waves now glittering like a mobster’s moll, cautioned us our tide was turning. In the thunderous white noise of wind and waves, peace abounds; Nature’s promise of renewal kept.

Drying seaweed

Soon after arriving home, the back patio resembled Naples, strewn with all shapes and sizes and colors of seaweed drying on clotheslines and absconded oven and cake racks. We’d rinsed the seaweeds repeatedly, liberating a shocking quantity of sand, grit, crabs, and large seabugs. Roughly 90% water, seaweed dries quickly; within the space of a day in the hot sun, the dried seaweed was ready for storage in airtight glass jars to line pantry shelves, reminding us of our morning forage and how, ultimately, seaweed just may save the world.

Recipe for Soba Dashi

Bemoaning my lack of familiarity cooking with seaweed to Chef Curtis Di Fede of Napa’s Miminashi, he assured me it was a pantry item I’d soon be reaching for to flavor most everything.

Surely, he’d know. A native of Napa and a graduate of both the London and Paris campuses of Le Cordon Bleu culinary school, Chef Di Fede has worked with some of the most talented chefs in the food world. He opened the highly acclaimed Italian dining room Oenotri, before opening the nearby Miminashi, which focuses on ramen, yakitori, local meats, fish and seasonal produce. Japan was long a source of fascination and inspiration for Curtis, from his days as a culinary extern at London’s Wagamama, to his time working with chef Hiro Sone at Terra in St. Helena, to his culinary tours of the island.

“The first time I went to Japan, I fell in love with the country and the cuisine,” he said. “Even during the years I spent focused on Italian cuisine, Japan was always in the back of my mind and I began to see this common ground between the two countries: a dedication to purity and simplicity.”

His kitchen makes their own pickles, kimchi and broths, and smokes fish, seaweed and meat over a wood hearth. But it was actually his cred as a Northern California boy who fishes, dives for abalone, and forages for seafood and seaweed that impressed me most. His knowledge is deep.

Curtis suggested using our dried kombu to make dashi, a broth made with seaweed or bonito, and used as the base for miso soup, clear broth, noodle broth, and many kinds of simmering liquids. Soba dashi has the addition of daikon, soy and mirin in the broth. Dashi is perfect for a warming breakfast, energizing lunch or light supper.

Curtis began by lightly smoking several pieces of the reconstituted seaweed, which can be done at home by hanging the kombu over coals in a fireplace or smoker for a couple of hours. If the time or tools are unavailable, unsmoked dried kombu works brilliantly. Curtis emphasized cooking with the very best ingredients one could locate, which include using filtered water to make the broth.

The broth is meant to be served cooled if the noodles are chilled. If the noodles are not chilled and served warm, they’ll stick. It can also be served warm with warm noodles.


-One gallon filtered water

-2 ounces dried kombu

-1–2 tablespoons of mirin (a Japanese sweet rice wine)

-1–2 tablespoons of soy sauce (90% soy, 10% wheat)

-One bundle of soba noodles per person

-One bunch Tokyo Negi onion (found at Asian markets) the green parts chopped into wisps. A perennial allium native to Siberia and Northwestern China, the onion is grown primarily in Japan. Chopped scallion is a fine substitute.

-Daikon radish

-Spice to taste with either Ichimi (ground red chili pepper); or Shichi-mi tōgarashi (a premixed blend of red chili pepper, Sansho Japanese pepper, roasted orange peel, black sesame seed, white sesame seed, hemp seed, ground ginger, ground nori seaweed and poppy seed); or Sancho Japanese green peppercorn leaf powder.

Bring one gallon of filtered water to boil, then turn off the heat, and add two ounces of dried kombu to the water, allowing it to steep for twenty minutes. Take care not to boil the seaweed, as it’s fragile and will fall apart, losing valuable nutrients. Strain the broth through fine mesh, setting aside the seaweed. Taste the broth. The pale blush of green is bright and vibrant, with a gentle nod to a mermaid.

Add 1–2 tablespoons each of Mirin (for sweetness) and soy sauce (for depth). Taste and adjust seasoning accordingly. Cool the broth.

Bring a pot of tap water to boil and cook soba noodles 4–5 minutes. Soba is the Japanese name for buckwheat, usually referring to thin noodles made from buckwheat flour, or a combination of buckwheat and wheat flours.

Cool noodles in a quick ice bath. Pluck the soba noodles with three fingers, making a small nest and place it in the center of each bowl. A secret known by Japanese chefs, these little nests create the perfect mouthful.

Fill the bowls with the cooled broth.

On a ginger grater, microplane or Saikai Japanese Copper Grater, shave the daikon radish and scrape the goodness into each soup bowl.

Scatter finely chopped Tokyo Negi or scallion onto the soup and finish with a sprinkle of spice.

The kombu can be cut into small strips and eaten with the soup, or can be re-dried (and re-smoked) to be used again in a niban dashi, or second dashi. But the ichi dashi, or first dashi, is the ichi ban, or best. Slurp the soup, not just as a compliment to the chef, but to aerate it to taste every bit of its umami and ocean nuance.

culinary art and antiques maven. sommelier. hunter-gatherer. fisherman. cook. writer. traveler. wanderer.