Ryan Okano didn’t harvest limu as a young man in Pepeekeo, about eight miles north of Hilo on Hawaii island. In fact, he didn’t know much about Hawaii’s brand of seaweed beyond its flavorful role in poke.

That all changed when he attended graduate school at the University of Hawaii and studied limu under the tutelage of the late and beloved Isabella Aiona Abbott, a revered Native Hawaiian botany professor who single-handedly discovered more than 200 species of seaweed and whose work was so prolific she became known as the First Lady of Limu.

“I would come back with limu and she would ask me where I got it from. I’d say Black Point, and she’d say, ‘What is that place? You tell me the Hawaiian name,’” Okano recalls, getting emotional talking about his mentor. “I learned to appreciate and respect the culture.”

Okano, now 50 with a doctorate in botany and a job as program manager of ecosystem protection with the state’s Division of Aquatic Resources, has a passion for Hawaii’s limu. He harvests the macroalgae when he’s diving, taking only what he needs and figuring out different ways to use it. He likes to chop up limu eleele and toss it into a bowl of saimin.

He made lau lau with chunks of palani, also known as eyestripe surgeonfish, that he caught and limu akiaki — instead of taro and pork — and cooked them in an imu; the hearty seaweed is known as imu limu and turned into something like noodles in the lau lau. And he’s starting make his own poi, using taro he grows, using an immersion blender and adding limu kohu to it.

“For me, I like being able to grow my own food, to catch my own food,” he says. “It gives me a sense of freedom. I don’t have to depend on other people or depend on stores.”

Okano is part of the generation that didn’t grow up picking limu at the beach on weekends or spending hours cleaning and preparing the limu to eat. I’m part of that generation, too. And it seems like, with the scarcity of native limu growing wild in our oceans, this next generation — including my son — may not learn that practice, either.

But there are projects aimed at changing that.

At Waikalua Loko Ia, a 12-acre fishpond in Kaneohe Bay owned and operated by the nonprofit Pacific American Foundation, researchers are growing various species of native limu in an integrated multi-trophic aquaculture system, which is a system where two or more organisms are farmed together.

In this case, they’re growing limu with amaama, or striped mullet, supplied by the Oceanic Institute and, soon, loli, or sea cucumbers. The goal is to supply limu to people who live in the area to eat and to community groups like the Waimanalo Limu Hui to outplant in nearshore environments.

So far, the fishpond has given out more than 100 pounds of limu huluhuluwaena, eleele and lepe-o-hina to outplant.

The Waimanalo Limu Hui has been holding monthly limu planting in Waimanalo Bay since 2017. Its goal is to regrow the once-abundant limu manauea — aka ogo — and other native seaweed in the bay. It started because a kupuna from Waimanalo wanted to be able to see limu thrive again in the bay, to be able to share it with her grandchildren.

So what happened to all the limu in the first place?

Flip through Heather J. Fortner’s “The Limu Eater: A Cookbook of Hawaiian Seaweed” — originally printed by Hawaii Sea Grant in 1978 and rereleased in 2022 in honor of Year of the Limu — and you’ll see photos of seaweed piled on Hawaii shorelines and locals gathering limu during low tide on coral flats.

There are even photos of native limu being sold in local markets alondside opihi and tako in the ‘70s. A chart shows the price of limu in 1976: limu kohu, salted and in containers, sold between $4.50 to $9 a pound, and limu manaeua prepared in kimchi was $1.99 a pound.

Back then you could find at least eight different types of native limu in markets; today, you’ll likely find only limu manauea, which today is farmed commercially by Royal Hawaiian Sea Farms on Hawaii island and Olakai Hawaii on Oahu.

According to an article published in the journal Botanica Marina in 2019, about 79,366 pounds of fresh limu were gathered by families to eat in 1976; another 104,366 pounds of various Hawaiian limu were collected and sold in markets that same year.

Old-timers wax nostalgic about the mounds of limu on the beach in Ewa; that’s all gone. And you’ll find way more gorilla ogo, an invasive algae first found in the islands in 1971, in Maunalua Bay than native limu.

The reasons for the decline in wild limu range from overharvesting — the harvest of any Gracilaria limu is regulated by the state — to competition from non-native algae. Nutrient-rich (aka polluted) groundwater isn’t helping, either; it promotes the growth of invasive algae and there aren’t enough herbivorous fish to maintain balance in the ecosystem, Okano explains.

Bringing back limu — in the ocean and on tables — can have a significant impact on Hawaii’s food security. Marine macroalgae are critical components of our ocean ecosystems — limu are nutrient recyclers and food for herbivorous fish, invertebrates and green sea turtles — and it has cultural significance. Some limu were used for medicinal purposes — limu lipoa was used to treat mouth sores in children — and others in hula and other cultural practices.

If the limu is gone, this part of Hawaiian culture will be gone, too.

“The practice is being lost, the knowledge is being lost, and that’s part of what we’re trying to do: to preserve the practice, to preserve the knowledge,” Okano says. “To me, it’s kind of like hula. It’s what makes Hawaii Hawaii.”

“Hawaii Grown” is funded in part by grants from the Stupski Foundation, Ulupono Fund at the Hawaii Community Foundation and the Frost Family Foundation.