From Iki to the World: Regenerating Seaweed with Artificial Reefs "Reef Balls" to Revive Abundant Fishing Grounds (Part 1)

Various initiatives for carbon neutrality are underway in Japan. Among them, "blue carbon"—the process of carbon sequestration by marine ecosystems—is gaining significant attention. As a measure that simultaneously addresses global warming and preserves marine biodiversity, interest is growing in Japan, a nation surrounded by the sea.

Transformation SHOWCASE focuses on one such blue carbon initiative: the artificial reef "Reef Ball," which holds great potential. We bring you interviews with those working to promote it. In our first article, we spoke with Mr. Osamu Ikeda, President of Asahi Tech Co., Ltd. in Nagasaki Prefecture, who brought the Reef Ball, developed in the USA, to Japan.Working closely with Mr. Ikeda to promote this technology is Hisanori Tayama, Representative Director of the General Incorporated Association Marine Habitat Iki. For our second article, we focus on Mr. Tayama's activities, including conducting Reef Ball demonstration experiments in his hometown of Iki City, where he was born and raised. Takashi Fuji of Dentsu Inc. interviews him.

His Desire to Contribute Locally and His Encounter with the Leaf Ball

Fuji: What prompted you, Mr. Tayama, to become actively involved with Leaf Ball?

Tayama: I'm turning 32 this year, but when I entered my 30th year, I felt a strong urge: "I must contribute something to my hometown of Iki." At the time, I was working for a cleaning supplies company in Isahaya City, Nagasaki Prefecture. Having personally joined the Isahaya Junior Chamber International in 2017 and participated in various community activities there, my desire to "do something for my own hometown" suddenly intensified.

I realized that if I didn't change my environment, I couldn't change myself. So, without thinking about the future at all, I decided on just one thing: "I'm quitting my job" (laughs).I wanted to contribute fully to the company before leaving, so I was doing cold calling more aggressively than ever. That's when I happened to visit Asahi Tech, run by President Ikeda. When I told President Ikeda I was from Iki, he said, "I just came from talking with the mayor of Iki," and told me about Leaf Ball. I thought this was amazing and decided that very day to help spread Leaf Ball.

Fuji: You decided that very day you met Mr. Ikeda?

Tayama: Yes. Mr. Ikeda and I hit it off, and we talked about many things over drinks that evening. Hearing about how Leaf Ball could be used to restore Japan's seas, I felt I had to tell the people of Iki about it as soon as possible. Iki has traditionally thrived on coastal fishing, with shellfish like sea urchins, abalone, and turban shells—which grow by feeding on seaweed—being vital marine resources.But in Iki, coastal erosion has caused seaweed to stop growing, leading to the decline of these organisms. Fishermen's incomes have plummeted as a result. I wanted to find a way to address this situation.

So, while continuing my day job, I started spending weekends traveling around Iki to spread the word about Reef Balls. I first consulted my father and uncle back home, seeking someone willing to host a Reef Ball trial. I organized meetings for local fishermen and invited President Ikeda to explain the concept, gradually advancing the initiative.

Success in seaweed cultivation through the Leaf Ball demonstration experiment

Fuji: How did you secure collaborators for the experiment?

Tayama: I was explaining Leaf Ball around April, which is when the seaweed Akamoku releases its spores. If we couldn't conduct the Leaf Ball experiment by April, we'd have to wait another year until April. That's why I absolutely wanted to decide on the experiment timing for this period.I went around asking for their cooperation in the experiment, explaining that we would cover the costs and provide the Leaf Balls. However, since I was only on Iki Island on weekends, I couldn't find enough time for detailed discussions, and I struggled to gain their understanding.

Then, one Sunday, I suffered a major injury—a ruptured Achilles tendon—right here on Iki. It sounds strange to say this, but thanks to the injury, I didn't have to return to Isahaya the following Monday.Thinking, "Well, since I'm stuck on Iki anyway," I visited a certain fisheries cooperative with my father, using crutches, and explained the Leaf Ball project. They understood, and granted permission to install Leaf Balls at a site where they were already conducting seaweed bed restoration experiments. Thanks to that, we were able to start the Leaf Ball experiment within April.

Fuji: What a dramatic turn of events (laughs). What were the results of that experiment?

Tayama: Within a year, seaweed had grown magnificently, completely covering the Reef Balls. Since they were carefully enclosed with nets to prevent fish from eating them, we achieved results without any damage from grazing. I want to continue this experiment steadily, letting as many people as possible know about the power of Reef Balls and spreading the word. Right now, we're still in the experimental phase, gradually increasing the number of people who understand.

At other experimental sites, the installed sea area didn't match the Reef Ball size, and some were washed away by typhoons. That could lead people to conclude, "Reef Balls just don't work," and conducting experiments isn't easy. Currently, experiments are being conducted not only in Iki but also in neighboring Tsushima City. We aim to establish solid role models in both Iki and Tsushima.

Mr. Tayama, who promotes Reef Balls in his hometown of Iki, says that steady efforts and demonstration experiments are what gradually increase the number of people who understand the value. In the second part, we'll cover Mr. Tayama's determination to pursue this as a business and report on the demonstration experiments.

• From Iki to the World: Regenerating Seaweed with Artificial Reefs "Reef Balls" to Revive Abundant Fishing Grounds (Part 2)