Why the Shakotan Method is Now Attracting Attention Nationwide: The Successful Cycle of "Region x Environment x Economy" Born from Sea Urchin Fishing (Part 1)

This September, the event was held at the 2025 Osaka-Kansai Expo "BLUE OCEAN DOME (ZERI JAPAN)".6th Japan Sustainable Seafood Awards (JSSA2025)At the awards ceremony, the winner in the leadership category was the "Sea Urchin Reproduction Cycle and Blue Carbon Creation Project Using the Shakotan Method of Circulating Seaweed Bed Creation."

In the sea off Shakotan Town in Hokkaido, known for its "Shakotan Blue," sea urchin fishermen have been working to restore seaweed beds for half a century, successfully increasing the number of sea urchins while reducing waste, and have developed a circulation model that will create blue carbon.The SHAKOTAN Sea Forest School, an organization that provides experiential education, has also been established.Now, a wave of innovation centered on sea urchin fishing is spreading from Shakotan Town to the rest of the country.

How did the activities initially initiated by fishermen themselves to address the problem of coastal barrenness develop into a model for recycling the region, the environment, and the economy? We spoke to Yoshio Mizutori, a fisheries technology instructor at the Agriculture, Forestry and Fisheries Division of Shakotan Town Hall, who has supported the project for 15 years.

In Part 1, we were joined by Sakurai Tamaro of Tsugikinomori Co., Ltd., which is involved in part in the Shakotan Method. He spoke about the company's research into sea urchin shell fertilizer, technological developments aimed at restoring seaweed beds, and the actual challenges faced in kelp farming.

[Project to create a regenerative seaweed bed using the Shakotan method for breeding sea urchins and creating blue carbon]
The "Shakotan Method" is a locally-led environmental restoration model that has been developed from the seaweed bed restoration activities (ocean forest creation) that began in 2009 by the "Amikuni Beautiful Sea Creation Council" and "Yobetsu Umi HUG Kumitai," which are made up of fishermen from Shakotan Town.
By restoring seaweed beds that were lost due to coastal denudation and linking the restored seaweed beds to the proliferation of sea urchins and the circulation of resources within the region, we are simultaneously achieving seaweed bed restoration, resource recovery, waste reduction, and the creation of blue carbon.Links

Half a century ago, fishermen rose to the challenge of changing ocean conditions: the origins of the "Shakotan Method"

-First, please tell us about the sea urchin fishery and the restoration of seaweed beds in Shakotan Town. What was the background that led the fishermen to take the initiative to start these activities?

Mizutori-sanShakotan Town's economy has relied on sea urchin fishing since herring fishing declined. The effects of coastal denudation began to appear in the 40s (around 1965), and sea urchin production continued to decline. In this situation, fishermen, who believe it is important to act as stakeholders themselves, without relying on local governments, have taken the lead in various initiatives.
First, they collected sea urchin larvae floating in the ocean (natural seedlings) and raised them in underwater cages while feeding them, a method known as "underwater intermediate rearing," and were the first in the world to successfully release them into the sea. Later, when natural seedling collection became difficult due to environmental changes, they switched to a method of artificially fertilizing sea urchins in test tubes, and built a "fisheries seedling production center" within the town to raise seedlings for release on land.,We have established a system to distribute the product to five nearby fishing cooperatives. We have also succeeded in using giant knotweed (a wild plant) as feed to replace kelp, which was in short supply.

These technologies were developed by the Hokkaido Fisheries Experimental Station, and Shakotan Town has developed the results into an actual business. The creation of seaweed beds is the result of fishermen themselves taking on the challenge for over half a century, while making use of the knowledge of research institutions, and the next generation of young fishermen have continued to improve the technology by inheriting the will of their predecessors.

Currently, the seaweed beds have regenerated, providing an abundant source of food for sea urchins.

- When did you first become involved in this initiative? Could you tell us about any particular events that led you to do so?

I was assigned to Yoichi Town as a fisheries industry improvement and extension officer in 1979. Around that time, I was in charge of research and testing for the sea urchin propagation project already underway in Shakotan Town, and at the time, fishermen were collecting sea urchin seedlings in the wild and cultivating them underwater, and I was also involved in providing guidance.

I was transferred in 1986 and travelled around Hokkaido, but when I was about to retire in 2016, Shakotan Town was looking for local revitalisation volunteers. I applied without hesitation, thinking I could once again put to use the knowledge and experience I had gained in Shakotan Town as a young man. So I returned to Shakotan once again, and this time I started working on creating seaweed beds to serve as food for sea urchins.

From "throwing away" to "growing" - How sea urchin shells are reborn as kelp fertilizer

-In 2019, you successfully developed kelp fertilizer using discarded sea urchin shells. Could you tell us how the idea for turning sea urchin shells into fertilizer came about and if you faced any administrative or technical difficulties?

Mizutori-san: On the administrative side, we had to overcome several hurdles. Sea urchin shells are considered "general waste," so they cannot be dumped into the ocean in their original state. Therefore, we first developed a method to harden the sea urchin shells with rubber and recycle them, and received approval from Shakotan Town to classify them as "valuable materials." We then created a test plan for creating sea urchin shell fertilizer and a test plan for verifying the fertilizer's effectiveness in natural fishing grounds. After obtaining the consent of the fishing cooperative and going through multiple procedures, including consultations with the Hokkaido Fisheries and Forestry Department and reporting to the Japan Coast Guard, we were finally able to obtain approval to carry out the tests. As a result, we were able to confirm the effectiveness of the fertilizer for three consecutive years from the first year, which became a major catalyst for expanding our business.

Making sea urchin shell fertilizer by hand

Sakurai-san: From a technical standpoint, the fundamental differences with fertilizers for terrestrial plants were a challenge. On land, microorganisms in the soil break down organic matter, making it easier for plants to absorb, but this process doesn't work in the ocean, so it's necessary to ensure that the "mineralized" nutrients are delivered to the places where they are needed. Also, while there are nutrients that cannot be supplied by sea urchin shell fertilizer alone, if all of them are applied at once, there is a risk that the nutrients will react with each other in the ocean, so we are continuing our research to optimize the type, location, amount, and condition of the nutrients to be applied.

- Under what circumstances is sea urchin shell fertilizer actually given to kelp? Please tell us about the situation on-site.

Mizutori-san: Several fishermen load the sea urchin shell fertilizer onto their boats, carry it to the desired sea area, and drop it into the sea. They then dive into the sea to collect and pile it up in the desired location. However, this work is highly dependent on the weather and sea conditions, and can be dangerous in rough seas.

The work to create the seaweed beds is mainly done in the middle of winter, from December to March of the following year, when the seawater temperature is only around 2-3°C. You won't get wet directly in the seawater, but the heat escapes quickly, so your body will become completely cold within 30 minutes. Despite this, the fishermen have continued to work in these harsh conditions for many years. I believe it is thanks to the fishermen's hard work that the lush seaweed beds we have today have been restored.

The seaweed bed creation activities are mainly carried out underwater during the harsh winter months, as shown in the photo.

Empathy attracts funding, which in turn leads to the next challenge – a chain of social recognition

-You were crowned the winner in the Leadership category of the 6th Japan Sustainable Seafood Awards. What was the reaction from the local community and other stakeholders?　　　

Mizutori-san: I have entered several contests up until now, but my goal is the same as this award. The work that fishermen are doing is truly wonderful, but the fishermen themselves only take it for granted. So I started entering contests in the hope that it would be an opportunity to raise awareness of their activities in society. I have presented the efforts of fishermen in each contest, and thankfully I have won prizes in all the contests I have entered so far.

As a result, they were featured in the media more often, and they began receiving requests to give lectures and inquiries from all over the country and in various places. Furthermore, when they applied to a program run by a private company that supports organizations working to protect the environment, they were able to receive financial support in recognition of their experience winning the contest. They used the funds to buy new diving equipment that had become outdated, and to help Sakurai and his friends with their "Tsugikinomori Co., Ltd." was able to launch the

At the award ceremony, Sakurai (left), Mizutori (center), and Koyama (right) received the trophy and performed the sea urchin pose in celebration.

Fishermen are the main players, and trust is born from sharing the space - Mizutori-san's communication style

-Please tell us about the things you have valued and the innovations you have made in your long-term collaboration with fishermen, government, and businesses.

Mizutori: Our activities are based on the autonomy of fishermen, and the fishing cooperative, town hall, and supporting companies are involved only "behind the scenes," handling the administrative procedures for the activity expenses provided by the government, providing technical guidance, and financial support. For this reason, what we value most is the "relationship of trust" between each other. Since I live close to the work site, I try to meet in person rather than talk by phone, and I accompany the work as much as possible, even in winter. I don't have to give instructions on site, but I am able to offer my own advice when something goes wrong. I think that by sharing the actual work site and our experiences in this way, we have been able to build the relationships of trust that we have built up to now.

Currently, Mizutori and his team are receiving requests from all over the country, including Kitakyushu and Rishiri Town, to share their knowledge of the "Shakotan Method" for the sake of regional development. They are also working on further plans, aiming not just to restore resources but also to create a town centered around sea urchin fishing.

Part2では、Ｊブルークレジット申請へのステップや認証後に受けた影響、SHAKOTAN海森学校の小山彩由里さんにも同席していただき、SHAKOTAN海森学校のコンセプトや今後の展望について伺います。

Written by: Ryoko Nakagawa

After working as a practical and research assistant for environmental education courses for citizens at a university, she became a freelancer in 2023. She is a staff member at Sakanayamarukama, a cooperative fish sales outlet that connects the local community. She is also a member of the Science Readings Research Association newsletter editorial department. She writes while being involved in science education and environmental education.