Revitalizing Japan’s coastal ecosystems through satoumi, science & school

Japan is a maritime nation whose history, culture and way of life are shaped by the sea. An archipelago of more than 14,000 islands on the western edge of the Pacific Ocean, it is also one of the world’s top five economies based on GDP. Its wealth is inextricably linked to the ocean through trade, fisheries, energy and the emerging “blue economy”. Japan is making significant strides in the latter, including blue carbon projects, such as planting sea grass beds to capture carbon, rehabilitating coastal ecosystems, and committing to protect 30% of its marine territory by 2030.

This shift is being driven in part by a concerted effort toward ocean advocacy and education, led by high profile public figures, including Sakana-kun, a renowned Japanese ichthyologist [fish specialist], professor and artist. His spirit of curiosity and hands-on exploration is at the heart of his work, and his tireless energy and enthusiasm have inspired millions of children across Japan. Through his SD Blue Earth (SDBE) General Incorporated Association, he leads the Sakana-kun Exploration Team, an organization that encourages young people to fall in love with the ocean through hands-on activities, workshops and teaching moments designed to foster a lifelong connection with the marine environment. At the same time, Japan is reviving a more reciprocal relationship with the ocean by combining conservation-oriented science with revitalized reverence for the natural world. 

Like developed economies everywhere, growth during the industrial era came at great cost to Japan—especially after World War II. The country’s coastal waters have been severely impacted by overfishing, development, pollution and climate change. But up until the 19th century, Japan’s relationship with the ocean had been much more reciprocal, built on deeply embedded traditions and religious and cultural practices. For centuries, the country’s prosperity depended largely on an intuitive, practical understanding of coastal ecosystems—when to harvest, when to wait, and how to intervene without knocking things out of kilter.

Coastal communities consciously developed sustainable, integrated systems of marine management, like imposing seasonal fishing restrictions, farming seaweed and constructing artificial reefs of stone and bamboo, and harvesting in rotation. They also held tenure over local marine ecosystems, which prevented overexploitation.

From a cosmological standpoint, this emphasis on balance and reciprocity between humans and nature was rooted in Shintoism—a spiritual tradition indigenous to Japan that imbues nature with living spirits, known as kami, and whose roots date back 2,000 years.

Rapid industrialization fractured this relationship, especially in the decades following World War II. By the 1970s, one tract of ocean in particular embodied this rupture more than anywhere else in Japan: the Seto Inland Sea. Bounded by Japan’s three main islands—Honshu, Shikoku and Kyushu—it became synonymous with pollution and ecological decline in the form of red tides, fish kills and oxygen-starved bays. But today, Seto tells a very different story—an ongoing journey of recovery that revives the Shinto principle of harmony with nature in combination with cutting-edge environmental science, recalibrating the relationship between coastal communities and marine ecosystems, based on a principle known as satoumi.

Unlike the more widely known concept of Satoyama, which refers to sustainably managed rural landscapes, satoumi focuses on coastal waters shaped by long-term human interaction, like the Seto Inland Sea. Here, the premise is not preserving marine ecosystems by excluding humans, but enhancing them through positive interactions. Both marine biodiversity and human communities can prosper where there is a reciprocal relationship between the two.

Sakana-kun is an enthusiastic proponent of satoumi and of community-based conservation efforts. For him, it means connecting directly with marine ecosystems—understanding how they operate, integrating with them, and even imagining things from a fish’s perspective, as he puts it. 

So how is satoumi playing out in the Seto Inland Sea? Hinase is a small fishing community in Okayama Prefecture. Vast beds of eel grass, Zostera marina, once thrived in its shallow, sheltered coastal waters, functioning as nurseries for smaller fish. Generations of artisanal fishers had understood that healthy seagrass meant healthy catches.

Coastal development, dredging and pollution saw the eel grass beds decline from 1,460 acres in the 1940s to just 30 acres by the mid-1980s, leading to the near collapse of the local fishery. Faced with extinction, the community decided to take matters into its own hands—literally. With the help of marine scientists, fishers began manually replanting eel grass, gathering seeds, mapping currents and learning how factors from light to sediment levels to turbidity affected their survival.

They developed a sophisticated circular system of aquaculture, where oyster rafts mitigated wave action and filtered water, creating optimal conditions for eel grass to flourish. The eel grass itself filtered out pathogens, providing a beneficial environment for the oysters. Once harvested, oyster shells that would otherwise have been discarded were spread in thick layers on the seabed, stabilizing the mud and making it easier for the eel grass to take root. This symbiosis, set in motion by human hands, saw Hinase’s eel grass beds bounce back to around 620 acres by 2015. Today, Hinase is Japan’s third largest center for oyster farming.

The story of Hinase and of the Seto Inland Sea as a whole is one of gradual recovery driven by community action, enlightened environmental policy and cultural revival in the form of active stewardship and intergenerational education. And not only the education that takes place in classrooms, but the kind of direct contact with marine ecosystems that can ignite children’s enthusiasm to find out about the mysteries of the ocean.

The Exploration Team activities led by Sakana-kun are featured in the first episode of the Prada Re-Nylon 2026 campaign, created by National Geographic CreativeWorks, Prada’s storytelling partner for the fourth year, and starring actor Benedict Cumberbatch and Elisabetta Zavoli—photojournalist, National Geographic Explorer and SEA BEYONDer, Goodwill Ambassador of the project.

The dialogue with the sea is a central element of SEA BEYOND, the Prada Group project conducted in partnership with UNESCO to raise awareness of sustainability and ocean preservation on a global scale, to create the next generation of ocean custodians.