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Sanriku Fukkō NP, Miyagi
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Tachi-amamo, one of Shizugawa Bay’s seagrasses, can grow to 7 m tall from the seabed—an underwater giant listed as Vulnerable in Japan and described as the world’s longest seagrass.
Each winter, black brant arrive from Arctic breeding grounds and feed on seagrass in Shizugawa Bay. Research found their energy-rich eelgrass feeding spots are limited patches—a small but important dining room in a vast bay.
A local seagrass once had a practical second life: Minamisanriku’s plan records that fishers dried tough sugamo leaves and made them into waist skirts. Sugamo is one of the four seagrasses found in Shizugawa Bay.
Shizugawa Bay has four seagrasses—amamo, tachi-amamo, suge-amamo and sugamo—alongside kelp, arame and sargassum beds. This 5,793-hectare marine wetland joined the Ramsar list in 2018.
Amamo is a flowering plant, not seaweed: it produces small white flowers underwater in early summer and forms seeds. It can also spread by underground stems, so the meadow grows both from seed and from its roots.
The 2011 tsunami churned Shizugawa Bay’s sandy seafloor and swept away much of its eelgrass. The meadows began returning in the years that followed—a recovery later documented in the bay’s environmental records.
A restoration partnership launched in 2023 brought together Minamisanriku, Shizugawa fishers, researchers and companies to work on restoring both amamo and giant tachi-amamo, while sharing what they learn with the community.
The Kuroshio, Oyashio and Tsugaru currents all influence Shizugawa Bay. More than 200 seaweed and seagrass species and over 700 marine species have been recorded there—an astonishingly busy neighborhood beneath the surface.
