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Sanriku Fukkō NP, Iwate / Miyagi
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After 2011, Tokura farmers cut raft numbers to one-third and spaced them 40 m apart. Oysters reached market size in about 1 year, not 2–3, and the fishery earned Japan’s first ASC certification in 2016.
A low-sitting raft can signal a heavy crop: oysters hang beneath it on ropes, and their growing weight pulls the frame close to the water. Higher rafts may be newly set or recently harvested.
Nearly all Sanriku aquaculture gear was swept away in 2011, including an estimated 4,000 timber rafts. In Hirota Bay, forestry supplied rare 10.5 m cedar poles, and crews built 8 rafts in a single day.
Oyster larvae settle on strings of scallop shells, which serve as tiny nurseries. Miyagi growers use about 70–80 shells per collector, then expose the young oysters to air and tides to leave hardier ones.
In 1924, a method of hanging shells to collect young oysters was devised. Miyagi’s history records that seed oysters began to be exported around the world following this innovation.
Unlike farmed fish, raft-raised oysters are not given feed; they live on nutrients naturally carried by the sea. Ropes simply hold them beneath the rafts, where they grow in the bay’s water.
Sanriku’s ria inlets create calm bays suited to oyster farming, yet narrow inlets can also amplify tsunami height and destructive power. The same coastline shelters livelihoods and demands respect.
