A death rate of up to 90%, attributed to warming seas, is threatening the trade in Hiroshima prefecture, which produces most of the country’s farmed oysters A death rate of up to 90%, attributed to warming seas, is threatening the trade in Hiroshima prefecture, which produces most of the country’s farmed oysters Chefs prepare oysters at the Kure oyster festival. This year, local businesses and consumers say the shellfish have been scarce and smaller than usual Oyster farming in Mitsuguchi Bay