Japan’s oyster farmers face ruin amid rising sea temperatures: ‘dying en masse’
Japan’s oyster farms hit by 90% deaths due to rising sea temperatures and high salinity, threatening the country’s top production area

In some coastal areas surrounding the Seto Inland Sea in western Japan – an area that accounts for more than three quarters of Japan’s farmed oyster production – around 90 per cent of cultivated oysters are dead.
“I’ve never experienced this in my whole career,” said Tatsuya Morio, who has farmed oysters for more than 20 years.
Shoichi Yokouchi, an official in the Hiroshima area, which borders the Seto Inland Sea, said he suspected “high water temperatures, together with other factors, are the culprit of oysters dying en masse”.
This year average water temperatures along Hiroshima’s coast from July to October – an important period for oyster cultivation – were 1.5 to 1.9 degrees Celsius higher than the 1991-2020 average, according to prefecture data.
Sea temperatures are rising globally due to climate change.