Oyster Crisis: Warming Seas Devour Hiroshima's Harvest

A severe oyster die-off, with mortality rates reaching up to 90%, is devastating Hiroshima prefecture, Japan's primary oyster farming region. Rising sea temperatures and the intensely hot summer of 2025, which reduced oxygen and food availability, are identified as the main culprits by experts.

This ecological crisis is profoundly impacting the local economy, affecting everything from oyster festivals to the availability of oysters for restaurants and consumers. Fishers like Taketoshi Niina report that 80% of their harvest is dead or of poor quality, leading to significant financial losses and threatening the viability of businesses.

The problem extends to other prefectures bordering the Seto Inland Sea, but Hiroshima, responsible for nearly two-thirds of Japan's farmed oysters, is most severely affected. The fisheries agency has implemented support measures, including five-year government loans at virtually zero interest, to aid the struggling aquaculture industry.

Scientists warn that such mass die-offs could become more frequent due to climate change. Potential mitigation strategies include relocating oyster rafts to cooler waters or suspending them at greater depths, though the long-term future of the industry remains uncertain for families who have farmed oysters for generations.