High Temperatures, Low Rainfall Zap Oyster Output in West Japan

In Japan’s top oyster-producing prefecture, Hiroshima, 80% to 90% of farmed oysters have been dead at the time of landing since the start of this season’s shipments in mid-October, Chinami Takeichi reported for Mainichi Japan.

The Hiroshima Prefectural Fisheries and Marine Technology Center believes this year’s record-breaking heat and low rainfall weakened oysters through prolonged exposure to high water temperatures and elevated salinity. (Photo: Hyogo Tourism)

When oysters die, their shells open and the flesh falls out, resulting in harvests consisting largely of empty shells.

While the proportion of affected oysters varies by area, regions along the Seto Inland Sea in western Japan — including Okayama, Hyogo, Tokushima, Kagawa and Ehime prefectures — are reporting damage.

The Hiroshima Prefectural Fisheries and Marine Technology Center believes this year’s record-breaking heat and low rainfall weakened oysters through prolonged exposure to high water temperatures and elevated salinity.

Another expert said weather conditions, including wind direction, may have caused oxygen-depleted water from the seabed to rise into farming areas, leading to oxygen shortages.

Many oyster-related festivals have been canceled. Some municipalities that offered raw oysters as return gifts for “hometown tax” donations have suspended those programs.

According to a survey by Tokyo Shoko Research Ltd.’s Hiroshima branch, the impact on aquaculture and related businesses in the prefecture is estimated at about 30 billion yen (roughly $193 million).