Japanese pearl industry rocked by 20 million oyster die-off

While the cause of the die-off is unclear, oyster producers have started taking steps to minimize the damage.

It takes three to four years to produce a cultured pearl, which the oysters make by depositing layers of nacre around a tiny bead inserted into their shells.

Ehime, the largest producer of Akoya pearl oysters in Japan, noticed the die-off in late July. At the end of September, the young shellfish cultured there stood at about 11 million, nearly 70 percent below average.

The die-off was the first in Japan since 1996, according to Takeshi Miura, a professor at Ehime University’s Faculty of Agriculture.

Though the exact cause has not been identified, Miura said, “It occurred as a result of multiple factors,” including underfeeding and overcrowded environments.

The cost to Ehime reached ¥300 million at the end of September, and the loss is expected to dent production of cultured pearls, which are a huge income source for its economy.

Pearl production by value in Ehime fell to about ¥5.2 billion in fiscal 2019 from ¥6.1 billion in fiscal 2018, mainly due to the economic slowdown in China, a major export destination. In fiscal 2020 the figure is expected to sink to around ¥4 billion.