UWAJIMA, EHIME PREF. – The mysterious death of over 20 million Akoya pearl oysters in Ehime, Mie and other prefectures this summer is expected to hobble pearl production next year and beyond.
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.
In fiscal 2021 or later, when the young shellfish that died this year were to be harvested, production is expected to fall further.
Badly hit by the die-off, the Shimonada Fishery Cooperative in Uwajima is hiking output of young shellfish. The co-op and the prefecture plan to supply 8.5 million shellfish to pearl farmers by the end of the month.
Given the size of the loss, the pearl farmers in Ehime are likely to be forced to temporarily scale back production.
“As many of the farmers are elderly, they may find it difficult to resume production after a one-year hiatus,” Hiroyasu Takebe, head of the cooperative, said glumly.