Farm-raised oysters in the Seto Inland Sea in western Japan are dying en masse, leaving restaurants and retailers feeling uneasy as the high season for various oyster dishes such as nabe hot pots has arrived.

Wholesale prices for oysters have soared due to the extreme shortage, forcing businesses to pass on the higher costs to customers.

※Our business is tough even after we hiked prices,§ Masao Iwami, the owner of a Japanese restaurant in Tokyo, said.

Maximum wholesale prices for peeled oysters rose by almost 10% in November from a year before to nearly ?6,500 ($41.7) per kilogram at the Toyosu fish market in the Japanese capital.

Iwami has increased the price of a fried oyster lunch set meal by more than ?100 from about ?1,300. Still, ※It won*t pay off,§ he said. He has reduced the number of oyster set meals to around five a day.

※It can*t be helped,§ a male customer, 58, said while complaining that ※lower prices would be better.§

Colowide, a restaurant chain operator, sources oysters mainly from Hiroshima Prefecture facing the Seto Inland Sea.

While the company has secured oysters for this year, prospects for next year*s supplies are uncertain. ※We*re groping in the dark,§ a Colowide official said.

Supermarket chain Aeon Retail has reduced the net weight of oysters as ingredients while keeping their sales price unchanged.

※We*ll work to maintain stable oyster supplies by procuring oysters from several production sites,§ said an official at Ito-Yokado, another supermarket chain.