TOKYO // Only small fries with that? McDonald’s in Japan is limiting the serving size of fries as stocks of potatoes run short due to labour disruptions on the US West Coast.

McDonald’s began rationing its fries on Wednesday morning. It said prolonged labour negotiations with port workers on the West Coast have made it difficult to meet demand despite an emergency airlift of 1,000 tons of potatoes and an extra shipment from the US East Coast by sea.

December shipments are expected to be just over half the normal level.

Frozen french fries — ready for the deep-fryer — are a leading US export.

Japanese consume more than 300,000 tons of french fries a year, mostly at fast-food restaurants, and largely made from imports of frozen, processed potatoes from America. But demand is rising as convenience stores are increasingly also selling fries.

McDonald’s has 3,100 outlets in Japan. It cut prices for set meals on Wednesday to compensate for only including small fries.

Customers expressed disappointment as they left a downtown Tokyo branch of McDonald’s.

“The kids like the bigger sizes, like [medium] and [large], so it’s a shame,” said businessman Kenichi Kuniki, 45.

Japan’s locally grown potatoes are mostly eaten fresh, rather than as fries. Production has been declining for years, however, and Japan enforces strict limits on where and how fresh potatoes are imported.

The US’ powerful dockworkers union and multinational shipping lines have been negotiating a new contract for about 20,000 West Coast workers. In the meantime, labour disruptions have slowed shipments and driven costs higher.

Japan is also facing a shortage of butter that has prompted grocery stores to limit shoppers to one or two packages apiece. That shortage stems from declining domestic production plus trade barriers and other restrictions that limit imports.

The restrictions are meant to ensure that local farmers who face high costs here are protected from foreign competition, to ensure Japan maintains some self-sufficiency in its food supply. But supply doesn’t always meet demand.

“It’s a bit sad,” said Hiroko Inomata, 34, clutching the bag of small fries and a teriyaki burger that she bought for lunch. “But it is so that everyone can have some.”

* Associated Press