Fukuo Ota, former director of the Nori Research Laboratory in Japan, says the Kumamoto oyster has had “advantageous good luck.” The beach-hardened oyster was choked out of its native Japan by pollution, but history fortunately brought it to North America, where it continues to thrive. Now, market demand for the moon-coloured mollusc shows no sign of waning.
According to Ota, Kumamoto oysters had been farmed on the tidal flats of Japan’s Shiranui Sea since the second half of the 1860s, but they were not popular because the Japanese market preferred the larger, faster-growing Pacific oyster. The United States also preferred the Pacific oyster. They began importing Japanese Pacific seeds in the 1890s, when oysters native to the west coast of the US were being destroyed by waste from farms and sawmills. Colder North American waters made spawning difficult, keeping American markets dependent on imported Japanese seed until World War II abruptly halted Japanese imports to the US and Canada.
In October 1945, two months after the bombing of Hiroshima and Nagasaki, General Douglas MacArthur asked the Japanese government to export 80,000 boxes of oyster seeds to the United States. This marked the end of the wartime embargo on Japanese goods. Unfortunately, lack of manpower and low oyster stocks threatened Japan’s ability to fill the order. Seeds from the little-known Kumamoto oyster were used to help fill the shipments.
The first test shipment of 30 boxes of Kumamoto oyster seeds arrived in Seattle, Washington, in 1946. Within eight months, Kumamoto oysters were produced. Their small, plump white body and fruity aroma attracted the attention of American oyster farmers and connoisseurs. Soon the Kumamoto became one of the top three Japanese oysters on the Chicago Stock Exchange, and was known as the Western Gem. Full-scale US production of the oyster followed in the 1960s.
It is fortunate that the Kumamoto was exported to the US when it was, because from 1932 to 1968, the Chisso chemical factory pumped mercury into the Kumamoto’s Japanese habitat, near Minimata, Japan. Mercury poisoning was named Minimata disease after this disaster. It killed hundreds of people, and wiped out the Kumamoto oyster in Japan.
Today, even though it still isn’t grown in Japan, strict regulations and careful monitoring ensure the health of Kumamoto oysters grown in North America. At Joe Fortes Seafood and Chop House, in Vancouver, British Columbia, more Kumamotos are sold than almost any other oyster. Scott Pratico, executive chef at Joe Fortes, estimates that 35,000 to 40,000 Kumamoto oysters are sold annually at the restaurant. Unlike its flat-shelled Pacific cousin, the Kumamoto is a delicate but meaty, deep cupped, beach-hardened oyster. This makes it one of the more expensive oysters on the market. Because the Kumamoto is a small, slow-growing oyster, taking up to five years to reach its typical two-inch length, cultivating it demands careful attention.
Typically, oyster seeds hang from racks on the ends of weighted nylon ropes. The racks are lowered into the sea to keep them at the right temperature. Oysters grown this way are thin, brittle, and irregular, and sell at a lower price. On the other hand, beach-hardened oysters are put in cages in a tidal zone, where they are constantly exposed to beating waves. This creates a smoother, thicker shell and a cleaner shucked oyster.
Kumamotos are best served on the half-shell with only a splash of vinegar or a touch of lemon. Champagne, or white wines with a citrus component, such as Sauvignon Blancs or spicier Gewürztraminers, are the perfect accompaniment to the Kumamoto’s delicate watermelon flavour. According to Scott Pratico, Kumamotos are the “Cadillac of oysters”
Not only is it in a class of its own among oyster connoisseurs, but the Kumamoto has also survived one of the greatest threats to our existence: pollution. Its survival is a reminder that what we savour and enjoy in life must be nurtured. As Fukuo Ota put it, “It’s wrong to think that humans are superior to oysters.”