Back in the 1970s oyster growers were looking to produce a high quality oyster for sales in summer, when the Miyagi oyster naturally goes into reproduction. The Miyagi meats become filled with gonadal material that makes the meat very creamy and soft. Once the oyster releases this gonadal material to make baby oysters, the adult oyster is ‘spent’ and the meat is thin and watery. This is not very appetizing.
So oyster seed producers looked around and realized that the Kumamoto oyster (Crassostrea sikam), another Japanese oyster, spawned in the winter. The Kumamoto is a delicious oyster but it grows VERY slowly. The hatcheries attempted to cross breed Miyagi and Kumamoto, hoping to get a fast growing, Kumamoto flavored, winter spawning oyster. What resulted was a slow growing, summer spawning, Miyagi tasting oyster. At this point the growers told the hatcheries that they would plant a smaller amount of pure Kumamoto oysters to be able to offer a greater variety of oysters to the public. By the way, scientists have developed methods to produce Miyagi oyster seeds that grow into oysters that do not spawn. These are called triploids and are essentially a seedless oyster, similar in concept to seedless watermelons, grapes, etc. I use this Miyagi oyster through the summer months.
Kumamoto oysters have a rich taste that feels like eating real butter for the first time in your life. I primarily use Kumamoto oysters from producers in Puget Sound, Willapa Bay, and occasionally from Humboldt Bay.
Notice the tiger paw appearance of this oyster and how full the meat fills the shell.
Look at the small size of these fully grown Kumamoto oysters.
Kumamoto oysters are native to the southern islands of Japan. Miyagi oysters are found in the northern part of Japan, north of Tokyo