【Reading】うばがい

【English Name】Sakhalin surf clam

Spisula sachalinensis (ubagai), a bivalve of the family Mactridae, is widely called "hokkigai" (surf clam) in the fisheries trade and is also abbreviated to "hokki." In the Ainu language, distinctive names such as "pokusei" and "tsutsureppu" survive.

The shell has an outline resembling a slightly triangular oval; the shell skin is white in the juvenile stage, turns yellow as a young clam, and deepens to yellowish-brown or blackish-brown as an adult. Its distribution centers on the Japanese coast north of the Kashima Sea and Toyama Prefecture, and Hokkaido, extending to the waters of Sakhalin, the Kuril Islands, and the northern Korean Peninsula, with its habitat being sandy bottoms from the intertidal zone to depths of about 20 m.

It grows slowly, taking 4 to 6 years to reach the harvest size of 7 to 8 cm shell length, and individuals living over 30 years have been reported. The main fishing method is the beam trawl, a mechanism that blows high-pressure water at the seabed to lift the clams out of the sand and recovers them with a net. Tomakomai, Bekkai, Nemuro, and Kushiro (Hokkaido) and Misawa (Aomori Prefecture) are the main production areas.

In sushi, nigiri is the representative way to eat it, and it also suits a variety of preparations such as sashimi, butter-grilling, frying, and vinegared dishes. Along the Pacific coast of Hokkaido and the Tohoku region, "hokki meshi," rice cooked with surf clam, has taken root as a local dish. Nutritionally, it is rich in amino acids such as glycine and alanine. Note that much of the surf clam imported into Japan as a frozen product is the closely related species Mactromeris polynyma (naga-ubagai), landed off the Atlantic coast of Canada and heat-treated.