【Nigiri sushi: Kai】
What is Hokkigai?
The official name of this shellfish is ubagai, but at the markets, it’s called hokkigai. Hokkigai doesn’t grow very quickly and it takes 3 to 10 years for one to grow to the 7 or 8 cm required to be sold at the market. They have a long lifespan of 30 years or longer. Hokkigai lives in the sandy areas in the Tohoku region and further north. They can be found from the Hokkaido coast to the Choshi coast in Chiba.
It wasn’t originally used as an Edomae sushi topping. Tokyo sushi restaurants started using Hokkigai relatively recently, as the sushi toppings that can be found in Tokyo Bay started waning. Hokkigai was used in sushi in the Tohoku and Hokkaido regions before it was used in Tokyo. It can even be considered a staple sushi topping in Tohoku and Hokkaido.
What does Hokkigai (Sakhalin surf clam) nigiri sushi taste like?
Leg portions are eaten as sushi toppings. Immersion in hot water turns the dark tip into a pale purple color and sweetens the taste. Hokkigai is often compared to Akagai and though it’s not as fragrant, Hokkigai is sweeter and more flavorful. There are two types of Hokkigai. One is an expensive black Hokkigai and the other is a more reasonably priced brown Hokkigai. Needless to say, the black one is used as a sushi ingredient.
It contains relatively high amounts of protein, lipids and carbohydrates. The carbohydrate level is especially high which makes it seem sweet. The meat has a satisfying texture with a nice crunch when you bite into it, making it a popular topping.
Incidentally, at conveyor belt sushi (kaiten-zushi) and similar restaurants, a cheaper, related species known as Surf clam is used. Most of these are boiled in North America, especially Canada, and delivered frozen, so the taste is lacking compared to the real Hokkigai. However, the lean leg portion is refreshing and also pleasant to look at so it is highly esteemed in the foodservice industry.
Also called Japanese surf clam.
This clam has a long lifespan, which is said to be over 30 years. It reaches maturity in the third year, so it’s not very different from other shellfish. The best time for Sakhalin surf clam is the winter season, when the glycogen (polysaccharide) content increases, increasing the umami flavor.
List of Shellfish (Kai)
Hokkaido Aomori Iwate