Ishigakigai is a shellfish found from Kashimanada northward, Hokkaido, from the Kuril Islands to the Aleutian Islands and even on the west coast of North America. It lives off of plankton in the shallow sandy mud bottoms of the sea at depths of about 50 meters.
Aquaculture in Hirota Bay, Iwate Prefecture, has been successful and it started to appear at the Tsukiji Fish Market starting in about 2008, distributed as Ishigakigai. According to brokers, someone in the business at Tsukiji Fish Market misheard “Ishikage” as “Ishigaki” and the name stuck in the market. While Torigai meat looks black, Ishigakigai looks whiter, so it is also called “Shirotorigai”. The official name is “Ezoishikagegai”.
It starts to become common at the market when the Japanese rainy season ends, at the beginning of summer every year, which is around the end of the Torigai season. It then disappears from the market at the end of summer. A number of sushi restaurants start using it as a substitute for Torigai all at the same time, so Ishigakigai nigiri sushi suddenly started appearing on menus. Frankly, it is somewhat conservative as a nigiri topping but is known for the crunchy texture when biting into it. It also has strong sweetness and umami, which goes exquisitely with Shari. The sushi chef slaps the meat in his hand directly before serving to stiffen it–a way to increase the crunchy texture characteristic of shellfish. Naturally this texture is evidence of its freshness.
As the season of availability is short and the production sites are limited, Ishigakigai often fetches a high price. Those up for sale at the Toyosu Market go for $2 to $4 each. Wild-caught Ishigakigai is rarely found on the market, but when they are, the price is double that of the farmed version.
A relative of the Torigai, the Ishigakigai is rich in amino acids such as taurine, glycine and arginine. It is also resilient and can live for days, even outside its shell.
We hope this information will be helpful.
Revision date: September 7, 2021
It goes without saying, that each type of fish has its very own scientific name. However, in places like the Toyosu Fish Market, there are seafoods that end up sharing a name.
The official Japanese name of ama ebi (sweet shrimp) is “Hokkoku Akaebi” (scientific name: Pandaluseous Makarov). In Japan, ama ebi lives naturally along the Sea of Japan coast and the coasts of Hokkaido, and the ama ebi sold at Toyosu market is caught from Toyama prefecture and northward to Hokkaido and southward. When made into nigiri sushi, it is harmonious with the acidity of the vinegared rice and the thick sweetness is irresistible. It really lives up to its “sweet” name.
However, what dominates the Toyosu Market is frozen shrimp of the same pandalidae family, called “Honhokkoku Akaebi” (scientific name: pandalus borealis kroyer) from Iceland and Greenland. This is distributed as “Ama ebi” at the market, but strictly speaking it is a different type of shrimp. As far as appearance goes, it is impossible to tell the difference and they say that even the flavor is the same.
The majority of ama ebi used at conveyor belt sushi is produced in Greenland and imported to Japan through China. The reason for this import circumvention is that the processing to turn the shrimp into ready-made sushi toppings is done using inexpensive labor in China. The frozen ama ebi is thawed in China, processed (head, shell, etc., are removed) and then frozen again. Of course, this process diminishes the freshness of the fish. Preservatives are used to help prevent this. For example, pigment fixing agents are used in order to reduce discoloration from fading. Furthermore, acidity regulators and antioxidants are used to prevent changes in the quality and color of the meat. Ama ebi is stored in packs of 50, imported en masse to Japan, and can be used for sushi or sashimi immediately upon thawing.
As this ama ebi caught in the North Atlantic Ocean is considerably cheaper than domestic ama ebi, the reality is that conveyor belt sushi wouldn’t survive in Japan without these imports.
We hope this information will be helpful.
Revision date: September 1, 2021