Kazunoko (Herring Roe) and Komochi Kombu (Herring Roe on Kelp) Sushi

Kazunoko / Komochi Konbu / Herring Roe / Herring Roe on Kelp

Fish Roe

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Order Clupeiformes, Family Clupeidae, Genus Clupea

Kazunoko is herring eggs or ovaries that have been salted or dried, while komochi konbu (herring roe on kelp) is kelp on which herring have laid their eggs. Domestic herring have declined sharply, so imported products account for most of the kazunoko and herring roe on kelp.

Both kazunoko and komochi konbu are processed products of herring eggs and ovaries. Kazunoko is made by taking the eggs or ovaries from female herring and salting or drying them; the yellow eggs are connected together in an elongated shape about 10 centimeters long. Komochi konbu is salted kelp onto which herring have laid their eggs. Rather than relying on natural spawning, the mainstream method is to drive egg-bearing herring into an area with hanging kelp so they lay their eggs on the kelp. It is used for herring-roe-on-kelp sushi and osechi (New Year's dishes), but because domestic production is very small, it is mainly imported from countries such as Canada. It is a luxurious sushi topping with the rich flavor of kazunoko combined with the umami of kelp. Herring inhabit cold-water regions all over the world, including Japan. Long ago they were not expensive, but today domestic herring from areas such as Hokkaido have declined sharply. Fresh herring is still distributed, but most processed products such as kazunoko, komochi konbu, and migaki nishin (dried herring) are imported from Canada, Russia, China, Scotland, Alaska, and elsewhere. At conveyor-belt sushi restaurants, products made by re-binding crumbled loose eggs of Atlantic herring or processed capelin roe are often used.

Texture and Umami That Vary by Region

Herring can be broadly divided into Pacific and Atlantic types. Atlantic herring mainly lay their eggs on rocky areas, so the eggs are less sticky and the kazunoko is softer. Pacific herring, on the other hand, lay their eggs on kelp and the like, so the eggs are characteristically very sticky. Also, even within the Pacific, herring from colder regions such as Russia are fattier, so their roe comes apart more easily and has a softer texture. Kazunoko from the waters around Hokkaido has moderate fat and umami and a crisp, crunchy texture, making it prized as delicious, though it is very expensive.

Roe-Bearing Herring Sushi?

Have you heard of the "roe-bearing herring sushi" often seen overseas?
This is different from real roe-bearing herring (herring carrying eggs in their bellies) or herring-roe-on-kelp sushi. It is capelin roe that has been colored and flavored and attached to vinegar-cured herring. The eggs are usually yellow, but some are green or red.

With no fishy smell, the sweet-and-sour taste of the vinegar-cured herring and the flashy, colorful appearance appeal to foreigners, and it can be found with fairly high probability at overseas sushi restaurants, especially in Southeast Asia.