# Kazunoko

Kazunoko (数の子), in Japanese cuisine, are the eggs or the ovaries (egg skeins) of the Pacific herring (Japanese: kazunoko nishin) that have been salted or dried.

## Overview

Kazunoko is a product processed by removing the roe sacs (or "egg skeins") from female herrings intact in its shape, then preserving by sun-drying (hoshi kazunoko) or by salting or brining (shio kazunoko). The eggs are individually tiny, but together they form oblong clusters measuring approximately 8 centimetres (3.1 in) long and 3 centimetres (1.2 in) wide.
The kazunoko, symbolizing fertility, has been a staple of the osechi assortment of food for the New Year.　From around 1955 domestic herring catches fell sharply for Japan (mostly only caught around Hokkaido in the north), and nearly all supplies now depend on imports, mostly from the Pacific coasts of Canada and Alaska but also including the use of Atlantic herring. A technique for bleaching into uniform gold color was established, and the lucrative commodity earned the nickname of "yellow dia[mond]".
A subtype is the komochi kombu (子持ち昆布) or "spawn on kelp", which are Pacific herring eggs laid on various seaweed regarded as "kelp", now harvested mostly in British Columbia, Canada.
Historically, the oldest records of kazunoko in Japan date to the 15th and 16th centuries, served e.g. to Toyotomi Hideyoshi, during the spring season (Cf. § history below). The harvest of kazunoko from herring occur in the spring, but the dried product was being sold as a New Year's season item by the end of the 17th century. The history of its production overlaps with the history of producing dried migaki nishin [ja] for food, that came into full force around Kyōho (1716–36) with the availability of salt up north, and later the production of kasu or fishmeal rom early 19th century onwards.
The traditional harvesting of span on kelp by natives, including the use of hemlock branches for the purpose, are surveyed (Cf. § First Nations food source).
There are various socio-economic issues which concerns Pacific herring fishing overall, with regards to native fishing grounds being overtaken by modern mass commercialized production, But aspects particular to herring roe have been taken up below, e.g., the "kazukono ledger" to record the debts to be worked off by Ainu women. Also, North American herring fishing since the 1960s have has principally been aimed at harvesting the kazunoko for the Japanese market, waste/sustainability issues have been raised (cf. also Pacific herring § Roe fishery).

## Etymology

Both "kazunoko" and the archaic kadonoko occur in medieval or post-medieval writings and also written in Sinitic forms such as 鯟子, 鰊子, 鯡子, 鯑. or 䱧.
There are two or three etymological hypotheses that have been presented.
The derivation of kazunoko as the corrupted form of kado no ko, where kado is the old name for herring, is the generally accepted etymology according to some sources. This explanation is already attested in the Honchō shokkan [ja] published 1697. The entry under 鯟 kado in the Honchō shokkan clarifies the pronunciation of the character by the supply the phonetic reading as kato/kado (加登). It goes on to state that kazunoko (數子) has been phonetically written as ka-to-no-ko (加登乃古/加豆乃古). Even beyond the Edo Period, kado or kado iwashi still survives in dialect as local name for herring, even though nishin is the standard Japanese term.
The alternate etymological theory holds that kazunoko may well have derived from the literal verbatim meaning of 'child of numbers/numerousness', as had been suggested by Ōishi Chibiki [ja]'s Gengentei (言元梯) (1830/1834), and in fact, early usage writes the word as kazunoko (cf. § History below).
A third theory is discernible in the Edo Period essay Kiyū shōran [ja] (1830), which mentions that kazunoko was known by the alias kazukazu (かずかず) in contemporary women's language [ja] (onna kotoba), juxtaposed with the information that Muromachi period literature wrote of kozukozu (cod organ) as a New Year's dish. The connection between these two (similarly sounding) terms as synonymous (cognates?) are made in the Daigenkai [ja] dictionary.
There is speculation that Japanese kado must have derived from some Ainu word, but the known Ainu word for "herring" is heroki, (with variant spellings), and linguist Minoru Umegaki [ja] rejects this hypothesis.

## Japanese cuisine

Kazunoko marketed in Japan fall into these groups: hoshi kazunoko (干し数の子, 'dried herring roe'), shio kazunoko (塩数の子, lit. 'salt herring roe') and ajitsuke kazunoko (味付け数の子, lit. 'flavored herring roe').
Only limited supplies of the dried are now manufactured. The flavored type using Atlantic roe have been characterized as "secondary market", or even "substitute" products by American sources (but see further discussion below).
Kazunoko a standard part of New Year's fare called osechi, and are soy-sauce marinaded to keep for days (or made into kasuzuke).
Kitaōji Rosanjin, eminent gourmet connoisseur and restaurateur, commented in his time that although raw or salted kazunoko was becoming available, dried kazunoko reconstituted with water was the best, taste-wise (essay, loosely translated "Kazunoko is about eating the sound", 1930). While it is typically served topped with bonito flakes and splashed with soy sauce, Rosanjin insists on not letting the sauce seep in too much; his rule also opposes introducing other flavors such as miso or sakekasu, or pickling/marinating in soy sauce. However, there is also the opposite opinion, that the dried kazunoko is "more delicious after letting the soy sauce soak in well"".
Matsumaezuke is a soy-pickled dish that typically contains chunks of kazunoko in the mix of julienned dried squid (surume) and kombu seaweed. The addition of kazunoko allegedly only dates back to 1929, as an arrangement on what was originally a squid and kelp recipe.
The kazunoko is known for its texture or mouthfeel (crunchiness), the sound of biting into it described onomatopoeically as puchi puchi (cf. § Quality assessment by region) The Atlantic herring is deemed overall to have less crunchiness, so that they are largely consigned to becoming "flavored kazunoko" or a side dish (sōzai, equivalent to okazu). But Atlantic herring of some regions are made into the normal salted/brined variety (Cf. § Quality assessment by region).
The "komochi kombu" (aka kazunoko kombu) or "spawn on kelp" may be eaten on its own as a delicacy, or sliced up and used for sushi. and can command very high prices.

### Quality assessment by region

Of the diminished Japanese herring catch in Hokkaido, only a minuscule fraction now gets used for exploiting the eggs. According to one comparative study, the Canada Pacific herring roe taken in British Columbia, or Alaskan roe harvested in Sitka or Kah Shakes Cove produce quality eggs, suited for salted (or even dried).
Atlantic herring roe according to some sources are considered to be limper. But they are not always being downgraded as "flavored kazunoko" quality, and some are considered fit for making into regular salted/brined kazunoko, particularly roes from Baltic and North Sea area fish. Thus the Baltic group (subspecies C. harengus menbrus) has been rated best among Atlantic species fit to be made into salted (shio kazunoko), as are the roes originating in Scotland (Shetlands), Ireland, and Netherlands have been Other than texture, viscosity (ability to bind together into a lump) is another criterion for quality, and eggs that fall apart easily is a disqualifying factor for manufacturing whole salted kazunoko.
The Atlantic herring, with the crunchiness (hagotae) somewhat wanting. And one study does concur the Atlantic types do not solidify as firmly, and are mostly processed as flavored kazunoko, but generalizations aside, the same study assesses the Baltic Sea Baltic catches (subspecies C. harengus menbrus) to be superlative in Atlantic, and these do get used for making salted kazunoko, even though the individual egg size is smaller (half by weight) according to other studies.

### Nutritional value

A basic nutritional value and energy assessment has been made in a study of Edo Period foods, including kazunoko.
While kazunoko is high in cholesterol (as are fish roe in general), it also contains a high concentration of EPA and DHA fatty acids, known to reduce cholesterol levels. While herring is classed as an aozakana (lit. 'blue fish') consisting of fish considered good sources of omega-3 fatty acids, herring (or 'blue fish' in general) had been blacklisted as food to avoid for gout (gouty arthritis) patients due to purine content, though recent studies and guideline have muted the warning against 'blue fish', unless it is the dried or semi-dried himono type. But even though fish roe are generally to be avoided by gout sufferers, kazunoko is listed as containing very low concentrations of purine (<50 mg per 100g). Similar dieteary cautions and recommendations apply to those diagnosed with hyperuricemia, which is considered a preliminary stage towards gout.$^{:1}$

## History

In Japan, the custom of serving kazunoko for the New Year's season may date back to the Muromachi Period, according to some sources. As aforementioned, there is the record of kozukozu (不来々々) being served for the New Year according to the mid-Muromachi Period Diary of Ninagawa Chikamoto (親元日記, Chikamoto nikki) (Kanshō 6/1465), but this was actually cod's innards, probably the male cod's milt; howbeit, kozukozu has been treated as an alias for kazunoko by some dictionaries. The kazunoko (かずの子) is attested to be the offspring(eggs) of the kado fish in an even earlier source Satsujōshū (撮壌集) (1454) which names it alongside the kurukuru (alias of kozukozu).
The name kazunoko also appears on the menus in later Muromachi period and Azuchi–Momoyama period documents.
It was offered as menu item during a visit by the Ashikaga shogunate to Echizen Province in 1568 (Eiroku 11), recorded in Asakura-tei onariki (朝倉亭御成記).
Later Toyotomi Hideyoshi was offered kazunoko on the menu when he was hosted by the Maeda clan of Kaga Province, as recorded in the Kaga no chūnagon dono e onari no koto (加賀之中納言殿江御成之事) of the 4th lunar month of Bunroku 3 ( 1594).

### Edo Period

In the Edo Period, documents from the Kanbun era (1661–1673) for instance indicate shipments of dried herring and kazunoko occurring out of Ezo (Hokkaido).
The work Honchō shokkan (本朝食鑑) (published 1697) attests that kazunoko was an item that circulated in the market during the lunar 12th and 1st month.
The repertoire of herring products was limited until salt became readily available locally and products such as migaki nishin [ja] appeared, around the Kyōho] Period. Production of the migaki nishin and kazunoko (for food), as well as dried milt, gills (and guts) for fertilizer are depicted in an 18th-century series of folding screen pictures entitled Esashi-hama nishin no zu (江指浜鰊之図, 'Picture of herring[s] at Esashi beach').　Damaged (crumbled) kazunoko pieces were also relegated to becoming fertilizer material. Note that kasu or shimekasu (herring meal squeezed of oil) was not manufactured at this time, and would not commence until several decades later in the early 19th century, or perhaps earlier.
Matsumae clan records from Kyōho 2/1717 show that kazunoko was being loaded on ships from various provinces, while the dried milt and herring for fertilizer headed particularly to the Chūgoku region provinces and Ōmi Province.
The kazunoko was all part of the fertilizer trade according to some commentators, though other sources regard the kazunoko as food item. The document also records that yose kazunoko (寄鰊子) (eggs that were pried apart, re-gathered and molded into rectangles, cf. below) was being sent as kenjōhin [ja] or tribute to the Shogunate. The kazunoko during the Tokugawa period were packed in straw tawara [ja] (俵), then at Osaka unpacked and re-boxed.
A Kyōho 2/1719 memorandum from the hamayaku ("beach official") also lists kazunoko and yose kazunko as tribute items to the bakufu (shogunate). yosekazunoko (寄数子), aka yoseko (寄せ子) is described as a kazunoko broken up into individual eggs, with stringy tissue removed, then molded into a square shape (or disc-shape), and cut up into smaller rectangular logs to be used. Other sources say yose kazunoko were shaped into squares.
The kazunoko became the byproduct of a much more intensely traded commodity once herring meal or ニシン粕/〆粕 (nishin kasu/shimekasu, lit 'herring-pressed residue') began to be manufactured in the 19th century according to one study though some commentators place the date earlier by some decades, as afore stated.
This herring meal (oil residue) grew to become increasingly sought-after as a replacement solution to the price-hiking, diminishing supplies of hoshika (干鰯, dried sardine, actually anchovy) fertilizer.
The 8th Tokugawa shogun Yoshimune, known for his Kyōhō Reforms promoting frugality, allegedly devised a 3-item sake snacks (三つ肴, mitsu zakana) menu: kazunoko, gomame [ja] (aka tazukuri, an anchovy dish), and black soybeans [ja] to accompany New Year's sake drinking, so that the common folk and the shogun alike could celebrate the holiday season in similar fashion.
The salted herring roe (鹽數子（塩数の子, shio kazunoko) was available by the 19th century, and recorded as a tribute item (for the 12th month) to the shogunate either in the Bunka (1804–1818) or Tenpō (1831–1845) eras, supplied by the Matsumae and also Ise-Kameyama Domain. Anecdotal evidence of its being a prized delicacy is that the Ichiriki Chaya restaurant of Kyoto charged 2 shu gold (minted 1824, 1 shu = 1/16 ryō) per dish.

## Processing methods

Domestically caught kazunoko in Japan were principally the dried type, and though some roe were eaten fresh locally, most were roe harvested and sundried as byproducts of dried herring (migaki nishin) . The "salted" (or brined) type did not overtake the supply until 1954–1955, just when the domestic herring fishery collapsed.

### Dried

There are different grades of dried kazunoko. According to Taishō era government literature, production of hokawari nishin (外割り鰊, subtype of migaki, with the spine removed) entailed the removal of hararago (鮞, roe skein) which were then cleansed in a pool of water, sundried on top of straw mats, then graded for size and quality.
However older (formerly conventional) methods dried the roe without rinsing, so that the adhering blood tissues would cause darkening of the roe as it dried, leading to the method being called kokkan hō (黒乾法, 'black-drying method'). This method was long abandoned by the Showa era. There were subsequently the "modified" and "semi-modified" methods (kairyōhō, hankairyōhō) . Although both involved dousing the roe in saltwater (with water changes) until the blood leeched out sufficiently, the former method was significantly labor-intensive, since it prescribed using precisely measured concentrations of saltwater (4%), and arranging the roe individually. The semi-modified method substituted seawater, and dumping the cleansed roe onto a su (bamboo-braided drip trays).。

### Salted

Salted or shio kazunoko was already mentioned above as tribute to the shogunate, though some seafood processors claim manufacture did not begin until the 1900s (Meiji 30s). According to sources around this time (Meiji 27=1894) a shio kazunoko was made by first "flushing" the roe by submerging in water (changing water several times), then salting the roe in a tub. However in later years, the method was to cure the roe in saline solution or saturated saline solution.
The "salted" kazunoko intensified in the 1960s and thereafter and according to statistics, the primary fishing ground around Hokkaido had little catch beyond 1954, and from that point on, dried kazunoko began to disappear, ceding the market share to salted types.
While still often referred to as "salted" or "salt preserved" by Japanese writers, the product of modern processing methods is probably better characterized as "brined". In fact, sodium chloride solution is used in three steps: first, the egg-bearing (gravid) herring itself is brined in order to stiffen the roe for extraction, second, washed in weak solution, and third, cured in saturated brine.

#### Bleaching

After domestic Japanese herring could not be procured, there were ex-Soviet (Russian) frozen herring being imported during the transitional period, and in the narrow margin of time c. 1960 shio kazunoko developed a reputation for gamy odor and inferior quality to dried. However, in 1963, a seafood processing company based in Rumoi, Hokkaido established a technique of bleaching the kazunoko using hydrogen peroxide The technique also effectively mitigated odor, according to lab results, and the color turned uniformly golden yellow, earning the moniker "yellow dia[mond]" turning it into a high-priced commodity.
Bleaching is still used in the manufacture of kazunoko. Although excess residue was already being removed from product using enzymes, concern levels rose when studies found that for rats deficient in the specific enzyme catalase, it posed a minor carcinogen risk. In 1980, the Ministry of Health and Welfare did not ban, but mandated zero-level tolerance for residual peroxides in food, and as a result, all the other industries abandoned its use, except for kazunoko operators.

### Roe-stripping

Extracting the egg sacs from fresh (unfrozen) herring, as done in the past was a delicate operation. According to the description of pre-industrial herring processing at Esashi in Ezo country, it is observed that even the removal of the fish from gillnets without scarring the eggs inside involved recruiting inveterate fishermen. Removal of egg sac, milt, etc. was known as nishin tsubushi (鰊潰し, 'herring crushing, squeezing'), and was considered women's work, and the fish were gutted without a knife, using just the fingers outfitted with finger cots. The roe was dried and made into hoshi kazunoko, but some crumbled pieces wound up as fertilizer, together with the dried milt and gills which were entirely sold as fertilizer.
Herring-squeezing (roe stripping) was not just women's work, but often depended largely on the recruitment of Ainu women. At Sōya (northern tip of Hokkaido), it is explicitly stated, herring-squeezing was the work for menoko (メノコ, 'adult Ainu woman'), according to the work Igen zokuwa (夷諺俗話, 'Tales of Ezo Customs', Kansei 4/1792) concerning the bakufu government's otameshi kōeki (御試交易, 'experimental trade') post there. Merchants peddled Japanese-made goods to the Ainu on maegashi (前貸し, 'advance loan'), then collect any remaining balance in the form of providing labor for seafood production. At the Aniva Bay operation (southern tip of Sakhalin), there has been found a loan ledger for "sudare", whereby the Ainu made repayments by crafting and delivering the surdare grass screens after the winter season. Any outstanding balance was then copied onto the kazunokocho (数子帳, or presumably read as such), indicating how much debt was still owed, to be discharged by service to kazunoko, etc. production.
According to the 1792 work, removed milt can be handled right away to be dried, but kazunoko are fragile and will break apart unless they are first "rested" for 2 or 3 days in boxes or barrels before manipulating them to be sun-dried.
Later, during the heyday of the earlier Showa era, when domestic production did not depend on freezing technologies, the roe-stripping was done manually from fresh herring.
Early Alaska roe stripping operation from around 1960 employed the coarse method of heaping herring and shoveling salt over it, allowing the fish to "age" for 4, 5 days, after which "herring squeezer" could easily "pop" the roe skein, without need of any skill. Though the crude method persisted until the mid-1970s, it was superseded by the practice (since c. 1970) of shipping frozen egg-bearing herring whole to Japan. Freezing firms the roe partially making them more easily removable, and this avoids the problem of industrial waste-management when high concentration salt is used, however, freezing improperly could lead to sponginess of texture.

### Mold-shaped kazunoko

There were kazunoko remolded into disks or squares after being dissembled, called yose kazunoko, which used to be presented to the shogun, as aforementioned. In more recent times, stray eggs gathered were salvaged and solidified together, then cut out into flower-shapes, to be sold as hana kazunoko. Also imitation kazunoko have been made using capelin eggs as substitute (though stray herring eggs may also be added).

## Fishing grounds

The main fishing grounds for herring were in Hokkaido (formerly Ezochi), targeting the particular schools that feed and spawn on the Sea of Japan side. Thus the main production center administrated by the Matsumae clan was at Esashi (or Matsumae), on the southwestern coast. Later, the clan extended control over the fisheries north and eastward, as far as Southern Sakhalin (Minami Karafuto), and opened Hakodate port on the east coast.
The Matsumae clan was outsourcing the seafood fishing and trade to merchants basho or akinaiba trading posts, in a contracting system (basho ukeoi-sei). The clan lost control of the territory and fishing trade in Ezo to the central government (shogunate) for certain periods. responding to a perceived Russian threat. The herring production in Sakhalin thus shifted between Japanese control (Tokugawa period, Meiji to Showa) and Russia (postwar).including kazunoko.
After the principal fishing grounds on the Seas of Japan side collapsed c. 1955 (Showa 30), as aforementioned, and for a few years thereafter, Japanese herring ships had to operate in greatly scaled-down fashion seeking regional herring groups, or at Gulf of Patience and Aniva Bay in Southern Sakhalin The egg-bearing (or "gravid") herring were being imported from Russia in the 1960s and 1970s, and also in increasingly large volumes from Alaska from c. 1960 onward, as aforementioned (§ Imports into Japan). In the year 1980 (Showa 55) the "bubble burst" for the herring roe industry. Prices soared, with rumors of speculative hoarding. The government stiffened regulation on peroxide bleaching agents. The market reacted by not buying, and companies were left with a huge dead inventories of overpaid herring roe.

### Imports into Japan

As already discussed, Japan largely imports Pacific herring roe from British Columbia; Canada, Alaska, USA, and also Atlantic herring roe from Europe.
Alaska has been known for having some of the shortest seasons for the catch, sometimes counted in hours. Alaska's allotted quotas at the main fisheries (mostly targeting roe herring) in 2022 were: Sitka Sound, late March,45,164 short tons (41,000 t; 90 million pounds), Kodiak Island, April, 8,075 short tons (7,000 t; 16 million pounds), and Togiak, May, 65,107 short tons (59,000 t; 130 million pounds). However, there was no prospect of catching full quotas. Japanese taste had changed, and the price fallen since the $1000 per ton in the heyday of the 1990s, and the gross receipt of $60 million for the fishermen has fallen to $5 million by 2020. In 2023, Togjk's last processing plant indicate it would not be buying for the coming year, and the fishing season was cancelled.
There has also been criticism regarding the harvesting of herring in Alaska primarily for the herring roe cash value, since all the male and rest of the female fish, about 90% in weight of the catch, were discarded up to the 1990s, minced into liquid sludge. Though this was replaced with using the residue as meal for petfood or fertilizer, issues have been raised regarding this non-optimal use of resources from a bioenergetics standpoint. The problem of sludge waste has been also discussed in the literature concerning Canadian processing plants (cf. "stickwater").

## First Nations food source

The native peoples of the Pacific coast of Canada and Alaska (current major producing regions of kazunoko) have had a tradition of gathering herring eggs on seafood or wood branches during the spring herring runs when the fish come to spawn.
The Sitka, Alaska area was one of the oldest Tlingit village settlements, and had been collecting eggs on seaweed or hemlock branches since time immemorial, according to descendant testimony. These are the spawn on kelp (Tlingit: daaw) or on hemlock (haaw). One seaweed type used is called "hair kelp" or "hair seaweed" though not a "kelp" in a strict sense, identified as Desmarestia sp. or more precisely Desmarestia viridis, belonging to a non-kelp ordo. There are a number of testimonies from European explorers during the 18th and 19th centuries.
The Haida who inhabit Haida Gwaii (formerly Queen Charlotte Islands) in Canada as a base point also traditionally gather k'aaw These may be eaten fresh on site, or may be sun-dried, and the dried may be eaten as is, or reconstituted in water then blanched or fried.
A seaweed known in Haida as "raven's moustache" (x̱uya sg̱yuug̱a") in Haida folklore is said to be usable, but inferior to hemlock as a medium for gathering eggs. Probably a Desmarestia species is meant here also. Again Western Hemlock (Tsuga heterophylla) is the species of the branch used to lure egg-laying. The attached Haida origin myth holds that when the Raven stuck his beak in the dancing hall of the Herring People, the eggs stuck on his mustache were not so appetizing, so he discarded the mustache, which became seaweed. He then stuck a sprig of hemlock in the hall, which grew thick with egg and was good-tasting. Hence the lesson to mankind that hemlock is the better implement to use.
On the opposite from the Haida dwell the Tsimshian of Lax Kwʼalaams (formerly Port Simpson), who also engaged in the egg-gathering practices. In the Tsimshian languages, the spawn on hemlock branches are called xs'waanx. And spawn-on-kelp are also locally referred to as gyoos meaning "kelp".
In the Bristol Bay (east extreme of Bering Sea) area including Togiak and nearby communities, the Yup'ik Eskimo also traditionally engaged in fishing herring and gathering their eggs. The spawn on kelp (Central Alaskan Yupʼik: qaryaq,) are preserved frozen, salted, or dried, and customarily eaten with seal oil. Yup'ik communities on Nelson Island (Alaska)　also go out to sea to collect spawn on kelp. Although residents say they usually consume these quickly, they may preserve spawn on kelp packed in seal oil, inside a sealskin poke (puuq), as they do with preserve herrings. The Bering Strait zone is generally Iñupiat Eskimo country, but an informant from Stebbins (which was settled by Nelson Islanders) stated that the collection of spawn on kelp (Yup'ik, Neson-Stebbins subdialect: ellquat) is a time honored tradition. The Iñupiat of the region also gather and consume herring egg.

## Ainu cuisine

In Ainu cuisine there is a dish named after the cow parsnip Heracleum lanatum (syn. Heracleum maximum. Japanese: hanaudo, actually ōhanaudo) that adds herring roe as ingredient. The foraged vegetable is called pittok (ピットㇰ) or siturukina (シト゜ルキナ) and the stems, or more precisely the stalks of the radical leaves [ja] which have been peeled and preserved are reconstituted and sliced up. Dried herring roe (Ainu: pere (ペレ/ぺレー) and seal fat are pounded until milky white, and mixed with the vegetable and diatomaceous earth (added to counteract the acerbity. The liquid squeezed from this dish was used as ersatz milk for infants.).

## In poetry

In haiku poetry, kazunoko is a kigo (季語, 'season word') for the New Year season and jinji ( human affairs). An example Kazunoko ni itokenaki ha wo narashi keri (数の子にいとけなき歯を鳴らしけり, "Herring roe, upon which the young 'uns teeth resound") read by Mokkoku Tamura [ja].