Sea urchins are abundant in many areas off the coasts of the United States and Canada. These highly armored creatures protect their soft parts with sharp spines and a hard shell, though during most of the year there is precious little inside the shell to protect. Sea urchins perhaps provide the least to eat of any other edible animal. It is reported that sea urchins were utilized by coastal Indians and certain immigrant groups--especially Italians. In Maine there has been a minor fishery supplying urchins to New York and Boston during much of this century231,232 , and until recently there has been intermittent fishing in California However, the number of urchins utilized for American markets has 232 always been small; on the East Coast it averaged only about 35 tons per year

The eggs and milt of marine animals are not relished by many Americans, yet they may be prized by people of other nationalities. At the present, the national group willing to pay the most for these products is the Japanese. They pay high, and sometimes outrageously high, prices for the gonads of salmon, herring, crabs, sea cucumbers, and sea urchins. As the yield of these products from Japanese waters cannot be increased easily, the gonads of salmon, herring and, to some extent, sea urchins are already being imported to Japan from many areas. The increase in imports will probably continue as long as the Japanese economy continues to expand, and the Japanese are able to use more of their paychecks to pay for food luxuries.

Premium prices are paid for fresh sea urchin gonads. In 1974 the average wholesale price paid for this product in the Tokyo Metropolitan Wholesale Market 264 was 3,981 yen per kilogram. Assuming 300 yen are equal to I dollar, the price was $13.29 per kilogram, or $6.42 per pound. In the winter when the price is usually the highest, the average price in January was 5,984 yen per kilogram ($19.93 per kilogram, or $9.59 per pound). At these prices, air freighting the gonads can be commercially feasible; but because of the fast-fluctuating field of imports from Korea, Mexico, Canada, and the United States, the market prices are far from stable. For example, the average price paid for gonads in January 1973 was one of the lowest values of the whole year. Figure 1 shows the monthly fluctuations in the wholesale price in the Tokyo Market. Note that during the summer months, the price of salted gonads increases, and the price may nearly equal the price paid for fresh gonads.

As sea urchin gonads are one of the highest-priced commodities sold in Japanese markets, and the demand for this product in our country is small, it makes sense to market as many of our coastal sea urchins as possible where they are clearly desired. This is especially so because in some areas a reduction in the numbers of sea urchins may actually be beneficial for the environment. In California, where 150,000 tons of kelp are harvested annually, there have been many attempts to eradicate sea urchins from the kelp beds. Now instead of just killing the urchins, there have been efforts by the National Marine Fisheries Service to develop and expand the sea urchin fishery.

Sea urchins belong to the Phylum Echinodermata which means that they are related to starfishes as well as sea cucumbers, sea lilies, and sand dollars. The most obvious similarity between a sea urchin and a starfish is the presence of tube feet and the almost radial symmetry. It is easiest to recognize the five-fold, star-like symmetry of a sea urchin by looking at a cleaned shell--or more technically, at a cleaned test. Looking at the test from the top (aboral) or bottom (oral) side, one can see double rows of numerous tiny holes (pore arcs). These holes are the openings through which tube feet are extended or withdrawn. The five areas of the test that possess tube feet are called ambulacral areas from the Latin root ambulare which means walk. This root is also used in the words "ambulate" and "ambulance". The five radiating areas between the ambulacral areas are called the interambulacral areas.

Each tube foot is like a highly elastic tube-balloon. When the "balloon" is filled with liquid, it elongates, and it can be "blown up" so it is longer than any of the spines. Without the liquid, the tube foot "deflates", and it is not conspicuous. The tip of the tube foot is shaped so it can,act like a suction disc. Thus, sea urchins can hold firmly onto the substrate using the suction of the tube feet. This is especially important for urchins that live where there is wave action. Sea urchins can also crawl along the bottom or even up vertical surfaces by holding on with the tube feet. The- tube feet have many other functions: they are sensitive to chemicals and to touch; they absorb oxygen; they may catch drifting alqae for food; and they keep the test clean.

One of the conspicuous features of the cleaned test is the presence of numerous symmetrically placed bumps (tubercles) each of which marks the base of a spine. The bottom of the spine and the tubercle form a neat ball and socket joint and, as a consequence, the spine can be moved in many directions. The and fast-moving urchins are more likely to use the spines than the tube feet for locomotion. The most important use ' of the pines for all sea urchinss thouqh. is to discouraqq_,_Rnqq@@ion. In some species the spines may even contain poison. The spines are on both the ambulacral and interambulacral areas of the test, but the ambulacral spines are shorter than the interambulacral spines.

For predators that are not discouraged by spines, the sea urchin can inflict ainful wounds using numerous small pinchers called peqicel,14,r,14.p.,.l singular, pedicellaria). When a sea urchin detects the presence of a predator, such as a starfish, the pinchers nearest the starfish extend, gape open, and the long spines move out of the way. Starfish are obviously affected by the poison, and they may retreat after being stung. However, as the pedicellariae can only be used once, a persistent starfish may still win in these encounters. During less stressful times, the pedicellariae serve to keep the surface of the shell clean or, conversely, they may hold objects onto the surface of the test for either camouflage'or shade. They may also sometimes catch drifting seaweeds, and pass the seaweed from one pincher to the next, down to the mouth where it can be eaten.

The internal anatomy of the sea urchin also shows much five-fold radial metry. The most important of these organs from a fisheries standpoint are five gonads located in the top (aboral) half of the test. Each gonad is centered in one of the five interambulacral areas; the hole-perforated ambulacral areas lie between the gonads. This fact is important during shucking because if the test is broken along the ambulacral-sections, the gonads will not be that conspicuous internal organs are the teeth and the gut. The mouth of the urchin is on the bottom (oral) part of the test. Food is chewed by five teeth which are part of a large, complex.mechanism called Aristotle's lantern. The chewed food then moves through a distinct esophagus, stomach, and intestine. When the food enters the intestine, it is formed into round pellets; and these pellets are later excreted at the top (aboral) side of the test through the anus. The urchin then cleans the surface of the test using the spines, pedicellariae, and tube feet.

Surrounding the teeth is the peristomal membrance. This is the only place where the sea urchin is not protected by the hard test. This is the weak spot of the urchin, and many predators use this to their advantage. If the sea urchin can hold tightly to the substrate and keep the membrane protected, it will survive at least some encounters with potential predators.

The gonads are the main nutrient storage organs of the sea urchin. When food is abundant, nutrients are stored in special cells (nutritive phagocytes and the gonads increase in size so they may compose one-quarter of the total weight of the urchin. Then if the urchin is starved, the urchine egg is reabsorbed and the gonads will shrink in size. Sex products are not produced in the gonads until the spawning season ap roaches. At this time, much of the gonad may be converted into gametes, and when these are extruded into the sea, there is a corresponding decrease in gonad size. Well-fed sea urchins do not use all of the nutrients stored in the gonads for the production of gametes, but the gonads of poorlv fed., tied after spawning.

Because of the spawning cycle, the size and quality of the gonad change greatly during the year and, in order to derive the maximum benefit from thisresource, these chod. For the purposes of discussion, the gonad cycle can be divided into five stages. During tagsI, the resting stage, the size of the gonads is at a minimum. Either spawning has recently occurred or the urchin is still immature. The gonads do not contain eggs or sperm, but the sex of the urchins can be determined microscopically. Near the gonad walls, spermatogonias will be present in males and obgonias will be present in females. Otherwise, the male and female gonads are so similar that they cannot be distinguished. The water ,qnim exceed 80%. h The gonads of a well-fed urchin may weigh 5 to 10% of the Fry weight at this stage.

During State II (the growing stage), the urchins eat actively, and the excess nutrients are stored in the gonads. Spermatocytes and obcytes (immature eggs and sperm) are produced, but the male and female gonads are still indistinguishable except under a microscope. The commer fo the qonads is eat its pehe latter part of this stage and the ea Stage III content is near a minimum and there are not taste or color en male and female gonads.

In Stage III the pre-mature s gi), the gonad weight approaches the maximum. Eggs and sperm are produced and, as the number of these sex products gonads changes sexes can t@he@@ s 0-@tv@-- -- increases, the coloration of De distinguished visually.

The weight of the gonad reaches a maximum during Stage IV (the mature stage), and the gonads may weigh up to 25 to 30% of the total weight. However, numbers are limited in the information they can give. Index numbers provide only a rough approximation of the stage of maturation or quality of the gonads. Also, the index numbers are not truly comparable from one year class to another. The gonad ratio first rises abruptly with size and then drops for the largest animals.

Initiation of Gamete Production

The environmental conditions that initiate the production of eggs and sperm have not been intensively studied, but there are indications that the same factors are not responsible in all species. The reproductive rycle of Lytechinus variegatus is definitely affected by the tides.180 In the casp f Strongylocentrotus purpuratus there is evidence that the length of the day is an important factor. When specimens were maintained in a laboratory at 'i5 C, those urchins given 6 hours of artificial illumination daily produced gametes. The gonads of urchins which were illuminated 14 hours a day, on the other hand, contained very few gametes.

Initiation of Spawning

The sex products are not shed as they are produced, but they accumulate in the gonads until the gonads become so full that leakage occurs or something stimulates spawning. When stimulated, certain muscles contract and squeeze the gonads. This forces the eggs or sperm out pores (gonopores) in the genital plates into the sea. Artificial methods of inducing spawning were discussed earlier. In nature the spawning of populations is probably synchronized because urchins can detect the presence of leaked gametes. In one study 132 , ripe males usually responded to the presence of a suspension of female gonads by releasing sperm within about 5 minutes and, likewise, the females usually spawned when they detected the presence of a suspension of male gonads.

FOOD

Certainly one of the major factors in the ability of the sea urchin I in such diverse coastal regions is their ability to live on almost any tyl food. If seaweed is plentiful, the sea urchins will be grazers. If the L live where no seaweed can grow, they can scavenge on dead animals or drifting algae; or when the opportunity arises, they may prey on other animals. In the absence of such food, the urchins may still persist even in areas that eem completely barren. Here the urchins scrape rocks and ingest sand, and they live off the associated microorganisms such as diatoms, radiolarians, and other protozoa. They may even be able to live on the organic matter that is discharged in sewage. The cery much affected by the type of food eaten on anything but seaweed, the gonads are likely to be unmarketable. Also, some seaweeds are more conducive to the growth of high-qual.ity gonads than others. Some seaweed genera that have been found to give good growth are Alaria, Scytosiphon, Ulva, and Laminaria.64 Sea urchins gather drifting food using the tube feet, spines, and pedicel- lariae. Small fish may also be caught using these structures. If a fish touches the spines or tube feet, the spines may fold over the fish trapping it.76 The food is then carried to the mouth by the tube feet. It takes about 4 hours for the chewed food to reach the intestine 10 where it is formed into the characteristic fecal pellets. After that, the movement through the intestine may be quite slow, especially if no more food is available. In starved urchins, all of the fecal pellets may not be voided until up to 2 weeks after a feeding, and during this time, a larger percentage of the food is digested .

PREDATORS

Sea urchins are preyed upon by-a number of animals including lobsters9o, 90 33,90,152,224,225 33 crabs , starfish, sea anemones flat fish, olf fiqh, sculpi ns, 33,152,15-a@- sea gulls , and sea otters . but in most areas, predation is not a par- ticul'arly important factor in controlling the numbers of sea urchins. This is because-two of the major predators (sea otters on the West Coast and lobsters on the East Coast) have been greatly reduced in number by man.

Each predator has a characteristic method of attacking sea urchins. Fish usually swallow the urchins whole. Sea gulls, crabs, afid lobsters normally break into the tests through the peristomal membrane. Sea otters float on their backs and break the sea urchins open with rocks. Starfish have two ways of eating urchins: small urchins may be swallowed whole 160, and larger urchins may be digested extraorally In the latter case, the stomach of the star fish is everted over the sea urchin and the tissues on the outside of the test are digested causing the spines to fall off. Then an opening is made in the

2b Prevailing coloration of spines pale greenish; tube feet darker than spines, and usually purple; diameter of test up to about 8 cm; intertidal as well as subtidal Strongylocentrotus droebachiensis (O.F. MUller, 1876)
3a Prevailing coloration of living animal orange-pink; cleaned test pale orange-pink, extremely fragile; subtidal at depths greater than 100 m Allocentrotus fragilis (Jackson, 1912)
3b Prevailing coloration of living animal red or purple; cleaned test usually gray or pale purple, not extremely fragile; intertidal as well as subtidal
4
4a Prevailing coloration usually bright red, reddish-purple, or maroon, although the larger spines of lighter specimens may be rose and the smaller spines almost white; diameter of test up to 15 cm; spines up to 7 cm long in larger individuals; intertidal and subtidal Strongylocentrotus franciscanus (A. Agassiz, 1863)
4b Prevailing coloration purple; diameter of test not exceeding 9 cm; spines rarely more than 2.5 cm long; largely intertidal on rocky shores having considerable wave action, but subtidal to some extent Strongylocentrotus purpuratus (Stimpson, 1857)

StrongZlocentrotus franciscanus

The red sea urchin, Strongylocentrotus franciscanus, is the largest sea urchin occurring on our coasts. It lives at shallow depths, typically from 5-10 meters; though it may also be found intertidally or at depths up to 125 meters. It is usually found on rocky substrates in zones of brown seaweeds and where the currents are moderate to swift. It is distributed from Baja, California, northward to Alaska, across the Aleutialh Islands to the Asiatic coast, and as far south as southern Hokkaid5, Japan.

Because of its abundance, large size, and gonad color, the U.S. and Canadian sea urchin fisheries are almost entirely dependent on this species. However, despite its commercial importance, S. franciscanus has been little studied. Most of the parameters that would be useful to know for fishery management are unknown or can only be hinted at from inadequate data.

The species spawns largely during the colder months of the year. Spawning has been recorded in December and January at Corona Del Mar 157 , February through March at Pacific Grove , April and May at John Hopkins Marine Station March and April in Puget Sound 105 , and possibly June and July near Vancouver Island The larvae are planktonic for about 2 ..before settling to the bottom. The juveniles apparently do not select habitats that differ greatly from the adults. They may be "hidden in crevices or amongst kelp holdfasts in the high subtidal zone ,163 . The adults and juveniles are often found within a few inches of each other. Assuming that this is the most usual habitat for the juveniles, it appears that larval recruitment-is sporadic. Miller (1974) could find no indication of significant settlement from the intertidal zones to a depth of 12 meters in the summer of 1974.

Since the red sea urchin is so large, it can be expected that the growth rate is more rapid than the smaller species in the family. Therefore, the fastest growth rate indicated in Table 2 could be considered as an absolute minimum for this species. There is good reason to believe this species grows much faster than any of the species shown in the table. In a rearing experiment where specimens of S. franciscanus with a mean test diameter of 29 mm were reared for a year, the growth increment was 23 mm; specimens with an average test diameter of 49 mm grew 13 mm. 249 In another study, specimens with a mean test diameter of 28.3 mm grew 2.1 mm in about a month and a half. 197 The test diameters of the first and second year classes may be 30 mm and 50 to 60 mm, respectively.

More study on the growth of this species is certainly needed, and a study of the genital plates could prove most useful.

The red sea urchin has marked, d preferences. In an experiment where specimens were offered equal amounts of seven different seaweeds, the preferr, food was the kelp Macrocystis p.yrifera. The seaweeds in descending order of preference were ' Macrocystis pyrifera, 34%; Gigartina armata, 17%; Laminaria farlowii, 16%; Eisenia arboreal 11%; Pterygophora californica, 10%;. laevigata, 10%; and Cystoseria osmundacea, 2%. 149

Strongylocentrotus droebachiensis,

The distribution of the green sea urchin is circumpolar. In the eastern Pacific, it is found as far north as Point Barrow, Alaska and southward to Washington state where it is the dominant sea urchin in Puget Sound it occurs in the Aleutian Islands and westward to Kamchatka,-Korea, and Hokkaid6, Japan. In the north Atlantic it may be found on the East Coast of the U.S. and Canada, and in Greenland, Iceland, and northern Europe.. It lives at water depths up to 70 fathoms, but more commonly it is found in shallower water up to about the low mean tide line. 247 It prefers rocky, gravelly, or shelly substrates, but it may also be found on sandy or rarely muddy bottoms

PREPARATION

Shucking

Shucking the sea urchin is a time-consuming and therefore expensive operation. The most ' common technique is to insert a knife into the soft peristomal membrane and crack the urchin so it breaks along the hole-perforated, ambulacral sections of the test. Then the gonads are carefully extracted using a small spoon or spatula. When the test is cracked, it is easy for spines and pieces of the test to fall into the soft gonads. All of this material, including the soft membranes which adhere to the gonads, must be meticulously removed.

The gonads are washed, and they may be finned with a dilute alum solution.

There are various techniques that are sometimes used which reduce the amount of material that falls into the gonads. Some shuckers remove the peristomal membrane and the Aristotle's lantern before cracking the test. Other shuckers may remove all of the spines before they break the test. (This latter procedure could probably be easily mechanized.)

Fresh Gonads

Fresh, gonads are ,oranqe in color,, and they have a smooth texture--rather like a soft paste. When the shucking has been carefully done, the gonads will be unbroken; and the natural, bumpy surface of each onad will be retained. These gonads are sorted according to color, size, and quzlity; and the gonads are laid side by side in small wooden or styrofoam con- tainers. The containers are made so they can be stacked on top of each other and yet still allow air to circulate underneath each container. Also, the bottom of the container is adapted to allow the gonads to drain. The fresh sea urchin is almost never sold to the Japanese consumers through markets; almost all of the fresh product is served in those restaurants that a sushi bar. Sushi is a term which describes a variety of Japanese foods contain rice seasoned with salt, sugar, and rice vinegar. his rice is typically served with a large variety of appetizers--largely seafoods. All of the appetizers that are available at the restaurant are attractively displayed at the sushi bar, so the customer can select his preferences. When a customer eats at the bar, he selects appetizers one at a time. He informs the cook behind the counter of his choice, and the cook forms two oval balls (about 4 cm long and 2 cm in diameter) out of rice that has been prepared earlier. He then tops both balls with the same appetizer and serves them. Because the customer can always see and choose exactly what will be served, the appearance and freshness of the appetizers is extremely important.

Most of the toppings are slices of raw fish or shellfish, and the slices are just laid on top of the rice ball. Sea urchin gonads, on the other hand, are very soft and require support to stay on top of the rice. Therefore, these rice balls are first wrapped lengthwise with a piece of seaweed, and the sea urchin is then placed on top of the rice, but inside the seaweed wrapper. Sea urchin is one of the most expensive appetizers, and costs 200 yen (67t) for about two teaspoonfuls'of gonads. This is about 4 times as much as the less expensive appetizers such as shrimp and octopus. Frozen Gonads

Though sushi restaurants pay premium prices for sea urchin gonads, they demand a very fresh product. This means that the gonads must be served in the restaurants within a few days after they are removed from the sea urchins. In the United States the product must move very rapidly to international airports such as Seattle or Anchorage, and this require ent effectively eliminates large-coastal regions from being potential supply areas to the Japanese market.

As getting fresh gonads to metropolitan markets is also sometimes a problem in Japan, there have been studies on the feasibility of freezing the gonads. Initial efforts were discouraging. Not only did the gonads tend to liquefy, but chemical changes took place in the frozen gonads which caused a deterioration in the taste. Gonads are less likely to liquefy when they are defrosted if some of the fluids have been removed. Fukushima (1974) described a process where 10% of the liquid was removed with a vacuum pump while the gonads were kept at 2-3 C. Only after the water was removed were the gonads frozen. Tanaka and Matsuda (1970) obtained fair results when they caused an ice glaze to form over the gonads during freezing and then stored the gonads at -20 C. Then, before defrosting, the gonads and ice glaze were partly dehydrated by lyophilization (freeze-drying). The gonads were thawed at 5-10 C. Valladares and Pinilla (1970) improved the frozen product by using the additives citric acid and propylgallate.

Canned Sea Urchin Gonads

An effective way to preserve gonads which cannot be marketed fresh is to can them. Canned sea urchin gonads are sold in many small Japanese grocery stores, and the price is quite high. In 1975, a can of gonads holding 110 grams of product retailed at 990 yen ($13.60 a pound) most of the toppings are slices of raw fish or shellfish, and the slices are just laid on top of the rice ball. Sea urchin gonads, on the other hand, are very soft and require support to stay on top of the rice. Therefore, these rice balls are first wrapped lengthwise with a piece of seaweed, and the sea urchin is then placed on top of the rice, but inside the seaweed wrapper (Fig- ure 7A). Sea urchin is one of the most expensive appetizers, and costs 200 yen (67@) for about two teaspoonfuls'of gonads. This is about 4 times as much as the less expensive appetizers such as shrimp and octopus.

Salted Sea Urchin Gonads

Sea urchin gonads have been preserved by salting since olden times, and numerous salting techniques have developed. The necessity for preserving the gonads with salt has now been largely eliminated due to the existence of fast transport and canning techniques, but large quantities are still desired by Japanese consumers. Often the best-quality gonads are marketed fresh, and only lower-grade gonads are salted. However, a premium grade of salted gonads can also be sold at very high prices. One salted product sold by secondary whole-salers in Tokyo went for 13,000 yen per kilogram ($19.65 a pound). Most of the salted product sold in Tokyo is priced much lower (Figure 1B). This lower-grade product is bought by secondary processors and is used in some of the seafood mixes that will be described later.

As salting the gonads is rather uncomplicated, much of this type of processing is done at home by relatives of the fishermen, or at fishery cooperatives. Typically there are four steps in making salted products: (1) salt is mixed with the gonads; (2) the gonads are drained of excess moisture; (3) alcohol is mixed with the drained gonads; and (4) the product is fermented at room temperature.

The salt has two effects on the gonads. It causes the gonads to extrude water, so the salt content and moisture content of the finished product are related. Also, the salt controls fermentation. Spoilage will occur if there is insufficient salt; but if there is too much, a good fermented taste will not develop. In general, those products with a minimum of salt taste best. The amount of salt mixed with the fresh gonads in various products is from 10 to 40% by weight. The salt may be mixed directly with the gonads, or the gonads may be soaked in a salt brine.

In most products the extruded water is drained. (An exception is a product called mizu uni, or watery sea urchin.287 ) There is no best moisture content for the drained gonads; this depends on what type of product is intended. Some products may contain 45% moisture while others have 56% . However, for each particular product the amount of moisture is critical. The moisture content of the fresh, unprocessed gonads influences how much salt is required, and the moisture content of the drained gonads has a direct bearing on how much alcohol -or other additives will be needed. If there is too much moisture relative to the additives, liquid will separate out of the finished product. If there is too little moisture, the texture may be adversely affected. The range of acceptable moisture contents which cause neither problem may be only 4-6%. In order to obtain consistent results, the best moisture range for each product must be determined with controlled experiments.

Alcohol is a preservative; and when it is used, less salt is needed in the finished product. Typically, only 10-15% salt is required. Ethyl alcohol (95- 99% pure) is used, and since it also has a strong taste, the products with a minimum of the alcohol have the best flavor. Commonly, the weight of the added alcohol is 10-15% of the drained gonad weight. The salt must be mixed evenly with the gonads when the alcohol is added, otherwise the absorption of the alcohol will not be uniform.

After the preservatives have been mixed with the gonads, the product may be immediately bottled, or it may be packed in wooden tubs. If the quantity of salt, alcohol, and moisture were appropriate, the fermented flavor that develops during storage will normally be acceptable. However, spoilage may still occur if the preservatives were not thoroughly mixed with the gonads or if the product was filled with air bubbles.

Various flavor and color additives are often used, and they may be added before or after fermentation has occurred. Common flavorings are monosodium glutamate, sweet sake (mirin), sake lees, sugar, and starch. The preferred color is orange, and most products need food coloring to achieve the desired color.

The two most common fermented products that are marketed to Japanese consumers are neri uni (blended sea urchin) and tsubu uni (granular sea urchin). Following are descriptions of products produced by the large Ogawa Sea Urchin Company in Shiminoseki and sold in many small Japanese grocery stores. Neri uni is a smooth-textured paste which is made by blending sea urchin gonads. The Ogawa product contained 75% salted sea urchin, 5% starch, alcohol, sugar, and artificial seasons and colorings. In 1975, a bottle containing 60 grams retailed at 245 yen ($6.17 a pound). Tsubu uni tastes very similar to neri uni, but the texture is slightly different. When the preservatives and flavorings are mixed with the gonads, care is taken so the original bumpy texture is not completely destroyed; and the finished product contains small lumps. (Tsubu uni cannot be made from soft gonads because all of the lumps are broken during mixing.) Tsubu uni is more expensive than neri uni, and a 60-gram bottle retailed at 375 yen ($9.45 a pound). The Ogawa product contained 90% salted sea urchin gonads, plus alcohol, sugar, starch, and artificial seasons and colorings.

Fermented sea urchin paste is used in a variety of mixtures called uni aemono. Typically the mixtures contain lower-priced seafoods such as herring eggs, squid, dried jellyfish, or abalone; and sea urchin makes up less than 20% of the product. Consequently, uni aemono is relatively inexpensive. Kazunoko uni (herring eggs and sea urchin) is a typical product, and in 1975 an 80-gram container retailed at 150 yen ($2.84 a pound). This mixture contained 35% herring eggs, 16% sea urchin, 19% sake lees, plus alcohol, sweet sake, sugar, starch, and artificial seasonings and colorings. A similarly priced product made with jelly- fish (kurage uni) contained 45% jellyfish, 17% sea urchin, 17% sake lees, plus the seasonings.

Updated: Wednesday, June 20, 2007.