Tobiko is the Japanese word for flying fish roe. It is most known for its use in creating certain types of sushi; the eggs are small. For comparison, tobiko is smaller than ikura. Natural tobiko has a red-orange color, a mild smoky or salty taste, a crunchy texture. Sometimes, tobiko is colored to change its appearance, other natural ingredients are used to accomplish the change, such as squid ink to make it black, yuzu to make it pale orange, or wasabi to make it green and spicy. A serving of tobiko can contain several pieces, each having a different color; when prepared as sashimi, it may be presented on avocado wedges. Tobiko is used in the creation of many other Japanese dishes, it is used as an ingredient in California rolls. Masago is substituted for tobiko, due to its similar appearance and flavor; the smaller size of the individual eggs is apparent to the experienced diner, however
The starry sturgeon known as stellate sturgeon or sevruga, is a species of sturgeon. It is native to the Black, Azov and Aegean sea basins, but it has been extirpated from the last and it is predicted that the remaining natural population will follow soon due to overfishing, it is considered critically endangered by the IUCN and international trade in this species is restricted by CITES. The starry sturgeon is an anadromous species; the starry sturgeon weighs up to 80 kg. It is a slim-bodied fish distinguished from other sturgeons by its long and straight snout. A row of five small barbels lies closer to the mouth than to the tip of the snout; the scales on the lateral line number between thirty and forty and these features distinguish this fish from the Russian sturgeon. Its general colouring is dark greyish-green or brown with a pale underside; the scales on the lateral line are pale. The maximum reported; the starry sturgeon is a harmless species that feeds on fish, worms and mollusks. It lies on the bottom during the day and feeds at night.
This fish moves upriver into shallow waters to spawn. The starry sturgeon is an important commercial species of fish, it is one of the three most important species for caviar, see "Sevruga caviar", along with the Beluga sturgeon and the Ossetra sturgeon. Its flesh is considered an expensive delicacy in the Caspian region, it is used to make kabaabs, or broiled, or smoked. There have been several attempts in Russia, Iran and the United States to adapt this species for aquaculture, with varying degrees of success; the resilience of this species is low. The minimum population doubling time is 4.5 – 14 years. World Sturgeon Conservation Society Media related to Acipenser stellatus at Wikimedia Commons
The sterlet is a small species of sturgeon from Eurasia native to large rivers that flow into the Black Sea, Azov Sea, Caspian Sea, as well as rivers in Siberia as far east as Yenisei. Populations migrating between fresh and salt water have been extirpated. Due to overfishing and dams, the sterlet has declined throughout its native range and is considered vulnerable by the IUCN. Restocking projects are ongoing, it has been introduced to some regions outside its native range, but the latter have not become self-sustaining. Today, the majority of the international trade involves sterlets from aquaculture; the sterlet may reach 16 kg in weight and 100 to 125 cm in length exceeding a length of 3 ft. It is quite variable in coloration, but has a yellowish ventral side, it is distinguishable from other European species of sturgeons by the presence of a great number of whitish lateral scutes, fringed barbels, an elongated and narrow snout variable in length. The sterlet's main source of food is benthic organisms.
The sterlet reaches the age of 22 to 25 years. Males reach sexual maturity at 3–7 years old and females at 4–12 years old. Spawning occurs from the middle of April to the beginning of June. Females may lay from 15,000–44,000 eggs, at water temperatures preferably 12–17 °C. Sterlets require large ponds with good water conditions, may get entangled in plants such as blanketweed, they may require special food such as sterlet sticks, as they are unable to digest the vegetable proteins found in commercial fish foods. In Russia, it is held in high esteem on account of its excellent flesh, contributing to the best kinds of caviar and isinglass. Sterlet x Beluga = Sterlet x Siberian Sturgeon ] Sterlet x Diamondback Hybrids are hardier than their parents
The beluga or European sturgeon is a species of anadromous fish in the sturgeon family of order Acipenseriformes. It is found in the Caspian and Black Sea basins, in the Adriatic Sea. Fished for the female's valuable roe—known as beluga caviar—the beluga is a huge and late-maturing fish that can live for about 118 years. Going on maximum size, it is the second most massive living species of bony fish behind the ocean sunfish; the species' numbers have been reduced by overfishing and poaching, prompting many governments to enact restrictions on its trade. The common name for the sturgeon, as for the unrelated beluga whale, is derived from the Russian word белый, meaning "white" referring to the extensive pale colour on the underside in beluga compared to other sturgeons; the beluga are a large predator which feeds on fish rarely consuming waterfowl and seal pups. The beluga will pursue prey in the pelagic zone unlike Acipenser sturgeons which remain more so in brackish areas for foraging, thus the beluga will pursue marine fish.
However much prey is taken in brackish areas such as river herrings, the asp and anchovies. Like most sturgeons, the beluga is anadromous, migrating upstream in rivers to spawn. Males attain sexual maturity at 12-16 years of age. In both sexes, they will go to spawn every 4 to 7 years. At one time, beluga sturgeons could migrate up to 1,000 km upriver to spawn but dams in every major tributary they utilize has impeded historic spawning routes; the female lays her eggs on gravel from 4 to 40 m underwater. Upon hatching, the embryo are 11 to 14 mm long, 10-14 days when they absorb their yolk sack, the length is 18 to 20 mm. Thereafter, the larvae subsist on benthic invertebrates but at as small as 10 cm in length will switch to a fish-based diet. While swimming back to the ocean, the young sturgeons may cover up to 60 km a day; the largest accepted record is of a female taken in 1827 in the Volga estuary at 1,571 kg and 7.2 m. Another specimen weighed 1,220 kg and measured 6.1 m in length. Several other records of aged sturgeon exceed 5 m.
These great sizes mark the beluga as the largest freshwater fish in the world. A few other species of sturgeon can attain great sizes but none match the maximum sizes known for the beluga, like Chinese, Pacific White, Oceanic European, Atlantic and Kaluga, the latter a close cousin which can attain a maximum weight of 1,000 kg, thus attaining the second largest known sturgeon size, it may be considered as a rival in size to the ocean sunfish among all extant bony fishes, although that passive marine giant has neither been nearly as fished nor takes as long to attain great size, so more attains massive weights. The beluga may be the second longest extant bony fish as well, after the giant oarfish, far more slender in build; the Beluga rivals the great white shark, the Greenland shark, the tiger shark for the title of largest predatory fish, with only the great white exceeding the beluga's maximum size. The giant belugas are much larger than the Mekong giant catfish, the arapaima or other sizable rivals for the title of largest freshwater fish.
Some scientists still consider the Mekong giant catfish to be the largest true freshwater fish, owing to sturgeons' ability to survive in seawater and that it spends much of its life in brackish environments. Beluga of such great sizes are old and have become rare in recent decades due to the heavy fishing of this species. Today, mature belugas that are caught are 142–328 cm long and weigh 19–264 kg; the female beluga is 20% larger than the male. An exceptionally big beluga caught reportedly weighed 960 kg and measured 3.4 m. Beluga caviar is considered a delicacy worldwide; the flesh of the beluga, though, is not renowned but is a hearty white meat similar to that of swordfish. Beluga caviar has long been scarce and expensive and its endangered status has made its caviar more expensive in worldwide markets outside of the United States, its air bladder is said to make the best isinglass. IUCN classifies the beluga as critically endangered, it is a protected species listed in appendix III of the Bern Convention, its trade is restricted under CITES appendix II.
The Mediterranean population is protected under appendix II of the Bern Convention, prohibiting any intentional killing of these fish. The United States Fish and Wildlife Service has banned imports of beluga caviar and other beluga products from the Caspian Sea since October 6, 2005, after listing beluga sturgeon under the U. S. Endangered Species Act. "Huso huso". Integrated Taxonomic Information System. Retrieved 24 January 2006. Annex II of the Convention on the Conservation of European Wildlife and Naturaabitats. Revised 1 March 2002
Roe or hard roe is the ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp and sea urchins. As a seafood, roe is used both as a raw ingredient; the roe of marine animals, such as the roe of lumpsucker and salmon, is an excellent source of omega-3 fatty acids. Roe from a sturgeon or sometimes other fish is the raw base product; the term soft roe or white roe denotes fish milt. The large indigenous population in KwaZulu-Natal consumes fish roe in the form of sour curry or battered and deep fried. In southern Brazil, in particular in the litoral parts of the state of Santa Catarina, Mullet roesacks are consumed deepfried or pan-seared by the locals. In the province of New Brunswick, roe of the Atlantic sturgeon is harvested from the Saint John river. Roe from the cisco is harvested from the Great Lakes for overseas markets. Roe is extracted from herring and sea urchins. In coastal British Columbia, Fraser River white sturgeon are sustainably farmed to produce caviar.
In Chile, sea urchin roe is a traditional food known as an "erizo de mar". Chile is one of many countries that exports sea urchins to Japan in order to fulfill Japanese demand. In Dominican Republic and smoked herring roe is eaten. Unlike in some countries, it's cooked before consumption. In Peru, roe is served in many seafood restaurants sauteed and pan fried, sometimes accompanied by a side of fresh onion salad, it is called Huevera Frita. Cojinova yields the best roe for this dish. Despite the fact that many people like it, it is hardly considered a delicacy. Upscale restaurants are not expected to offer it, but street vendors and smaller restaurants will make their first daily sales of it before they run out. Cojinova itself is caught for its fish meal, not for its roe, considered a chance product. Sea urchin roe is considered a delicacy and it is used to add strength to ceviche. In the United States, several kinds of roe are produced: salmon from the Pacific coast and herring species like the American shad and alewife, paddlefish, American bowfin, some species of sturgeon.
Shad and other roe are sometimes pan-fried with bacon. Spot Prawn roe is a delicacy from the North Pacific. Flounder roe, pan-fried and served with grits is popular on the Southeastern coast. Roe from the Ilish fish is considered a delicacy in Bangladesh; the roe is deep-fried, although other preparations such as mashed roe where the roe crushed along with oil and pepper, or curry of roe can be found. In many regions in China and urchin roes are eaten as a delicacy. Crab roe are used as topping in dishes such as "crab roe tofu". Nanxiang Steamed Bun Restaurant serves "crab roe xiaolongbao" as their special. Shrimp roes are eaten in certain places around the downstream of Yangtze River, such as Wuhu, as toppings for noodle soup. Among the tribal populace of eastern India, roe, roasted over an open fire is a delicacy. In this region, the roe of rohu is considered a delicacy and is eaten fried or as a stuffing within a fried pointed gourd to make potoler dolma. All along the Konkan coast and Northern Kerala, the roe of sardines, black mackerel and several other fish is considered a delicacy.
The roe can be eaten fried and as a thick curry. In Goa, roe is first steamed or poached coated with salt and chilli powder and shallow fried or roasted on a tawa. In the state of Kerala, roe is deep fried in coconut oil, is considered a delicacy. A common method of quick preparation is to wrap the roe in wet banana leaves and cook it over charcoal embers. In Odisha and West Bengal, roe of several fresh-water fish, including hilsa, are eaten, the roe being cooked separately or along with the fish, the latter method being preferred for all but large fishes. Roe, either light or deep-fried are eaten as snacks or appetizers before a major meal. All along the Indus River and Specially South Pakistan Sindh, the roe of Palla and several other fish is considered a delicacy; the roe can be eaten fried and as a thick curry. Coated with salt and chilli powder and shallow fried or roasted on a tawa. In the Caspian provinces of Gilan and Mazandaran, several types of roe are used. Called ashpal or ashbal, roe is consumed grilled, salted, or mixed with other ingredients.
If salted or cured, it is consumed as a condiment. If used fresh, it is grilled, steamed, or mixed with eggs and fried to form a custard-like dish called "Ashpal Kuku". Besides the much sought-after caviar, roe from kutum, Caspian roach and Caspian salmon are prized. Roe from carp is less common and barbel roe is occasionally used. Several sections of the Israeli cuisine include roe. In Modern Hebrew, roe is referred to by its Russian name "ikra"; when necessary, the color is mentioned: white or pink, as appropriate. Israeli "white ikra" is made of carp or herring eggs, while "red ikra" is made of flathead mullet eggs or, in rarer cases, salmon eggs; the term "caviar" is separate, denotes only sturgeon eggs. Ikra is served as a starter dish, to be eaten with pita or similar breads in Arab restaurants, it can be purchased in stores, in standard-sized p
Nacre known as mother of pearl, is an organic-inorganic composite material produced by some molluscs as an inner shell layer. It is strong and iridescent. Nacre is found in some of the most ancient lineages of bivalves and cephalopods. However, the inner layer in the great majority of mollusc shells is porcellaneous, not nacreous, this results in a non-iridescent shine, or more in non-nacreous iridescence such as flame structure as is found in conch pearls; the outer layer of pearls and the inside layer of pearl oyster and freshwater pearl mussel shells are made of nacre. Other mollusc families that have a nacreous inner shell layer include marine gastropods such as the Haliotidae, the Trochidae and the Turbinidae. Nacre is composed of hexagonal platelets of aragonite 10–20 µm wide and 0.5 µm thick arranged in a continuous parallel lamina. Depending on the species, the shape of the tablets differ. Whatever the shape of the tablets, the smallest units they contain are irregular rounded granules.
These layers are separated by sheets of organic matrix composed of elastic biopolymers. This mixture of brittle platelets and the thin layers of elastic biopolymers makes the material strong and resilient, with a Young's modulus of 70 GPa. Strength and resilience are likely to be due to adhesion by the "brickwork" arrangement of the platelets, which inhibits transverse crack propagation; this structure, at multiple length sizes increases its toughness, making it as strong as silicon. The statistical variation of the platelets has a negative effect on the mechanical performance because statistical variation precipitates localization of deformation. However, the negative effects of statistical variations can be offset by interfaces with large strain at failure accompanied by strain hardening. On the other hand, the fracture toughness of nacre increases with moderate statistical variations which creates tough regions where the crack gets pinned. But, higher statistical variations generates weak regions which allows the crack to propagate without much resistance causing the fracture toughness decreases.
Nacre appears iridescent because the thickness of the aragonite platelets is close to the wavelength of visible light. These structures interfere constructively and destructively with different wavelengths of light at different viewing angles, creating structural colours; the crystallographic c-axis points perpendicular to the shell wall, but the direction of the other axes varies between groups. Adjacent tablets have been shown to have different c-axis orientation randomly oriented within ~20° of vertical. In bivalves and cephalopods, the b-axis points in the direction of shell growth, whereas in the monoplacophora it is the a-axis, this way inclined; the interlocking of bricks of nacre has large impact on both the deformation mechanism as well as its toughness. In addition, the mineral–organic interface results in enhanced resilience and strength of the organic interlayers. Nacre formation is not understood; the initial onset assembly, as observed in Pinna nobilis, is driven by the aggregation of nanoparticles within an organic matrix that arrange in fibre-like polycrystalline configurations.
The particle number increases successively and, when critical packing is reached, they merge into early-nacre platelets. Nacre growth is mediated by organics, controlling the onset and form of crystal growth. Individual aragonite "bricks" are believed to grow to the full height of the nacreous layer, expand until they abut adjacent bricks; this produces the hexagonal close-packing characteristic of nacre. Bricks may nucleate on randomly dispersed elements within the organic layer, well-defined arrangements of proteins, or may grow epitaxially from mineral bridges extending from the underlying tablet. Nacre differs from fibrous aragonite – a brittle mineral of the same form – in that the growth in the c-axis is slow in nacre, fast in fibrous aragonite. Nacre is secreted by the epithelial cells of the mantle tissue of various molluscs; the nacre is continuously deposited onto the inner surface of the shell, the iridescent nacreous layer known as mother of pearl. The layers of nacre smooth the shell surface and help defend the soft tissues against parasites and damaging debris by entombing them in successive layers of nacre, forming either a blister pearl attached to the interior of the shell, or a free pearl within the mantle tissues.
The process is called encystation and it continues as long as the mollusc lives. The form of nacre varies from group to group. In bivalves, the nacre layer is formed of single crystals in a hexagonal close packing. In gastropods, crystals are twinned, in cephalopods, they are pseudohexagonal monocrystals, which are twinned; the main commercial sources of mother of pearl have been the pearl oyster, freshwater pearl mussels, to a lesser extent the abalone, popular for their sturdiness and beauty in the latter half of the 19th century. Used for pearl buttons during the 1900s, were the shells of the great green turban snail Turbo marmoratus and the large top snail, Tectus niloticus; the international trade in mother of pearl is governed by the Convention on International Trade in Endangered Species of Wild Fauna and Flora, an agreement signed by more than 170 countries. Nacre has been used for centuries for a variety o
The Siberian sturgeon is a species of sturgeon in the Acipenseridae family. It is most present in all of the major Siberian river basins that drain northward into the Kara and East Siberian Seas, including the Ob, Yenisei Lena, Kolyma Rivers, it is found in Kazakhstan and China in the Irtysh River, a major tributary of the Ob. The species epithet honors the German Russian biologist Karl Ernst von Baer. Siberian sturgeon is divided into two subspecies. However, recent studies suggest they may be monotypic, forming continuous genetically connected populations throughout their vast range; the nominate taxon accounts for 80% of all Siberian sturgeon and resides in the Ob River and its tributaries. This subspecies migrates to mouth of the Ob during the winter due to seasonal oxygen deficiency, swims thousands of kilometers upstream to spawn; the subspecies A. b. baicalensis, known as the Baikal sturgeon, is a unique lake form found in the northern end of Lake Baikal and migrates up the Selenga River to spawn.
Once considered a third form, "A. b. stenorrhynchus" resides in the eastern Siberian rivers and displays two life history patterns: a more abundant migratory one which swims considerable distances upstream from estuaries and deltas to spawn, a nonmigratory form. This form is now considered to be a junior synonym of A. b. baerii. Siberian sturgeon weigh about 65 kg, with considerable variability between and within river basins; the maximum recorded weight was 210 kg. As with all other acipenserids, the Siberian sturgeon are long-lived, late to reach sexual maturity, they spawn in strong current main stem river channels over gravel substrates. The Siberian sturgeon feeds on a variety of benthic organisms, such as crustaceans and chironomid larvae; the species had been in steep decline in its natural range due to habitat loss and poaching. Up to 40% of the Siberian sturgeon spawning habitat has been made inaccessible by damming. High levels of pollution in certain places have led to significant negative impacts on the reproductive development of gonads.
While wild catches have been declining, the Siberian sturgeon is farmed both for meat and to produce caviar from its roe. Because the Lena population of A. baerii completes its lifecycle in fresh water and sexually matures early, it is the most common original broodstock for captive-bred specimens. The main producer of Siberian sturgeon caviar is France, while the largest meat producers are Russia and China. G. I. Ruban, Siberian Sturgeon Acipenser baerii Brandt. A. baerii - IUCN assessment CITES Siberian sturgeon FAO fact page on A. baerii aquaculture