Sprattus
Encyclopedia
Sprattus is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of small oily fish
Oily fish
Oily fish have oil in their tissues and in the belly cavity around the gut. Their fillets contain up to 30 percent oil, although this figure varies both within and between species...

 of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Clupeidae
Clupeidae
Clupeidae is the family of the herrings, shads, sardines, hilsa and menhadens. It includes many of the most important food fishes in the world.-Description and biology:...

. One can find many varieties served from the Iberian peninsula
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...

 to the Caucasus. They are commonly fried and eaten in British and Bulgarian cuisine. In northern and north-eastern Europe, European sprat
European sprat
The European sprat, Sprattus sprattus, also known as bristling, brisling or skipper, is a small, herring-like, marine fish. Found in European waters, it has silver grey scales and white-grey flesh. Specific seas in which the species occurs include the Irish Sea, Baltic Sea and Sea of the Hebrides...

s are commonly smoked and preserved in oil, which retains a strong smoky flavor. They are also recognized for their nutritional value, which contain high levels of polyunsaturated fats which are considered beneficial to the human diet. This highly active fish is recognized as a member of the family Clupeidae and tend to travel in large schools of other fish and swim continuously throughout the day.

They have also been often passed for other fish: for instance, the products sold as "anchovies" (since the 19th century) and "sardine
Sardine
Sardines, or pilchards, are several types of small, oily fish related to herrings, family Clupeidae. Sardines are named after the Mediterranean island of Sardinia, around which they were once abundant....

s" have often been prepared from Sprats, as the authentic ones used to be less accessible.

The fish itself is known for its smooth flavour and is often mistaken for baby sardines.

Species

  • Sprattus antipodum (Hector
    James Hector
    Sir James Hector was a Scottish geologist, naturalist, and surgeon who accompanied the Palliser Expedition as a surgeon and geologist...

    , 1872)
    (New Zealand blueback sprat)
  • Sprattus fuegensis (Jenyns
    Leonard Blomefield
    Leonard Jenyns, later known as Leonard Blomefield was a clergyman-naturalist.He was the youngest son of George Leonard Jenyns and his wife Mary the daughter of Dr. William Heberden . The Jenyns lived on Bottisham Hall property which his father had inherited on the death of his cousin Soame Jenyns...

    , 1842)
    (Fueguian sprat)
  • Sprattus muelleri (Klunzinger, 1879) (New Zealand sprat)
  • Sprattus novaehollandiae (Valenciennes
    Achille Valenciennes
    Achille Valenciennes was a French zoologist.Valenciennes was born in Paris, and studied under Georges Cuvier. Valenciennes' study of parasitic worms in humans made an important contribution to the study of parasitology...

    , 1847)
    (Australian sprat)
  • Sprattus sprattus (Linnaeus, 1758) (European sprat)
    • The most common species of Sprat that is discussed in research is the Sprattus sprattus, mostly because of its prevelance in the Baltic Sea.


Environment

The environment consists of locations in various parts of the world including New Zealand, Australia, and parts of Europe. By far, the most common ecological niche in which the Sprat, most commonly Sprattus sprattus, resides is the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

, located in Northern Europe. The Baltic Sea provides the Sprat with a highly diverse environment, with spacial and temporal potential allowing for successful reproduction. One of the most well-known locations in the Baltic Sea where they feed within is the Bornholm
Bornholm
Bornholm is a Danish island in the Baltic Sea located to the east of the rest of Denmark, the south of Sweden, and the north of Poland. The main industries on the island include fishing, arts and crafts like glass making and pottery using locally worked clay, and dairy farming. Tourism is...

 Basin, located in the southern portion of the Baltic Sea. Although the Baltic Sea has undergone several ecological changes during the last two decades, the Sprat has dramatically increased in population. Some of the environmental changes that have occurred in the Baltic Sea since the 1980s include a decrease in the salinity and the oxygen levels as a direct effect from less water flow into the sea itself.

Growth

The average length of time from fertilization to hatching is approximately fifteen days, with environmental factors playing a major role in the size and overall success of the Sprat.The development of young larval Sprat and reproductive success of the Sprat have been largely influenced by environmental factors. Some of these factors that are affecting the Sprat can be seen in the Baltic Sea, where specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

, water temperature, depth, and other such factors play a role in the success of the Sprat. The amount of Sprat over the last two decades has fluctuated due primarily to availability of zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

, a common food source, and also from overall changes in Clupeidae total abundance. Although the overall survival rates of the Sprat decreased in the late 1980s and early 1990s, there has been an increase in the last two decades. Recent studies suggesting that there is a progression in the reproductive success of the Sprat acknowledge that there has been a significant increase in spawning stock biomass, or SSB. One of the main concerns for reproductive success for the Sprat include winters that are exceedingly cold, as cold temperatures, especially in the Baltic Sea, have been known to affect the development of Sprat eggs and larvae.

Metabolism

The metabolic rate of the Sprat is highly influenced by environmental factors such as water temperature. Several related fish such as C. harengus have a much lower metabolic rate than that of the Sprat and this may be due to size differences among the related species. The reason for high levels of metabolism for the Sprat is due to exceedingly high activity levels throughout the day.

Predation and Feeding

In the Baltic Sea, Cod
Cod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...

, Herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...

, and Sprat are considered the most important species. Cod is the top predator while the herring and Sprat are recognized primarily as prey. This has been proven by many studies that analyze the stomach contents of such fish, often finding contents that immediately signify predation among the species. Although cod primarily feed on adult Sprat, Sprat tend to feed on cod before they have been fully developed. The Sprat tends to prey on the cod eggs and larvae. Furthermore, Sprat and herring are considered highly competitive for the same resources that are available to them. This is most present in the two species' vertical migration in the Baltic Sea, where they compete for the limited zooplankton that is available and necessary for their survival.

Sprat are highly selective in their diet and are completely zooplanktivourous. They eat various species of zooplankton in accordance to changes in the environment, as temperature and other such factors affect the availability of their food. During autumn, Sprat tend to have a diet high in Temora longicornis and Bosmina maritime. During the winter, their diet includes Pesudocalanus elongates. In both autumn and winter, there has been a tendency for Sprat to avoid eating Acartia spp. The main reason for Sprat not including Acartia spp. in their diet is that they tend to be very small in size and have a high escape response to predators such as the herring and Sprat. Although Acartia spp. may be present in large numbers, they also tend to dwell more towards the surface of the water, whereas the Sprat, especially during the day, tend to dwell in deeper waters.

Nutritional values

Sprat, if smoked, is considered to be one of the foods highest in purine
Purine
A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen-containing heterocycle in nature....

 content. People who suffer from gout
Gout
Gout is a medical condition usually characterized by recurrent attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe is the most commonly affected . However, it may also present as tophi, kidney stones, or urate...

 or high uric acid in the blood
Hyperuricemia
Hyperuricemia is a level of uric acid in the blood that is abnormally high. In humans, the upper end of the normal range is 360 µmol/L for women and 400 µmol/L for men.-Causes:...

 should avoid eating such foods. The main nutritional factor which Sprat contains are long-chain polyunsaturated fatty acids, including eicosapentaenoic acid
Eicosapentaenoic acid
Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...

 (EPA), and docosahexaenoic acid
Docosahexaenoic acid
Docosahexaenoic acid is an omega-3 fatty acid that is a primary structural component of the human brain and retina. In chemical structure, DHA is a carboxylic acid with a 22-carbon chain and six cis double bonds; the first double bond is located at the third carbon from the omega end...

(DHA). Present in amounts that are comparable to Atlantic Salmon, and up to seven times higher in EPA and DHA than common fresh fillets of gilthead, the Sprat contains approximately 1.43g/100g of these polyunsaturated fatty acids that have been found to help prevent mental, neural, and cardiovascular diseases. Further comparision of the canned fish that contain high amounts of polyunsaturated fatty acids show that although this is a canned species, the content of polyunsaturated fatty acids exceeds that of some terrestrial animal products such as Thai fermented pork sausage that contains only 0.01g/100g DHA, with no EPA being detected at all.
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