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Sprat is the common name applied to a group of forage fish belonging to the genus Sprattus in the family Clupeidae. The term also is applied to a number of other small sprat-like forage fish (Clupeoides, Clupeonella, Corica, Ehirava, Hyperlophus, Microthrissa, Nannothrissa, Platanichthys, Ramnogaster, Rhinosardinia, and Stolothrissa). Like most forage fishes, sprats are highly active, small, oily fish. They travel in large schools with other fish and swim continuously throughout the day.
They are recognized for their nutritional value, as they contain high levels of polyunsaturated fats, considered beneficial to the human diet. They are eaten in many places around the world. Sprats are sometimes passed off as other fish; products sold as having been prepared from anchovies (since the 19th century) and others sold as sardines sometimes are prepared from sprats, as the authentic ones once were less accessible. They are known for their smooth flavour and are easy to mistake for baby sardines.
Species
True sprats
True sprats belong to the genus Sprattus in the family Clupeidae. The five species are:
{| class="wikitable collapsible"
|-
! colspan="11"| Sprattus species
|-
! Common name
! Scientific name
! Maximum<br/>length
! Common<br/>length
! Maximum<br/>weight
! Maximum<br/>age
! Trophic<br/>level
! Fish<br/>Base
! FAO
! ITIS
! IUCN status
|-
| New Zealand blueback sprat
| Sprattus antipodum <small>(Hector 1872)</small>
| align="right" | 12.0 cm
| align="right" | 9.0 cm
| align="right" |
| align="right" |
| align="center" | 3.0
| align="center" |
| align="center" |
| align="center" |
| align="center" | LC IUCN 3 1.svg <small>Least concern</small>
|-
| Falkland sprat
| Sprattus fuegensis <small>(Blomefield, 1842)</small>
| align="right" | 18.0 cm
| align="right" | 15.0 cm
| align="right" |
| align="right" |
| align="center" | 3.4
| align="center" |
| align="center" |
| align="center" |
| align="center" | LC IUCN 3 1.svg <small>Least concern</small>
|-
| New Zealand sprat
| Sprattus muelleri <small>(Klunzinger, 1879)</small>
| align="right" | 13.0 cm
| align="right" | 10.0 cm
| align="right" |
| align="right" |
| align="center" | 3.0
| align="center" |
| align="center" |
| align="center" |
| align="center" | LC IUCN 3 1.svg <small>Least concern</small>
|-
| Australian sprat
| Sprattus novaehollandiae <small>(Valenciennes, 1847)</small>
| align="right" | 14.0 cm
| align="right" |
| align="right" |
| align="right" |
| align="center" | 3.0
| align="center" |
| align="center" |
| align="center" |
| align="center" | LC IUCN 3 1.svg <small>Least concern</small>
|-
| European sprat*
| Sprattus sprattus <small>(Linnaeus, 1758)</small>
| align="right" | 16.0 cm
| align="right" | 12.0 cm
| align="right" |
| align="right" | 6 years
| align="center" | 3.0
| align="center" |
| align="center" |
| align="center" |
| align="center" | LC IUCN 3 1.svg <small>Least concern</small>
|}
<small>* Type species</small>
Other sprats
The term also is commonly applied to a number of other small sprat-like forage fish that share characteristics of the true sprat. Apart from the true sprats, FishBase lists another 48 species whose common names ends with "sprat". Some examples are:
{| class="wikitable collapsible"
|-
! colspan="11"| Sprat-like species
|-
! Common name
! Scientific name
! Maximum<br/>length
! Common<br/>length
! Maximum<br/>weight
! Maximum<br/>age
! Trophic<br/>level
! Fish<br/>Base
! FAO
! ITIS
! IUCN status
|-
| Black Sea sprat
| Clupeonella cultriventris <small>(Nordmann, 1840)</small>
| align="right" | 14.5 cm
| align="right" | 10 cm
| align="right" |
| align="right" | 5 years
| align="center" | 3.0
| align="center" |
| align="center" |
| align="center" |
| align="center" | LC IUCN 3 1.svg <small>Least concern</small>
|}
Characteristics
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The average length of time from fertilization to hatching is about 15 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 affecting the sprat can be seen in the Baltic Sea, where specific gravity, water temperature, depth, and other such factors play a role in their success.
In recent decades the number of sprat has fluctuated, due primarily to availability of zooplankton, a common food source, and also from overall changes in Clupeidae total abundance.
One of the most well-known locations in the Baltic Sea where they forage for their food is the Bornholm Basin, 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. One of the environmental changes that has occurred in the Baltic Sea since the 1980s includes a decrease in water salinity, due to a lack of inflow from the North Sea that contains high saline and oxygen content. 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.
In both autumn and winter, a tendency exists for sprats to avoid eating Acartia spp., because 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 toward the surface of the water, whereas the sprats, especially during the day, tend to dwell in deeper waters.
File:Global total production sprats.png|The total capture of sprats in 2010 reported by the FAO was 667,000 tonnes.
Sprats contain long-chain polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). They are present in amounts comparable to Atlantic salmon, and up to seven times higher in EPA and DHA than common fresh fillets of gilt-head bream. The sprats contain about 1.43 g/100 g of these polyunsaturated fatty acids that have been found to help prevent mental, neural, and cardiovascular diseases.
<gallery widths=160px>
File:Sprattus sprattus.jpg|Sprattus sprattus, the European sprat
File:Visserijmuseum048.jpg|Creel with sprat, National Fishery Museum, Belgium
File:Visserijmuseum047.jpg|Oven for smoking sprat, National Fishery Museum, Belgium
</gallery>
References
Further reading
- Tony Ayling & Geoffrey Cox, Collins Guide to the Sea Fishes of New Zealand, (William Collins Publishers Ltd, Auckland, New Zealand 1982)