Tuesday, October 15, 2013

Seafood of the Week - Shrimp

Palaemon serratus, a caridean shrimp


The term shrimp is used to refer to some decapod crustaceans, although the exact animals covered can vary. Used broadly, it may cover any of the groups with elongated bodies and a primarily swimming mode of locomotion – chiefly Caridea and Dendrobranchiata. In some fields, however, the term is used more narrowly, and may be restricted to Caridea, to smaller species of either group, or to only the marine species. Under the broader definition, shrimp may be synonymous with prawn, covering stalk-eyed swimming crustaceans with long narrow muscular tails (abdomens), long whiskers (antennae) and slender legs. They swim forwards by paddling with swimmerets on the underside of their abdomens. Crabs and lobsters have strong walking legs, whereas shrimp have thin fragile legs which they use primarily for perching.
Shrimp are widespread and abundant. They can be found feeding near the seafloor on most coasts and estuaries, as well as in rivers and lakes. To escape predators, some species flip off the seafloor and dive into the sediment.[2] They usually live from one to seven years. Shrimp are often solitary, though they can form large schools during the spawning season. There are thousands of species, and usually there is a species adapted to any particular habitat. Any small crustacean which resembles a shrimp tends to be called one.
They play important roles in the food chain and are important food sources for larger animals from fish to whales. The muscular tails of shrimp can be delicious to eat, and they are widely caught and farmed for human consumption. Commercial shrimp species support an industry worth 50 billion dollars a year, and in 2010 the total commercial production of shrimp was nearly 7 million tons. Shrimp farming took off during the 1980s, particularly in China, and by 2007 the harvest from shrimp farms exceeded the capture of wild shrimp. There are significant issues with excessive bycatch when shrimp are captured in the wild, and with pollution damage done to estuaries when they are used to support shrimp farming. Many shrimp species are small as the term shrimp suggests, about 2 cm (0.79 in) long, but some shrimp exceed 25 cm (9.8 in). Larger shrimp are more likely to be targeted commercially, and are often referred to as prawns, particularly in Britain.






Shrimp are swimming crustaceans with long narrow muscular abdomens and long antennae. Unlike crabs and lobsters, shrimp have well developed pleopods (swimmerets) and slender walking legs; they are more adapted for swimming than walking. Historically, it was the distinction between walking and swimming that formed the primary taxonomic division into the former suborders Natantia and Reptantia. Members of the Natantia (shrimp in the broader sense) were adapted for swimming while the Reptantia (crabs, lobsters, etc.) were adapted for crawling or walking. Some other groups also have common names that include the word "shrimp"; any small swimming crustacean resembling a shrimp tends to be called one.



Shrimp and prawn
From Raymond Bauer in Remarkable Shrimps:
* Shrimp is characteristically used to refer to those crustaceans with long antennae, slender legs, and a laterally compressed, muscular abdomen that is highly adapted for both forward swimming and a backward (retrograde) escape response.
* Prawn is often used as a synonym of shrimp for penaeoidean and caridean shrimp, especially those of large size.
From the English Oxford Dictionaries:
* Shrimp: a small free-swimming crustacean with an elongated body, typically marine and frequently of commercial importance as food.
* Prawn: a marine crustacean which resembles a large shrimp.




Double-rigged shrimp trawler with one net up and the other being brought aboard


Commercial techniques for catching wild shrimp include otter trawls, seines and shrimp baiting. A system of nets is used when trawling. Baited traps are common in parts of the Pacific Northwest.
Shrimp trawling can result in very high incidental catch rates of non-target species. In 1997, the FAO found discard rates up to 20 pounds for every pound of shrimp. The world average was 5.7 pounds for every pound of shrimp. Trawl nets in general, and shrimp trawls in particular, have been identified as sources of mortality for species of finfish and cetaceans. Bycatch is often discarded dead or dying by the time it is returned to the sea, and may alter the ecological balance in discarded regions. Worldwide, shrimp trawl fisheries generate about 2% of the world's catch of fish in weight, but result in more than one third of the global bycatch total.
The most extensively fished species are the akiami paste shrimp, the northern prawn, the southern rough shrimp, and the giant tiger prawn. Together these four species account for nearly half of the total wild capture. In recent years, the global capture of wild shrimp has been overtaken by the harvest from farmed shrimp.






A shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe. The total global production of farmed shrimp reached more than 1.6 million tonnes in 2003, representing a value of nearly 9 billion U.S. dollars. About 75% of farmed shrimp are produced in Asia, in particular in China, Thailand and in the Philippines. The other 25% are produced mainly in Latin America, where Brazil is the largest producer. The largest exporting nation is Thailand.



Shrimp tail ready for eating



Shrimp are marketed and commercialized with several issues in mind. Most shrimp are sold frozen and marketed based on their categorization of presentation, grading, colour, and uniformity. Shrimp have high levels of omega-3 fatty acids and low levels of mercury. Usually shrimp is sold whole, though sometimes only the meat of shrimp is marketed.
As with other seafood, shrimp is high in calcium, iodine and protein but low in food energy. A shrimp-based meal is also a significant source of cholesterol, from 122 mg to 251 mg per 100 g of shrimp, depending on the method of preparation. Shrimp consumption, however, is considered healthy for the circulatory system because the lack of significant levels of saturated fat in shrimp means that the high cholesterol content in shrimp actually improves the ratio of LDL to HDL cholesterol and lowers triglycerides.
Shrimp and other shellfish are among the most common food allergens. They are not kosher and thus are forbidden in Jewish cuisine. Shrimp are halal according to some madhāhib, and therefore permissible to most, but not all, Muslims.







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