Crangon crangon is a commercially important species of caridean shrimp fished mainly in the southern North Sea, although also found in the Irish Sea, Baltic Sea, Mediterranean Sea, and Black Sea, as well as off much of Scandinavia and parts of Morocco's Atlantic coast. Its common names include brown shrimp, common shrimp, bay shrimp, and sand shrimp, while translation of its French name crevette grise (or its Dutch equivalent grijze garnaal) sometimes leads to the English version grey shrimp.
Adults are typically 30–50 mm (1.2–2.0 in) long, although individuals up to 90 mm (3.5 in) have been recorded. The animals have cryptic colouration, being a sandy brown colour, which can be changed to match the environment. They live in shallow water, which can also be slightly brackish, and feed nocturnally. During the day, they remain buried in the sand to escape predatory birds and fish, with only their antennae protruding.
Crangon is classified in the family Crangonidae, and shares the family's characteristic subchelate first pereiopods (where the movable finger closes onto a short projection, rather than a similarly sized fixed finger) and short rostrum.
Distribution and ecologyEdit
C. crangon has a wide range, extending across the northeastern Atlantic Ocean from the White Sea in the north of Russia to the coast of Morocco, including the Baltic Sea, as well as occurring throughout the Mediterranean and Black Seas. Despite its wide range, however, little gene flow occurs across certain natural barriers, such as the Strait of Gibraltar or the Bosphorus. The populations in the western Mediterranean Sea are thought to be the oldest, with the species' spread across the north Atlantic thought to postdate the Pleistocene.
Adults live epibenthically (on or near the sea-floor) especially in the shallow waters of estuaries or near the coast. It is generally highly abundant, and has a significant effect on the ecosystems where it lives.
Females reach sexual maturity at a length around 22–43 mm (0.87–1.69 in), while males are mature at 30–45 mm (1.2–1.8 in). The young hatch from their eggs into planktonic larvae. These pass through five moults before reaching the postlarval stage, when they settle to the sea-floor.
Historically, the commercial fishery was accomplished by horse drawn beam trawls on both sides of the Dover straits. In the sandy shallows of Morecambe Bay (Lancashire, UK) horses have been replaced by tractors. Some small fishing vessels also use beam trawls for brown shrimp. A few artisanal fishermen use hand-pushed nets. In all UK shrimp fisheries, the catch is first 'riddled' to release the young of shrimps and fish. The shrimps are then traditionally boiled on board before landing.
The UK lands an annual average of 1000 tonnes of brown shrimp, but the catch is highly variable between 1500 and 500 tonnes. In the Lancashire fishery for brown shrimp it has been shown that landings in any year are related to the annual catch, average annual air temperature (inverse) and total rainfall in the previous year. That has enabled a good prediction of annual landings one year in advance. Moreover, for the port of Lytham, the abundance of shrimp (annual catch per unit effort) was found to be closely correlated with the mean annual Zurich sunspot number for the period 1965-1975. Given that sunspot numbers are predictable, this provides another tool for the prediction of annual shrimp catch. Sunspot cycle No. 23 (1997-2008) is a good example of the correlation between UK annual brown shrimp catch and mean annual sunspot number.
The brown shrimp enjoys great popularity in Belgium, the Netherlands, northern Germany, and Denmark.
Shrimp in general are known as garnalen in Dutch. It is the basis of the dish tomate-crevettes, where the shrimp are mixed with mayonnaise and served in a hollowed-out uncooked tomato. The shrimp croquette is another Belgian speciality; the shrimp are in the interior of the battered croquette along with béchamel sauce. Freshly cooked, unpeeled brown shrimp are often served as a snack accompanying beer, typically a sour ale or Flemish red such as Rodenbach.
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- Based on data sourced from the FishStat database, FAO.
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- Ibid 10
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