| Nephrops norvegicus | |
|---|---|
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Family: | Nephropidae |
| Genus: | Nephrops |
| Species: | N. norvegicus |
| Binomial name | |
| Nephrops norvegicus | |
| Synonyms[2] | |
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Nephrops norvegicus, known variously as theNorway lobster,Dublin Bay prawn,langoustine (comparelangostino) orscampi, is a slim, coral-coloredlobster that grows up to 25 cm (10 in) long.[3] It is now the only extant species in the genusNephrops, after several other species were moved to the closely related genusMetanephrops. It lives in the north-easternAtlantic Ocean, and parts of theMediterranean Sea, but is absent from theBaltic Sea andBlack Sea. Adults emerge from their burrows at night to feed on worms and fish.
Nephrops norvegicus has the typical body shape of alobster, albeit narrower than the larger-bodied genusHomarus.[3] It is pale orange in colour, and grows to a typical length of 18–20 centimetres (7–8 in), or exceptionally 25 cm (10 in) long, including the tail andclaws. Acarapace covers the animal'scephalothorax, while the abdomen is long and segmented, ending in a broad tail fan. The first three pairs of legs bear claws, of which the first are greatly elongated and bear ridges ofspines. Of the two pairs ofantennae, the second is the longer and thinner.[4] There is a long, spinousrostrum, and thecompound eyes arekidney-shaped, providing the name of the genus, from theGreekrootsνεφρός (nephros, "kidney") andὄψ ("eye").[3]
Nephrops norvegicus is found in the north-easternAtlantic Ocean andNorth Sea as far north asIceland and northernNorway, and south toPortugal. It is found in theMediterranean Sea and is common in theAdriatic Sea,[5] notably the north Adriatic.[6] It is absent from both theBlack Sea and theBaltic Sea. Due to its ecological demands for particular sediments,N. norvegicus has a very patchy distribution, and is divided into over 30 populations. These populations are separated by inhospitable terrain, and adults rarely travel distances greater than a few hundred metres.[3]
Nephrops norvegicus adults prefer to inhabit muddy seabed sediments, with more than 40 percent silt and clay.[3] Theirburrows are semi-permanent,[7] and vary in structure and size. Typical burrows are 20 to 30 centimetres (8 to 12 in) deep, with a distance of 50 to 80 centimetres (20 to 30 in) between the front and back entrances. Norway lobsters spend most of their time either lying in their burrows or by the entrance, leaving their shelters only to forage or mate.[3]
Nephrops norvegicus is ascavenger andpredator[8] that makes short foraging excursions,[9][10] mainly during periods of subdued light. They feed on active prey, includingworms andfish,[11] which they capture with theirchelipeds and walking legs, and food is conveyed to the mouth using the anterior walking legs, assisted by themaxillipeds.[3]
There is evidence thatNephrops norvegicus is a major eater ofjellyfish.[12][13]
Nephrops norvegicus is thehost to a number ofparasites andsymbionts. A number ofsessile organisms attach to theexoskeleton ofN. norvegicus, including thebarnacleBalanus crenatus and theforaminiferanCyclogyra, but overallNephrops suffers fewer infestations of suchepibionts than other decapod crustaceans do.[14] In December 1995, thecommensalSymbion pandora was discovered attached to themouthparts ofNephrops norvegicus, and was found to be the first member of a newphylum,Cycliophora,[15] a finding described bySimon Conway Morris as "the zoological highlight of the decade".[16]S. pandora has been found in many populations ofN. norvegicus, both in the north Atlantic and in the Mediterranean Sea.[17] Individuals may be found on most segments of the lobster's mouthparts, but are generally concentrated on the central parts of the larger mouthparts, from themandible to the thirdmaxilliped.[18]
The most significant parasite ofN. norvegicus is adinoflagellate of the genusHematodinium, which has causedepidemic infection in fished populations ofN. norvegicus since the 1980s.Hematodinium is a genus that contains major pathogens of a wide variety of decapod crustaceans, although its internal taxonomy is poorly resolved. The species which attacksN. norvegicus causes asyndrome originally described as "post-moult syndrome", in which thecarapace turns opaque and becomes highly pigmented, thehaemolymph becomes milky white, and the animal appearsmoribund. Other parasites ofN. norvegicus include thegregarineprotozoanPorospora nephropis, thetrematodeStichocotyle nephropis and thepolychaeteHistriobdella homari.[14]
The typicallife span ofN. norvegicus is 5–10 years,[19] reaching 15 years in exceptional cases.[20] Itsreproductive cycle varies depending on geographical position: "the periods of hatching and spawning, and the length of the incubation period, vary with latitude and the breeding cycle changes from annual to biennial as one moves from south to north".[3] Incubation of eggs istemperature-dependent, and in colder climates, the duration of the incubation period increases. This means that, by the time hatching occurs, it may be too late for the females to take part in that year's breeding cycle. In warmer climates, the combined effects of recovery frommoulting and ovary maturation mean that spawning can become delayed. This, in turn, has the effect of the female missing out a year of egg carrying.[21]
Adult maleNephrops norvegicusmoult once or twice a year (usually in late winter or spring) and adult females moult up to once a year (in late winter or spring, after hatching of the eggs).[3] In annual breeding cycles, mating takes place in the spring or winter, when the females are in the soft, post-moult state.[22] The ovaries mature throughout the spring and summer months, and egg-laying takes place in late summer or early autumn. After spawning, the berried (egg-carrying) females return to their burrows and remain there until the end of the incubation period. Hatching takes place in late winter or early spring. Soon after hatching, the females moult and mate again.[3]
During the planktonic larval stage (typically 1 to 2 months in duration) the nephrops larvae exhibit a diel vertical migration behaviour as they are dispersed by the local currents. This complex biophysical interaction determines the fate of the larvae; the overlap between advective pathway destination and spatial distributions of suitable benthic habitats must be favourable in order for the larvae to settle and reach maturity.[23]
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The muscular tail ofNephrops norvegicus is frequently eaten, and its meat is known asscampi orlangoustine.N. norvegicus is eaten only on special occasions inSpain and Portugal, where it is less expensive than the common lobster,Homarus gammarus.[24]N. norvegicus is an important species forfisheries, being caught mostly bytrawling. Around 60,000 tonnes are caught annually, half of it in theUnited Kingdom'swaters.[25][failed verification]
Besides the established trawling fleets, a significant number of fleets usinglobster creels have developed. The better size and condition of lobsters caught by this method yield prices three to four times higher than animals netted by trawling. Creel fishing was found to have a reduced impact on the seafloor, require lower fuel consumption, and allow fishermen with smaller boats to participate in this high-value fishery. It has therefore been described as a reasonable alternative to demersal towed gears, and the allocation of additional fishing rights for this type of take has been suggested.[26]
The North East Atlantic individual biological stocks ofNephrops are identified as functional units. A number of functional units make up the sea areas over which a total allowable catch (TAC) is set annually by the EU Council of Ministers. For example, the TAC set for North SeaNephrops is based on the aggregate total tonnage of removals recommended by science for nine separate functional unit areas. This method has attracted criticism because it can promote theoverexploitation of a specific functional unit even though the overall TAC is under-fished. In 2016, the UK implemented a package of emergency technical measures with the cooperation of the fishing industry aimed at reducing fishing activity to induce recovery of theNephrops stock in the Farn(e) Deeps off North East England which was close to collapse. A stock assessment completed in 2018 by the International Council for the Exploration of the Sea (ICES) shows that fishing pressure has been cut and this stock is now below FMSY and that stock size is above MSY Btrigger meaning that the Farne Deeps nephrops stock is being fished at a sustainable level. However, ICES also warn that any substantial transfer of the current surplus fishing opportunities from other functional units to the Farne Deeps would rapidly lead to overexploitation. This suggests that controls on fishing effort should continue at least until the biomass reaches a size that is sustainable when measured against the level of fishing activity by all fishermen wanting to target the stock.[27] In July 2023 the area north-east of Farnes Deep was one of three sites designated as aHighly Protected Marine Area.[28]
Discards fromNephrops fishery may account for up to 37% of theenergy requirements of certain marinescavengers, such as thehagfishMyxine glutinosa.[29] Boats involved inNephrops fishery also catch a number of fish species such asplaice andsole, and it is thought that without that revenue,Nephrops fishery would be economically unviable.[30]
Nephrops norvegicus was one of the species included byCarl Linnaeus in his 175810th edition ofSystema Naturae, the starting point forzoological nomenclature. In that work, it was listed asCancer Norvegicus, with atype locality ofin Mari Norvegico ("in the Norwegian sea").[31] In choosing alectotype,Lipke Holthuis restricted the type locality to theKattegat at theKullen Peninsula in southernSweden (56°18′N12°28′E / 56.300°N 12.467°E /56.300; 12.467). Twosynonyms of the species have been published[2] – "Astacus rugosus", described by the eccentric zoologistConstantine Samuel Rafinesque in 1814 from material collected in theMediterranean Sea,[32] and "Nephropsis cornubiensis", described byCharles Spence Bate andJoshua Brooking Rowe in 1880.[33]
As new genera were erected, the species was moved, reaching its current position in 1814, whenWilliam Elford Leach erected the genusNephrops to hold this species alone.[2][34] Sevenfossil species have since been described in the genus.[35]
Populations in theMediterranean Sea are sometimes separated as "Nephrops norvegicus var.meridionalis Zariquiey, 1935", although this taxon is not universally considered valid.[3]
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