Merluccius merluccius

Merluccius merluccius is a slim-bodied fish with a large head and large jaws in which are set a number of large curved teeth, The inside of the mouth and the branchial cavity are black. The body is at its widest just behind its head. It has two dorsal fins, the first triangular, high with a short base, while the second is long, nearly the same length as the anal fin, and both the second dorsal fin and the anal fin have a slightly convex profile. The caudal fin is well developed and has a truncate margin. The lateral line is straight and darker than the background colour. It is blue-grey on the back, silvery on the flanks and whitish on the underside. They grow to but this is rare and a more common larger size is . ==Distribution==

Merluccius merluccius is found in the eastern Atlantic from Norway and Iceland, south along the European coast to the Straits of Gibraltar and south along the west coast of Africa to Mauritania. It also occurs in the Mediterranean Sea. In the Baltic Sea it does not normally extend further east than the Kattegat but it has been recorded as far east as Lithuania. ==Habitat and biology==

The European hake is normally found at depths of between and , although it may also occur within a wider range of depths, being found from inshore waters as shallow as down to . During the day it stays close to the bottom and at night it becomes more active and uses more of the water column. This species has a very long spawning period, which differs between populations, spawning occurring latest in the more northerly populations. In the Mediterranean spawning lasts from December to June, February–May in the Bay of Biscay, April–July off western Iceland and May–August off western Scotland. In the central Mediterranean Sea the young hake, between and in total length, fed predominantly on the euphasiid Nictiphanes couchi and the mysid Lophogaster typicus with decapods as secondary prey. At total lengths between and had a more varied diet with an increased utilisation of euphausiids but they also consumed an increased number of decapods, these were from a wide variety of species, such as Chlorotocus crassicornis, Alpheus glaber, Plesionika heterocarpus, Pasiphaea sivado, and Solenocera membranacea with fish and mysids being less important. Small cephalopods especially Sepiolidae, Sepietta oweniana and Alloteuthis media were also taken. As the hake grows larger fish become more important in the diet, hake with total lengths of between and have diets dominated by clupeids, especially pilchards and anchovies. Once a length of was attained the fish had shifted to an entirely piscivorous diet and the favoured prey changed to centracanthids such as Spicara flexuosa and Centracanthus cirrus with the importance of clupeids declining at the same time. Decapods were also taken, especially Processa spp. and Solenocera membranacea while mysids, euphausiids and cephalopods were not a feature of the diets of these larger fish. The rate of cannibalism recorded increased with increasing size with the larger fish having a diet consisting of up to 71% smaller conspecifics. Its habit of feeding on clupeids led to the vernacular name "herring hake", this may lead to hake being netted along with the herring. This is consistent with a 19th-century account: "It is a very voracious fish, devouring great numbers of herrings and pilchards; hence it is frequently called the Herring Hake." Parasites Merluccius merluccius parasites have been well studied and as many as nineteen species of metazoan parasites have been identified on hake in a single study from the Mediterranean. These included five species of ectoparasite, one species of Monogenea and four species of Copepoda and fourteen species of endoparasite made up of Platyhelminthes: four digeneans, two cestodes and six nematodes: as well as two acanthocephalans. ==Fisheries==

Merluccius merluccius is one of the most important demersal quarry species for fisheries over the western European continental shelf and this means that it is extensively studied. There are two main stocks of European Hake in the Atlantic, a northern and a southern one. The northern stock is thought to be being exploited within its safe biological limits and to have an increasing population, although in 2011 the total allowable catch was exceeded by up to 30%. The southern and Mediterranean populations are thought to be being overexploited and the fisheries to be outside sustainable limits. The main fishing areas where hake at caught are to the north and west of Scotland, the west and south of Ireland, the Bay of Biscay, the Portuguese coast and the western coast North Africa. ==Conservation==

The northern European hake stock has recovered since the introduction of measures in 2001. Fisheries are regulated through restrictions on fishing effort, such as selectivity, fishing closures and minimum landing size. Additionally, individual states lay down their own regulations on matters such as minimum landing size, examples being Turkey where the minimum landing size is or Morocco where it is , this is also the European Union's minimum landing size. M. merluccius has been assessed on some Regional red Lists and the population in the Mediterranean is classed a Vulnerable, in the Baltic as Near Threatened and that in the Eastern Central Atlantic as Least Concern. Overall the Northeast Atlantic stock appears to be expanding its range, and of the two distinct stocks, northern and southern, the northern stock has shown an increase in stock biomass, which over the five years to 2015 increased by a factor of five. On the other hand, the southern stock is still overfished, albeit slightly, and the stock biomass in the 10 years to 2015 increased. Therefore, the IUCN class Merluccius merluccius as Least Concern. ==Use as food==

European hake is mainly sold in its fresh form, but it may also be frozen, dried, salted and canned. The flesh has a mild flavour, more subtle than that of cod with a white flaky texture. The raw flesh is quite soft but when it has been cooked the texture changes to firm and meaty. In France this popular species is marketed as "colin" and occasionally as "saumon blanc", i.e. "white salmon". It is also a popular food fish in Iberia where it is grilled, pan-fried and baked. The meat can be matched with strong flavours and hake is often cooked with tomatoes, garlic, chorizo and paprika. A medium-sized hake, known in Spanish as , is often presented with its mouth biting its tail receiving the name of ("torus hake"). , "the hake that bites its tail", is a proverbial Spanish expression for circular reasoning and vicious circles. ==References==