The cusk or tusk (''Brosme brosme'') is a North Atlantic

cod Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not call ...

-like fish in the ling family

Lotidae The Lotidae are a family of cod-like fishes commonly known as lings or rocklings. They are found in the Arctic, Atlantic, and Pacific Oceans. Except for a few species of ''Gaidropsarus'', all are restricted to the Northern Hemisphere. All speci ...

. It is the only species in the genus ''Brosme''. Its other common names include torsk, European cusk, and brosmius.Cusk
Fish and seafood fact sheets.

Agriculture and Agri-Food Canada Agriculture and Agri-Food Canada (AAFC; sometimes Ag-Canada; french: Agriculture et Agroalimentaire Canada)''Agriculture and Agri-Food Canada'' is the applied title under the Federal Identity Program; the legal title is Department of Agriculture ...

Description

It is easily distinguished at a glance from other cod-like fish, as it has only one

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

. Also characteristic of the fish is the nature of its dorsal, caudal, and anal fins; they are continuous at the base, but separated by very deep notches so that they are obviously distinct. Moreover, the caudal fin is evenly rounded. It is variable in color, from slate to reddish brown above, and paling to gray on the lower sides and underneath. Older fish are usually plain-colored, while the young often have transverse yellow bands on their sides. Their maximum length is about 4 ft (120 cm) and top weight is about 45 lb (20 kg). The IGFA world record stands at 37 lb 14 oz (17,20 kg), caught by Anders Jonasson outside Sørøya in northern Norway.

Distribution and habitat

It is distributed on both sides of the North Atlantic, mostly in moderately deep water. On the North American coast, it is regularly found southward to

Cape Cod Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer mont ...

and occasionally off

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

. Its maximum range covers most of the North Atlantic, including the waters around

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...

and the

Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe * Norwegians, both a nation and an ethnic group native to Norway * Demographics of Norway *The Norwegian language, including ...

coast. It is also found on the

Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North ...

. Cusk show little genetic differentiation over large distances, except where populations are surrounded by deep-water areas, namely on the Mid-Atlantic Ridge and the

Rockall Bank Rockall () is an uninhabitable granite islet situated in the North Atlantic Ocean. The United Kingdom claims that Rockall lies within its exclusive economic zone (EEZ) and is part of its territory, but this claim is not recognised by Ireland. ...

. This suggests deep-water areas are barriers for adult movements, and though they have pelagic eggs and larvae, dispersal during early life stages is not effective over long distances. It is normally found in water deeper than 600 ft (200 m), and practically always is taken over rough bottoms where rocks, ledges, or gravel are common. Good fishing areas are usually much more limited than is the case with

haddock The haddock (''Melanogrammus aeglefinus'') is a saltwater ray-finned fish from the family Gadidae, the true cods. It is the only species in the monotypic genus ''Melanogrammus''. It is found in the North Atlantic Ocean and associated seas wher ...

, or

pollock Pollock or pollack (pronounced ) is the common name used for either of the two species of North Atlantic marine fish in the genus ''Pollachius''. '' Pollachius pollachius'' is referred to as pollock in North America, Ireland and the United Kingd ...

. It is an offshore fish and rarely is one taken in a harbor. It should not be confused with the

burbot The burbot (''Lota lota'') is the only gadiform (cod-like) freshwater fish. It is also known as bubbot, mariah, loche, cusk, freshwater cod, freshwater ling, freshwater cusk, the lawyer, coney-fish, lingcod, and eelpout. The species is closel ...

, which is also called the "freshwater cusk", of a different Lotidae genus.

Pollution

Like many other marine animals, the cusk is directly affected by

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

. A specific pollutant that affects them is inorganic mercury (Hg). Within aquatic ecosystems, mercury can get converted to methylmercury (MeHg), which is one of the most toxic species of mercury compounds. MeHGg is subject to

biomagnification Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a ...

and bioaccumulation within marine

food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one o ...

s. Cusk are a food source for many other organisms, so the toxins they accumulate over time directly affect any other organism that consumes them, including humans. Studies conducted in Western Norway, Central Europe, and the Mediterranean have shown that mercury concentrations within fish are highest in wild-marine fish, which sometimes exceed food-safety guidelines of 500 μg/kg, whereas wild-freshwater and farmed fish have less mercury within their system. This is probably due to the fact that most mercury first enters rivers from inland sources and then accumulates in marine environments where the cusk live. In addition to this, it has also been shown that mercury concentrations are higher within

fjords In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Icela ...

rather than coastal and open areas. This is likely due to the morphology of the fjords, or to local human activity. MercuryFoodChain-01

Habits

It spawns in the spring and summer, usually between April and early July. A medium-sized female has been known to produce more than two million buoyant eggs. The young live near the surface until they are about 2 in (5 cm) long, and then seek out rocky ocean floors in deep water.

Food

It is strictly a bottom-dwelling species, and is sluggish and a rather weak swimmer. It eats

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s and other soft-bodied

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s and

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

Fishing technique

Cusk are primarily fished on the North American North Atlantic coastal shelf near the American state of

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and ...

and the Canadian Maritimes. In the

Gulf of Maine , image = , alt = , caption = , image_bathymetry = GulfofMaine2.jpg , alt_bathymetry = , caption_bathymetry = Major features of the Gulf of Maine , location = Northeast coast of the ...

, cusk are chiefly taken on hook and line. Line trawls account for most of the commercial catch off the

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the Can ...

coast, and most of them are caught during the winter and spring. The commercial catch individuals run between 1 and 2 feet long (30–60 cm), and average about 5 lb (2 kg). It is an excellent food fish. It is marketed as fresh or frozen fillets; a part of the catch is smoked.

Conservation status

Fisheries and Oceans Canada Fisheries and Oceans Canada (DFO; french: Pêches et Océans Canada, MPO), is a department of the Government of Canada that is responsible for developing and implementing policies and programs in support of Canada's economic, ecological and sci ...

(DFO) considers this species endangered based on a 2012 Committee on the Status of Endangered Wildlife in Canada assessment. COSEWIC Species Database: Cusk. COSEWIC The status report identified that catches of cusk in the DFO summer bottom-trawl survey had declined by roughly 90% from 1970 to the late 1990s.SARA registry report on ''Cusk''
(PDF) - Fisheries and Oceans Canada report on the state of cusk fisheries A landings limit of 1000 mt was put in place in 1999 in the 4X North American Fisheries Organization area and was further restricted to 750 t and expanded to include the 4VWX5Z NAFO areas in 2003. Cusk are still commonly caught as bycatch in the longline and lobster fisheries and can be found in supermarkets in Atlantic Canada despite its threatened status. A study that was conducted in the Gulf of Maine region showed that the conservation status of cusk was partly dependent on future greenhouse gas emissions. Higher emissions showed greater habitat reduction, as much as 80% by the end of the century. Cusk is a US National Marine Fisheries Servic
species of concern
which are those species about which the National Oceanic and Atmospheric Administration
National Marine Fisheries Service
has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under th
Endangered Species Act
On March 9, 2007 the National Marine Fisheries Service announced the initiation of a status review to determine whether the species warrants listing under the act.NMFS. ''Endangered and Threatened Species; Initiation of a Status Review under the Endangered Species Act for Cusk''.''Federal Register;; v72, (March 9, 2007), 10710-10711.