Atlantic halibut
Encyclopedia
The Atlantic halibut, Hippoglossus hippoglossus, is a flatfish
of the family Pleuronectidae
. They are demersal fish, that live on or near sand, gravel or clay bottoms at depths of between 50 and 2000 m (164 and 6,561.7 ft). The halibut
is among the largest teleost
(bony) fish in the world. Halibut are strong swimmers and are able to migrate
long distances. Halibut size is not age-specific, but rather tends to follow a cycle related to halibut (and therefore food) abundance.
The native habitat of the Atlantic halibut is the temperate waters of the northern Atlantic
, from Labrador
and Greenland
to Iceland
, the Barents Sea
and as far south as the Bay of Biscay
. It is the largest flatfish in the Atlantic and one of the largest species of flatfish in the world, reaching lengths of up to 4.7 metres (15.4 ft) and weights of 320 kilograms (705.5 lb). Its lifespan can reach 50 years.
is seasonal, although its timing varies somewhat with location. In the eastern Atlantic spawning occurs chiefly in March, April and May, although may span from January to June. Off the American coast, however, the spawning season appears to continue through the summer as late as September. After spawning both sexes migrate northwards in search of food. Young Atlantic halibut individuals feed on crustacean
s like crab
s and prawn
s. These halibut lie motionless and invisible on the sea bed, capturing any fish that pass within reach, although they may also hunt for fish in open water.
, drifting relatively helplessly, but at around four centimetres they migrate to the bottom. Young between the ages of two and four years live close to the shore, moving into deeper waters as they grow older.
in the food chain
.
, haddock
, herring
, pogge
, sand eel
s and capelin
, but it will also eat cephalopod
s, large crustacean
s and other benthos
organisms.
s, and are a staple food
of the Greenland shark
.
, Hippoglossus stenolepis.
. As of 2006, five countries - Canada, Norway, the UK, Iceland and Chile - were engaged in some form of Atlantic halibut aquaculture
production.
the Atlantic halibut now faces a high risk of extinction
in the wild, and in 1996 the IUCN rated it as Endangered
and placed it on its Red List
.
The Atlantic halibut is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. government’s 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 the U.S. Endangered Species Act(ESA). The American Fisheries Society has classified the species as "Vulnerable".
In 2010, Greenpeace International has added the atlantic halibut to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
of the family Pleuronectidae
Pleuronectidae
Righteye flounders are a family, Pleuronectidae, of flounders. They are called "righteye flounders" because most species lie on the sea bottom on their left side, with both eyes on the right side. The Paralichthyidae are the opposite, with their eyes on the left side.Their dorsal and anal fins are...
. They are demersal fish, that live on or near sand, gravel or clay bottoms at depths of between 50 and 2000 m (164 and 6,561.7 ft). The halibut
Halibut
Halibut is a flatfish, genus Hippoglossus, from the family of the right-eye flounders . Other flatfish are also called halibut. The name is derived from haly and butt , for its popularity on Catholic holy days...
is among the largest teleost
Teleostei
Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in the Triassic period, includes 20,000 extant species in about 40 orders; most living fishes are members of this group...
(bony) fish in the world. Halibut are strong swimmers and are able to migrate
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
long distances. Halibut size is not age-specific, but rather tends to follow a cycle related to halibut (and therefore food) abundance.
The native habitat of the Atlantic halibut is the temperate waters of the northern Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, from Labrador
Labrador
Labrador is the distinct, northerly region of the Canadian province of Newfoundland and Labrador. It comprises the mainland portion of the province, separated from the island of Newfoundland by the Strait of Belle Isle...
and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
to Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
, the Barents Sea
Barents Sea
The Barents Sea is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents...
and as far south as the Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...
. It is the largest flatfish in the Atlantic and one of the largest species of flatfish in the world, reaching lengths of up to 4.7 metres (15.4 ft) and weights of 320 kilograms (705.5 lb). Its lifespan can reach 50 years.
Description
The Atlantic halibut is a right-eyed flounder. It is flattened sideways and habitually lies on the left side of its body with both eyes migrating to the right side of its head during development. Its upper surface is a uniformly dark chocolate, olive or slate colour, and can be almost black (though younger fish are lighter and more mottled); the underside is pale. The end of the caudal fin is concave. Young fish are paler with more mottled colouration.Biology
The Atlantic halibut has a relatively slow growth rate and late onset of sexual maturity, with males attaining maturity at seven to eight years old, females at ten to eleven years, and individuals are thought to live up to 50 years. Little is known about their breeding except that spawningSpawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
is seasonal, although its timing varies somewhat with location. In the eastern Atlantic spawning occurs chiefly in March, April and May, although may span from January to June. Off the American coast, however, the spawning season appears to continue through the summer as late as September. After spawning both sexes migrate northwards in search of food. Young Atlantic halibut individuals feed on crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s like crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s and prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
s. These halibut lie motionless and invisible on the sea bed, capturing any fish that pass within reach, although they may also hunt for fish in open water.
Habitat
This marine fish usually lives on the ocean floor at depths of between 50 to 2000 metres, but it occasionally comes closer to the surface. The larvae are pelagicPelagic zone
Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...
, drifting relatively helplessly, but at around four centimetres they migrate to the bottom. Young between the ages of two and four years live close to the shore, moving into deeper waters as they grow older.
Role in ecosystem
The Atlantic halibut occupies a relatively high trophic levelTrophic level
The trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism...
in the food chain
Food chain
A food web depicts feeding connections in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs...
.
Diet
The diet of the Atlantic halibut consists mainly of other fish, e.g. codCod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
, haddock
Haddock
The haddock , also known as the offshore hake, is a marine fish distributed on both sides of the North Atlantic. Haddock is a popular food fish and is widely fished commercially....
, herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
, pogge
Pogge
Pogge is a German surnamePeople with the surname Pogge include:*Justin Pogge , Canadian ice hockey goal keeper*Thomas Pogge , German philosopher*Paul Pogge , German explorer of Africa...
, sand eel
Sand Eel
Sand eel or sandeel is the common name used for a considerable number of species of fish. Most of them are sea fish of the genera Hyperoplus , Gymnammodytes or Ammodytes...
s and capelin
Capelin
The capelin or caplin, Mallotus villosus, is a small forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat a great deal of krill and other crustaceans...
, but it will also eat cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s, large crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and other benthos
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
organisms.
Predators
Atlantic halibut are eaten by sealPinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
s, and are a staple food
Staple food
A staple food is one that is eaten regularly and in such quantities that it constitutes a dominant portion of a diet, and that supplies a high proportion of energy and nutrient needs. Most people live on a diet based on one or more staples...
of the Greenland shark
Greenland shark
The Greenland shark, Somniosus microcephalus, also known as the sleeper shark, gurry shark, ground shark, grey shark, or by the Inuit languages name Eqalussuaq, is a large shark native to the waters of the North Atlantic Ocean around Greenland and Iceland. These sharks live farther north than any...
.
Commercial fishing
The Atlantic halibut was formerly a very important food fish, but due to its slow rate of population growth it is unable to recover quickly from overfishing, and the fishery has largely collapsed. Consequently, fish labelled as "halibut" is usually one of the other large flatfishes, often Pacific halibutPacific halibut
The Pacific halibut is found on the continental shelf of the North Pacific Ocean and Bering sea. They are demersal, living on or near the bottom. The halibut is among the largest teleost fish in the world. Halibut are strong swimmers and are able to migrate long distances...
, Hippoglossus stenolepis.
Farming
Due to its popularity as a food fish, Atlantic halibut has attracted investment in fish farmingFish farming
Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...
. As of 2006, five countries - Canada, Norway, the UK, Iceland and Chile - were engaged in some form of Atlantic halibut aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
production.
Conservation status
Following overfishingOverfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
the Atlantic halibut now faces a high risk of extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
in the wild, and in 1996 the IUCN rated it as Endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
and placed it on its Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
.
The Atlantic halibut is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. government’s 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 the U.S. Endangered Species Act(ESA). The American Fisheries Society has classified the species as "Vulnerable".
In 2010, Greenpeace International has added the atlantic halibut to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."