Demersal fish, also known as groundfish, live and feed on or near the bottom of

sea A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...

s or

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s (the demersal zone).Walrond
Carl . "Coastal fish - Fish of the open sea floor"
Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks. In coastal waters, they are found on or near the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

, and in deep waters, they are found on or near the

continental slope A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margi ...

or along the continental rise. They are not generally found in the deepest waters, such as abyssal depths or on the

abyssal plain An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They ...

, but they can be found around

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

s and islands. The word ''demersal'' comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''demergere'', which means ''to sink''. Demersal fish are

bottom feeder A bottom feeder is an aquatic animal that feeds on or near the bottom of a body of water. Biologists often use the terms ''benthos''—particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bristlew ...

s. They can be contrasted with

pelagic fish Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs. ...

, which live and feed away from the bottom in the open water column. Demersal fish fillets contain little

fish oil Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega−3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors of certain eicosanoids that are known to reduce inflammation in the bod ...

(one to four per cent), whereas pelagic fish can contain up to 30 per cent.

Types

Demersal fish can be divided into two main types: strictly

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

fish which can rest on the sea floor, and benthopelagic fish which can float in the water column just above the sea floor. Benthopelagic fish have

neutral buoyancy Neutral buoyancy occurs when an object's average density is equal to the density of the fluid in which it is immersed, resulting in the buoyant force balancing the force of gravity that would otherwise cause the object to sink (if the body's de ...

, so they can float at depth without much effort, while strictly benthic fish are denser, with negative buoyancy so they can lie on the bottom without any effort. Most demersal fish are benthopelagic. As with other bottom feeders, a mechanism to deal with substrate is often necessary. With demersal fish the sand is usually pumped out of the mouth through the

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In c ...

. Most demersal fish exhibit a flat ventral region so as to more easily rest their body on the substrate. The exception may be the

flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish Order (biology), suborder Pleuronectoidei, also called the Heterosomata. In many species, both eyes lie on one side of the head, one or the other migrating through or around ...

, which are laterally depressed but lie on their sides. Also, many exhibit what is termed an "inferior" mouth, which means that the mouth is pointed downwards; this is beneficial as their food is often below them in the substrate. Those bottom feeders with upward-pointing mouths, such as stargazers, tend to seize swimming prey.

Benthic fish

Benthic fish are denser than water, so they can rest on the sea floor. They either lie-and-wait as

ambush predator Ambush predators or sit-and-wait predators are carnivorous animals that capture their prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey u ...

s, at times covering themselves with sand or otherwise camouflaging themselves, or move actively over the bottom in search for food. Benthic fish which can bury themselves include dragonets,

and

stingray Stingrays are a group of sea Batoidea, rays, a type of cartilaginous fish. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae (deepwate ...

Flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish Order (biology), suborder Pleuronectoidei, also called the Heterosomata. In many species, both eyes lie on one side of the head, one or the other migrating through or around ...

are an order of ray-finned benthic fishes which lie flat on the ocean floor. Examples are

flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuary, estuaries. Taxonomy The name "flounder" is used for several only distantly related speci ...

, sole,

turbot The turbot ( ) ''Scophthalmus maximus'' is a relatively large species of flatfish in the family Scophthalmidae. It is a demersal fish native to marine or brackish waters of the Northeast Atlantic, Baltic Sea and the Mediterranean Sea. It is a ...

, plaice, and halibut. The adult fish of many species have both eyes on one side of the head. When the fish hatches, one eye is located on each side of its head. But as the fish grows from the larval stage, one eye migrates to the other side of the body as a process of

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

. The flatfish then changes its habits, and camouflages itself by lying on the bottom of the ocean floor with both eyes facing upwards. The side to which one eye migrates depends on the species; with some species both eyes are ultimately on the left side, whereas with other species the eyes are on the right. File:Pseudopleuronectes americanus.jpg,

Flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuary, estuaries. Taxonomy The name "flounder" is used for several only distantly related speci ...

have both eyes on one side of their head File:Flounder camo md.jpg, Some flatfish can camouflage themselves on the ocean floor File:Taeniura lymma 2.jpg, Bluespotted ribbontail rays migrate in schools onto shallow sands to feed on mollusks, shrimps, crabs and worms. File:Sphyrna mokarran head.jpg, The

great hammerhead The great hammerhead (''Sphyrna mokarran'') is the largest species of hammerhead shark, belonging to the family Sphyrnidae, attaining an average length of and reaching a maximum length of . It is found in tropical and warm temperate waters world ...

detects the electrical signatures of stingrays buried in the sand and pins them with its "hammer". Flounder ambush their prey, feeding at soft muddy area of the sea bottom, near bridge piles, docks, artificial and coral reefs. Their diet consists mainly of fish spawn,

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

s and small fish. The

swings its head in broad angles over the sea floor to pick up the electrical signatures of stingrays buried in the sand. It then uses its "hammer" to pin down the stingray.Hammerschlag, Rick
Sandy Plains: Great Hammerhead Shark
''ReefQuest Centre for Shark Research''. Retrieved: 6 June 2022. File:Pacific hagfish Myxine.jpg, Pacific hagfish resting on bottom. Hagfish coat themselves and any dead fish they find with noxious slime making them inedible to other species. File:Bathypterois grallator.jpg, The tripodfish ('' Bathypterois grallator''), a species of spiderfish, uses its fin extensions to "stand" on the bottom. File:Caelorinchus mirus (Gargoyle fish).gif, Gargoyle fish File:Fringe-Lipped Flathead.jpg, The fringe-lipped flathead is found in estuaries Some fishes do not fit into the above classification. For example, the family of nearly blind spiderfishes, common and widely distributed, feed on benthopelagic zooplankton. Yet they are strictly benthic fish, since they stay in contact with the bottom. Their fins have long rays they use to "stand" on the bottom while they face the current and grab zooplankton as it passes by. The bodies of benthic fish are adapted for ongoing contact with the sea floor. Swimbladders are usually absent or reduced, and the bodies are usually flattened in one way or another.Moyle and Cech, 2004, p. 13 Following Moyle and Cech (2004) they can be divided into five overlapping body shapes:

Benthopelagic fish

Benthopelagic fish inhabit the water just above the bottom, feeding on benthos and zooplankton. Most demersal fish are benthopelagic. Deep sea benthopelagic

teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

s all have swimbladders. The dominant species, rattails and cusk eels, have considerable biomass. Other species include deep sea

cod Cod (: cod) is the common name for the demersal fish genus ''Gadus'', belonging to the family (biology), 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 ''Gad ...

s ( morids), deep sea eels, halosaurs and notacanths.Bone 2008, p. 43. Benthopelagic sharks, like the deep sea squaloid sharks, achieve neutral buoyancy with the use of large oil-filled livers.Bone 2008, p. 42. Sharks adapt well to fairly high pressures. They can often be found on slopes down to about 2000 metres, scavenging on food falls such as dead whales. However, the energy demands of sharks are high, since they need to swim constantly and maintain a large amount of oil for buoyancy. These energy needs cannot be met in the extreme oligotrophic conditions that occur at great depths. Shallow water stingrays are benthic, and can lie on the bottom because of their negative buoyancy. Deep sea stingrays are benthopelagic, and like the squaloids have very large livers which give them neutral buoyancy. Benthopelagic fish can be divided into flabby or robust body types. Flabby benthopelagic fishes are like bathypelagic fishes; they have a reduced body mass, and low metabolic rates, expending minimal energy as they lie and wait to

ambush An ambush is a surprise attack carried out by people lying in wait in a concealed position. The concealed position itself or the concealed person(s) may also be called an "". Ambushes as a basic military tactics, fighting tactic of soldi ...

prey. An example of a flabby fish is the cusk-eel ''Acanthonus armatus'', a predator with a huge head and a body that is 90 per cent water. This fish has the largest ears (

otolith An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle (ear), utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule ...

s) and the smallest brain in relation to its body size of all known vertebrates.Fine ML, Horn MH and Cox B (1987
"''Acanthonus armatus'', a Deep-Sea Teleost Fish with a Minute Brain and Large Ears"
''Proceedings of the Royal Society B'', 230(1259)257-265. Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey. They often live around features, such as

s, which have strong currents. Commercial examples are the orange roughy and Patagonian toothfish.

Habitats

The edge of the

marks the boundary where the shelf gives way to, and then gradually drops into abyssal depths. This edge marks the boundary between coastal, relatively shallow, benthic habitats, and the deep benthic habitats. Coastal demersal fishes live on the bottom of inshore waters, such as bays and estuaries, and further out, on the floor of the

. Deep water demersal fish live beyond this edge, mostly down the

s and along the continental rises which drop to the

s. This is the

continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental marg ...

, constituting about 28% of the total oceanic area.P. J. Cook, Chris Carleton (2000) "Continental Shelf Limits: The Scientific and Legal Interface", Other deep sea demersal fish can also be found around

s and islands. The term ''bathydemersal fish'' is sometimes used instead of "deep water demersal fish". ''Bathydemersal'' refers to demersal fish which live at depths greater than 200 metres. The term ''epibenthic'' is also used to refer to organism that live on top of the ocean floor, as opposed to those that burrow into the seafloor substrate. However the terms ''mesodemersal'', ''epidemersal'', ''mesobenthic'' and ''bathybenthic'' are not used.

Coastal

Coastal demersal fish are found on or near the seabed of coastal waters between the

shoreline A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

and the edge of the

, where the shelf drops into the deep ocean. Since the continental shelf is generally less than 200 metres deep, this means that coastal waters are generally

epipelagic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

. The term includes demersal reef fish and demersal fish that inhabit

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

inlet An inlet is a typically long and narrow indentation of a shoreline such as a small arm, cove, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea. Overview In ...

s and bays. File:Mangrovejack.jpg, The mangrove jack eats

s File:Puffer Fish DSC01257.JPG, Many puffer fish species crush the shells of

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

s File:Opsanus beta 1.jpg, The venomous toadfish, a

, blends into sandy or muddy bottoms. File:Titan Triggerfish.jpg, Triggerfish use a jet of water to uncover sand dollars buried in sand Young mangrove jacks, a sought after eating and sport fish, dwell in

around

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

roots, fallen trees, rock walls, and any other snag areas where smaller prey reside for protection. When they mature, they migrate into open waters, sometimes hundreds of kilometres from the coast to spawn. Uranoscopus sulphureus

Stargazers are found worldwide in shallow waters. They have eyes on top of their heads and a large upward-facing mouth. They bury themselves in sand, and leap upwards to ambush benthopelagic fish and

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s that pass overhead. Some species have a worm-shaped lure growing out of the floor of the mouth, which they wiggle to attract prey. Stargazers are venomous and can deliver

electric shock An electrical injury (electric injury) or electrical shock (electric shock) is damage sustained to the skin or internal organs on direct contact with an electric current. The injury depends on the Current density, density of the current, tissu ...

s. They have been called "the meanest things in creation." Other examples of coastal demersal fish are

, plaice, monkfish and sole.

Deep water

Deep water demersal fish occupy the benthic regions beyond the continental margins. On the

, demersal fishes are common. They are more diverse than coastal demersal fish, since there is more habitat diversity. Further out are the

s. These flat, featureless regions occupy about 40 per cent of the ocean floor. They are covered with

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

but largely devoid of benthic life ( benthos). Deep sea benthic fishes are more likely to associate with canyons or rock outcroppings among the plains, where invertebrate communities are established. Undersea mountains (

s) can intercept deep sea currents, and cause productive upwellings which support benthic fish. Undersea mountain ranges can separate underwater regions into different ecosystems.Moyle and Cech, 2004, p. 587 Rattails and brotulas are common, and other well-established families are eels, eelpouts,

hagfish Hagfish, of the Class (biology), class Myxini (also known as Hyperotreti) and Order (biology), order Myxiniformes , are eel-shaped Agnatha, jawless fish (occasionally called slime eels). Hagfish are the only known living Animal, animals that h ...

es, greeneyes, batfishes and lumpfishes. The bodies of deep water demersal fishes are muscular with well developed organs. In this way they are closer to mesopelagic fishes than bathypelagic fishes. In other ways, they are more variable. Photophores are usually absent, eyes and swimbladders range from absent to well developed. They vary in size, and larger species, greater than one metre, are not uncommon. Giant grenadier

Deep sea demersal fish are usually long and narrow. Many are eels or shaped like eels. This may be because long bodies have long lateral lines. Lateral lines detect low-frequency sounds, and some demersal fishes have muscles that drum such sounds to attract mates.Haedrich RL (1996
"Deep-water fishes: evolution and adaptation in the earth's largest living spaces"
''Journal of Fish Biology'' 49(sA):40-53. Smell is also important, as indicated by the rapidity with which demersal fish find traps baited with bait fish. The main diet of deep sea demersal fish is

s of the deep sea benthos and

carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...

. Smell, touch and lateral line sensitivities seem to be the main sensory devices for locating these.Moyle and Cech, 2004, p. 588 Like coastal demersal fish, deep sea demersal fish can be divided into benthic fish and benthopelagic fish, where the benthic fish are negatively buoyant and benthopelagic fish are neutrally buoyant. The availability of plankton for food diminishes rapidly with depth. At , the biomass of plankton is typically about 1 per cent of that at the surface, and at about 0.01 per cent. Given there is no sunlight, energy enters deep water zones as organic matter. There are three main ways this happens. Firstly, organic matter can move into the zone from the continental landmass, for example, through currents that carry the matter down rivers, then plume along the continental shelf and finally spill down the continental slope. Other matter enters as particulate matter raining down from the overhead water column in the form of

marine snow In the deep ocean, marine snow (also known as "ocean dandruff") is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to ...

, or as sinking overhead plant material such as eelgrass, or as "large particles" such as dead fish and whales sinking to the bottom. A third way energy can arrive is through fish, such as vertically migrating mesopelagic fishes that can enter into the demersal zone as they ascend or descend. The demersal fish and invertebrates consume organic matter that does arrive, break it down and recycle it. A consequence of these energy delivery mechanisms is that the abundance of demersal fish and invertebrates gradually decrease as the distance from continental shorelines increases.Moyle and Cech, 2004, p. 594 Although deep water demersal fish species are not generally picky about what they eat, there is still some degree of specialisation. For example, different fish have different mouth sizes, which determines the size of the prey they can handle. Some feed mostly on benthopelagic organisms. Others fed mostly on epifauna (invertebrates on top of the seafloor surface, also called ''epibenthos''), or alternatively on infauna (invertebrates that burrow into the seafloor substrate). Infauna feeders can have considerable sediment in their stomachs. Scavengers, such as snubnosed eels and

, also eat infauna as a secondary food source.Sedberry GR and Musick JA (1978
"Feeding strategies of some demersal fishes of the continental slope and rise off the mid-Atlantic coast of the USA"
''Marine Biology'', 44:357-375. File:Simenchelys parasiticus.jpg, Snubnosed eel File:Ilyophis brunneus.jpg, Muddy arrowtooth eel File:Urophycis tenuis.jpg, White hake Some feed on carrion. Cameras show that when a dead fish is placed on the bottom, vertebrate and invertebrate scavengers appear very quickly. If the fish is large, some scavengers burrow in and eat it from the inside out. Some fish, such as

grenadier A grenadier ( , ; derived from the word ''grenade'') was historically an assault-specialist soldier who threw hand grenades in siege operation battles. The distinct combat function of the grenadier was established in the mid-17th century, when ...

s, also appear and start feeding on the scavenging invertebrates and amphipods. Other specialization is based on depth distribution. Some of the more abundant upper continental slope fish species, such as

cutthroat eel Cutthroat eels are a family, Synaphobranchidae, of eels, the only members of the suborder Synaphobranchoidei. They are found worldwide in temperate and tropical seas. Cutthroat eels range from in length. They are Benthos, bottom-dwelling fish, ...

and longfinned hake, mainly feed on epipelagic fish. But generally, the most abundant deep water demersal fish species feed on invertebrates.Moyle and Cech, 2004, p. 595 At great depths, food scarcity and extreme pressure limits the ability of fish to survive. The deepest point of the ocean is about 11,000 metres. Bathypelagic fishes are not normally found below 3,000 metres. It may be that extreme pressures interfere with essential enzyme functions.Ryan
"Deep-sea creatures: The bathypelagic zone"
''Te Ara - the Encyclopedia of New Zealand''. Updated 21 September 2007. The deepest-living fish known, the strictly benthic '' Abyssobrotula galatheae'', eel-like and blind, feeds on benthic invertebrates. A living example was trawled from the bottom of the Puerto Rico Trench in 1970 from a depth of 8,370 metres (27,453 ft). In 2008, a shoal of 17 hadal snailfish, a species of deep water snailfish, was filmed by a UK-Japan team using remote operated landers at depths of in the Japan Trench in the Pacific. The fish were 30 centimetres long (12 in), and were darting about, using vibration sensors on their nose to catch shrimps. The team also reported that the appearance of the fish, unlike that of most deep sea fish, was surprisingly "cute", and that they were surprised by how active the fish were at these depths.

Demersal fisheries

Most demersal fish of commercial or recreational interest are coastal, confined to the upper 200 metres. Commercially important demersal food fish species include

, such as

, sole,

, plaice, and halibut. Also important are

, hake, redfish, haddock,

bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Wood * Bass or basswood, the wood of the tilia americana tree Music * Bass (sound), describing low-frequency sound or one of several instruments in th ...

conger ''Conger'' ( ) is a genus of marine congrid eels. It includes some of the largest types of eels, ranging up to or more in length, in the case of the European conger. Large congers have often been observed by divers during the day in parts of t ...

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

s, rays and chimaeras.Grainger RJK and Garcia SM (1996
"Chronicles of Marine Fishery Landings (1950-1994): Trend Analysis and Fisheries Potential"
''

FAO The Food and Agriculture Organization of the United Nations; . (FAO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition ...

: Fisheries technical paper 359.'' Rome. . The following table shows the world capture production of some groups of demersal species in tonnes. Black sea bass inhabit US coasts from

Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...

to NE

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

and the eastern

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

, and are most abundant off the waters of New York. They are found in inshore waters (bays and sounds) and offshore in waters up to a depth of 130 m (425'). They spend most of their time close to the sea floor and are often congregated around bottom formations such as rocks, man-made reefs, wrecks, jetties, piers, and bridge pilings. Black sea bass are sought after recreational and commercial fish, and have been overfished. File:Hippoglossoides platessoides.jpg, American plaice are usually found between 90 and 250 metres (but have been found at 3000 m). They feed on small fishes and invertebrates. File:Atlantic cod.jpg,

Atlantic cod The Atlantic cod (: cod; ''Gadus morhua'') is a fish of the family Gadidae, widely consumed by humans. It is also commercially known as '' cod'' or ''codling''.Black sea bass File:Epinephelus malabaricus.jpg,

Grouper Groupers are a diverse group of marine ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all members of this f ...

are ambush predators with a powerful sucking system that sucks their prey in from a distance

are often found around reefs. They have stout bodies and large mouths. They are not built for long-distance or fast swimming. They can be quite large, and lengths over a meter and weights up to 100 kg are not uncommon. They swallow prey rather than biting pieces off it. They do not have many teeth on the edges of their jaws, but they have heavy crushing tooth plates inside the

pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

. They lie in wait, rather than chasing in open water. They are found in areas of hard or consolidated substrate, and use structural features such as ledges, rocks, and coral reefs (as well as

artificial reef An artificial reef (AR) is a human-created freshwater or marine benthic structure. Typically built in areas with a generally featureless bottom to promote Marine biology#Reefs, marine life, it may be intended to control #Erosion prevention, erosio ...

s like wrecks and sunken barges) as their habitat. Their mouth and

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

s form a powerful sucking system that sucks their prey in from a distance. They also use their mouth to dig into sand to form their shelters under big rocks, jetting it out through their gills. Their gill muscles are so powerful that it is nearly impossible to pull them out of their cave if they feel attacked and extend those muscles to lock themselves in. There is some research indicating that roving coral groupers (''Plectropomus pessuliferus'') sometimes cooperate with giant morays in hunting. File:Toothfish.jpg, The Patagonian toothfish is a robust benthopelagic fish File:Orange roughy.png, The orange roughy is also a robust benthopelagic fish File:Macruronus novaezelandiae.jpg, The blue grenadier (hoki), a deep water demersal fish, is subjected to a large sustainable fishing industry in New Zealand. Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey. They often live around features, such as

s, which have strong currents. Commercial examples are the orange roughy and Patagonian toothfish. Because these fish were once abundant, and because their robust bodies are good to eat, these fish have been commercially harvested.

Conservation status

Major demersal fishery species in the

North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...

such as

, plaice, monkfish and sole, are listed by the ICES as "outside safe biological limits." The by-catch problem A major problem in conservation of demersal fish populations is that of by-catch, whereby fish are caught by accident when targeting other species. The European Commission has written that “A key issue is that many of the most important demersal stocks (i.e. those that live on or near the bottom of the sea) are caught in mixed fisheries. In practice, this means that each time a vessel retrieves its fishing gear, its catch will consist of a mix of different species.” This has led to a situation whereby, even when the International Council for the Exploration of the Sea recommends a Total Allowable Catch of zero for a given demersal species in order to allow replenishment of population, the European Council nonetheless sets the Total Allowable Catch far above zero so long as the catch is by-catch, in order not to prevent trawlers fishing for other species. This means that those threatened species do not get the chance to replenish even when not directly targeted by trawlers. * The Common Sole, '' Solea solea,'' is sufficiently broadly distributed that it is not considered a threatened species; however,

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

in Europe has produced severely diminished populations, with declining catches in many regions. For example, the western

English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...

and

Irish Sea The Irish Sea is a body of water that separates the islands of Ireland and Great Britain. It is linked to the Celtic Sea in the south by St George's Channel and to the Inner Seas off the West Coast of Scotland in the north by the North Ch ...

sole fisheries face potential collapse according to data in the UK Biodiversity Action Plan. * Sole, along with the other major bottom-feeding fish in the North Sea such as cod, monkfish, and plaice, is listed by the ICES as "outside safe biological limits." Moreover, they are growing less quickly now and are rarely older than six years, although they can reach forty. World stocks of large predatory fish and large ground fish such as sole and flounder were estimated in 2003 to be only about 10% of pre-industrial levels. According to the

World Wildlife Fund The World Wide Fund for Nature (WWF) is a Swiss-based international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the ...

in 2006, "of the nine sole stocks, seven are overfished with the status of the remaining two unknown." Data is insufficient to assess the remaining stocks; however, landings for all stocks are at or near historical lows." * World stocks of large predatory fish and large ground fish such as sole and flounder were estimated in 2003 to be only about 10% of pre-industrial levels, largely due to overfishing. Most overfishing is due to the extensive activities of the fishing industry. Current research indicate that the flounder population could be as low as 15 million due to heavy overfishing and industrial pollution along the Gulf of Mexico surrounding the coast of Texas. * Seafood Watch have placed on their list of seafood that

sustainability Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...

-minded consumers should avoid the following demersal fish:

sturgeon Sturgeon (from Old English ultimately from Proto-Indo-European language, Proto-Indo-European *''str̥(Hx)yón''-) is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the ...

(imported wild), Chilean seabass, cod (Atlantic, imported Pacific),

(Atlantic), halibut (Atlantic), sole (Atlantic),

grouper Groupers are a diverse group of marine ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all members of this f ...

, monkfish, orange roughy, demersal

, red snapper and tilapia (Asia farmed).

Notes

References

* Bone Q and Moore RH (2008
''Biology of Fishes''
Taylor & Francis Group. * Merrett NR and Haedrich RL (1997
''Deep-sea demersal fish and fisheries''
Chapman and Hall. . * Moyle, PB and Cech, JJ (2004) ''Fishes, An Introduction to Ichthyology.'' 5th Ed, Benjamin Cummings.
Demersal fisheries
Fishery Research Services. Retrieved 22 July 2009.
Deep water demersal fisheries
Joint Nature Conservation Committee. Retrieved 22 July 2009.

External links

Groundfish retention
{{DEFAULTSORT:Demersal Fish Aquatic ecology Marine biology Ichthyology Fishing industry