Barndoor skate
Encyclopedia
The barndoor skate, Dipturus laevis, is a species
of marine
cartilaginous fish
in the skate
family
(family Rajidae) of the order Rajiformes
. It is native to the northwestern Atlantic Ocean
, and is found from the Grand Banks
of Newfoundland and the southern side of the Gulf of St. Lawrence south to North Carolina
. The fish is one of the largest skates found in the North Atlantic Ocean, reaching lengths of up to 1.5 metres (5 ft). It is carnivorous
, feeding on invertebrate
s and other fish
found near the sea floor.
After peaking in the 1950s, the population of the barndoor skate dramatically declined in the 1960s and early 1970s as a result of overfishing and is now listed as endangered by the World Conservation Union
. Barndoor populations have increased substantially since 1990. In most cases, the barndoor skate is not intentionally harvested by the commercial fishing industry—it is usually considered by-catch
in the trawling
nets used to target other species of fish.
into broad, flat, wing
-like appendages used to propel the fish through the water. These fins have a concave front edge with rounded posterior corners. Like shark
s, it has a boneless skeleton
made of cartilage
, a tough, elastic substance composed of collagen
ous and/or elastic fibers, cells
, and a firm, gel-like substance called the matrix. It has slot-like body openings called gill slit
s on the underside of the body beneath the pectoral fins that lead from the gill
s. The dorsal fin
s are close together and far removed from the tail. It has two eyes on its dorsal surface, located approximately 5.5 centimetres (2.2 in) apart.
The fish's upper surface is brown to reddish brown with many scattered darker spots, lighter streaks, and reticulations. The center of each pectoral fin is marked with an oval spot or blotch. The lower surface is light, white to grey, blotched irregularly with gray spots. The barndoor skate is unique from other species of skate in its having a straight line that begins at the snout and ends at the anterior margin of the outer corner of the disk, but stopping short of the disk.
The barndoor skate is one of the largest skates found in the North Atlantic Ocean. It can reach lengths of up to 1.5 metres (5 ft) and can weigh up to 18 kilograms (39.7 lb). There have been unconfirmed reports of individuals reaching lengths of 1.8 metres (6 ft). A 71 centimetre barndoor skate weighs an average of 2–3 kg (4.4–6.6 lb).
The tail is moderately short and does not have large thorn-like structures called dermal denticles that are normally found on skates. This lack of denticles distinguishes it from all but two species of skates that are found in the western Atlantic. Larger individuals do have three rows of smaller denticles on the tail, and mature females also possess denticles on the head and shoulders, and along the dorsal midbelt of the disk and tail. Denticles are completely absent on small individuals.
down to North Carolina
. There were reports in the 19th century that the range of the fish extended as far south as northeastern Florida
, but more recent research suggests that the Florida discoveries may have actually been a misidentification of R. floridana. It is found on various types of ocean bottoms including soft muddy, sandy, and rocky bottoms. It can be found from the shoreline to depths of up to 750 metres (2,460.6 ft), although it is most commonly found at depths of less than 150 metres (492.1 ft). It inhabits waters in a broad range of temperatures, from just above freezing to 20 °C (68 °F). It appears to move closer to shore in the autumn and further out to sea in the warmer months. It tolerates brackish water
where the salinity
is as low as 21 to 24 parts per thousand, but it prefers salinity between 31 and 35 parts per thousand. It is believed to not exhibit any north-south migratory
patterns.
The fish is carnivorous
, with its prey consisting mainly of benthic
invertebrates and fish
es. Such food items include polychaete
s, gastropods, bivalve mollusks
, rock crabs
, cancer crabs
, spider crabs
, lobster
s, shrimp
s, squid
s, and fishes including spiny dogfish
, alewife
, Atlantic herring
, menhaden
, hake
s, sculpin
s, cunner, tautog
, sand lance
, butterfish
, and various flounder
s. Juveniles primarily subsist on benthic invertebrates such as polychaetes, copepod
s, amphipods, isopods, crangon shrimp
, and euphausiids. Individuals have been found with the denticles on the snout worn smooth, indicating that the snout is used to dig in the mud or sand to obtain bivalve mollusks.
that has commercial value, but of those, the species that are most frequently targeted are the winter skate (Leucoraja ocellata) and the thorny skate
(Amblyraja radiata
). The barndoor skate is most commonly considered by-catch
by commercial trawlers operating in the northwestern Atlantic that target other commercially valuable species of fish using bottom trawling
. When harvested, the flesh of the barndoor skate is used as bait
, fish meal
, pet food, and the meat from its wings is sold for human consumption. Since 1981, landings of skates have increased substantially, partly in response to increased demand for lobster bait, and more significantly, to the increased export market for skate wings. Currently, commercial retention and sale of barndoor skate is prohibited in the United States.
. After a 12-month study, the NMFS announced in 2002 that listing the species as endangered or threatened was not warranted. It cited increases in abundance and biomass of barndoor skate observed during surveys since 1993, which had become quite rapid by that time. . In 1994, the World Conservation Union
had listed the barndoor skate as "vulnerable" under the 1994 Categories and Criteria, but in 2003, it reassessed the species as "endangered" on the IUCN Red List
. .
Each year the National Oceanic and Atmospheric Administration
(NOAA) estimates current population levels for a variety of aquatic species of special interest, and releases an annual report showing the progress being made to reduce harvesting of overfished species. When a species has been determined to be either overfished or subject to overfishing, the regional fishery management councils are required to develop a plan to correct the problem. In 2006, NOAA published a press release stating that as a result of conservation efforts, between 2004 and 2005, monitored stocks of the barndoor skate had grown to a level that the NOAA no longer considers "overfished".. In 2010, Greenpeace International has added the barndoor skate (dipturus laevis) 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."
in 1818. The scientific name was later changed to the currently valid name Dipturus laevis. It has also been misidentified as Raja granulata by Theodore Gill
, an American ichthyologist, in 1879. The genus name, Dipturus, is derived from the Greek
words di, meaning two, and pteryx, meaning wing. Raja
, the original genus which was coined by Carolus Linnaeus
in 1758, is still recognized as a valid subgenus
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of marine
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
cartilaginous fish
Chondrichthyes
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...
in the skate
Skate
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. There are more than 200 described species in 27 genera. There are two subfamilies, Rajinae and Arhynchobatinae ....
family
Family
In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...
(family Rajidae) of the order Rajiformes
Rajiformes
Rajiformes is one of the four orders of batoids, flattened cartilaginous fishes related to sharks.Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion...
. It is native to the northwestern Atlantic Ocean
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...
, and is found from the Grand Banks
Grand Banks
The Grand Banks of Newfoundland are a group of underwater plateaus southeast of Newfoundland on the North American continental shelf. These areas are relatively shallow, ranging from in depth. The cold Labrador Current mixes with the warm waters of the Gulf Stream here.The mixing of these waters...
of Newfoundland and the southern side of the Gulf of St. Lawrence south to North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. The fish is one of the largest skates found in the North Atlantic Ocean, reaching lengths of up to 1.5 metres (5 ft). It is carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
, feeding on invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s and other fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
found near the sea floor.
After peaking in the 1950s, the population of the barndoor skate dramatically declined in the 1960s and early 1970s as a result of overfishing and is now listed as endangered by the World Conservation Union
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
. Barndoor populations have increased substantially since 1990. In most cases, the barndoor skate is not intentionally harvested by the commercial fishing industry—it is usually considered by-catch
By-catch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
in the trawling
Trawling
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....
nets used to target other species of fish.
Physical description
The barndoor skate is a flat-bodied fish with a large, disk-like body with sharply angled corners and a pointed snout. Its pectoral fins have evolvedEvolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
into broad, flat, wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...
-like appendages used to propel the fish through the water. These fins have a concave front edge with rounded posterior corners. Like shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, it has a boneless skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
made of cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
, a tough, elastic substance composed of collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
ous and/or elastic fibers, cells
Chondrocyte
Chondrocytes are the only cells found in cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteoglycans...
, and a firm, gel-like substance called the matrix. It has slot-like body openings called gill slit
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, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s on the underside of the body beneath the pectoral fins that lead from the gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s. The dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s are close together and far removed from the tail. It has two eyes on its dorsal surface, located approximately 5.5 centimetres (2.2 in) apart.
The fish's upper surface is brown to reddish brown with many scattered darker spots, lighter streaks, and reticulations. The center of each pectoral fin is marked with an oval spot or blotch. The lower surface is light, white to grey, blotched irregularly with gray spots. The barndoor skate is unique from other species of skate in its having a straight line that begins at the snout and ends at the anterior margin of the outer corner of the disk, but stopping short of the disk.
The barndoor skate is one of the largest skates found in the North Atlantic Ocean. It can reach lengths of up to 1.5 metres (5 ft) and can weigh up to 18 kilograms (39.7 lb). There have been unconfirmed reports of individuals reaching lengths of 1.8 metres (6 ft). A 71 centimetre barndoor skate weighs an average of 2–3 kg (4.4–6.6 lb).
The tail is moderately short and does not have large thorn-like structures called dermal denticles that are normally found on skates. This lack of denticles distinguishes it from all but two species of skates that are found in the western Atlantic. Larger individuals do have three rows of smaller denticles on the tail, and mature females also possess denticles on the head and shoulders, and along the dorsal midbelt of the disk and tail. Denticles are completely absent on small individuals.
Habitat and diet
The barndoor skate occurs in a range extending from the banks of Newfoundland, the southern Gulf of St. Lawrence, and along the northeastern coast and offshore banks of Nova ScotiaNova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
down to North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. There were reports in the 19th century that the range of the fish extended as far south as northeastern Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, but more recent research suggests that the Florida discoveries may have actually been a misidentification of R. floridana. It is found on various types of ocean bottoms including soft muddy, sandy, and rocky bottoms. It can be found from the shoreline to depths of up to 750 metres (2,460.6 ft), although it is most commonly found at depths of less than 150 metres (492.1 ft). It inhabits waters in a broad range of temperatures, from just above freezing to 20 °C (68 °F). It appears to move closer to shore in the autumn and further out to sea in the warmer months. It tolerates brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
where the salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
is as low as 21 to 24 parts per thousand, but it prefers salinity between 31 and 35 parts per thousand. It is believed to not exhibit any north-south migratory
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...
patterns.
The fish is carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
, with its prey consisting mainly of benthic
Benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...
invertebrates and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es. Such food items include polychaete
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
s, gastropods, bivalve mollusks
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
, rock crabs
Grapsidae
Grapsidae is a family of crabs known variously as marsh crabs, shore crabs or talon crabs. It is not confirmed that the family forms a monophyletic group and some taxa may belong in other families...
, cancer crabs
Cancer (genus)
Cancer is a genus of marine crabs in the family Cancridae. It includes 8 extant species and 3 extinct species, including familiar crabs of the littoral zone, such as the European edible crab , the Jonah crab and the red rock crab...
, spider crabs
Majidae
Majidae is a family of crabs, comprising around 700 marine species with a carapace that is longer than it is broad, and which forms a point at the front. The legs can be very long in some species, leading to the name "spider crab"...
, lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...
s, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
s, and fishes including spiny dogfish
Spiny dogfish
The spiny dogfish, spurdog, mud shark, or piked dogfish, Squalus acanthias, is one of the best known of the dogfish which are members of the family Squalidae in the order Squaliformes. While these common names may apply to several species, Squalus acanthias is distinguished by having two spines ...
, alewife
Alewife
The alewife is a species of herring. There are anadromous and landlocked forms. The landlocked form is also called a sawbelly or mooneye...
, Atlantic herring
Atlantic herring
Atlantic herring is a fish in the family Clupeidae. It is one of the most abundant fish species on earth. Herring can be found on both sides of the Atlantic Ocean, congregating in large schools. They can grow up to in length and weigh more than...
, menhaden
Menhaden
Menhaden, also known as mossbunker, bunker and pogy, are forage fish of the genera Brevoortia and Ethmidium, two genera of marine fish in the family Clupeidae.-Description:...
, hake
Hake
The term hake refers to fish in either of:* family Phycidae of the northern oceans* family Merlucciidae of the southern oceans-Hake fish:...
s, sculpin
Sculpin
A Sculpin is a fish that belongs to the order Scorpaeniformes, suborder Cottoidei and superfamily Cottoidea, that contains 11 families, 149 genera, and 756 species...
s, cunner, tautog
Tautog
The tautog or blackfish also known as the "poor-man's lobster" , Tautoga onitis, is a fish of the wrasse family found in salt water from Nova Scotia to Georgia...
, sand lance
Sand lance
A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lance are commonly known as "sand eels" or "sandeels", though they are not related to true eels. Another variant name is launce, and all names of the fish are references to its slender body and...
, butterfish
Stromateidae
The family Stromateidae of butterfishes contains 17 species of fish in 3 genera. Butterfishes live in coastal waters off the Americas, western Africa and in the Indo-Pacific.-Species:* Genus Pampus...
, and various flounder
Flounder
The flounder is an ocean-dwelling flatfish species that is found in coastal lagoons and estuaries of the Northern Atlantic and Pacific Oceans.-Taxonomy:There are a number of geographical and taxonomical species to which flounder belong.*Western Atlantic...
s. Juveniles primarily subsist on benthic invertebrates such as polychaetes, copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s, amphipods, isopods, crangon shrimp
Crangonidae
The family Crangonidae is a taxon of shrimps, of the superfamily Crangonoidea, including the commercially important species Crangon crangon. Its type genus is Crangon...
, and euphausiids. Individuals have been found with the denticles on the snout worn smooth, indicating that the snout is used to dig in the mud or sand to obtain bivalve mollusks.
Importance to humans
The barndoor skate is one of five skates in the Gulf of MaineGulf of Maine
The Gulf of Maine is a large gulf of the Atlantic Ocean on the east coast of North America.It is delineated by Cape Cod at the eastern tip of Massachusetts in the southwest and Cape Sable at the southern tip of Nova Scotia in the northeast. It includes the entire coastlines of the U.S...
that has commercial value, but of those, the species that are most frequently targeted are the winter skate (Leucoraja ocellata) and the thorny skate
Thorny skate
The thorny skate is a species of fish in Rajidae family. It mainly lives near the bottom of the coastline of North Atlantic Ocean in depths ranging from 20 to 1000 metres and temperatures from 1 to 10 degrees Celsius. It was also located in Lake Melville, near Goose Bay, Labrador. Rivers empty...
(Amblyraja radiata
Thorny skate
The thorny skate is a species of fish in Rajidae family. It mainly lives near the bottom of the coastline of North Atlantic Ocean in depths ranging from 20 to 1000 metres and temperatures from 1 to 10 degrees Celsius. It was also located in Lake Melville, near Goose Bay, Labrador. Rivers empty...
). The barndoor skate is most commonly considered by-catch
By-catch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by commercial trawlers operating in the northwestern Atlantic that target other commercially valuable species of fish using bottom trawling
Bottom trawling
Bottom trawling is trawling along the sea floor. It is also often referred to as "dragging".The scientific community divides bottom trawling into benthic trawling and demersal trawling...
. When harvested, the flesh of the barndoor skate is used as bait
Bait (luring substance)
Bait is any substance used to attract prey, e.g. in a mousetrap.-In Australia:Baiting in Australia refers to specific campaigns to control foxes, wild dogs and dingos by poisoning in areas where they are a problem...
, fish meal
Fish meal
Fish meal, or fishmeal, is a commercial product made from both whole fish and the bones and offal from processed fish. It is a brown powder or cake obtained by rendering pressing the cooked whole fish or fish trimmings to remove most of the fish oil and water, and then ground...
, pet food, and the meat from its wings is sold for human consumption. Since 1981, landings of skates have increased substantially, partly in response to increased demand for lobster bait, and more significantly, to the increased export market for skate wings. Currently, commercial retention and sale of barndoor skate is prohibited in the United States.
Conservation
Abundances of barndoor skate dropped precipitously in the 1960s and early 1970s, coinciding with the period of intense fishing by foreign factory trawlers. The abundance remained very low through around 1990, but increased nearly exponentially from 1990-2005, and have been approaching the levels observed in the 1960s In 1998, Casey and Myers published a controversial study claiming that barndoor skate was nearly extinct. However, they only presented data through 1993, so that the recovery that started in the early 1990s was not clearly evident. In 1999, two conservation groups, GreenWorld, based in Cambridge, Massachusetts, and The Center for Marine Conservation, based in Washington, D.C., petitioned the National Marine Fisheries Service (NMFS) to have the barndoor skate listed under the Endangered Species ActEndangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
. After a 12-month study, the NMFS announced in 2002 that listing the species as endangered or threatened was not warranted. It cited increases in abundance and biomass of barndoor skate observed during surveys since 1993, which had become quite rapid by that time. . In 1994, the World Conservation Union
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
had listed the barndoor skate as "vulnerable" under the 1994 Categories and Criteria, but in 2003, it reassessed the species as "endangered" on the IUCN 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...
. .
Each year the National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
(NOAA) estimates current population levels for a variety of aquatic species of special interest, and releases an annual report showing the progress being made to reduce harvesting of overfished species. When a species has been determined to be either overfished or subject to overfishing, the regional fishery management councils are required to develop a plan to correct the problem. In 2006, NOAA published a press release stating that as a result of conservation efforts, between 2004 and 2005, monitored stocks of the barndoor skate had grown to a level that the NOAA no longer considers "overfished".. In 2010, Greenpeace International has added the barndoor skate (dipturus laevis) 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."
Taxonomy and naming
The fish was originally described as Raja laevis by Samuel Latham MitchillSamuel Latham Mitchill
Samuel Latham Mitchill was an American physician, naturalist, and politician from New York. He was born in Hempstead, New York...
in 1818. The scientific name was later changed to the currently valid name Dipturus laevis. It has also been misidentified as Raja granulata by Theodore Gill
Theodore Gill
Theodore Nicholas Gill was an American ichthyologist, mammalogist, malacologist and librarian.Born and educated in New York City under private tutors, Gill early showed interest in natural history. He was associated with J...
, an American ichthyologist, in 1879. The genus name, Dipturus, is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
words di, meaning two, and pteryx, meaning wing. Raja
Raja (genus)
Raja is a genus of skates in the family Rajidae, containing nearly thirty species. They are flat-bodied cartilaginous fish with a rhombic shape due to their large pectoral fins extending from or nearly from the snout to the base of their tail. Their sharp snouts produced by a cranial projection of...
, the original genus which was coined by Carolus Linnaeus
Carolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
in 1758, is still recognized as a valid subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
.