Order - Rajiformes
Family - Rajidae
Genus - Dipturus
Species - laevis
The barndoor skate was described in 1818 by Mitchill with the original combination of Raja laevis. The scientific name was later changed to the currently valid name Dipturus laevis. The genus name, Dipturus, is derived from the Greek words, di, meaning two, and pteryx, meaning fin. Raja, the original genus of Dipturus laevis, which was coined by Linnaeus in 1758, is still recognized as a valid subgenus.
The common name in the English language include barndoor skate, barn-door skate, and barn-door winter skate. Other
language common names include deurrog (Dutch), grande raie (French), and ladeportsrokke (Danish).
The barndoor skate is the largest skate residing in waters along the Atlantic coast of North America. Its northernmost border
includes the banks of Newfoundland, the southern Gulf of St. Lawrence, and the outer coast of Nova Scotia. To the south,
the barndoor skate inhabits areas as far as the northeast coast Florida (US). During the warmer summer and autumn months,
the barndoor skate moves offshore, returning to inshore waters in the winter and spring.
World distribution map for the barndoor skate
The barndoor skate can be found on various types of ocean bottom including soft muddy, sandy, and rocky bottoms. It can be
found from shoreline to, though it is most abundant at depths less than 492 feet (150 m), depths of up to 2,460 feet (750 m).
The broad temperature range in which the barndoor skate lives and breeds, from just above freezing to 68°F (20°C), can account
for the depth distribution of the species. Though the barndoor skate has been found in brackish water where the salinity is
21 to 24 parts per thousand (ppt), it prefers salinity between 31 and 35 ppt.
Importance to Humans
Barndoor skate: ventral and dorsal views
Bigelow and Schroeder (1948) FNWA
- · Distinctive Features
The broad disk of the barndoor skate has sharply angled corners and a pointed snout. The front edges of the skate's disk are
concave and its dorsal fins are close together. The posterior disk corners are rounded and the tail is moderately short. The
barndoor skate can be distinguished from other skates by a straight line that begins at the snout and ends at the anterior
margin of the outer corner of the disk, but does not intersect the disk.
- · Coloration
The upper surface of the barndoor skate is brown to reddish brown. This surface is marked with darker spots and blotches,
along with lighter streaks and reticulations. In particular, the center of each pectoral fin is marked with an oval spot
or blotch. The barndoor skate has a light, white to gray, lower surface. This surface is marked with gray blotches on the
snout that are more numerous in larger individuals. Both surfaces contain darkly pigmented ampullar pores near the eyes,
snout and on much of the anterior disk.
Barndoor skate dentition: A. Upper teeth from center of a jaw from a female, B. Teeth from
center of jaw from a male
Bigelow and Schroeder (1948) FNWA
The teeth of female and immature male barndoor skates are close-set and have rounded cusps. Teeth of mature males are widely
spaced and arranged in rows, with sharp-pointed cusps. The upper jaw of this skate consists of 30- to 40-tooth rows and the
rows of the lower jaw each contain between 28 and 38 teeth.
Denticles are absent from small specimens of the barndoor skate. Larger specimens have relatively small thorns on
anterior and posterior orbital rims and along the midline and in a line along the lateral aspect of the tail and between
the dorsal fins. Mature females also possess dermal denticles on the head and shoulders, and along the dorsal midbelt of
the disk and tail. The thorns are absent from the dorsal midline of the disk and from the shoulder region of the skate to
the base of the tail.
- ·Size, Age, and Growth
The barndoor skate is one of the largest skates in the north Atlantic Ocean. It is long-lived and slow growing. Reportedly,
one captured specimen measured nearly 59 inches (150 cm) TL and weighed almost 40 pounds (18.0 kg). There have been
unconfirmed reports of specimens that have reached 71 inches (180 cm) TL. Studies show that a barndoor skate weighing
4-7 pounds (2-3 kg) averages a length of 28-30 inches (71-76 cm).
Barndoor skates feed on a variety of prey including squid
© Doug Perrine
- · Food Habits
The prey of the barndoor skate consists mainly of fishes and invertebrates associated with the bottom. Such food items
include polychaetes, gastropods, bivalve mollusks, squids, crustaceans and fishes. Small individuals subsist on benthic
invertebrates such as polychaetes, copepods, amphipods, isopods, crangon shrimp, and euphausiids. Larger specimens are
capable of capturing larger and more active prey, including razor clams, large gastropods, squids, cancer crabs, spider
crabs, lobsters and fishes. Garman noticed that many times, the thorns on the snout of barndoor skates are worn smooth,
as though the snout is used to dig in the mud or sand to obtain bivalve mollusks.
- · Reproduction
The barndoor skate is oviparous, meaning it lays eggs from which the young hatch. The skate becomes sexually mature at 11
years of age and reproduction takes place over the entire range of the species. During mating it is known that a distinct
pairing with embrace occurs; though this activity has not been studied extensively in this species. The barndoor skate
deposits single fertilized eggs in the yellowish and greenish egg capsules in sandy or muddy flats. Incubation takes
approximately 6 to 12 months. The smooth egg capsules of the skate are rectangular, with a short horn at each corner and
fine filaments along the anterior and posterior margins. Though small specimens are rarely captured, hatchlings have been
measured at (180-190 mm) TL. It has also been noted that young barndoor skates tend to follow large objects such as their
- · Predators
Due to the large size of the barndoor skate, large sharks are its only likely predator of adult barndoor skates.
- · Parasites
The numerous parasites of this skate include turbellarians, trematodes, cestodes, nematodes and copepods.
The barndoor skate is one of five skates in the Gulf of Maine that has commercial value and is also considered a
gamefish. It is often captured in commercial trawling nets such as otter and scallop trawls. There is also a directed
fishery for dogfish and skates on the Georges Bank which has resulted in the decline of this species. The flesh is
used as bait, fish meal, pet food, and meat from its wings is sold for human consumption.
Danger to Humans
Barndoor skates are considered harmless to humans.
Intensive trawling has threatened the barndoor skate with extinction, mainly through by-catch in multi-species
fisheries. Also, shallow water populations have been severely overfished because skates have been targeted as a more
valuable species to harvest. Fisheries independent studies by the National Marine Fisheries Service indicate a peak
abundance in the early 1960s, declining to a low in the 1980s. From the mid 1960s to the 1990s, barndoor skates declined
96-99% with 400 miles of the center of its longitudinal range on the southern shelf. In the 1990s, fishing effort has declined in shallow areas of barndoor skate habitat and the number of juveniles is increasing in no-take zones on Georges Bank and Southern New England shelf as well as adjacent areas to the north and south. The barndoor skate is currently a prohibited species in US waters while the biomass is slowly recovering from its overfished condition. The World Conservation Union (IUCN) has listed the barndoor skate as "Endangered" on the Red List.
Mary Jane Wettstein