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Leucoraja ocellata

(Winter big skate)

Overview

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Family : Skates ; Prefer sandy and gravelly bottoms in shoal water in the north range ; to at least 90 m in south[1]. Those caught at Cans, Nova Scotia in Canada were found to have eaten dollarfish, cunner, and squid. Mostly inactive during daylight hours, but active under dark conditions[2]. Oviparous . Distinct pairing with embrace. Young may tend to follow large objects, such as their mother [3]. Eggs are oblong capsules with stiff pointed horns at the corners deposited in sandy or muddy flats[3]. Egg capsules are 5.5-9.9 cm long and 3.5-5.3 cm wide[4][5][6]. Electric organ discharge (EOD) activity seemed more frequent during dark periods[7]. The individual EOD of this species is monophasic, head-negative, and lasts 217 ms[8]. This species is used only for the manufacture of fish meal .

Endangered

Threat status

Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in Danish:

Vinterrokke

Common Names in Dutch:

Spiegelrog, Winterrog

Common Names in English:

big skate, eyed skate, Winter big skate, Winter Flounder, winter skate

Common Names in Finnish:

Täplärausku

Common Names in French:

Raie Ronde, Raie Tachet, raie tachetée, raie tâchetée, raie tâchetée, raie t‚chetée

Common Names in Italian:

Razza occhiata

Common Names in Mandarin Chinese:

眼斑鰩, 眼斑鳐

Common Names in Portuguese:

Raia-inverneira

Common Names in Swedish:

Vinterrocka

Description

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Physical Description

Species Leucoraja ocellata

Distinctive Features: The disc of the winter skate is rounded with a blunt pectoral fin tips . The anterior margins are slightly concave for a distance close behind the snout while the posterior margins are gently convex . The snout is bluntly rounded. The first and second dorsal fins are similar size and shape . The pelvic fins are moderately concave outwardly. The tail has narrow lateral folds with males possessing claspers that trail about halfway down the length of the tail.

Dentition: There are 72-110 teeth in each jaw with those of the young and of females being rounded or having a blunt cusp and close set in quincunx. Mature males have teeth that are more widely spaced in transverse series and that have high conical cusps with blunt tips. The number of teeth helps to distinguish the winter skate (72-110) from the little skate (38-66).

Denticles : Young winter skates have 3-4 thorns on each shoulder and others near the eyes and along the edges of the rostral ridge to the snout tip. There is a row of 12-16 thorns along the midline of the disc and 16-18 thorns on the tail to the first dorsal fin. This row of the thorns on the tail is flanked by a second less organized row of smaller thorns from close to the pectoral girdle and by a third irregular row of yet smaller thorns lower down on either side of the midsection of the tail. Small thorns are also present on the outer anterior portion of the pectorals while the posterior corners and areas along the side of the mid-dorsal ridge are bare.

As winter skates grow, the thorns of the mid-dorsal row are lost from the disc and tail and those near the eyes decrease in number. The thorns increase in number along the shoulder and become present on the central portion of the posterior lobe of each pelvic fin.

When maturity is reached, the thorns decrease along the shoulder areas, around the eyes and the rostral ridge. Bare areas expand over the majority of the inner portions of the pectorals and the posterior lobes of the pelvic fins while mature females develop large thorns that spread over the posterior corners of the pectoral fins. Alar spines are present near the snout and eyes, along the disc margins, and along the tail while the center of the tail is free of thorns.

Color:

The winter skate is light brown dorsally with many roundish dark spots on the disc, pelvic fins, tail, and claspers of mature males. There may also be 1-4 dark ocellar spots edged with white on the posterior portion of each pectoral fin. There is whitish translucent area on each side of the snout in front of the eyes. The ventral surface of the winter skate is usually white with irregular brownish blotches of varying sizes on the posterior portion of the disc as well as sometimes long the tail.

Size/Age/Growth

The winter skate grows to approximately 41 inches (105 cm) total length and 15 pounds (7 kg ) weight . Males reach sexual maturity at 11 years of age which corresponds to 29 inches (73 cm) total length while females are mature at 11-12 years of age and 30 inches (76 cm) total length. The lifespan of this skate is approximately 19 years.

Habitat

Residing in waters from the surface to 300 feet (90 m ) in depth, the winter skate prefers sand and gravel bottoms in shoal water in the northern portion of its range . This skate is relatively inactive during the day, with most activity occurring during the night time hours.

Typically found in water with a depth of 0 to -2,697 meters (0 to -8,848 feet).[9]

Ecology: Winter Skate is a benthic species. Habitat ranges from shoreline to 317 m , but they are most abundant at depths
Size, reproduction and age data in life history table below. Winter Skates are slow-growing, produce few eggs each year. Size at maturity increases with latitude (McEachran and Martin 1977). On Georges Bank and Gulf of Maine, individuals mature between 70 and 109 cm total length (TL ). The Gulf of St Lawrence population however matures at a smaller size and does not reach as large a size as other populations (McEachran and Martin 1977). Length at 50% maturity for female winter skate on the eastern Scotian Shelf is thought to be around 75 cm (Simon and Frank 2000).

Eggs of Winter Skate are deposited throughout the year off southern New England and from summer to autumn off Nova Scotia (Vladykov 1936, Collette and Klein-MacPhee 2002). However, a peak in the reproductive season was observed during the summer months in the Gulf of Maine (Sulikowski et al. 2004). Industry has previously noted females extruding complete purses only in the late summer/early autumn west of Sable Island and suggestions were made that this may be a spawning area (Simon and Frank 2000). Frisk et al. (2002), suggest winter skate fecundity to be between 18?35 eggs per year.

Winter Skate migrate to deeper colder waters during summer months in some areas and the species is sometimes termed a winter periodic (Scott and Scott 1988). Research vessel survey data for the Scotian Shelf, however, show that winter skate appear to be concentrated in deeper warmer waters in the winter and move into shallower waters during spring and summer.

Most important prey items appear to be fish, decapods, amphipods and molluscs . Primary food sources shift from invertebrates to fish as skates increase in size. Moreover, the prey size also increases as the skates become larger and older. Studies of food habits of winter skate and little skate by McEachran et al. (1976) have shown that although the two species occur together over most of their range they avoid serious competition by eating different proportions of the same food resources . Winter Skate tended to eat infauna and Little Skate eat epifauna .

Little is known about predation on Winter Skate, but they are eaten by many predators including sharks , other rays (such as L. erinacea), and Grey Seals (Scott and Scott 1988). Winter Skate are also prone to several parasites, including protozoans , myxosporidian, haematazoa, trematodes and nematodes (Scott and Scott 1988).[10].

List of Habitats:

Biology

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Diet

As a non-selective predator , the diet of the winter skate includes fish and crustaceans. In Canadian waters, the winter skate is known to feed on dollarfish, cunner, and squid.

Reproduction

Winter skates are oviparous . Although there is no defined reproductive season , winter skate reproduction peaks during the summer months. Each female produces approximately 40 egg cases per year, each containing one embryo. The egg cases are released by the female in offshore waters on rock bottom habitats . The egg cases are oblong in shape with stiff pointed horns at the corners, measuring 5.5-9.9 cm long and 3.5-5.3 cm wide. Embryos remain in the egg cases during the gestation period of about a year and a half. Upon leaving the egg case, young winter skates tend to follow large objects.

Behavior

Predators:

Predators of the winter skate are primarily large fishes .

Taxonomy

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Synonyms

Leucoraja ocellata • Raja naevus Müller & Henle • Raja ocellata • Raja ocellata Mitchill, 1815

Notes

Name Status: Accepted Name .

Last scrutiny: Data last modified by FishBase 30-Sep-1999

Sympatric to the Little Skate, immature specimens of the two species are often confused, especially females. However, chance of misidentification decreases as they mature . Disk is rounded , with many small dark spots on upper surface. Usually 1-4 ocelli are found on the upper surface on each side of disk, each with a dark brownish center and pale edge . Young have long middorsal row of large spines on disk and tail. Upper jaw has 72 rows of teeth. Lower surface is usually white but marked with irregular pale brownish blotches (although this colouration is found in several other species within range ).[10].

Similar Species

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Members of the genus Leucoraja

ZipcodeZoo has pages for 17 species and subspecies in this genus:

L. caribbaea (Maya Skate) · L. circularis (Cuckoo Ray) · L. compagnoi (Tiger-Tail Skate) · L. erinacea (Little Summer Skate) · L. fullonica (Shagreen Ray) · L. garmani (Rosette River Stingray) · L. garmani garmani (Freckled Skate) · L. garmani virginica (Leopard Skate) · L. lentiginosa (Speckled Skate) · L. leucosticta (Whitedappled Skate) · L. melitensis (Maltese Skate Or Ray) · L. naevus (Butterfly Skate) · L. ocellata (Winter Big Skate) · L. pristispina (Sawback Skate) · L. virginica (Virginia Skate) · L. wallacei (Yellospotted Skate) · L. yucatanensis (Yucatan Whiteskate)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal February 29, 2008:

Identifiers

Footnotes

  1. Robins, C.R. and G.C. Ray (1986). A field guide to Atlantic coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 354 p. [back]
  2. Bratton, B.O. and L.J. Ayres (1987). Observations on the electric organ discharge of two skate species (Chondrichthyes: Rajidae) and its relationship to behavior. Environ. Biol. Fish. 220:241-254. [back]
  3. Breder, C.M. and D.E. Rosen (1966). Modes of reproduction in fishes. T.F.H. Publications, Neptune City, New Jersey. 941 p. [back]
  4. Ishihara, H. (1990). Study on the systematics and fishery resources of the North Pacific skates (Pisces: Chondrichthyes: Rajidae). Tokyo University. 186 p. Ph.D. dissertation. [back]
  5. Bigelow, H.B. and W.C. Schroeder (1953). Fishes of the Gulf of Maine. U.S. Fish. Wildl. Serv. Fish. Bull. 74, 53:1-577. [back]
  6. BirdLife International 2004. In IUCN 2008. 2008 IUCN Red List of Threatened Species. IUCNRedList.org. Downloaded July 18, 2008. [back]
  7. Mortensen, F.J. and R.H. Whitaker (1973). Electric discharge in free-swimming female winter skates (Raja ocellata). Am. Zool. 13:1266. [back]
  8. Moller, P. (1995). Electric fishes: history and behavior. Chapman & Hall, London. 584 p. [back]
  9. Mean = -239.380 meters (-785.367 feet), Standard Deviation = 525.030 based on 8,615 observations. Ocean depth information for each observation from British Oceanographic Data Centre. [back]
  10. Kulka, D.W., Sulikowski, J. & Gedamke, T. 2009. Leucoraja ocellata. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 01 February 2012. [back]
Last Revised: 7/15/2012