Dipturus nidarosiensis

Dipturus nidarosiensis

Common name: Norwegian skate , Black skate
Order: Rajiformes
Family: Rajidae 
Synonyms: Raja nidarosiensis
Misidentifications: Dipturus cf. batis

  • photo credit: Sergio Ramirez

Short description

Very large skate, dark underparts often covered in blackish mucus. Very long and pointed snout. Larger than long rhombic disc, with anterior margins very concavous. Smooth dorsal surface. Row of 40-50 small spines along the tail.

Color: Dark brown-grey above, lacking distinct patterns. Dark brown underparts.


  • Total length (TL): up to 58 – 150 cm (max 200 cm, possibly 250 cm)
  • Disk width (DW): 58-61 cm
    Males are smaller than females.
  • Swimming pattern: Undulatory and pelvic fin locomotion (walking and punting).

Egg case

Very large capsules with a long rectangular shape and pointed horns at the corners, deposited on sandy and muddy bottoms. Well developed anterior and posterior apron. Straight anterior apron whereas the posterior is rounded and slightly shorter. Short posterior and anterior horns. Adhesive fibres attached to well developed lateral keels. In the central-western Mediterranean, eggs were found at depth from 974 to 1212 m.

Size: 18.2 – 26.0 cm length, 9.2 – 11.3 cm wide.

Distinctive features:

  • Well-developed aprons.
  • Surface of the egg-case not covered with fibers.

Dipturus: Short horns or reduced to a simple shape. Length > 100 mm.

Rajiformes / Rajidae: Rectangular egg-case, width no greater than twice the capsule length.

Biology / Ecology

Feeds on bottom animals, mainly decapod crustaceans, bony fishes and occasionally cephalopods, small elasmobranchs and polychaetes.

Reproduction: Oviparous.

Habitat: Demersal on deep slope waters and probably on the mid-slope at depths from 120 m to 1600 m.

The deep depth distribution of the species could explain the lack of information for this species.

Distinguishing characteristics

  • Dark ventral side.
  • Very long and pointed snout (but less than D. oxyrinchus).
  • A row of 40-50 small spines along the tail.

Rajiformes / Rajidae: Depressed body. Circular to rhombic disc. Tail well demarcated from disc.


Worldwide: along the Northeast Atlantic

Mediterranean: Recorded for the first time in 2005.

  • Occurrence: Rare.
  • Latest records: Adriatic, Ionian and Sardinia Sea (2005-2020, 2008-2010, 2013-2016), Strait of Sicily (2017), Syria (2014-2016), Adriatic Sea (2008-2010), Alboran Sea (2012, 2013 and 2017), Saros bay (2005-2007).

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Threats: Taken as bycatch with deep-sea fisheries targeting the red shrimp species.

Protection level:

  • Global, Europe: Near Threatened (IUCN 2015, last assessment: 2014)

Key references

  • Cannas R. Follesa M.C., Cabiddu S., Porcu C., Salvadori S., Iglesias S.P., Deiana A.M., Cau A. 2010. Molecular and morphological evidence of the occurrence of the Norwegian skate Dipturus nidarosiensis in the Mediterranean Sea. Mar. Biol. Res. 6: 341–350.
  • Carbonara P., Bellodi A., Zupa W., Donnaloia M., Gaudio P., Neglia C., Follesa M. C. 2021. Morphological Traits and Capture Depth of the Norwegian Skate (Dipturus nidarosiensis (Storm, 1881)) from Two Mediterranean Populations. Journal of Marine Science and Engineering 9(12): 1462.
  • Carbonara P., Cannas R., Donnaloia M., Melis R., Porcu C., Spedicato M.T., Zupa W., Follesa M.C. 2019. On the presence of Dipturus nidarosiensis (Storm, 1881) in the Central Mediterranean area. PeerJ 7: e7009.
  • Follesa M.C., Cannas R., Cabiddu S., Cau A., Mulas A., Porcu C., Cau A. 2012. Preliminary observations of the reproductive biology and diet for the Norwegian skate Dipturus nidarosiensis (Rajidae) from the Central Western Mediterranean Sea. Cybium 36: 473–477.
  • Geraci M.L., Di Lorenzo M., Falsone F., Scannella D., Di Maio F., Colloca F., Vitale S., Serena F. 2019. the occurrence of norwegian skate, Dipturus nidarosiensis (elasmobranchii: Rajiformes: Rajidae), in the Strait of Sicily, central Mediterranean. Acta Ichthyologica et Piscatoria 49(2): 203-208.
  • Isajlović I., Dulčić J., Piccinetti C., Vrgoč N., Manfredi C., Dragičević B. 2020. Additional records of Norwegian skate Dipturus nidarosiensis (Storm, 1881) (Pisces: Rajidae) in the Adriatic Sea. Acta Adriatica 61(2): 217-222.
  • Mulas A., Bellodi A., Carbonara P., Cau A., Marongiu M.F., Pesci P., Porcu C., Follesa M.C. 2021. Bio-Ecological Features Update on Eleven Rare Cartilaginous Fish in the Central-Western Mediterranean Sea as a Contribution for Their Conservation. Life 11: 871.
  • Ramírez-Amaro S., Ordines F., Puerto M.Á., García C., Ramon C., Terrasa B., Massutí E. 2017. New morphological and molecular evidence confirm the presence of the Norwegian skate Dipturus nidarosiensis (Storm, 1881) in the Mediterranean Sea and extend its distribution to the western basin. Mediterranean Marine Science 18(2): 251-259.
  • Yığın C.Ç, Ismen A. 2010. Age, growth, reproduction and feed of longnosed skate, Dipturus oxyrinchus (Linnaeus, 1758) in Saros Bay, the north Aegean Sea. J. Appl. Ichthyol 26: 913-919.