Amblyraja radiata
Thorny Skate
Collection Details
Event Specimens
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Taxonomic Hierarchy
Chondrichthyes (Cartilaginous Fishes)
Rajiformes (Skates)
Rajidae (Skates)
Amblyraja
Amblyraja radiata (Thorny Skate)
Description
This species account was compiled from
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Characters
Body shape: other. Adults are rhomboid in shape, young are rounder (Ref. 7251). Short, stiff, bluntly triangular snout; tail shorter than body (Ref. 5578). Upper surface very rough, with solid thornlets scattered all over disc and tail, underside smooth, except for some prickles on snout; a constant pattern of separate orbital thorns, a regular row of 13-17 large thorns from nape to first dorsal fin (Ref. 3167); large, close-set thorns with star-shaped bases at upper disc (Ref. 5578). Coloration highly variable; brownish grey with scattered irregular black blotches dorsally; white ventrally; with darker spots and blotches on tail and pelvic fins; black spot on tip of tail (Ref. 2708).
Distribution
North Atlantic and adjacent Arctic.
Habitat Associations
Brackish, marine. demersal. depth range 5-1540 m.
Biology
Eurybathic, eurythermic (Ref. 4426) and benthic (Ref. 58426). Cold temperate species found in offshore waters (Ref. 88171) on all kinds of bottoms (Ref. 3167), mainly sandy and muddy (Ref. 82311). In the northeast Atlantic most common between 50-100 m depth (Ref. 88187) at temperatures of 2-5 °C (Ref. 89120). Some seasonal migrations have been reported from the western Atlantic (Ref. 52109, 89121). Migration experiments showed that 85 % of tagged individuals remained within 93 km of the release site, with longest distance travelled at 180 km (Ref. 82319). Feed mainly on fish, crustaceans (Ref. 5951) and polychaete worms (Ref. 5578), but also on hydroids, molluscs, cephalopods and echinoderms (Ref. 49751); known to be a scavenger (Ref. 89122). Diet changes with increasing body size (Ref. 82311). Different populations of starry rays mature at different ages and sizes (Ref. 88171). Oviparous (Ref. 3167). Maturity size varies from 44-90 cm TL. Young hatch at ca. 8-12 cm TL (Ref. 114953). Young may tend to follow large objects, such as their mother (Ref. 205). Rarely reaches 60 cm in the North Sea (Ref. 88187). Able to detect weak electric fields generated by potential prey organisms and may also generate its own weak electric fields (Ref. 10311). Probably taken by hake trawlers (Ref. 5578). Few are dried and salted in Iceland (Ref. 6902). It is a common Skate whose landings are converted to fish-meal (Ref. 117245). It has been mentioned that North American specimens grow to a larger size than East-Atlantic specimens (Arve Lynghammar, pers.comm., 11/09).
Max length: 105.0 cm TL; max weight: 11400 g; max age: 28 years.
Reproductive mode: dioecism; fertilization: internal (oviduct); nonguarders (open water/substratum egg scatterers); parental care: none. Distinct pairing with embrace. Oviparous, laying 10-45 egg cases each year (Ref. 44869, 41305). Eggs are oblong capsules with stiff pointed horns at the corners deposited in sandy or muddy flats (Ref. 205). Egg capsules are 3.4-8.9 cm long and 2.3-6.8 cm wide (Ref. 41250). Paired eggs are laid. Embryos feed solely on yolk (Ref. 50449). In the North Sea, fully formed individuals hatch after 4 months and pups are about 8-11 cm in length (Ref. 44869, 37969). In the Barents Sea, low water temperature may lengthen embryonic development time to 2.5-3 years (Ref. 44869).
IUCN Red List Status: Vulnerable (VU), assessed 2019-07-01. Resilience: Low (K=0.17; tm=4; Fec=13-20).
Commercial or Environmental Importance
Fisheries: minor commercial; gamefish.
References
Stehmann, M. and D.L. Bürkel (1984) Rajidae. p. 163-196. In P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese (eds.) Fishes of the north-eastern Atlantic and Mediterranean. UNESCO, Paris. vol. 1.
Compagno, L.J.V., D.A. Ebert and M.J. Smale (1989) Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p.
Bigelow, H.B. and W.C. Schroeder (1953) Sawfishes, guitarfishes, skates and rays. p. 1-514. In J. Tee-Van et al. (eds.) Fishes of the western North Atlantic. Part two. New Haven, Sears Found. Mar. Res., Yale Univ.
Berestovskiy, E.G. (1990) Feeding in the skates, Raja radiata and Raja fyllae, in the Barents and Norwegian Seas. J. Ichthyol. 29(8):88-96.
Greenstreet, S.P.R. (1996) Estimation of the daily consumption of food by fish in the North Sea in each quarter of the year. Scottish Fish. Res. Rep. No. 55.
McEachran, J.D. and K.A. Dunn (1998) Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs (Chondrichthyes: Rajidae). Copeia 1998(2):271-290.
Skjæraasen, J.E. and O.A. Bergstad (2000) Distribution and feeding ecology of Raja radiata in the northeastern North Sea and Skagerrak (Norwegian Deep). ICES J. Mar. Sci. 57(4):1249-1260.
Sulikowski, J.A., J. Kneebone, S. Elzey, J. Jurek, P.D. Danley, W. Huntting Howell and P.C.W. Tsang (2005) Age and growth estimates of the thorny skate (Amblyraja radiata) in the western Gulf of Maine. Fish. Bull. 103:161-168.
Coad, B.W. and J.D. Reist (2018) Marine fishes of Arctic Canada. Toronto (ON, Canada): University of Toronto Press. xiii+618 p.
Mecklenburg, C.W., A. Lynghammar, E. Johannesen, I. Byrkjedal, J.S. Christiansen, A.V. Dolgov, O.V. Karamushko, T.A. Mecklenburg, P.R. Møller, D. Steinke and P.R. Wienerroither (2018) Marine fishes of the Arctic Region.Volume I. Conservation of Arctic Flora and Fauna, Akureyri, Iceland. [CAFF Monitoring Series Report 28:1-454.]
Comments On Amblyraja radiata