Elasmobranchii (sharks and rays) > Rajiformes
(Skates and rays) > Rajidae
Etymology: Amblyraja: Greek, amblys = darkness + Latin, raja, -ae = ray (Raja sp.) (Ref. 45335).
Environment / Climate / Range
Marine; brackish; demersal; oceanodromous (Ref. 51243); depth range 20 - 1000 m (Ref. 4426), usually 50 - 100 m (Ref. 4426). Temperate; -1°C - 14°C (Ref. 49751); 72°N - 33°N, 78°W - 41°E (Ref. 55275)
Length at first maturity / Size / Weight / Age
Maturity: Lm 87.5  range ? - ? cm
Max length : 105 cm TL male/unsexed; (Ref. 53748); max. published weight: 11.4 kg (Ref. 53748); max. reported age: 28 years (Ref. 88929)
Morphology | Morphometrics
soft rays: 0. 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).
Eastern Atlantic: Svalbard, Greenland and Iceland to the English Channel, including the North Sea (except southern part) and the western part of the Baltic; also off Cape Town, South Africa (Ref. 5578). Western Atlantic: Greenland and Hudson Bay, Canada to South Carolina, USA (Ref. 7251).
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). 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 has been mentioned that North American specimens grow to a larger size than East-Atlantic specimens (Arve Lynghammar, pers.comm., 11/09).
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).
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. (Ref. 27314)
IUCN Red List Status (Ref. 96402)
CITES (Ref. 94142)
Threat to humans
Fisheries: minor commercial; gamefish: yes
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5010 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00447 (0.00224 - 0.00891), b=3.17 (3.00 - 3.34), based on LWR estimates for species & (Sub)Family-body shape (Ref. 93245
Trophic Level (Ref. 69278
): 4.2 ±0.3 se; Based on diet studies.
Resilience (Ref. 69278
): Low, minimum population doubling time 4.5 - 14 years (K=0.17; tm=4; Fec=13-20).
Vulnerability (Ref. 59153
): Moderate to high vulnerability (51 of 100) .