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Thornback Ray, Thornback Skate, Roker, Maiden Ray, Hardback, 
Stekelrog (Ne), Raie Bouclée (Fr),  Nagelroche (De), Raya de Clavos 
(Es), Piggskate (No).

Thornback Ray 

Raja clavata

Raja rubus  (Schneider, 1801), Raja aspera (Risso, 1810), Raja pontica 
(Pallas, 1811), Dasybatis clavata (Bonaparte, 1840), Raja capensis 
(Müller & Henle, 1841), Raja rizacanthus (Regan, 1906), Betaraia 
clavata (Leigh-Sharpe, 1924).

COMMON NAMES

  Long thorny tail with distinctive light/dark banding.
  Upper surface light brown to grey.
  Variable patterning including dark and yellow patches with dark 

spots.

  Lower surface creamy white with greyish margin.
  Scattered buckler thorns on upper surface.
  Row of 30–50 thorns along midline to first dorsal fin.

Thornback Ray males can grow to a maximum of 105cm total length 
while females can reach 130cm, although most are less than 85cm 
(Whitehead et al., 1986; Lockley, 2009). The teeth of both species are 
arranged into 36–44 rows in the upper jaw, pointed in males, blunter 
in females and juveniles (Clark, 1926). Both sexes are reported to have 
a maximum longevity of 12 years (Fowler et al., 2005).

The tail is long and solid with rows of thorns running 

longitudinally. The dorsal surface is covered in spines in both sexes 
while large females may have spiny ventral surfaces (Whitehead et 
al., 1986). In sexually mature fish some of the spines are thickened 
with button-like bases, known as bucklers. These are particularly well 
developed on the tail and back of sexually mature females and may 
be present ventrally. There are 0–2 thorns between the dorsal fins 
(Whitehead et al., 1986).

Colouration varies from light brown to grey with darker blotches 

and numerous yellow patches. The yellow patches are sometimes 
surrounded by small dark spots. The underside is creamy-white with a 
greyish margin (Whitehead et al., 1986). When young they can be pale 
with large, dark eyespots on each wing. The Thornback Ray shows an 
incredibly large variation in colouring making identification of the 
species potentially challenging.

The Thornback Ray 
occurs throughout 
the northeast 
Atlantic from the 
Faroe Islands, 
Iceland and Norway 
as far south as 
Namibia. Found in 
the Mediterranean, 
Black and western 
Baltic Seas. It occurs 
off western Africa 
and has recently 
been reported 
from the southwest 
Indian Ocean 
(Fowler, S. L. et al; 
2005).

SYNONYMS

DISTRIBUTION

APPEARANCE

RJ

C

N

T

N

AT

M

ED

 B

LK

No Records
Occasional
Range

Map base conforms with ICES grid squares.

Dorsal View (

♀)

Ventral View (

♀)

Text & Illustrations © Shark Trust 2009

Ventral View (

♂)

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(Not to scale)

SIMILAR SPECIES

Amblyraja radiata, Starry Skate
Leucoraja circularis, Sandy Ray (not illustrated)
Leucoraja fullonica, Shagreen Ray (juv.) (not illustrated)
Raja brachyura, Blonde Ray

Skates and rays are very variable in their colouration and 
patterning,  particularly the Thornback Ray. Around the 
UK it can be solid dark brown without the distinct marble 
patterning, although there tend to some (2–10) creamy 
white spots left on the pectoral fins close to the midline 
arranged in regular patterns. In other areas it is paler and 
can be misidentified as the Blonde Ray, Raja brachyura. 
The creamy white spots remain on these specimens but 
are much less distinct. What causes this morphological 
plasticity is not known.

Studies from the Mediterranean have shown that the 

rajids are genetically very close (Turan, 2007). This means 
that interbreeding between the more common UK skates 
is a possibility and could lead to hybrid individuals with 
indistinct colouration and morphology.

 

Thornback Ray

Raja brachyura,
Blonde Ray

Amblyraja radiata, 
Starry Skate

Colouration similar to 
the Blonde Ray

Colouration similar to 
the Starry Skate

Dark pattern

Heavy pattern

Light pattern

Text & Illustrations © Shark Trust 2009

Supported by:

(Not to scale)

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Thornback Ray 

Raja clavata

TEETH

  Less than 60 rows of unicuspid 

teeth, usually 36–44 in the 
upper jaw

 

(Clark, 1926).

  Teeth in males are sharper than 

in females and juveniles (Ellis 
and Walker, 2000).

HABITAT

The Thornback Ray inhabits continental shelf and upper slope 
waters from 10-300m (32-985ft) through most of their range, with 
the notable exception of the eastern Ionian Sea where it occurs from 
300-577m (985–1,890ft) (Whitehead et al., 1986). Around European 
coastal waters, it is most abundant from 10-60m (32–195ft). Studies 
from the Thames Estuary have shown the Thornback Ray to be 
seasonally migratory, spending the winter in deeper water and 
coming into shallower areas in the late spring and summer to breed 
(Hunter et al., 2005). Juveniles are more likely to found in shallower, 
coastal waters than adults as these areas are used as nursery 
grounds.

Studies from the Bristol Channel have shown the Thornback 

Ray, along with the Small Spotted Catshark, Scyliorhinus canicula, 
to be one of the most important elasmobranch species to the local 
ecology. As with most demersal skate, it prefers soft substrates such 
as mud and sand but can also be found over gravel and rock beds. It 
is known to segregate by sex and size (Fishmap, Unknown).

ECOLOGY & BIOLOGY

DIET

Juvenile Thornback Rays feed predominantly on small crustaceans 
such as amphipods, mysids and crangonid shrimps. Adults feed 
on larger crustaceans and small teleost fish such as sandeels, small 
gadoids and dragonets (Fishmap, Unknown). Studies from the Black 
Sea have shown sprat, horse mackerel and anchovy are the most 
important prey items (Orlov, 1998).

REPRODUCTION

The Thornback Ray spends the winter in deeper water, migrating 
inshore to breed and lay eggs during the spring and summer 
(Hunter et al., 2005). It is estimated to reach 50% maturity at a total 
length of around 77cm (8.8 years) for females and 68cm (7.1 years) 
for males in the North Sea (Fishmap, Unknown). However, Ryland 
and Ajayi (1984) reported that they first spawn earlier than this in 
their 5

th

 year (Ryland and Ajayi, 1984). Other estimates from the 

northeast Atlantic have given size at maturity figures of 60-81cm 
total length for males and 60-101cm total length for females 
(Fishmap, Unknown).

EGGCASE

1.  50–90mm in length (excluding horns).
2.  Almost as wide as long.
3.  Obvious keels and fields (Shark Trust, 2008).

Similar eggcase to the Blonde Ray, Raja brachyura.

REPRODUCTION CONTINUED

Spawning occurs in inshore waters between February and 

September (Fowler et al., 2005), with a peak in May and June and a 
theoretical maximum of 140-160 eggs being laid a year. The actual 
number of eggs laid is likely to be closer to 48-74

 

(Fishmap, Unknown). 

Incubation generally lasts for 4-6 months depending on the water 
temperature and the young hatch measuring 11-13cm total length 
(Fishmap, Unknown).

Text & Illustrations © Shark Trust 2009

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COMMERCIAL IMPORTANCE

THREATS, CONSERVATION, LEGISLATION

The Thornback Ray is a commercially important species targeted 
across much of its range and taken as bycatch in multispecies 
fisheries. Although little species-specific landing data is available, 
market sampling indicates that the Thornback Ray is one of the 
most frequently landed skates across Europe. Between 1982 and 
1994 in France, Thornback Rays accounted for more than 30% of 
all skates and rays landed (Fishmap, Unknown). However, there has 
been some evidence of declining catch rates in northwest Europe 
and concern that the current intensity of fishing pressure is not 
sustainable. Due to its large size and thorns, the Thornback Ray 
rarely escapes from trawl nets. Coupled with the slow growth rates 
and low fecundity common to all skates, they could be extremely 
vulnerable to over fishing (Ellis and Walker, 2000).

All rajids are managed under a Total Allowable Catch (TAC) 

system in EU waters. Between 1999 and 2005 the 6,060t TAC was 
reduced by 47% and by a further ~50% from 2005 to 2008 (ICES, 
2008). Originally the TAC applied only to areas IIa and IV, however in 
January 2009 the TAC was extended to include ICES divisions IIa, IIIa, 
IV, VIa-b, VIIa-k, VII and IX. The table below gives a summary of the 
TAC’s for the years 2004 to 2009.

ICES 
Division

2004 2005 2006 2007 2009 2009

2009

IIa, IV

3,503 3,220 2,737 2,190 1,643 1,643

1,643

IIIa

N/A

N/A

N/A

N/A

N/A

68

68

VIa-b, 
VIIa-c, 
VIIe-k

N/A

N/A

N/A

N/A

N/A

15,748

15,748

VIId

N/A

N/A

N/A

N/A

N/A

1,044

1,044

VIII, IX

N/A

N/A

N/A

N/A

N/A

6,423

6,423

 (All figures in tons. European Union; 2009)

Since 2008 European countries have been required to record 

most skate and ray landings by species to give a clearer picture of 
the status of populations in EU waters (ICES, 2008). This may be 
difficult however due to the variability in colouration exhibited 
by the Thornback Ray (Ellis and Walker, 2000). Some Sea Fisheries 
Committees (SFC) around the UK have byelaws which stipulate a 
minimum disc width (DW) for landed skates and rays, measured 
from the extreme tips of the pectoral fins. The SFC’s which 
implement these and the details are shown in the table below.

SFC

DW (cm) 

Other

Cumbria

45

Cannot land wings less than 22cm 
in their maximum dimension

Kent & Essex 40

Cannot land wings less than 19cm 
in their maximum dimension

Southern

40

Cannot land wings less than 20cm 
in their maximum dimension

South Wales

45

Cannot land wings less than 22cm 
in their maximum dimension

States of 
Guernsey

36

IUCN RED LIST ASSESSMENT

Near Threatened (2000).

HANDLING AND THORN ARRANGEMENT

  Handle with care.
  Large, scattered buckler thorns on dorsal surface and 

occasionally ventral surface.

  Strong midline of thorns.
  Lateral pairs of thorns sometimes present on tail.

 

Thornback Ray

The Thornback Ray is one of the most commonly found rajids in 
European fish markets and constitutes an extremely important part 
of many commercial fisheries. It is targeted by gillnet and longline 
fisheries and is taken as bycatch in otter and beam trawls. It is also 
caught using set nets and is targeted by recreational anglers (Fish-
map, Unknown).

(Cumbria SFC, Unknown, Kent & Essex SFC, Unknown; South Wales 
SFC, Unknown; Southern SFC, 2006; NFFO, 2004)

However, such localised management strategies are unlikely to 

be significant for the conservation of wider populations (Fowler et al., 
2005). There is currently no effective European management plan for 
the Thornback Ray.

THREATS, CONSERVATION, LEGISLATION

Text & Illustrations © Shark Trust 2009

Supported by:

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CLARK, R. S. 1926. Rays and Skates. A Revision of the European 

Species. Fishery Board for Scotland. HM Stationary Office. 
Edinburgh, UK.

CUMBRIA SFC. 2008. Minimum Fish Sizes. www.cumbriasfc.org.uk.

ELLIS, J., WALKER, P. 2000. Raja clavata. In: IUCN 2008. 2008 IUCN 

Red List of Threatened Species. www.iucnredlist.org.

EUROPEAN UNION. 2009. Council Regulation (EC) No. 43/2009. 

Official Journal of the European Union, L22/1. www.mfa.gov.uk.

FISHMAP. Unknown. Thornback Ray. Raja clavata. ICES. 

Copenhagen, Denmark. www.ices.dk.

FOWLER, S. L., CAVANAGH, R. D., CAMHI, M., BURGESS, G. H., 

CAILLIET, G. M., FORDHAM, S. V., SIMPFENDORFER, C. A., 
MUSICK, J. A. 2005. Sharks, Rays and Chimaeras: The Status of 
the Chondrichthyan Fishes. IUCN SSC Shark Specialist Group. 
IUCN Publications. Cambridge, UK.

HUNTER, E., BUCKLEY, A. A., STEWART, C., METCALFE, J. D. 2005. 

Migratory Behaviour of the Thornback Ray, Raja clavata, in the 
Southern North Sea. Journal of the Marine Biological Association 
of the United Kingdom, 85: 1,095–1,105.

ICES. 2008. Demersal elasmobranchs in the North Sea (Sub-area 

IV), Skagerrak (Division IIIa), and eastern English Channel 
(Division VIId). ICES advice 2008, Book 6. 

KENT & ESSEX SFC. 2008. Minimum Fish Sizes. www.kentandessex-

sfc.co.uk.

Lockley, P. 2009. Monster Ray Captured. Fishing News, 12/06/2009.

NFFO. 2004. Official Yearbook and Diary. Grimsby, UK.

ORLOV, A. M. 1998. The Diets and Feeding Habits of Some Deep-

Water Benthic Skates (Rajidae) in the Pacific Waters off the 
Northern Kuril Islands and Southeastern Kamchatka. Alaska 
Fishery Research Bulletin, 5 (1): 1–17.

RYLAND, J. S., AJAYI, T. O. 1984. Growth and population dynamics 

of three Raja species (Batoidei) in Carmarthen Bay, British Isles. 
J. Const. int. Explor. Mer, 41: 111-120.

SOUTH WALES SFC. 2008. Skate and Ray – Minimum Size. www.

swsfc.org.uk.

SOUTHERN SFC. 2008. Minimum Landing Size. www.southernsfc.

org.uk.

TURAN, C. 2007. Molecular Systematic Analyses of Mediterranean 

Skates (Rajiformes). Fisheries Genetics Laboratory, Faculty of 
Fisheries, Mustafa Kemal University, Iskenderun, Hatay, Turkey.

WHITEHEAD, P. J. P., BAUCHOT, M. L., HUREAU, J. C., NIELSEN, J., 

REFERENCES

Thornback Ray 

Raja clavata

TORTONESE, E. (Eds.). 1986. Fishes of the Northeast Atlantic and 
Mediterranean. UNESCO. Paris, France.

Text & Illustrations © Shark Trust 2009

Text: Richard Hurst.
Illustrations: Marc Dando.

Citation
Shark Trust; 2009. An Illustrated Compendium of Sharks, Skates, Rays 
and Chimaera. Chapter 1: The British Isles. Part 1: Skates and Rays.

Any ammendments or corrections, please contact:
The Shark Trust
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Tel: 01752 672008/672020

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