Thornback ray

Raja clavata

Image | by Marc Dando, Copywrite protected

Description

The thornback ray is the most abundant member of the skate family found in Cornish waters. It gets its name from numerous thorn like spines, which are modified ‘skin teeth’ on its upper surface and along the tail. Often marketed as skate wings.


Sustainability Overview

One of the most abundant ray species in Cornish waters the thornback is a medium sized ray of the skate family growing to cm maximum length. Like all skates Its biology makes it vulnerable to over fishing as it grows slowly and produces a small number of large eggs (in egg cases known as mermaids purses) each year. Populations in the Bristol Channel are increasing and although poorly studied populations in the Celtic sea are showing signs of increasing and fishing effort is not considered to be too high, in the western channel stocks are stable but fishing effort is currently unknown(ICES 2014) There are issues with by catch in net fisheries for ray and with impact on the seabed with trawl fisheries.

Find local fish

When is best to eat?

J
F
M
A
M
J
J
A
S
O
N
D
1
2
3
4
5

Gill Netting

Cornish boats landing to Cornish ports

Gill nets are lightweight nets made of nylon (monofilament) fishing line that are anchored to the seabed and are used to catch fish by entangling the gills.

Learn more
1
2
3
4
5

Demersal Trawl

Cornish boats landing to Cornish ports

Demersal trawls are large nets that are pulled through the water with the bottom edge of the net touching the seabed. At each edge the net is pulled open by metal ‘trawl doors’. Sometimes referred to as Otter trawling.

Learn more
1
2
3
4
5

Beam Trawling

Cornish boats landing to Cornish ports

Beam trawls are nets attached to a steel beam that holds the net open. The belly of the net is made of chains and the upper surface of the net is mesh. Beam trawlers pull two nets along the seabed simultaneously.

Learn more

How we rate fish

1
2
3
4
5

Cornwall Good Seafood Guide rates fish on sustainability using a scale of 1 to 5.

1, 2 and 3 are recommended, Fish to avoid are rated 5.

We use the system devised by the Marine Conservation Society (MCS) so our scores are comparable with the scores produced by MCS for the UK and fisheries from all around the world. For more information on scoring click here.

Sustainability Overview

One of the most abundant ray species in Cornish waters the thornback is a medium sized ray of the skate family growing to cm maximum length. Like all skates Its biology makes it vulnerable to over fishing as it grows slowly and produces a small number of large eggs (in egg cases known as mermaids purses) each year. Populations in the Bristol Channel are increasing and although poorly studied populations in the Celtic sea are showing signs of increasing and fishing effort is not considered to be too high, in the western channel stocks are stable but fishing effort is currently unknown(ICES 2014) There are issues with by catch in net fisheries for ray and with impact on the seabed with trawl fisheries.

Biology

Thornback rays are an inshore species of skate and are the most common species in Cornish waters. They are medium sized with females growing up to 130cm in length. Thornback rays are known to return to a specific location in order to breed or feed. They are a relatively slow growing species that matures late and produces a relatively small number of eggs each year. Females can grow to 118cm in length and 18kg in weight, while males can reach 98cm in length. Females mature between 60 and 85cm while males mature between 60 and 77cm (in both cases corresponding to an age of 5 to 10 years). The species has a maximum recorded age of 16 years.   

Stock Info

Stock status cannot be evaluated fully due to lack of data but according to qualitative date ICES say that stocks in the Celtic sea are increasing with the stock size indicator in the last two years (2012–2013) 60% higher than the average of the five previous years (2007–2011), and that fishing effort is appropriate. In the western English channel data is also limited but qualitative research suggests that stock is stable or increasing but fishing effort is unknown.
ICES advises that catches could be increased by 20% in in west Scotland, Irish Sea, Bristol Channel and southeast Ireland. The thornback ray is assessed as "lower risk, near threatened" by IUCN - The World Conservation Union. MMO landings show that 60 tonnes of Thornback ray were landed to Cornish ports in 2012 and 40 tonnes in 2013.
 

Management

There is no specific management plan for thornback rays. Thornback rays are part of a mixed quota along with spotted, cuckoo, blonde and small-eyed rays in the Celtic Sea region. Quotas alone may not adequately protect these species as there are differences amongst species in their vulnerabilities to exploitation and a restrictive quota may lead to discarding. Instead seasonal and/or area closures, effort restrictions and measures to protect spawning grounds for example are recommended.
There is no minimum landing size for thornback rays in Cornwall but they reach 50% maturity at a length of 77cm. It is not recommended that you buy skate wings that are smaller than 22cm
 

Capture Info

Thornback ray are caught in beam trawls, demersal trawls and gill nets. 
These fishing methods all have issues with by catch of non-target species and impacts on the wider marine environment. 
 

References

 
 
Chevolot, M., Hoarau, G., Rijnsdorp, A. D., Stam, W. T., and Olsen, J. L. 2006. Phylogeography and population structure of thornback rays (Raja clavata L., Rajidae). Molecular Ecology, 15: 3693–3705.
 
Ellis, J. R., Cruz-Martinez, A., Rackham, B. D., and Rogers, S. I. 2005. The distribution of chondrichthyan fishes around the British Isles and implications for conservation. Journal of Northwest Atlantic Fishery Science, 35: 195–213.
 
Gallagher, M. J., Nolan, C. P., and Jeal, F. 2005. Age, Growth and Maturity of the Commercial Ray Species from the Irish Sea. Journal of Northwest Atlantic Fishery Science, 35: 47–66. doi:10.2960/J.v35.m527.
 
 
Holden, M. J. 1975. The fecundity of Raja clavata in British waters. Journal du Conseil International pour l’Exploration de la Mer, 36: 110–118.
 
ICES. 2014a. Rays and skates in Divisions Celtic Sea and west of Scotland. In: Report of the ICES Advisory Committee, 2014. ICES Advice 2014, Book 5, Section 5.3.29.5.
 
McCully, S. R., Scott, F., and Ellis, J. R. 2012. Lengths at maturity and conversion factors for skates (Rajidae) around the British Isles, with an analysis of data in the literature. ICES Journal of Marine Science, 69: 1812–1822.
 
McCully S.R. and Ellis J. R., 2014. Latest Scientific Advice on Skates and Rays. Seafish Skates and Rays Group Meeting Friends House, London 8 October 2013.
 
Ryland, J. S., and Ajayi, T. O. 1984. Growth and Population Dynamics of three Raja species (Batoidea) in Carmarthen Bay, British Isles. Journal du Conseil International pour l’Exploration de la Mer, 41: 111–120.
 
Shark Trust Thornback ray factsheet www.sharktrust.org. - Shark Trust; 2009. An Illustrated Compendium of Sharks, Skates, Rays and Chimaera. Chapter 1: The British Isles. Part 1: Skates and Rays
 
 
 
 
 

Sustainable alternative recipies

Prev Next