October 10, 2011 Featured Article Read More →

Thornback Ray – Fishing and ID Guide

In the second of our Species Fishing and ID guides we look at the ever popular Thornback Ray. These guides aim to give anglers information about the biology of particular shark species that can be caught around the coast of Scotland and some pointers on targeting sharks from both the boat and shore.

If you have a picture of yourself with a Thornback Ray and want to show it off on this page please send it to contact@ssacn.org or post it on the Scottish Shark Tagging Programme’s Facebook page! Remember to keep checking www.tagsharks.com to make sure you don’t miss your chance to show off your PB shark, skate or ray!

#2 Thornback Ray

Biology

Other Names: Raja clavata, Roker

Description: Thornback Ray colouration is extremely variable and is often determined by the type of sea bed they live over, the illustrations below show some of the variations in Thornback Ray colouration. Dorsal surfaces may be dark or sandy brown with grey, black and purple patches or spots. Patterns vary significantly though all Thornback Rays have a distinctive barred tail with alternating light and dark stripes. As the name suggests, Thornback Rays often have many large thorns on their dorsal surface particularly along the spine and tail. Thorns may be present on both the dorsal and ventral surface on some fish and may be nearly absent on others.Thornback Map

Maximum Size: 130cm

Habitat: Thornback Rays are found over a wide range of sea beds though generally prefer soft sand, gravel or mud areas.

Depth: Shallows to 300m

Distribution: Extremely common along the west and north coasts of Scotland. Adult fish often migrate offshore during the winter and return to coastal waters to reproduce in the summer. Juvenile fish remain in coastal waters for several years before migrating offshore.

Feeding: Thornback Rays are opportunistic predators and scavengers and feed mainly on crabs, shrimp, shellfish and fish.

Biology: Males mature at 5 years old at around 60-77cm (10.9-23.4); females mature at 5-10 years old at around 60-85cm (10.9-31.6lb). Thornback Ray wingspans (cm) can be easily converted to weight (lb) using the SSTP calculator found here. Thornback Rays are oviparous (egg-laying); females lay around 100-150 eggs each year. Thornback Ray eggs are almost square in shape and around 5-9cm long. Egg cases are dark brown and have filaments known as tendrils at each corner, this allows eggs to become entangled and attached to fixed features on the sea bed such as seaweed fronds. Eggs are laid along the coast between February and September, after 4-5 months fully developed 8-10cm long Thornback Rays hatch and begin to feed actively. Thornback Rays may live for up to 20 years.

Caution: Thornback Rays often have many sharp thorns on their dorsal surface particularly along the spine and tail. Rays also have abrasive skin and strong jaws with crushing pads.

Current Fishery: Some targeted fisheries and are often taken as bycatch in mixed trawls. Heavy overfishing has been found to cause a reduction in size and age of fish at maturity.

Conservation Status: Near threatened. Some target fisheries and often taken in mixed trawls for human consumption.

GFAC Size: 95cm

Tagging: The minimum SSTP tagging size for Thornback Rays is 50cm wingspan (5.25lb). For advice on tagging rays please refer to the SSTP tagging guide here. If you are interested in tagging the fish you catch please send an email to contact@ssacn.org.

Targeting Thornback Rays in Scotland

 

Tackle: From the boat a 12-20lb class rod and suitable reel loaded with 30lb braid is sufficient. From the shore a 5-6oz beach rod paired with a strong multiplier or fixed spool reel loaded with 15-20lb monofilament mainline will handle most Thornback Rays in Scottish waters.

End Tackle: A single strong size 2/0 to 5/0 bronze barbless hook with a 60lb monofilament hook length is sufficient for Thornback Rays. In some areas there is a chance of picking up species such as Spurdog and small pack Tope when fishing for Thornback Rays, in such areas it is often advisable to use a heavier hook length. Popular Thornback Ray rigs include pulley rigs, up ‘n’ over rigs and clipped down fixed paternosters. Clipped down rigs are particularly useful when fish are feeding at distance and a long cast is needed.

Bait: Popular baits include mackeral, whiting, squid, sandeel, herring, lugworm and peeler crab. Certain baits are more successful in different areas. In the north west of Scotland fish and squid baits are very popular; along the south west coast peeler crab baits are sometimes more effective than fish baits.

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