Download Thornback Rays - Pen Llŷn a`r Sarnau

Angling for Answers to a Thorny Question
Thornback Rays
The Thornback Ray (Raja clavata) is one of the most common ray species found around the UK
and is regularly caught by fishers and recreational anglers.
Typically inhabiting continental shelf and upper slope waters from around 10 to 300 m (32 985 ft) and preferring soft substrates such as mud and sand, Thornback Rays can also be found
over gravel and rock beds. It is seasonally migratory, spending the winter in deeper water and
coming into shallower areas in the late spring and summer to breed. Juveniles are more likely to be
found in shallower, coastal waters than adults as these areas are used as nursery grounds.
The IUCN Red List classifies the species as Near Threatened and it is believed that some
populations around the country have declined significantly. It is therefore important we find out as
much about the species as possible if populations are to be preserved at a healthy level.
Why We’re Tagging
Previous studies of Thornback Rays in the southern North Sea indicate that there are localised
subpopulations with limited mixing between them. Information from anglers in North Wales has
revealed differences in the morphology of Thornback Rays around the Llŷn Peninsula; it appears
that rays in the south are significantly thornier than rays in the north.
To further investigate this difference, the Shark Trust and National Museums Liverpool
have initiated a tagging programme with local anglers, the primary aim of which is to investigate
whether these two morphotypes are from distinct populations with limited mixing between the two
stocks. The findings of this study will have implications for the management and conservation of
this species in North Wales and the Liverpool Bay area.
Reward for recaptures!
Anglers: If you catch a tagged Thornback Ray, please
record the information listed over the page before
carefully releasing the fish as close as possible to
the point where it was caught. Contact the Shark
Trust with this information to claim the £4 reward.
Commercial fishermen: If you catch a tagged Thornback
Ray, please record as much information (see
over) as possible before processing the fish.
Contact the Shark Trust with this information to
claim the £4 reward.
The reward is provided by National Museums Liverpool
as part of the Ray Watch Campaign.
A tagged Thornback Ray
Record your tag finds here:
The Shark Trust:
01752 672020
[email protected]
4 Creykes Court, The Millfields, Plymouth, PL1 3JB
This project is a collaboration between the Shark Trust and National Museums Liverpool
with funding from Environment Wales.
Shark Trust Vs 1. 09/09. Images © Shark Trust/Marc Dando
Tagging Guidelines
When catch and release fishing, the welfare of the animal is the primary concern. It is important to
return the fish to the water as soon as possible after tagging with the minimum of stress. This can
be achieved by following a few guidelines.
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Be prepared - make sure everything
you need to tag and release the fish is
on hand. Make a note of the tag
number before landing the fish.
Strike early - avoid gut-hooking the
fish and give it a higher chance of
survival. Use circle or semi-circle
hooks
Cannula and tag
Keep the ray in the water - when it is
necessary to bring the fish onto the boat, make sure to support as much of the body as
possible.
Position the tag – tagging the wing
close to the rear of the body cavity is
most effective. Be careful not to
penetrate the body cavity – if in doubt,
Tag
tag further into the wing.
Tag at a shallow angle - orientate the
tag towards the tail. Ensure it does not
penetrate to other side of the wing.
Twist and remove – once the barb is
fully inserted, turn the cannula while
removing it to ensure the tag remains
in place.
Photograph – if there is time, take a
quick photo of the tagged animal
Release as soon as possible –
carefully return the ray to the water as
close as possible to where it was
caught.
Release injured rays - if a ray is
injured in any way, release it as swiftly
as possible without tagging.
Take care - the skin of the Thornback
Ray is highly abrasive and the spines
Tagging at the correct angle
will easily pierce skin. Handle the ray
by the body rather than the tail to avoid
injuring the ray.
Essential information
Additional information
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Tag number.
Location.
Date and time.
Sex.
Contact details of the
angler.
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Length (nose tip to tail tip).
Width (wing tip to wing tip).
Posterior wing width
Weight.
Condition (lively or
sluggish).
Depth of capture and
bottom ground.
Shark Trust Vs 1. 09/09. Images © Shark Trust/Marc Dando