Ray, Undulate

Raja undulata

Method of production — Caught at sea
Capture method — Beam trawl
Capture area — North East Atlantic (FAO 27)
Stock area — English Channel
Stock detail — 7d,e
Picture of Ray, Undulate

Sustainability rating five info

Sustainability overview

The stock status of undulate rays in this area is unknown, though the stock size indicator has increased by over 20% between 2011-2015 and 2016-2017, approaching its highest level in 2017 and the index ratio has increased by over 50% in recent years. It is unknown if the species are undergoing overfishing in this area, however, there is concern for fishing mortality as there have been high levels of discards, with a lack of data regarding their survival rates. Additionally, landings have been higher than that recommended by scientific advice.

The EU had designated the Undulate Ray as a Prohibited Species for commercial fishing vessels in ICES areas 6, 7, 8, 9 and 10 but the fishery is open to a small amount of landings in this area. The level of landings are small and are only able to be collected as bycatch for scientific research. Undulate Rays are managed using a minimum landing length, a 3 month ban on their landings during their breeding season, a code of good practice with stakeholders, and requirements on how they are landed.

Biology

Undulate rays belong to the Rajidae family, which includes most of the skates and rays commonly found in British waters, and sold at fishmongers. The undulate ray is a medium sized shelf species growing to a maximum length of 100 cm and weight of 10 kg. The species has a maximum age of 20 years with size and age at maturity estimated at 75 cm and 9 years for females and 73 cm and 7.5 years for males. Eggs are laid from March to September. Undulate rays are at the northern edge of their range in UK waters. They form discrete populations isolated from other stocks, for example, on the southwest coast of Ireland, with occasional records in the English Channel. They are also present along the south coast of England.

Stock information

Criterion score: 0.75 info

Stock Area

English Channel

Stock information

There are no reference points for this undulate ray stock and therefore, it is unknown if the stock is overfished. However, stock size indicator has increased since 2010, and has increased by over 20% between 2011-2015 and 2016-2017, approaching its highest level in 2017 and the index ratio has increased by over 50% in recent years. Therefore, there is no concern for biomass.

It is unknown if the species are undergoing overfishing in this area, however, in 2017, ICES species-specific landings minimum estimate based on reported landings was 139 tonnes whilst the landings corresponding to advice 65 tonnes. Additionally 2434 tonnes were discarded and it is unknown how many of these undulate rays survive discarding. Therefore, there is concern for fishing mortality.

Management

Criterion score: 0.5 info

The EU had designated the Undulate Ray as a Prohibited Species for commercial fishing vessels in ICES areas 6, 7, 8, 9 and 10 but the fishery is open to a small amount of landings in this area. The level of landings are small and are only able to be collected as bycatch for scientific research. Catches must be reported separately under a specific code alongside important information about the catch. Undulate Rays are managed using a minimum landing length, a 3 month ban on their landings during their breeding season, a code of good practice with stakeholders, and requirements on how they are landed. The code of practice should be followed by fishermen to the greatest degree possible but greater enforcement is needed in fisheries to ensure these bans are effective.

There have been very restrictive management measures implemented in recent years, however, discards are now much higher than landings.

Capture Information

Criterion score: 0.75 info

Undulate Rays in this area are predominantly caught via bottom trawls. They are a commonly caught skate species in this area and area an important species for inshore fleets.

Bycatch
Common bycatch in bottom trawls include mixed crabs, urchins, lesser spotted dogfish, nursehound, Dragonet starry ray, smelt. Angel shark and common skate (critically endangered, IUCN) were depleted through incidental capture in trawls in this area. Invertebrates such as crabs and urchins are vulnerable to damage.

Discards
The landing obligation will be fully implemented into our seas from 2019. Skates and rays will be exempt from the landing obligation, due to their higher likelihood of survival when discarded. Member states will be required to report on skate and ray catches and discards, and any improvements in selectivity programmes. it’s difficult to avoid catching skates and rays in nets and because of their peculiar shape and size; it’s also difficult for them to escape the net once captured. Therefore, selectivity programmes are in place reduce skate and rays catches and their survival rates. Discard rates of skates and rays vary dramatically (30 - 70%), depending on the marketability and management measures in place. For example, nearly all skates below 30 cm LT are discarded by English vessels (Silva et al., 2012). Bycatch can include juvenile skate as they can hatch from their egg cases at sizes of 10-20 cm LT and therefore, may be able to escape through the nets (Ellis et al. 2018). Their survival rates upon discarding is extremely variable, depending on the fishing and handling methods used to capture them. Elasmobranchs have the potential for relatively high survival rates because they do not have swim bladders (and thereby are not as impacted by pressure changes), they can have thick and abrasive skins and thorns (which protect them) and some have spiracles and a buccal-pump respiratory which excrete a mucus, which allows the skate or ray to ventilate and acquire oxygen when out of the water (Ellis et al. 2018). Inshore and coastal fisheries using trawls, longlines, gillnets and tangle nets generally show low at-vessel mortality. Tag-recapture studies suggest show that thornback rays were found to be in a significantly better condition when caught using longlines and tangle nets, compared to when they were captured using otter trawl or drift trammel net.

Undulate ray survival may be higher than that for other skate species: their vigour (an indicator of health) was also found to be higher than that for other skate species, when caught using trawl and tangle nets (Ellis et al. 2018).

There are a lack of studies available on long-term skate and ray survival when they are released into the wild (Ellis et al. 2018).

As part of the cod-recovery plan trawlers have Square Mesh Panels (SMPs) which allows bycatch species to escape the nets including dogfish. Dogfish have really rough skin which harms other species in the net. By allowing them to escape, it means that skates and rays are more likely to be discarded alive. Discards of other species may include undersized or unmarketable fish or because they are choke species.

Habitat
Bottom trawling has the potential to cause significant impact to habitat, such as removing or destroying physical features and reducing biota and habitat complexity. Therefore, the recovery time of the seabed after trawling varies greatly, and depends on the fishing gear, the substrate, intensity of the trawl and how accustomed the seabed is to natural disturbance.

Undulate rays in this area are generally caught over sandy, gravel habitats.

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Dab
Halibut, Atlantic (Farmed)
Halibut, Pacific
Megrim
Plaice
Sole, Dover sole, Common sole
Sole, Lemon
Turbot (Caught at sea)
Turbot (Farmed)

References

Marine Management Organisation. 2017. Undulate Ray commercial bycatch. Available at: https://www.gov.uk/government/publications/undulate-ray-commercial-bycatch Advice 2016

ICES. 2018. Undulate ray (Raja undulata) in divisions 7.d-e (English Channel). Available at: http://ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/rju.27.7de.pdf. Published 13 July 2018

ICES. 2018. French request for updated advice on undulate ray (Raja undulata) in divisions 7.d-e and 8.a-b for 2018. Available at: http://ices.dk/sites/pub/Publication%20Reports/Advice/2018/Special_requests/fr.2018.13.pdf. Published 13 July 2018 ;

Ellis, J. R., Burt, G.J., Grilli, G., McCully Phillips, S.R., Catchpole, T.L., Maxwell, D.L. 2018. At-vessel mortality of skates (Rajidae) taken in coastal fisheries and evidence of longer-term survival. Journal of Fish Biology. 92, 1702-1719. doi:10.1111/jfb.13597

Mangi, S., Kupschus, S., Mackinson, S., Rodmell, D., Lee, A., Bourke, E., Rossiter, T., Masters, J., Hetherington, S., Catchpole, T. and Righton, D. 2018. Progress in designing and delivering effective fishing industry science data collection in the UK. Fish 00:1-21. https://doi.org/10.1111/faf.12279

Shark Trust; 2010. An Illustrated Compendium of Sharks, Skates, Rays and Chimaera. Undulate Ray. Available at: https://www.sharktrust.org/shared/downloads/id_guides/undulate_ray_st_id_guide.pdf

Marine Management Organisation. 2017. Undulate Ray survey - VII d. Available at: https://www.gov.uk/government/news/undulate-ray-survey-vii-d

MCS. 2017. Offshore Overfalls. Available at: https://www.mcsuk.org/mpa/show-UKMCZ0044 [Accessed on 30.11.2017].

Scientific, Technical and Economic Committee for Fisheries (STECF) - 56th Plenary Meeting Report (PLEN-17-03); Publications Office of the European Union, Luxembourg.