Version 2 July 2009 responsible sourcing guide: skates & rays

Introduction Skates and rays comprise a large group of fish, which includes the true skates (Order ) and species such as electric ray and stingray. The main commercial species within northern European waters are the true skates, which have common names that generally distinguish the large species with long snouts (skates) from the smaller species with short snouts

(rays). For the purposes of this guide, the term is used Thornback Ray in its generic (and commercial) sense to refer to all the true clavata © Marc Dando skates, and includes those skate species that have the term ‘ray’ in their common name.

Skates have a relatively high commercial importance in Europe and BUYERS’ TOP TIPS the UK. The total weight of the seven or eight most commonly landed 1. Know your source of supply 3. Comply with regulations species in UK ports in recent years and stock status Supporting those vessels that has been 2–3,000 tonnes (t) per year For management purposes, the record their landings by species will (1), with a first-sale value of about stocks of the various skate species help to improve stock management. £3million. There are more than 500 are allocated to management areas. Some Sea Fisheries Committees (7) species of skate and ray throughout To understand sustainability issues enforce a minimum landing size the world (2), including about 230 concerned with your supply, you (MLS) which should help to protect species of true skate, and total world need to know from which area a juvenile skates and rays. catches are about 250,000 t (3). species has been caught. Table 1 The purpose of this guide is to provide gives an overview of the status of 4. Use the Seafish Responsible a brief account of north European the stocks in the North East Atlantic. Sourcing Service skates that are of commercial Seafish has created a service at importance, outline the conservation 2. Have an informed buying policy www.seafish.org/b2b/rss that gives status of the main stocks marketed in Some skate species remain information on sustainability issues. the UK, and describe the measures abundant and, in many areas, There are also skate and ray being taken to manage and conserve cuckoo, spotted, smalleyed and identification sheets. This links to them. The guide also outlines some of thornback ray appear to have stable other sources of information and the the research being undertaken for catch rates. It should be possible to Responsible Fishing Scheme (BSi: improving the assessment and harvest these species sustainably. PAS 72:2006), aimed at ensuring management of skate fisheries. In contrast, the larger species such best quality and environmental as white skate and common skate, practice onboard vessels. Advice on the status of the various have disappeared from large parts stocks is based on data from scientific trawl surveys (4, 5) and on knowledge of their former range (6) and should of the ecology and life-history of the be avoided. various species.

1. Species and biology Some 25 species of skate and ray Norway and Iceland. Many species thornback ray and blonde ray grow to occur in waters around the British have distributions that extend to 110–120cm, whilst common skate and Isles (8). The most abundant species southern Spain and northwest Africa, white skate grow to more than 200cm. in inshore waters are thornback ray with several also occurring in the Skates typically mature at between (Raja clavata), blonde ray (Raja Mediterranean. The UK is at the five and 10 years of age, with the brachyura) and spotted ray (Raja southern limit of the starry ray smaller-bodied species maturing at an montagui) (4, 9). Cuckoo ray distribution in the North East Atlantic, earlier age. Male and female skates (Leucoraja naevus), shagreen ray and this species also occurs in the are easily identified, as males have a (Leucoraja fullonica) and common northwest Atlantic. pair of claspers (used in copulation) skate (Dipturus batis) are found alongside the pelvic fins. The females further offshore, with long-nosed skate Although locally-abundant skate lay fewer than 100 eggs per year, on (Dipturus oxyrinchus) and sandy ray species are targeted in some areas the sea floor, and these hatch after (Leucoraja circularis) occuring along (such as the thornback ray in the four to six months (10). the edge of the continental shelf. In Thames Estuary and blonde ray in St the central and northern North Sea, George’s Channel), most skates are The juveniles of inshore species (such starry ray (Amblyraja radiata) is the landed in mixed demersal fisheries, as thornback, spotted, blonde and most abundant skate species, along with flatfish and roundfish. smalleyed rays) occur in bays and although it is of little commercial coastal waters and move into deeper importance due to its small size. Skates are elasmobranchs, that is, water as they grow (9). Nursery Smalleyed ray (Raja microocellata) fish with a cartilaginous skeleton. grounds for offshore species are less and undulate ray (Raja undulata) are These fish are typically large bodied, well known. Adult fish move over most frequently found in the Bristol slow growing and with a late age at wider areas, though they may return Channel and English Channel maturity. They produce few young to certain areas to feed or breed respectively. compared to most bony fish, such as (11–13). Skates feed primarily on the cod, which may each shed millions of sea floor; juveniles eat small All these species occur widely in eggs every year. As a consequence, crustaceans, and the larger species European seas, though the British skates are susceptible to overfishing. eat shrimps, crabs and fish (14). Isles are at the northerly limits of blonde, spotted, smalleyed and There are differences in the growth of undulate ray distribution. Common skate species: smaller-bodied species and long-nosed skate, and shagreen such as spotted ray and cuckoo ray ray, may be found as far north as grow to about 70–80cm in length;

Assessment Historically these species have been upon this information which is A general rule is that the abundance recorded in a generic 'skates and summarised for sea areas around of large skates has declined and they rays' category. However, from 2009 the British Isles in Table 1. Whilst this are relatively more vulnerable to species-specific recording is is not a full stock assessment, it does exploitation, whilst those species that compulsory and the UK fishery give an overview of the relative status mature at a smaller size have departments have been implementing of these stocks. healthier populations. This is this recording from 2008. illustrated in Table 2, which shows the There is less known about the status IUCN conservation categories in Analysing the catch-per-unit-effort of skates in southern European seas. relation to body size of the more (CPUE) of skate species, that is the The disappearance of the largest commercially important skate species. catch per hour trawling taken in skate species has been reported from scientific fishing surveys, allows the the Bay of Biscay and Mediterranean, status of particular stocks to be whilst surveys off the northern coast assessed in the various sea areas. of Spain suggest that catch rates of These surveys, however, do not some of the smaller species (such as sample all skate species effectively. In thornback and cuckoo ray) are stable. 2008 ICES provided advice based

Egg cases (left to right) of blonde, thornback and spotted ray 2. Table 1 Status and Total Allowable Catches (TACs) for skates and rays

e m ) t a ( d n n 9 s a 0 ) e i 0 e 4 c c 2 i ( e t v t p n d n s C e a e A y n t c a T m i i m o f e d e r i e r m e g o t g A a n a e ) h m n t e n a r i o g 5 a u a e 1 c S C A ( M A S m

NORTH EAST ATLANTIC SKATE AND RAY STOCKS www.ices.dk North Sea and eastern Thornback Ray North Sea EU The distribution of thornback ray has declined in the North Sea, as English Channel 1643, has the overall catch-per-unit-effort. The stock status is classified as uncertain in the northern North Sea (ICES VIa,b) and stable or EU waters of ICES div IIa, Eastern English increasing in the southern North Sea (ICES VII d) and eastern English ICES sub area IV and VIId Channel 1044. Channel.

Spotted ray Catch-per-unit-effort seems to be stable or increasing; stock classified as stable/increasing.

Cuckoo ray Catch-per-unit-effort is considered to be stable; stock is described as stable.

Starry ray Catch-per-unit-effort increased in the 1980s and, although it has recently declined, starry ray remains one of the most abundant rays in the North Sea; stock described as stable. Irish Sea, Bristol Channel, Thornback ray 15,748 EU One of the most commonly caught skate species in the area and western English Channel catch-per-unit-effort is generally stable; stock classified as stable/increasing. and North West Scotland (ICES VIIa-c, e-k and sub Spotted ray One of the most commonly caught ray species in the area and catch- area VI) per-unit-effort is generally stable or increasing; stock in ICES VIa VIIf,g classified as stable/increasing.

Cuckoo ray Catch-per-unit-effort has declined slightly, but this remains one of the more common species in offshore areas of the Irish Sea and western English Channel. Stock status;West of Scotland (ICES division VIa) stable/increasing. Other areas uncertain.

Blonde ray Status uncertain. Being a large bodied species that has a patchy distribution, it is potentially vulnerable to over-exploitation.

Small-eyed ray Catch-per-unit-effort in the Bristol Channel (ICES div VIIf) is stable.

Sandy ray EU West of Scotland; ICES sub area VI;uncertain; ICES VIIb, c, h-k stable/increasing. This large bodied species is potentially vulnerable to exploitation.

Shagreen ray Status uncertain and now rarely recorded in inshore areas.

Other Norwegian or Catches of all EU Status uncertain with reason for concern. black skate these species may not be Undulate ray Status uncertain, though this large-bodied species is potentially retained on vulnerable to over-exploitation. board.They Common skate must be Common skate has disappeared from the shallow waters of the North released Sea, English Channel and Irish Sea. Catch-per-unit-effort in the northern North Sea, NW Scotland and Celtic Sea is low. Stock status; depleted. promptly Long-nosed unharmed in Status uncertain. A large-bodied species that is potentially vulnerable skate most EU to over-exploitation, though most common in deep water. waters. White skate This large-bodied species no longer occurs regularly in its former range in coastal waters of the English Channel, Irish Sea or along the west coast of Ireland. Stock status; severely depleted.

Organisation key EU: The European Union manages IUCN: World Conservation Union. SRPA: The Skate and Ray fisheries within the Exclusive Has developed the IUCN Red List Producers’ Association (17) is an Economic Zone. Criteria (16) which gives a general organisation of specialist producers, indication of whether a population whose membership covers Great ICES: International Council for the has declined (in either numbers or Britain and Ireland. It has played an Exploration of the Sea. Responsible distribution) and, if so, by how much. active role in working with for providing scientific advice for conservation organisations. North East Atlantic fishery management. 3. Fishing gear Species identification Skates are taken as a by-catch in 1 most bottom trawl fisheries, some of and distribution which may target skates in certain areas at certain times of the year. They are also a target species or by- catch in gillnet, tangle net and longline fisheries. Skates and rays identification Thornback ray

Common name Latin Name No Research Thornback ray Raja clavata 1 Undulate ray Raja undulata 2 Tagging studies have provided Small-eyed ray Raja microocellata 3 information with which to identify Cuckoo ray Leucoraja naevus 4 stocks or management units for Spotted ray Raja montagui 5 several of the more abundant species Blonde ray Raja brachyura 6 (e.g. thornback ray), but better data Shagreen ray Leucoraja fullonica 7 for other species are required to Sandy ray Leucoraja circularis 8 delineate stock boundaries (17). Common skate Dipturus batis 9 Because skates are highly vulnerable to most demersal net-fishing methods, Skate and ray illustrations © Marc Dando the success of management measures such as MLS and catch quotas rely on discarded fish being able to survive. Ongoing studies aim to provide estimates of survival of thornback rays discarded in the important inshore fisheries in the Undulate and Small-eyed ray southern North Sea and Bristol Channel.

Several aspects of the biology of skates require further scientific research to improve assessment of their status, and to identify management needs and solutions. In particular, the life-history, growth and longevity of the less abundant species is virtually unknown. Improved understanding of reproductive capacity (and, hence, sustainability) requires better information on the number of eggs laid per year, survival rates of eggs and juveniles (18), and whether egg- laying is site specific.

2 3

Thornback ray Raja clavata

4. 4 5 6

Cuckoo ray Spotted and Blonde ray

Shagreen and Sandy ray Common skate

7 8 9

5. Management and conservation

In recent decades there has been a There is a stipulated minimum mesh Management units decline in the abundance and size of 280mm in the cod end, and Currently, management units for distribution range of some UK skate 220mm in all other parts of the trawl skate stocks are based on what is species, particularly those that are for targeted skate fisheries. However, known about the distribution and either large-bodied (such as targeted fisheries in North Sea movements of the various species in common and white skate) and/or waters for these species is relation to management areas (ICES those with restricted distributions. discouraged, because vessels larger sub-areas and divisions). Tagging Whilst catch rates of thornback rays than 15m are only permitted to land studies on a few of the more in scientific surveys seem generally a maximum of 25% of the catch abundant skate species (11–12) and stable in many areas, there has (whole weight) as skates and rays. genetic studies (22) can help identify been a retraction in their overall stock units, but scientific distributional range in the North Sea. Management of fisheries in the North investigations are required to Survey catch rates for smaller East Atlantic specifically aimed at delineate stock boundaries more species, such as spotted ray, appear conservation of skates is relatively accurately, especially for species to be stable in recent years (see new, but is evolving along with distributed across several Table 1), suggesting that these improving scientific knowledge and management areas, such as the stocks are being harvested advice. cuckoo ray. sustainably. However, the current status of lesser-known skate There is more uncertainty in the Stock abundance species, such as shagreen ray, that assessments of skates than for most Existing routine scientific fishing are not sampled effectively in other commercial fish species. This surveys were designed primarily for surveys, is uncertain. has led to a growing realisation roundfish or flatfish, and the gear amongst fishermen, processors, used and survey locations may not There have been four substantial scientists and conservationists that be ideal for skates. Additionally, developments in the management of there is a need for a collaborative some species have a patchy skates and ray stocks around the approach to assess and manage distribution, so that only a few British Isles in the last two years these species; hence the formation catches in surveys may have (15); of the Skate and Ray Producers’ sufficient numbers of individuals to Association (SRPA) (17). assess their abundance. 1.ICES advice has been given by sea area for many species. Some of the main issues for Protection of juveniles management of skate stocks (20) There are no national or EU 2.Legislation has been introduced to are: measures to protect juvenile skates, ensure landings of skates and rays though several Sea Fisheries are recorded by species, and UK Insufficient knowledge of catches Committees (7) in England and authorities are working towards its Skate landings have long been Wales have a minimum landing size implementation. reported as 'skates and rays'. This (MLS; typically 40–45cm across the has made it impossible to detect wings) to stop juveniles being 3.The retention of common, white changes in the abundance of landed. One problem is that, in order and black or Norwegian skates individual species over time from to protect the juveniles of larger- (Dipturus nidarosionsis) and commercial data. To improve this bodied species (which tend to be the undulate rays is now illegal in most SRPA has been recording speciated most threatened), a high generic European waters. Fishermen are landings into a database (17). It is skate MLS would result in increased required to return individuals of now a legal requirement to land discarding of some of the smaller- these species to the sea alive. these species separately. bodied species.

4.Total allowable catches have been Species identification introduced for skates and rays in Identifying skates to species can be most European waters. These put a difficult, as colour patterns can vary cap on the total quantity of skates and closely related species are and rays that can be landed (TACs difficult to distinguish, especially the had already been implemented in juveniles. The production of the North Sea). improved, user-friendly identification material is aimed at easing this problem (17).

6. Management and conservation continued

Location and protection of A maximum landing length may help However, the situation is not the spawning stock protect the largest fish and the same for all species and areas, and Various skate species are known to mature females of the commercially it is important to work in a aggregate seasonally (for feeding or important species. collaborative way to build on breeding), and closing particular scientific and fishing industry areas to fishing has been suggested In summary, skates are vulnerable to knowledge to improve management as a useful management measure exploitation due to their biological of these stocks, starting with basic (23). However, the locations of characteristics. Management of the information such as identification of spawning grounds are usually not fisheries is difficult because most the species that will enable them to known. skates are taken as by-catch in be assessed separately. fisheries for other species.

Maximum Length (cm) Table 2: IUCN criteria0 for UK skates and8 5rays stocks 170 255

Common skate White skate Maximum Length (cm) Long-nosed skate 0 85 170 255 CommoBlonden ska rayte Critically endangered WhitSandye ska rayte Endangered Long-nosedThornback ska rayte Vulnerable ShagBlondereen ray CriNeartically threa endangeretened d UndulateSandy rayray LeasEndangeredt Concern TSmallehornbackyed rrayay DataVulnera deficientble ShagSpottereend rayray Near threatened UndulateCuckoo rrayay Least Concern SmalleStarryyed rayray Data deficient Spotted ray Cuckoo ray Starry ray

Table 2 illustrates the IUCN criteria include some of the more important many marine fishes broadly equates of UK skates in relation to body size, commercial species) are of some with those species that are depleted illustrating how the larger-bodied concern, whilst small-bodied skates and ‘outside safe biological limits’ skates are thought to have declined are not considered to be threatened. under ICES criteria (24). (and are of conservation concern). The IUCN define their criteria in The medium-sized skates (which terms of ‘extinction risk’, which for

7. Product characteristics Identification charts are useful for separating the different found in flatfish and roundfish. As with all skate species. The main edible parts of skates are the elasmobranchs, skates have a propensity to develop wings, and merchants should be able to identify most ammonia during storage; good handling practice species from the wings alone. The flesh is distinctive and concerning temperature control and shelf life help to the bones are soft cartilage rather than the hard bones control this tendency. Supply chain REFERENCES 1. Defra UK Sea Fisheries Statistics 13. Hunter, E et al (2005). J. Mar. Biol. standards (see Ass. UK, 85: 1199–1200. Responsible practice in the chilled http://www.mfa.gov.uk/statistics/uksea 14. Ellis, JR et al (1996). J. Mar. Biol. Ass. and frozen supply chain depends on fish.htm) UK, 76:89–106. using appropriate catching methods 2. Compagno, LJV (1999). Checklist of 15. *Council Regulation (EC) No and correct chilling or freezing, living elasmobranchs. In Sharks, 43/2009. skates and rays. The biology of processing and handling throughout 16. http://www.iucnredlist.org/ elasmobranch fishes (WC Hamlett, the chain. Seafish has developed 17. www.seafish.org/b2b/area.asp?p=189 standards that cover these aspects ed). The John Hopkins University Press, 471–498. 18. Pawson, MG and Ellis, JR (2005). J from capture to retailer: Northwest Atl. Fish. Sci., 35: 3. FAO Global Capture production. 173–193. http://www.fao.org/fishery/topic/2017 • Responsible Fishing Scheme 19. Cox, DL et al (1999). Trans. Am. Fish. 4. ICES (2007). Report of the Working Sets good practice standards for Soc., 128: 380–384. fishing vessels, based on British Group on Elasmobranch Fishes. ICES CM 2007/ACFM:27. 20. *Council Regulation (EC) No Standards Institution (BSi) 41/2006. specifications (BSi: PAS 72:2006): 5. Ellis, JR et al (2005). J. Mar. Biol. Ass. UK, 85: 1025–1047. 21. Ellis, JR et al. (In press). and Management of elasmobranch 6. Brander, K (1981). Nature, • British Retail Consortium (BRC) fisheries in the North Atlantic. In 290:48–49. Global Standard and Safe and ‘Advances in Fisheries Science: 50 7. www.asfc.org.uk Local Supplier Approval (SALSA) years on from Beverton and Holt’ certification Designed to raise 8. Wheeler, AC et al (2004). Additional (A.I.L. Payne, A.J. Cotter and E.C.E. standards in the seafood processing records and notes for Wheeler's Potter, eds.) Blackwell Publishing. (1992). List of the Common and and wholesaling sectors. 22. Chevolot, M et al (2006). J. Sea Res., Scientific Names of Fishes of the 56: 305–316. British Isles. Journal of Fish Biology 23. Hunter, E et al (2006). J. App. Ecol., 65 (Supplement B), 1–40. 43: 710–720. Seafish 9. Ellis, JR et al (2005). J. Northwest Atl. 24. Dulvy, NK et al. (2005). J. App. Ecol., Fish. Sci., 35: 195–213. Responsible 42: 883–891. 10. Ellis, JR and Shackley, SE (1995). Sourcing Services J.Fish Biol., 46:903–904. *European Legislation available on 11. Walker, PA et al (1997). ICES J. Mar. www.europa.eu This is one of a series of Sci., 54:797–808. Responsible Sourcing Guides 12. Hunter, E et al (2005). J. Mar. Biol. produced by Seafish. Further guides Ass. UK, 85: 1095–1105. and information fisheries conservation and gear technology may be found at www.seafish.org/b2b/rss

For further information contact: Bill Lart – Tel: 01472 252323 or email: [email protected] Karen Green – Email: [email protected]

Contact Seafish at: www.seafish.org http://sin.seafish.org

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