“GO Sars” and MS “Loran” in the Mid-Atlantic Ridge Area

Deepwater skates (Rajidae) collected during the 2004 cruises of R.V. “G.O. Sars” and M.S. “Loran” in the Mid-Atlantic Ridge area

Alexei ORLOV (1), Charles COTTON (2) & Ingvar BYRKJEDAL (3)

ABSTRACT. - The fauna of deepwater skates of the North Atlantic is insufﬁciently studied. Many deepwater species were discovered rather recently (second half of 20t h c e n t u r y) and are known from a few records only. In the summer 2004, studies of bottom ichthyofauna were conducted aboard Norwegian R.V. “G.O. Sars” (bottom trawls, depths down to 3,500 m) and longliner M.S. “Loran” (bottom longlines, depths down to 4,500 m) off the Mid-Atlantic Ridge (MAR) area from Azores to Charlie-Gibbs Fracture Zone. Only four species were identified, these were Richardson’s ray B a t h y r a j a r i c h a rd s o n i, pale ray Bathyraja pallida, Jensen’s skate Amblyraja jenseni, and Bigelow’s ray Rajella bigelowi. Richard- s o n ’s ray has until present been considered a rather rare species. It was described in the earlier 1960s from waters off New Zealand and subsequently found occasionally at great depths in the western and eastern North Atlantic. According to published data, the captures of only 66 specimens of this species are known to date. Our study showed that B. richard s o n i is a common skate in the area surveyed. The 151 specimens captured by the R.V. “G.O. Sars” and M.S. “Loran” allowed us to obtain new data on external morphology and distribution of this species. A capture of a single specimen of B. pallida represented the first for the MAR area. This skate, which was also described in the 1960s, has been known until present by records of twelve specimens only in the Northeast Atlantic from the Bay of Biscay to Rockall Trough. A. jenseni was also captured for the first time in the MAR area. This species was reported mostly from off the coasts of Canada and USA a n d only several captures have previously been known from the Northeast Atlantic. The records of juveniles and adults in postspawning condition, testify that the MAR area is a regular part of the range of A. jenseni, which is not limited to coastal waters of both sides but extends far into the open Atlantic Ocean waters. R. bigelowi was represented in catches by two neonates. Some morphological characters of the specimens examined neither fitted the original description nor published data that probably related to limited number of neonates of both species examined to date.

RÉSUMÉ. - Raies (Rajidae) bathyales récoltées en 2004 au cours des campagnes du N.O. “Sars” et du M.S. “Loran,” dans la zone de la dorsale médio-atlantique. La faune des raies bathyales de l’Atlantique nord est insuffisamment étudiée. Plusieurs espèces furent découvertes à une période relativement récente (seconde moitié du XXe siècle) et elles ne sont connues que par quelques spécimens seulement. Au cours de l’été 2004, des études sur l’ichtyofaune bathyale furent menées par le navire de recherche norvégien “Sars” (chalutage de fond jusque 3500 m de profondeur) et le palangrier “Loran” (palangres de fond jusque 4500 m de profondeur) sur la dorsale médio-atlantique (MAR) depuis la zone des Açores jusqu’à celle de la fracture Charlie-Gibbs. Quatre espèces seulement furent identiﬁées : la raie de Richardson Bathyraja richardsoni, la raie pâle Bathyraja pallida, la raie de Jensen Amblyraja jenseni, et la raie de Bigelow Rajella bigelowi. Jusqu’à présent, la raie de Richardson était consi- dérée comme une espèce rare. Elle a été décrite au début des années 1960 des eaux de la Nouvelle-Zélande, puis elle fut occasionnellement trouvée à grande profondeur dans l’Atlantique nord-est et nord-ouest. Selon les données publiées, seuls 66 spécimens ont été capturés. Notre étude montre que B. richard s o n i est une espèce commune dans la zone prospectée. Les 151 spécimens récoltés par le N.O. “Sars” et le palangrier “Loran” ont permis d’obtenir des données nouvelles sur la morphologie externe et la distribution de cette espèce. La capture d’un spécimen de B. pallida représente le premier signa- lement dans la zone MAR. Cette raie, qui a été aussi décrite dans les années 1960, n’était connue que par 12 spécimens récoltés dans l’Atlantique nord-est, du golfe de Gascogne au plateau Rockall. La raie A. jenseni a aussi été capturée pour la première fois dans la zone MAR. Cette espèce a été signalée des côtes du Canada et des USA, et quelques spécimens seulement étaient connus de l’Atlantique nord-est. La capture de juvéniles et d’adultes en phase de repos après reproduction, montre que la dorsale médio-atlantique est une zone régulière pour A. jenseni, sa distribution n’est donc pas limitée aux eaux côtières des deux côtes de l’Atlantique nord, mais s’étend loin au large dans l’Atlantique. R. bigelowi était représentée dans les captures par deux nouveaux-nés. Certains caractères morphologiques ne coïncidaient pas avec ceux de la description originale, ni avec les données publiées, ce qui est sans doute dû au nombre limité de nouveaux-nés connus pour cette espèce.

Key words. - Rajidae - Mid-Atlantic Ridge - ANE - Skates - Deepwater - Records - Range - Distribution - External morphology.

(1) Russian Federal Research Institute of Fisheries and Oceanography (VNIRO), 17 V. Krasnoselskaya, Moscow, 107140, RUSSIA. [[email protected]] (2) Virginia Institute of Marine Science, PO Box 1346, Rt. 1208 Greate Road, Gloucester Point, Virginia 23062, USA. [[email protected]] (3) Museum of Zoology (Bergen Museum), University of Bergen, Muséplass 3, N-5007 Bergen, NORWAY. [[email protected]]

Cybium 2006, 30(4) suppl.: 35-48. Deepwater skates of Mid-Atlantic Ridge ORLOV ET AL.

The fauna of deepwater skates of the North Atlantic is from the Norfolk Canyon to Greenland and off the Great i n s u fﬁciently studied. Many deepwater species were discov- Banks; in the Eastern Atlantic off the West African coast, in ered rather recently and are known from few records only. the Bay of Biscay, and east of Ireland (Stehmann, 1978, J e n s e n ’s skate Amblyraja jenseni was described by Bigelow 1991, 1995; Stehmann and Bürkel, 1984; Gordon and Dun- and Schroeder in 1950 from a specimen caught off southern can, 1987, 1989; Nielsen et al., 1992; Okamura et al., 1995; New England and two specimens taken off Georges Bank Lorance et al., 1999; Moore et al., 2003). In the central (Bigelow and Schroeder, 1950). This skate is rather common Atlantic R. bigelowi is known from off the Azores only in Canadian waters off Labrador coast where 147 specimens (Stehmann, 1978; Santos et al., 1997) and it has never previ- were captured, most of them since 1995 (D.W. Kulka, pers. ously been caught off the Mid-Atlantic ridge north of the comm.). However, since the original description there are Azores. A rather large number of R. bigelowi (30 specimens) known only nine published records of A. jenseni, most of have been examined in terms of their external morphology them taken off the North American coast (Bigelow and (Stehmann, 1978, 1995) though neonates of this species still S c h r o e d e r, 1953; Leim and Scott, 1966; Moore et al., 2000; remain insufﬁciently studied. Alpoim et al., 2002), but some also in the Northeast A t l a n t i c The main purpose of this paper is to present data on new o ff the European coast (Gordon and Duncan, 1987, 1989; captures of four deepwater rays caught in the North A t l a n t i c Quéro et al., 2000). Till present this species was unknown that show considerable extension of their known ranges, to form the central part of the North Atlantic including the provide external morphological characters that show previ- Mid-Atlantic ridge. The external morphology of A. jenseni ously unknown variations, and to present some data on has scarcely been studied. Some morphometrics of three ranges of depths they inhabit and sizes. specimens only have been available from the literature (Bigelow and Schroeder, 1927, 1950, 1953). R i c h a r d s o n ’s ray Bathyraja richard s o n i was described MATERIALAND METHODS from the waters off New Zealand (Garrick, 1961). Listed among representatives of New Zealand ichthyofauna (Gar- In the summer 2004, studies of bottom ichthyofauna rick and Paul, 1974; Paulin et al., 1989; Hardy, 1990; Cox were conducted aboard Norwegian R.V. “G.O. Sars” (bot- and Francis, 1997; Last and Ye a r s l e y, 2002, etc.) no addi- tom trawls, depths down to 3500 m) and longliner M.S. tional specimens of this species have been caught in New “Loran” (bottom longlines, depths down to 4500 m) off the Zealand waters since the original description. Subsequently Mid-Atlantic Ridge (MAR) area from Azores to Charlie- R i c h a r d s o n ’s rays were recorded in the North Atlantic both Gibbs Fracture Zone in the frame of international CoML o ff the North American and European coasts (Forster, 1965, (Census of Marine Life) field project MAR-ECO (Patterns 1967a, 1968; Tempelman, 1973a, 1973b; Stehmann and and Processes of the Ecosystems of the Northern Mid- Bürkel, 1984; Clarke, 2000; Stehmann and Merrett, 2001), Atlantic). but none in the Mid-Atlantic ridge. The external morphology Fourteen specimens of A. jenseni, 151 specimens of B . of this species is somewhat better known but rests on mor- r i c h a rd s o n i, one B. pallida, and two neonates of R. bigelowi phometrics and meristics of only sixteen adult and four were caught. Measurements and counts were taken from postembryonic specimens (Garrick, 1961; Forster, 1965; three, fifteen (one specimen with broken snout and without Tempelman, 1973a, 1973b; Stehmann and Merrett, 2001). tail end was excluded from the analysis), one and two speci- Pale ray Bathyraja pallida was described by Forster in mens respectively. In addition, the external morphology of a 1967 from two specimens caught in the Bay of Biscay single B. richardsoni from MNHN collections, six A. jenseni ( F o r s t e r, 1967b). This species, currently known by only from MCZ collections, three and seven R. bigelowi f r o m eight records from off northern Ireland and the northern Bay MNHN and MCZ collections, respectively, were examined. of Biscay (Forster, 1968; Stehmann and Bürkel, 1984; Gor- Published data on skate species’ morphology (Bigelow and don and Duncan, 1989; Clarke, 2000; Stehmann and Mer- S c h r o e d e r, 1927, 1950, 1953; Garrick, 1961; Forster, 1965, rett, 2002), has never been caught previously in the central 1967b; Tempelman, 1973b; Stehmann, 1978, 1995; North Atlantic. Data on the B. pallida external morphology Stehmann and Merrett, 2001) were used for comparrison. have been published for two specimens only (Forster, Measurements and counts were made according to Bigelow 1967b). and Schroeder (1953), Ishiyama (1958), Hubbs and Ishiya- B i g e l o w ’s ray Rajella bigelowi was described by ma (1968) and Stehmann (1985). Institutional abbreviations Stehmann in 1978 from specimen caught off US east coast, follow Leviton et al. (1985) and Leviton and Gibbs (1988). fourteen paratypes and eight additional specimens from dif- The maps of species’ distribution were drawn from pub- ferent parts of the North Atlantic (Stehmann, 1978). T h i s lished data and the new information obtained from the cruis- species is currently known by thirty six records from both es of R.V. “G.O. Sars” and M.S. “Loran”. In addition, new sides of the Atlantic Ocean: off the North American coast data from Scottish, French, Canadian, Danish, Spanish and

36 Cybium 2006, 30(4) suppl. ORLOV ET AL. Deepwater skates of Mid-Atlantic Ridge

Figure 1. - MAR-ECO specimens of Jensen’s skate Amblyraja jenseni. A, B: ME 11666 (dorsal and ventral views); C, D: ME 16098 (dorsal and ventral views); E, F: ME 16112 (dorsal and ventral views). [Spécimens MAR-ECO de raie de Jensen A m b l y r a j a j e n s e n i. A, B : ME 11666 (vues dorsale et ven - trale) ; C, D : ME 16098 (vues dorsale et ventrale) ; E, F : ME 16112 (vues dorsale et ventrale).]

Portuguese research cruises provided by John Gordon (1, no any capture data, identiﬁcation may be incorrect; Sven (SAMS), Pascal Lorance (IFREMER), Richard Haedrich Kullander, pers. comm.), ZMUC (10). (MUN), Peter Møller (ZMUC), Jose Gonzalez (Canarian Institute of Marine Sciences) and Gui Menezes (DOP, Uni- versidade dos Açores) were used. Unpublished data on RESULTS AND DISCUSSION s k a t e s ’ capture localities from fish collections of various museums displayed on the FishBase website (www. f i s h- External morphology b a s e . o rg) and found in museums catalogues were also Despite rather ancient description of A. jenseni ( B i g e l o w included on the maps of species’ distribution. Data sources and Schroeder, 1950) and number of its records in the North were as follows (number of specimens in brackets): A . Atlantic since then (Leim and Scott, 1966; Gordon and Dun- j e n s e n i - MCZ (8, five of them are referred by Moore et al., can, 1987, 1989; Quéro et al., 2000; Moore et al., 2003) 2003 with capture coordinates for specimens MCZ 132586 some morphometrics of three specimens only have been and MCZ 138020), YPM (1, referred by Moore et al., 2003 available from the published sources (Bigelow and Schroed- without capture data), ISH (7); B. richard s o n i - AMNH (3), e r, 1927, 1950, 1953). Examination at the MNHN of 3 juve- BMNH (15, no capture data for specimens 1999.10.1.1-2), nile specimens of A. jenseni (MNHN 0000-1910, capture ISH (1), MNHN (1), VIMS (2); R. bigelowi - BMNH (2), data is lacking, specimens were obtained during the 1910 ISH (3), MCZ (18, 16 of them referred by Moore et al., 2003 World Exhibition in Paris; Bernard Séret, pers. comm.) with length data of some specimens only), MNHN (3), NRM revealed incorrect species identification. Low teeth counts

Cybium 2006, 30(4) suppl. 37 Deepwater skates of Mid-Atlantic Ridge ORLOV ET AL.

Table I. - Measurements as percentage of T L and meristics of specimens of Jensen’s skate Amblyraja jenseni (1: Mid-Atlantic ridge: ME 11666, 16098, 16112; 2: Northwest Atlantic: MCZ 55011, 38354, 155628, 37899, 138020-1, 138020; 3: Northwest A t l a n t i c : Bigelow and Schroeder, 1927, 1955, 1953; 4: measurements made from drawings (Bigelow and Schroeder, 1953). [ M e s u res en pourc e n t - ages de la LT et caractères méristiques des spécimens de raie de Jensen A m b l y r a j a j e n s e n i (1 : Dorsale médio-atlantique : ME 11666, 16098, 16112 ; 2 : Atlantique nord - ouest : MCZ 55011, 38354, 155628, 37899, 138020-1, 138020 ; 3 : Atlantique nord - ouest: Bigelow et Schro e d e r, 1927, 1955, 1953 ; 4 : Mesures faites sur les dessins (Bigelow and Schroeder, 1953).]

(< 40) and presence of many thorns on dorsal side suggest misidentification, most probably of Arctic skate A. hyper - b o re a. The study of three MAR-ECO specimens (Fig. 1) and six specimens from MCZ collections (Ta b . I) provides with a new data on variations of external morphological characters, many of which were obtained for this species for the first time. Comparison with type series (Bigelow and Schroeder, 1927, 1950, 1953) shows that newly examined specimens have smaller preorbital and prenasal snout length, space between 5t h gill slit, distance between center of anus and tail tip, snout angle and larger number of median thorns and clasper length. We suggest that these differences are mainly due to considerably larger size of MAR-ECO specimens (range 696-111 3 mm, mean 958 mm v s range 223-691 mm, mean 382-516 mm in the Northwest Atlantic). The most distinctive feature of MAR-ECO specimens from those caught in the Northwest Atlantic is the lack of middorsal space. On the other hand, distinctions found may relate to diff e r e n t population status of specimens in the western North Atlantic and MAR that exist separately for a long time. Unfortu- n a t e l y, there are no morphometric and meristic data on species considered from the Northeast Atlantic. The pale ray B. pallida is the least of the species dealt with here. Despite the

38 Cybium 2006, 30(4) suppl. ORLOV ET AL. Deepwater skates of Mid-Atlantic Ridge

Table II. - Measurements as percentage of T L and meristics, of specimens of pale ray Bathyraja pallida (1: Mid-Atlantic ridge: ME 16322; 2: Northeast Atlantic: Forster, 1967b). [ M e s u res en p o u rcentage de la LT et caractères méristiques des spécimens de raie pâle Bathyraja pallida (1 : Dorsale médio-atlantique : ME 16322 ; 2 : Atlantique nord-est : Forster, 1967b).]

Figure 2. - MAR-ECO specimen of pale ray Bathyraja pallida M E 16322 (A: Dorsal view; B: Ventral view). [Spécimen MAR-ECO de raie pâle Bathyraja pallida (A : Vue dorsale ; B : Vue ventrale).] captures of eight specimens since original description ( F o r s t e r, 1968; Stehmann and Bürkel, 1984; Gordon and Duncan, 1989; Clarke, 2000; Stehmann and Merrett, 2001) only two B. pallida have been examined in terms of their external morphology (Forster, 1967b). Moreover, many morphometrics and meristics used in recent measurement scheme were not provided. Examination of single MAR- ECO specimen (Fig. 2) allows us to supply measurements beyond those provided with the original description (Ta b . I I). The variation of B. pallida morphological characters thus found is not caused by sizes variation (1490 mm in MAR-ECO specimen v s 1492-1565 mm in type specimens), but individual variations of morphological characters that still remain poorly understood. Other possible reason of such distinctions may be associated with spatial isolation of d i fferent populations inhabited MAR and European slopes after dispersion from common centre of species origin. The external morphology of B. richard s o n i is better known. There is a quite large number of specimens examined to date (sixteen adults) appeared from published papers (Garrick, 1961; Forster, 1965; Tempelman, 1973a, 1973b) though they lack many morphometrics and meristics used in vides new ranges for variation of many characters of exter- recent papers. Most recent paper (Stehmann and Merrett, nal morphology that were unknown till present. Paterns of 2001) comprises the full range of morphological characters external morphology of MAR and Northeast Atlantic speci- related to four postembryonic specimens. Examination of mens are quite similar and somewhat differ from those of MAR-ECO (Fig. 3) and MNHN specimens (Tab. III) pro- Northwest Atlantic specimens. The possible reason of these

Cybium 2006, 30(4) suppl. 39 Deepwater skates of Mid-Atlantic Ridge ORLOV ET AL.

Table III. - Measurements as percentage of TL and meristics of specimens of Richardson’s ray Bathyraja richardsoni (1: MAR-ECO specimens: ME 1643, 15751-1, 15751-2, 15751-3, 11638, 153030-1, 153030-2, 153030-3, 153030-4, 38.02, 11652, 16321, 16335, 16307; 2 : Northeast Atlantic: Stehmann and Merrett, 2001; 3: New Zealand waters: holotype, Garrick, 1961; 4: Northeast Atlantic: Forster, 1965; 5: Northeast Atlantic: NMHN 1999-1156; 6: Northwest Atlantic: Tempelman, 1973b; 7: horizontal diameter of eye; M: males; F: females). [ M e s u res en pourcentage de la LT et caractères méristiques des spécimens de raie de Richardson, Bathyraja richardsoni (1 : Spécimens MAR-ECO : ME 1643, 15751-1, 15751-2, 15751-3, 11638, 153030-1, 153030-2, 153030-3, 153030-4, 38.02, 11652, 16321, 16335, 1 6 3 0 7 ; 2 : Atlantique nord-est : Stehmann et Merrett, 2001 ; 3 : Nouvelle-Zélande : holotype, Garrick, 1961 ; 4 : Atlantique nord-est : F o r s t e r, 1965 ; 5 : Atlantique nord-est : NMHN 1999-1156 ; 6 : Atlantique nord - o u e s t : Tempelman, 1973b ; 7 : Diamètre horizontal de l’œil ; M : mâles ; F : femelles).]

40 Cybium 2006, 30(4) suppl. ORLOV ET AL. Deepwater skates of Mid-Atlantic Ridge

Figure 3. - Some MAR-ECO specimens of Richardson’s ray B a t h y r a j a r i c h a rd s o n i. A, B: ME 3802 (dorsal and ventral views); C, D: ME 15304 (dorsal and ventral views); E: ME 16307 (dorsal view). [Spécimens MAR- ECO de raie de Richardson B a t h y r a j a r i c h a r d s o n i. A, B : ME 3802 (vues dor - sale et ventrale) ; C, D : ME 15304 (vues dorsale et ventrale) ; E : ME 16307 (vue dorsale).] distinctions may relate to different population status of material. Also neonates from the Mid-Atlantic ridge have skates in areas mentioned above and their existence isolated notable interdorsal space (range 1.9-2.8, mean 2.4% TL) in each from the other protractedly. comparison with MCZ specimens (range 0-1.5, mean 0.7% Rajella bigelowi is probably the best-studied skate TL) while there was no space between dorsal fins observed among species considered in terms of external morphology previously (Stehmann, 1978, 1995). Speciﬁc morphological (30 specimens examined) (Stehmann, 1978, 1995). T h o u g h features of MAR-ECO specimens may evident the existence morphometric and meristic data of neonates are given only of the local population of R. bigelowi o ff Mid-Atlantic ridge for three specimens caught off the western A f r i c a that probably associated with different ways of species’ d i s- (Stehmann, 1995). The examination of MAR-ECO (Fig. 4) persion from the centre of origination and with existence of and MCZ juvenile R. bigelowi and their further comparison this population separately for a long time. It should be noted with other material (Tab. IV) showed that specimens from that identiﬁcation of neonate R. bigelowi via external exami- Mid-Atlantic ridge have notably longer disk, longer snout nation only is quite difficult because of similarity with con- (in preoral and prenasal directions), smaller tail width at V- generic deep-water ray R. bathyphila. This species diff e r tips, and longer head (ventrally). However, the most distinc- first of all by existence or absence of thorns on snout and tive feature of MAR-ECO specimens is the existence of scapular thorns (Stehmann, 1995). The examination of thorns between dorsal fins that are not observed in other MNHN specimens (MNHN 1988-361 and MNHN 1987-

Cybium 2006, 30(4) suppl. 41 Deepwater skates of Mid-Atlantic Ridge ORLOV ET AL.

Table IV. - Measurements as percentage of T L and meristics of specimens of Bigelow’s ray Rajella bigelowi (1: Mid-Atlantic ridge: ME 12265, ME 14025; 2: Northwest Atlantic: MCZ 55316a-c, 58444, 55314, 158964, 57327; 3: Northeast Atlantic: NMHN 1999-1162, 1988- 361, 1987-482; 4: West African coast: postembryonic specimens, Stehmann, 1995; 5: West African coast: adolescent specimens, Stehmann, 1995; 6: both Northwest and Northeast Atlantic: 1 holotype, 14 paratypes and 8 additional specimens, Stehmann, 1978). [ M e s u res en pourcentage de la LT et caractères méristiques des spécimens de raie de Bigelow, Rajella bigelowi ( 1 : Dorsale médio-atlan - tique : ME 12265, ME 14025 ; 2 : Atlantique nord-ouest : MCZ 55316a-c, 58444, 55314, 158964, 57327 ; 3 : Atlantique nord-est : NMHN 1 9 9 9 - 1162, 1988-361, 1987-482 ; 4 : Côtes ouest-africaines : nouveaux-nés, Stehmann, 1995 ; 5 : Côtes ouest-africaines : adolescents, Stehmann, 1995 ; 6 : Atlantique nord-est et nord-ouest : 1 holotype, 14 paratypes et 8 spécimens additionnels : Stehmann, 1978).]

42 Cybium 2006, 30(4) suppl. ORLOV ET AL. Deepwater skates of Mid-Atlantic Ridge

Figure 5. - Capture localities of Jensen’s skate Amblyraja jenseni in the North Atlantic (1: published data, 2: unpublished data from Canadian cruises, 3: unpublished data from museum collections, 4 : new data from MAR-ECO cruises). [Localités de capture de la raie de Jensen, Amblyraja jenseni, dans l’Atlantique Nord (1 : don - nées publiées, 2 : données non publiées des campagnes cana - diennes, 3 : données non publiées des collections de musées, 4 : nouvelles données des campagnes MAR-ECO).]

Figure 4. - MAR-ECO specimen of Bigelow’s ray Rajella bigelowi Figure 6. - Capture localities of pale ray Bathyraja pallida in the ME 14025 (A: Dorsal view; B: Ventral view). [Spécimen MAR- North Atlantic (1: published data, 2: new data from MAR-ECO ECO de raie de Bigelow, Rajella bigelowi ME 14025 (A : Vue dor - cruises). [Localités de capture de la raie pâle, Bathyraja pallida, sale ; B : Vue ventrale).] dans l’Atlantique Nord (1 : données publiées, 2 : nouvelles données des campagnes MAR-ECO).]

482) showed that both specimens had undeveloped triangles of thorns on the shoulders (one or two large thorns only), smallest specimens had no thorns on snout as well. Never- theless, analysis of X-ray images testifies that both specimens certainly belong to R. bigelowi according to low counts of pelvic rays, trunk vertebrae and teeth (Stehmann, 1978).

Distribution Till present the A. jenseni was unknown from open Figure 7. - Capture localities of Richardson ray B a t h y r a j a richardsoni in the North Atlantic (1: published data, 2: unpublished waters of the North Atlantic. It was frequently caught off the data from Scottish, French and Portuguese cruises, 3: unpublished North American coast (Fig. 5) and there were several cap- data from museum collections, 4: new data from MAR-ECO tures north of Ireland (Bigelow and Schroeder, 1950; Leim cruises). [Localités de capture de la raie de Richardson, B a t h y r a j a r i c h a r d s o n i dans l’Atlantique Nord (1 : données publiées, 2 : don - and Scott, 1966; Gordon and Duncan, 1987, 1989; Quéro e t nées non publiées des campagnes écossaises, françaises et port u - a l ., 2000; Moore et al., 2000). This species occurs in Cana- gaises, 3 : données non publiées des collections de musées, 4 : nou - dian waters very frequently. During bottom trawl surveys off velles données des campagnes MAR-ECO).] Labrador there were 147 specimens of A. jenseni c a u g h t , most of them since 1995 (D.W. Kulka, pers. comm.). T h i s ( D o l g a n o v, 2002) that the centre of origin of A m b l y r a j a skate is also known from Flemish Cap area (Alpoim et al., species in the northern hemisphere took place in A r c t i c 2002). New data show that A. jenseni has continuous range waters between modern Greenland and European coast. in the North Atlantic from US coast to Ireland waters includ- There were two ways of colonization of the North A t l a n t i c , ing Mid-Atlantic ridge. The northernmost record of this southward along American and European coasts. We suggest species was registered off the Labrador, at 60°02’N (D.W. the third way along the Mid-Atlantic ridge. Distinctions of Kulka, pers.comm.). The captures of juveniles, and adults in external morphology of skates in different areas may evident postspawning condition, testify that the Mid-Atlantic Ridge their different population status as result of separate exis- area is a regular part of the range of A. jenseni. It is believed tence protractedly.

Cybium 2006, 30(4) suppl. 43 Deepwater skates of Mid-Atlantic Ridge ORLOV ET AL.

Figure 8. - Capture localities of Bigelow’s ray Rajella bigelowi i n the North Atlantic (1: published data, 2: unpublished data from French cruises, 3: unpublished data from museum collections, 4 : new data from MAR-ECO cruises). [Localités de capture de la raie de Bigelow, Rajella bigelowi, dans l’Atlantique Nord (1 : don - nées publiées, 2 : données non publiées des campagnes françaises, 3 : données non publiées des collections de musées, 4 : n o u v e l l e s données des campagnes MAR-ECO).]

All previous records of B. pallida were registered in the Bay of Biscay and off Ireland (Fig. 6) (Forster, 1967b, 1968; Stehmann and Bürkel, 1984; Gordon and Duncan, 1989; Clarke, 2000). The capture of single specimen in Mid- Atlantic ridge waters represents the first record of the species for this area. According to Dolganov’s (2002) sug- gestions colonization of the North Atlantic by B a t h y r a j a species took place from Arctic and Antarctic waters. In both Figure 9. - Vertical distribution of deepwater skates in the North cases European coasts were colonized first following by Atlantic based on published and new data. [Distribution vert i c a l e des raies de profondeur dans l’Atlantique Nord d’après les don - waters off the North America. Our findings fit well this nées publiées et nouvelles.] scheme. Since B. pallida is most abundant off North Euro- pean and British Isles, we suggest this species penetrates Mid-Atlantic ridge from this area. they moved themselves to Mid-Atlantic ridge and southward Bathyraja richard s o n i was known to date from New to the Azores. Some morphological differences between Zealand waters (Garrick, 1961) and both Atlantic coasts specimens caught in different areas may confirm this ( F o r s t e r, 1965, 1967a, 1968; Tempelman, 1973a, 1973b; hypothesis. Stehmann and Bürkel, 1984; Clarke, 2000). The only single Rajella bigelowi was known by numerous records off the record of this species in New Zealand waters require verifi- North American waters from the Norfolk Canyon to New- cation and study of population based on molecular approach. foundland, off the Azores, off western Africa and east of The southernmost record in the northeastern Atlantic is off British Isles (Stehmann, 1978, 1991, 1995; Stehmann and the Canary Islands (Brito et al., 1998, 2002) and in the Bürkel, 1984; Gordon and Duncan, 1987, 1989; Nielsen e t northwestern part of the ocean is off the Norfolk Canyon al., 1992; Okamura et al., 1995; Santos et al., 1997; Lorance (VIMS specimens). New data (Fig. 7) show that species may et al., 1999; Moore et al., 2003). Our data show that this have an uninterrupted range in the North Atlantic from species is distributed continuously across the North A t l a n t i c American coast to the Mid-Atlantic ridge and off the British (Fig. 8) from the North America to Europe and West A f r i c a , Isles. Dolganov (2002) suggests that Bathyraja species mov- also inhabiting waters of West Greenland (ZMUC speci- ing from Arctic and Antarctic waters first reached area off mens). The capture of neonates in Mid-Atlantic ridge area Greenland, Iceland and British Isles and then they start to indicates that the central Atlantic is part of the spawning colonize American coast. We think that in the same time grounds. According to Dolganov (2002) colonization of

44 Cybium 2006, 30(4) suppl. ORLOV ET AL. Deepwater skates of Mid-Atlantic Ridge

Table V. - Capture depth and total length of deepwater skates in various Bathyraja pallida seems the most pronounced areas of the North Atlantic based on published and new data (range above deepwater species of the four skates. It was recorded the line, mean value under the line, n = number of specimens). [Profondeur de capture et longueur totale des raies de profondeur dans les diverses at depths 1869-2952 m (mean 2523 m). In the North- zones de l’Atlantique Nord, d’après les données publiées et nouvelles (les east Atlantic the mean depth of species’ captures is gammes de variations sont au-dessus de la ligne, les moyennes en dessous, 2508 m that is very close to new MAR-ECO record n = nombre de spécimens).] (2568 m). Bathyraja richard s o n i is found at depths 501- 3055 m (mean 2364 m) with maximum occurrence between 1800 and 2400 m (Fig. 9) and maximum catches (over 25 specimens) deeper 2800 m. T h e depths occupied by this species in different parts of the range do not vary considerably (Ta b . V). Individ- uals caught off the Mid-Atlantic ridge seem the deep- est (mean depth 2485 m v s 2088 m in the Northwest Atlantic and 2215 m in the Northeast Atlantic). Off the Canary Islands B. richardsoni was caught at 2500 m (Brito et al., 1998, 2002). Rajella bigelowi was captured at depths 625 to 4156 m (mean 1705 m) and most frequently occurred between 1400 and 2200 m with maximum catches at 1200-1600 m (Fig. 9). The depths inhabited in various areas of Atlantic differ considerably. Thus, We s t African specimens were caught in shallowest waters (mean 1359 m) while in the Northeast Atlantic it was recorded in deeper areas (mean 1965 m) (Tab. V). Atlantic by Rajella species took place from Arctic to Antarc- tic southward along both sides of the ocean. This scheme fit Length and weight well species’ distribution patterns (Fig. 8). However, we Total length of A. jenseni d i ffers in different areas think that there was third way of dispersion of species, along ( Ta b . V). The largest specimens (mean length 92.61 cm) are the Mid-Atlantic ridge southward to the Azores. recorded in Mid-Atlantic ridge area while on the A m e r i c a n and Europe continental slopes A. jenseni are considerably Bathymetry smaller (49.68 cm and 46.85 cm respectively). There was no A. jenseni is known in the Northwest Atlantic from 366- relation between total length and capture depth (Fig. 10) that 1088 m off Halifax, Nova Scotia and recorded off New Eng- could indicate the lack of size segregation of adults and land at depths of 1908-2296 m (Grey, 1956). It also found at juveniles by depths. Flemish Cap at depth of 650 m (Alpoim e t al., 2002). In the whole North Atlantic this is Table VI. - Differences between male and female deepwater skates in capture depth, total length and body weight in the North Atlantic based on published and new data recorded at depths 167 to 2548 m (mean (range above the line, mean value under the line, n = number of specimens). [ D i f - 1213 m). Most frequently it is caught within f é rences de profondeur de capture, de longueur totale et de poids du corps entre les ranges 200-400 m, 800-1000 m and 2000- mâles et les femelles des raies de profondeur de l’Atlantique Nord, d’après les don - nées publiées et nouvelles (les gammes de variations sont au-dessus de la ligne, les 2200 m (Fig. 9). However, the maximum moyennes en dessous, n = nombre de spécimens). catches (over two specimens) were registered between 1400 and 2200 m (the lack of catches at 1600-1800 m is probably due to the absence of observations in this range). There are some differences of depths inhabited by A. jenseni in different areas of the North Atlantic (Ta b . V). Thus, in the North- west Atlantic this species inhabits shallower waters (167-2311 m with mean 846 m) while in the northeastern part it lives in deeper areas (1800-2190 m with mean 2052 m).

Cybium 2006, 30(4) suppl. 45 Deepwater skates of Mid-Atlantic Ridge ORLOV ET AL.

Figure 11. - Relationships between total length and body weight of J e n s e n ’s skate Amblyraja jenseni and Richardson’s ray B a t h y r a j a r i c h a rd s o n i in the North Atlantic based on published and new data. [Relations entre la longueur totale et le poids du corps de la raie de Jensen, Amblyraja jenseni, et de la raie de Richardson, B a t h y r a j a richardsoni, dans l’Atlantique Nord d’après les données publiées et nouvelles. Figure 10. - Relation between total length and capture depth of deepwater skates in the North Atlantic based on published and new ern part of the ocean (Tab. V). The data on capture depths data. [Relation entre la longueur totale et la profondeur de capture chez les raies de profondeur dans l’Atlantique Nord d’après les and total lengths of B. richard s o n i (Fig. 10) show that there données publiées et nouvelles.] is no segregation of juveniles and adults of this species. There was a well-pronounced (R2 = 0.976) relation In A. jenseni relation between total length and body between total length and body weight of B. richard s o n i weight is expressed (R2 = 0.976) with power coeff i c i e n t ( F i g . 11). The comparison of male and female sizes showed close to three (Fig. 11). that males of this species are considerably longer (102.74 Some differences between males and females of A . cm v s 86.04 cm on the average) than females (Tab. VI). In j e n s e n i regarding depths inhabited and sizes were found the same time, males inhabit somewhat deeper areas (mean (Tab. V I). Males were longer (80.30 cm v s 72.31 cm) and depth 2454 m vs 2324 m in females). heavier (8302 g v s 6445 g) than females and live at slightly The maximum total length of R. bigelowi is 53 cm. Size deeper depths (mean 1860 m vs 1693 m). of this skate differs in various areas of the Atlantic Ocean There are very little data on length of B. pallida. Mini- ( Tab. V). The largest specimens (mean 35.54 cm) were mum and maximum total lengths are 30.6 and 162 cm recorded in the Northeast Atlantic while the smallest ones r e s p e c t i v e l y, with mean value 113.55 cm. A very limited were caught off the western Africa (26.19 cm). There are no number of known captures of B. pallida, however, indicate data on body weight of this species, therefore the relation- (Fig. 10) that juvenile and adult skates inhabit the same ship between total length and body weight remains depths. unknown. L a rgest B. richard s o n i (95-174 cm, mean 135.56 cm) As in the case of other skates, depths occupied by juve- were caught in the Northwest Atlantic while smallest skates nile and adult R. bigelowi are the same (Fig. 10). Males (25-168 cm, mean 77.47 cm) were recorded in the northeast- demonstrate more deepwater pattern (Tab. VI) in compari-

46 Cybium 2006, 30(4) suppl. ORLOV ET AL. Deepwater skates of Mid-Atlantic Ridge son with females (mean depth 1801 m vs 1667 m). There are B I G E L O W H.B. & W.C. SCHROEDER, 1953. - Sawfishes, gui- tarfishes, skates and rays. I n: Fishes of the Western North not so notable differences between male and female sizes as Atlantic. Part 2 (Te e - Van J. et al., eds). Mem. Sears Found. in the case of other species (mean total length 31.54 cm and Mar. Res., 1: 1-514. 30.12 cm in males and females respectively), which is most B R I TO A., PA S C U A L P.J., FALCÓN J.M., SANCHO A. & G. probably related to smallest linear size of Bigelow’s ray GONZÁLEZ, 2002. - Peces de las Islas Canarias. Catalogo comentado e ilustrado. 419 p. La Laguna, Santa Cruz de Te n e- among species considered. rife: Francisco Lemus. B R I TO A., PA S C U A L P., RABANAL R., HERNÁNDEZ M., A c k n o w l e d g e m e n t s. - This paper would not be possible without LOZANO I.J., BÁEZ A., SANCHO A., GONZÁLEZ G., the assistance of our numerous colleagues. Matthias Stehmann FALCÓN J.M. SANTA N A J.I. & J.A. GONZÁLEZ, 1998. - (Ichthys, Hamburg, Germany) advised on species identification and Peces cartilaginosos de Canarias. Los Tiburones de los Fondos gave valuable advises. James Orr (Alaska Fisheries Science Center, profundos y su aprovechamiento Pesquero. 171 p. Las Palmas Seattle, USA) and Hajime Ishihara (Tayo Engineering Co., Ltd., de Gran Canaria: Viceconsejería de Pesca del Gobierno de Tokyo, Japan) explained some specific skates’ morphometric mea- Canarias. surements. John Gordon (Scottish Association for Marine Sciences, CLARKE M.W., 2000. - Records of deep-water chondrichthyan Oban, Scotland), Pascal Lorance (Ifremer, Plouzané, France), Gui fish caught on long-line in the Rockall Trough. J. Mar. Biol. Menezes (University of Azores, Fajal, Azores, Portugal) and Jose Ass. U.K., 80: 377-378. Gonzalez (Canarian Institute of Marine Sciences, Gran Canaria, COX G. & M. FRANCIS, 1997. - Sharks and Rays of New Canary Islands, Spain) provided us with the data on captures of Zealand. 68 p. Christchurch: Canterbury Univ. Press. some skates in the Northeast Atlantic in Scottish, French, Por- tuguese and Spanish cruises. Richard Haedrich (Memorial Univer- D O L G A N O V V.N., 2002. - The origin and distribution of rays of s i t y, St. John’s, Canada) and Dave Kulka (Northwest Atlantic Fish- the suborder Rajoidei in the World Ocean. J. Ichthyol., 42 eries Science Center, St. John’s, Newfoundland & Labrador, Cana- (Suppl. 1): 1-22. da) shared with us the data on skates’ captures off Canadian coast. FORSTER G.R., 1965. - Raja richard s o n i from the continental Peter Rask Møller and Tammes Menne (Zoological Museum Uni- slope off south-west England. J. Mar. Biol. Ass. U.K., 45: 773- versity of Copenhagen, Copenhagen, Denmark), Romain Causse 777. (Museum National d’Histoire Naturelle, Paris, France), Darrell FORSTER G.R., 1967a. - A note on two rays lacking part of the Siebert (British Museum of Natural History, London, Great snout. J. Mar. Biol. Ass. U.K., 47: 499-500. Britain), Karsten Hartel and Andrew Williston (Museum of Com- parative Zoology, Harvard, USA), Horst Wilkens (Zoologisches FORSTER G.R., 1967b. - A new deep-sea ray from the Bay of Bis- Institut und Zoologisches Museum der Universität Hamburg, Ham- cay. J. Mar. Biol. Ass. U.K., 47: 281-286. b u rg, Germany), Barbara Brown (American Museum of Natural FORSTER G.R., 1968. - Line-fishing on the continental slope. II. J. H i s t o r y, New York, USA) and Sven Kullander (Naturhistoriska Mar. Biol. Ass. U.K., 48: 479-483. Riksmuseet, Stockholm, Sweden) provided the data on records of GARRICK J.A.F., 1961. - Studies on New Zealand Elasmo- skates from museums’ ichthyological collections. Romain Causse branchii. Part XIII. A new species of Raja from 1,300 fathoms. (Museum national d’Histoire naturelle, Paris, France) also did X- Trans. R. Soc. N.Z., 88: 743-748. ray images of some skates from MNHN collections. Bernard Séret (Museum national d’Histoire naturelle, Paris, France), Karsten GARRICK J.A.F. & L.J. PAUL, 1974. - The taxonomy of New Hartel (Museum of Comparative Zoology, Harvard, USA), Patrick Zealand skates (suborder Rajoidea), with descriptions of three Campbell and Roberto Miguez (British Museum of Natural Histo- new species. J. R. Soc. N.Z., 4: 345-377. r y, London, Great Britain) and Michéle Bruni (Monaco Oceano- GORDON J.D.M. & J.A.R. DUNCAN, 1987. - Deep-sea bottom graphic Museum, Monaco) made possible examination of some living fishes at two repeat stations at 2200 and 2900 m in the specimens and provided facilities and equipment. Natalia Popova Rockall Trough, northeast Atlantic Ocean. M a r. 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