7(2)Imp/ok 16-06-2003 12:10 Pagina 1 aqua2).pdf · 7(2)Imp/ok 16-06-2003 12:10 Pagina 47 aqua vol. 7 no. 2 - 2003 48 Diets, feeding habits, and trophic relations of six deep-benthic

aquaJournal of Ichthyology and Aquatic

BiologyVol. 7 (2), June 2003

AquapressISSN

0945-9871

7(2)Imp/ok 16-06-2003 12:10 Pagina 1

Managing Editor:

Heiko BleherVia G. Falcone 11, 27010 Miradolo Terme (PV), ItalyTel.: +39 0382 754707/08 - Fax: +39 0382 754129e-mail: [email protected]

Scientific Editor:

Dr. Walter IvantsoffSenior Research Fellow,Department of Biological Sciences,Macquarie University, N.S.W. 2109, AustraliaTel. +61 2 9850 8167 - Fax +61 2 9869 8886 e-mail: [email protected]

Editorial Board:

Gerald R. Allen, I Dreyer Road Roleystone, W. A. Australia 6111

George W. Barlow, Department of Integrative Biology,University of California, Berkeley, CA 94720-3140,U.S.A.

Henri J. Dumont, Rijksuniversiteit Gent, Laboratoriumvoor Ecologie der Dieren, Zoogeografie en Natuur-behoud, K. L. Ledeganckstraat, 9000 Gent, Belgium

Jacques Géry, Chemin du Plantier, 24200 Sarlat,France

Frank Kirschbaum, Institut für Gewässerökologie undBinnenfischerei, Abt. 4 Forschungsverbund Berlin e. V.Müggelseedamm 310, 12587 Berlin, Germany

Friedhelm Krupp, Forschungsinstitut Senckenberg,Senckenberganlage 25, 60325 Frankfurt am Main,Germany

Christian Lévêque, CNRS - Programme EnvironnementVie et Sociétès, 1 Place Aristide Briand, 92195 ParisCédex, France

Volker Mahnert, Muséum d’Histoire Naturelle, Route deMalagnou 1, 1211 Genève 6, Switzerland

Robert R. Miller, University of Michigan, Museum ofZoology, Ann Arbor, Michigan 48109, U.S.A.

Paolo Parenti, Department of Enviromental Sciences,University of Milan-Bicocca, Piazza della Scienza 1, I-20126 Milan, Italy

John E. Randall, Bishop Museum, 1525 Bernice Street,P.O. Box 19000-A, Honolulu, Hawaii, U.S.A.

Wolfgang Schneider, Hessisches Landesmuseum,Darmstadt, Friedensplatz 1, 64283 Darmstadt, Germany

Lothar Seegers, Grenzstraße 47b, 46535 Dinslaken,Germany

Wolfgang Villwock, Universität Hamburg, ZoologischesInstitut und Zoologisches Museum, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany

Chem Yi-yu, Institute of Hydrobiology, Academia Sinica,Wuhan Hubei, P. R. China

Scope and aims

aqua is an international journal which publishes originalscientific articles in the fields of systematics, taxonomy ,biogeography, ethology, ecology, and general biology offishes, amphibians, aquatic invertebrates, and plants.Papers on freshwater , brackish, and marine organismswill be considered. aqua is fully refereed and aims atpublishing manuscripts within 2-4 months of acceptance.With the publication of aqua we are pursuing a new con-cept: In view of the importance of colour patterns inspecies identification and animal ethology , authors areencouraged to submit colour illustrations as well asdescriptions of coloration. It is our aim to provide the international scientific community with an ef ficientlypublished series meeting high scientific and technicalstandards.

Call for papers

The editors welcome the submission of original manu-scripts which should be sent directly to the scientific editor. Full length research papers and short notes will beconsidered for publication. There are no page chargesand colour illustrations will be published free of charge.Authors will receive 50 free reprints of each paper .

Subscription Notice

A volume (4 issues) of aqua will be published each year,each issue comprising 48 pages (including cover). The annual subscription rate is US$ 26.00 plus postageUS$ 10.00 / Euro 26,00 plus postage Euro 10,00 (prior-ity postage US$ 17.00/Euro 17,00). Subscription enquires should be sent to the addressgiven below or our e-mail: [email protected]

ISSN 0945-9871Publisher: Aquapress, Redazione aqua, I-27010 Miradolo Terme (Pavia), ItalyPrinter: S.A.T.E. s.r.l. (Bergamo) ItalyTypesetting: Rossella Bulla© 2003 aqua, Journal of Ichthyology and Aquatic Biology

aqua - Journal of Ichthyology and Aquatic Biology

7(2)Imp/ok 16-06-2003 12:10 Pagina 2

KeywordsSkates, diets, feeding habits, Aleutian skate,

Bathyraja aleutica, Alaska skate, Bathyraja parmifera,Matsubara skate, Bathyraja matsubarai , white-blotched skate, Bathyraja maculata , white-browskate, Bathyraja minispinosa, Bering skate, Rhinorajainterrupta, western Bering Sea

AbstractThe diets of six species of skates inhabiting the

western Bering Sea were examined: Aleutian skateBathyraja aleutica, Alaska skate B. parmifera , Mat-subara skate B. matsubarai, white-blotched skate B.maculata, white-brow skate B. minispinosa , andBering skate Rhinoraja interrupta. The diets of preda-tory skates (Alaska, Aleutian, white-blotched, Matsub-ara, and white-brow skates) consisted of large crus-taceans, cephalopods and fishes. BenthophagicBering skates consumed mainly Tanner crabs, gam-marid amphipods, and shrimps. The consumption ofworms and crustaceans by predatory skates declinedwith increasing skate size, whereas consumption offishes increased. The consumption of worms andsmall crustaceans by benthophagic Bering skatesdeclined with increasing skate size while consumptionof crabs and squid increased. Diets of male andfemale skates dif fered, probably due mostly to theeffect of size. Among the species examined, threeskate pairs had a medium level of dietary similarity:Aleutian and Alaska skates, Alaska and white-browskates, and white-brow and Bering skates.

ZusammenfassungDie Nahrung von sechs Rochenarten aus dem west-

lichen Beringmeer wurde untersucht: Aleutian-RochenBathyraja aleutica, Alaska-Rochen B. parmifera, Mat-subara-Rochen B. matsubarai, Weißfleck-Rochen B.maculata, Weißbrauen-Rochen B. minispinosa undBering-Rochen Rhinoraja interrupta. Die Nahrung derräuberischen Rochen (Alaska, Aleutian, Weißfleck,Matsubara und Weißbrauen) bestand aus großenKrustentieren (Crustacea), Cephalopoden und aus Fis-chen. Auf dem Boden fressende Rochen nahmen

hauptsächlich Tannerkrebse, Gammariden Flohkrebse(Amphipoda) und Garnelen. Der Verzehr von Würmernund Krustentieren durch räuberische Rochen nahm mitder Größe der Rochen ab, wobei sich der V erzehr vonFischen erhöhte. Der Verzehr von Würmern undkleinen Crustacea durch am Boden fressende Bering-Rochen nahm mit steigender Größe der Rochen ab,während der Konsum von Krebsen und Kalmaren sicherhöhte. Die Nahrung von Männchen und W eibchenwar unterschiedlich, wahrscheinlich durch den Größen-effekt. Unter den untersuchten Arten hatten dreiRochenpaare eine mittlere Ebene von diätetischerÄhnlichkeit: Aleutian- und Alaska-Rochen, Alaska- undWeißbrauen-Rochen sowie W eißbrauen- und Bering-Rochen.

RésuméLes menus de six espèces de raies originaires de

l'ouest de la mer de Béring ont été examinés: la raiealéoutienne Bathyraja aleutica, la raie d'Alaska B.parmifera, la raie de Matsubara B. matsubarai, la raieà taches blanches B. maculata, la raie à sourcilsblancs B. minispinosa et la raie de Béring R hinorajainterrupta. Les menus de raies prédatrices (d'Alaska,aléoutienne, à taches blanches, de Matsubara et àsourcils blancs) consistent en grands crustacés,céphalopodes et poissons. Les raies benthophages deBéring se nourrissent principalement de crabes deTanner, d'amphipodes et de crevettes. La consomma-tion de vers et de crustacés par les raies prédatricesdiminue lorsque leur taille s'accroît, alors que l'absorp-tion de crabes et de calmars augmente. Les menusdes raies mâles et femelles dif fère, ce qui est sansdoute lié à leur taille respective. Parmi les espècesétudiées, trois paires de raies avaient un niveaumoyen de similarité de régime: les raies aléoutienne etd'Alaska, les raies d'Alaska et à sourcils blancs et lesraies à sourcils blancs et de Béring.

SommarioIn questo lavoro è stata esaminata la composizione

della dieta nelle seguenti sei specie di razze del Maredi Bering occidentale: la razza delle Aleutine Bathyraja

aqua, Journal of Ichthyology and Aquatic Biology

Diets, feeding habits, and trophic relations of six deep-benthic skates (Rajidae) in the western Bering Sea

Alexei M. Orlov

Russian Federal Research Institute of Fisheries and Oceanography (VNIRO).17, V.Krasnoselskaya, Moscow, 107140 Russia.

Tel. (095) 264-94-65, Fax: (095) 264-91-87. E-mail: [email protected]

Accepted: 29.04.2003

aqua vol. 7 no. 2 - 200345

7(2)Imp/ok 16-06-2003 12:10 Pagina 45

all.

aleutica, la razza dell’Alaska B. parmifera, la razza diMatsubara B. matsubarai, la razza maculata B. macu-lata, la razza dalla fronte bianca B. minispinosa e larazza di Bering Rhinoraja interrupta. Eccetto quest’ul-tima si tratta di specie predatrici, la cui dieta consiste dicrostacei, cefalopodi e pesci. La razza di Bering,bentofaga, consuma invece prevalentemente granchi,anfipodi e gamberetti. All’aumentare delle dimensionicorporee tutte le specie riducono il consumo di vermi ecrostacei, ma quelle predatrici aumentano il consumodi pesci, mentre la razza di Bering aumenta il consumodi granchi e calamari. La dieta dei maschi e diversa daquella delle femmine, probabilmente a causa dellediverse dimensioni. Tra le specie esaminate tre coppiehanno un livello medio di somiglianza di regime ali-mentare: le razze delle Aleutine e dell’Alaska, le razzedell’Alaska e dalla fronte bianca e la razza dalla frontebianca e quella di Bering.

IntroductionThe skate family, Rajidae, plays an important role in

ecosystems of the north Pacific basin. On the conti-nental shelves and slopes, skates consume commer-cially important species, such as Pacific herring Clu-pea pallasii, walleye pollock Theragra chalcogramma,flathead sole Hippoglossoides elassodon , yellowfinsole Limanda aspera , rock sole Lepidopsetta bilin-eata, Atka mackerel Pleurogrammus monopterygius ,Pacific cod Gadus macrocephalus , shortraker rock-fish Sebastes borealis , popeye grenadier Cory-phaenoides cinereus , red squid Berryteuthis magis-ter, species of Octopoda, golden king crab Lithodesaequispinis, T anner crabs Chionoecetes spp., andshrimp (Livingston and de Reynier , 1996; Orlov ,1998a, b; Glubokov and Orlov , 2000). Skates alsohave some commercial importance. For example,

they are processed into fish meat jelly and dried skatewing (Ishihara, 1990). Despite their commercialimportance, they remain the least investigated elas-mobranch group.

Until recently , the biology and ecology of northPacific rajid skates received little attention. The ageand growth of some species of the family Rajidaehave been described (Ishiyama, 1958), and Dolganov(1998a) has provided some information on their repro-duction in Russian waters. Some peculiarities of thespatial and bathymetric distribution of rajid skates arerecorded in papers by McEachran and Miyake (1990),Nakaya and Shirai (1992), Orlov (1998c), Dolganov(1998b, 1999), and Fatykhov et al. (2000). The diet ofthe Alaska skate Bathyraja parmifera is brieflydescribed in papers by Mito (1974) and Brodeur andLivingston (1988). Feeding habits of rajid skatesinhabiting Pacific waters off the northern Kuril Islandsand south-eastern Kamchatka, are described byOrlov (1998a, b). Dolganov (1998c) briefly reportedcombined data on the diet composition and feedinghabits of north-western Pacific skates of the familyRajidae. Chuchukalo et al. (1999) have provided dataon the diets and daily rations of three Bathyrajaspecies inhabiting the northern Sea of Okhotsk. Somefeeding habits of the Aleutian skate Bathyraja aleuticain the western Bering Sea were considered in a paperby Glubokov and Orlov (2000). The main purpose ofthis paper is to describe the diets and to consider thefeeding habits and trophic relations of six species ofdeep-benthic skates of the family Rajidae that inhabitthe western Bering Sea.

Material and methodsIn this study, the stomach contents of skates brought

aboard the Japanese trawler, Kayo Maru No. 28, from

aqua vol. 7 no. 2 - 2003 46


Fig. 1. Map of the study area, showing demersal trawl stations (hollow asterisks) at which stomachs of skates were sam-pled. Dashed lines and numbers show isobaths (m).

7(2)Imp/ok 16-06-2003 12:10 Pagina 46

aqua vol. 7 no. 2 - 200347

Alexei M. Orlov

Fig. 3. Matsubara skate (Bathyraja matsubarai) caught in the western Bering Sea . Photo by Alexei M. Orlov.

Fig. 2. Aleutian skate (Bathyraja aleutica) caught in the western Bering Sea . Photo by Alexei M. Orlov.

7(2)Imp/ok 16-06-2003 12:10 Pagina 47

aqua vol. 7 no. 2 - 2003 48


Fig. 5. White-brow skate (Bathyraja minispinosa) caught in the western Bering Sea . Photo by Alexei M. Orlov.

Fig. 4. White-blotched skate (Bathyraja maculata) caught in the western Bering Sea . Photo by Alexei M. Orlov.

7(2)Imp/ok 16-06-2003 12:10 Pagina 48

aqua vol. 7 no. 2 - 200349

Alexei M. Orlov

Fig. 6. Alaska skate (Bathyraja parmifera) caught in the western Bering Sea . Photo by Alexei M. Orlov.

Fig. 7. Bering skate (Rhinoraja interrupta) caught in the western Bering Sea . Photo by Alexei M. Orlov.

7(2)Imp/ok 16-06-2003 12:10 Pagina 49

aqua vol. 7 no. 2 - 2003 50


May to July 1997 were analyzed. The stomach sam-ples were selected without known bias from bottomtrawl hauls carried out around the clock in the westernBering Sea between 168° E and 179° W (Fig. 1).Skate species were identified using identification keysand descriptions published by Ishiyama (1958), Dol-ganov (1983), Masuda et al. (1984), Ishihara andIshiyama (1985), and Dolganov and Tuponogov(1999). Total lengths (TL; snout to the end of the tail)were measured. Skates showing signs of regurgita-tion (digested food items in the mouth or gill cavity, ora flaccid or water-filled stomach) or net-feeding(freshly consumed prey items in the mouth or throat)were excluded from analysis. The stomach contentswere placed in a Petri dish, sorted, identified to thelowest possible taxonomic level, counted andweighed. The weight of each prey taxon was recordedto the nearest 0.1 g. Prey groups were described as apercentage of total stomach content weight (%W) andby frequency of occurrence. The frequency of occur-rence was calculated as the number of stomachs thatcontained that prey group divided by the number ofstomachs that contained food. The diet overlapbetween pairs of skate species was calculated usinga diet similarity index proposed by Schoener (1970):

Cxy = 100 – 0.5 ∑ (|px – py |), whereCxy = dietary similarity index of species x and y, andp = %W of each food component consumed by

species x and y, respectively. The diet overlap wasconsidered as low (Cxy < 33%), medium (33% < Cxy <67%), or high (Cxy > 67%).

ResultsThe number of stomachs examined/stomachs with

food were as follows: 139/123 Aleutian skates, 19/18Matsubara skates, 8/8 white-blotched skates, 68/58white-brow skates, 1 13/86 Alaska skates, and189/179 Bering skates.

General description of diets:Among the skate stom-achs analyzed, four prey groups represented the major-ity of the diet: crustaceans, cephalopods, fishes, andfishery of fal (represented mostly by-products of pro-cessing of walleye pollock Theragra chalcogramma andconsisted of its heads, fins, bones, and guts) (Fig. 8).

Aleutian skates fed mostly on groundfishes, withwalleye pollock (41.5 %W) the most important prey inthat group (Table I). Fishery of fal (16.5 %W) was thesecond most important dietary item. Cephalopods inthe diet of Aleutian skate were third in rank, and redsquid had the greatest importance (10.1 %W) in thatprey category.

Matsubara skates consumed mostly red squid (61.8%W; Table II). Fishes were second in importance(16.1 %W) comprising mostly popeye grenadier andwalleye pollock. Crabs (hermit crabs (Paguridae),golden king crab, and triangle Tanner crab) were thirdin dietary importance (14.5 %W).

The diet of white-blotched skates consisted mainlyof fishery of fal (71.6 %W) and Tanner crabs (23.6%W; Table III). Other dietary components were rela-tively unimportant in the stomach contents.

Crabs were the most important component (42.3%W) in the diet of white-brow skate (Table IV). Fishes

Fig. 8. Diets of western Bering Sea skates categorized by percentage weight of main food items, summer 1997.

0%

20%

40%

60%

80%

100%

Aleutia

n

Matsub

ara

whiteb

lotch

ed

whiteb

rowAlas

kaBe

ring

Skate species

Com

posi

tion

by

wei

ght

worms small c rustaceans shrimpscrabs cephalopods mesopelagic fishgroundfish offal misc. preys

7(2)Imp/ok 16-06-2003 12:10 Pagina 50

aqua vol. 7 no. 2 - 200351

Alexei M. Orlov

were second in rank (28.3 %W), and Pacific herringwas the most important fish. Shrimp were also animportant food (14.8 %W), with humpy shrimp Pan-dalus goniurus the dominant prey in this category.

The diet of Alaska skates (Table V) consisted mostlyof fishes (64.7 %W) that were represented by a vari-ety of species such as Pacific herring, walleye pollock,longsnout prickleback Lumpenella longirostris , short-fin eelpout Lycodes brevipes , shortraker rockfish,porehead sculpin Icelus canaliculatus , and darkfinsculpin Malacocottus zonurus . The second mostimportant dietary component was fishery of fal (17.8%W). Cephalopods, especially red squid (8.6 %W),were the third most important prey item.

Bering skates consumed mainly crustaceans

(Table VI), and important among them (61.2 %W) avariety of crabs. Of secondary importance were smallcrustaceans (mysids, cumaceans, and gammaridamphipods), which constituted 10.1 %W of the stom-ach contents. Shrimp were also important prey of thisspecies (8.9 %W), with humpy shrimp the main preyin this category.

Food habits vs. skate size: Larger Aleutian skatesconsumed fewer worms and crustaceans but morefish and fishery of fal. Small crustaceans (mainlyamphipods and shrimp) were the most importantdietary items (79.9 %W) for small Aleutian skates (TL< 50 cm; Figure 9). Cephalopods seem to peak inimportance in the 71-90 cm TL category. Fishes werepredominant prey (69.6-86.4 %W) of 91-130 cm TL

Table I. Diet composition of Aleutian skate Bathyraja aleutica (Fig. 2) in the western Bering Sea, summer 1997.

Dietary component Frequency ofoccurrence Weight

Number % g %

Amphipoda (amphipods) 39 31.71 168.1 2.09Bathylagus pacificus (Pacific blacksmelt) 1 0.81 1.0 0.01Berryteuthis magister (red squid) 20 16.26 814.0 10.12Chionoecetes angulatus (triangle Tanner crab) 7 5.69 218.0 2.71Ch. bairdi (Tanner crab) 1 0.81 25.0 0.31Ch. tanneri (grooved Tanner crab) 4 3.25 33.0 0.41Ch. opilio (snow crab) 8 6.50 46.0 0.57Clupea pallasii (Pacific herring) 5 4.06 475.0 5.90Crangonidae (crangonid shrimps) 3 2.44 10.0 0.12Echiurida (echiurid worms) 1 0.81 2.0 0.02Fishery offal 15 12.19 1330.8 16.54Gymnocanthus detrisus (graypurple sculpin) 1 0.81 290.0 3.60Hydrozoa (jellyfish) 1 0.81 20.0 0.25Isopoda (isopods) 3 2.44 1.8 0.02Leuroglossus schmidti (northern smoothtongue) 1 0.81 1.5 0.02Liparidae gen. sp. (unidentified snailfishes) 1 0.81 6.0 0.07Lumpenella longirostris (longsnout prickleback) 6 4.88 204.0 2.53Myctophidae gen. sp. (unidentified myctophids) 1 0.81 1.5 0.02Mysidacea (mysids) 11 8.94 13.8 0.17Nematoda (roundworms) 5 4.06 11.5 0.14Octopoda (octopi) 7 5.69 98.0 1.22Ophiuroidea (brittlestar) 1 0.81 0.5 0.01Paguridae (hermit crabs) 4 3.25 56.4 0.70Pandalopsis dispar (sidestriped shrimp) 9 7.32 71.5 0.89Pandalopsis sp. (unidentified) 6 4.88 54.0 0.67Pandalus goniurus (humpy shrimp) 24 19.51 285.3 3.54Pandalus hipsinotus (coonstriped shrimp) 1 0.81 2.0 0.02Percis japonica (Japanese dog poacher) 1 0.81 20.0 0.25Polychaeta (polychaete worms) 9 7.32 13.4 0.17Stenobrachius nannochir (garnet lampfish) 3 2.44 25.5 0.32Theragra chalcogramma (walleye pollock) 10 8.13 3343.0 41.53Unidentified fish 12 9.76 181.2 2.25Unidentified organic material 12 9.76 33.7 0.42Unidentified pandalid shrimps 9 7.32 123.2 1.53Unidentified squid 1 0.81 3.0 0.04Unidentified Tanner crabs 8 6.50 66.0 0.82

Total food weight (g) 8049.7Number of stomachs analyzed 139Number of stomachs contained food 123Total length range (cm) 17-143Mean length (cm) ± standard error 75.38±2.98Body weight range (kg) 0.04-21.70Mean body weight (kg) ± standard error 4.60±0.48

7(2)Imp/ok 16-06-2003 12:10 Pagina 51

aqua vol. 7 no. 2 - 2003 52


skates, and the diet of larger Aleutian skates (TL >130 cm) consisted mostly of fishery of fal (49.6 %W),fishes (37.2 %W), and cephalopods (11.2 %W).

Smaller individuals of Matsubara skate (TL < 70 cm)fed mainly on cephalopods (70.1 %W) and shrimp(14.0 %W). With increasing body length, the con-sumption of shrimp decreased. Fish (39.5 %W), crabs(32.0 %W), and cephalopods (24.8 %W) were themajority of the diet of skates 71-80 cm TL. Larger Mat-subara skates (TL > 80 cm) fed mainly oncephalopods (86.1 %W).

White-blotched skates of various sizes fed mostly onfishery offal (86.5 %W, TL < 40 cm; 88.9 %W , 41-80cm TL; and 60.2 %W , TL > 80 cm). Larger white-blotched skates (TL > 80 cm) also consumed a con-siderable amount of crab (37.8 %W). Other dietaryitems were not very important.

The proportion of shrimp in the diet of white-browskates (11.1-17.8 %W) varied little with size (Fig. 10).Crabs increased in importance with increasing size,from 30.2 %W (TL < 65 cm) to 61.1 %W (TL > 75 cm).Consumption of fishery of fal declined with increasing

Table II. Diet composition of Matsubara skate Bathyraja matsubarai (Fig. 3) in the western Bering Sea, summer 1997.

Dietary component Frequency of occurrence Weight

Number % g %

Berryteuthis magister (red squid) 12 66.67 722.0 61.80Chionoecetes angulatus (triangle Tanner crab) 2 11.11 74.0 6.33Coryphaenoides cinereus (popeye grenadier) 1 5.56 85.0 7.28Fish eggs 2 11.11 28.0 2.40Fishery offal 2 11.11 40.0 3.42Lithodes aequispina (golden king crab) 1 5.56 60.0 5.14Mysidacea (mysids) 1 5.56 0.3 0.03Paguridae (hermit crabs) 4 22.22 35.0 3.00Pandalus goniurus (humpy shrimp) 1 5.56 13.0 1.11Stenobrachius nannochir (garnet lampfish) 2 11.11 13.0 1.11Theragra chalcogramma (walleye pollock) 1 5.56 65.0 5.56Unidentified fish 1 5.56 25.0 2.14Unidentified organic material 1 5.56 4.0 0.34Unidentified pandalid shrimps 2 11.11 4.0 0.34


Table III. Diet composition of white-blotched skate Bathyraja maculata (Fig. 4) in the western Bering Sea, summer 1997.


Number % g %

Berryteuthis magister (red squid) 1 12.5 3.0 1.03Chionoecetes angulatus (triangle Tanner crab) 1 12.5 55.0 18.85Chionoecetes opilio (snow crab) 1 12.5 11.0 3.77Euphausiacea (euphausiids) 2 25.0 0.6 0.21Fishery offal 7 87.5 209.0 71.65Gammaridea (gammarids) 2 2.5 2.4 0.82Hyperridea (hyperiids) 1 12.5 0.5 0.17Hyrudinea (leeches) 1 12.5 2.0 0.69Pandalus goniurus (humpy shrimp) 3 37.5 1.2 0.41Stenobrachius nannochir (garnet lampfish) 1 12.5 4 1.37Unidentified Tanner crabs 1 12.5 3.0 1.03


7(2)Imp/ok 16-06-2003 12:10 Pagina 52

aqua vol. 7 no. 2 - 200353

Alexei M. Orlov

Table IV. Diet composition of white-brow skate Bathyraja minispinosa (Fig. 5) in the western Bering Sea, summer 1997.


Number % g %

Berryteuthis magister (red squid) 5 8.62 84.0 4.16Chionoecetes angulatus (triangle Tanner crab) 2 3.45 30.0 1.48Ch. bairdi (Tanner crab) 1 1.72 10.0 0.49Ch. tanneri (grooved Tanner crab) 4 6.90 161.0 7.97Ch. opilio (snow crab) 9 15.52 248.0 12.28Clupea pallasii (Pacific herring) 5 8.62 403.0 19.95Crangonidae (crangonid shrimps) 10 17.24 59.5 2.94Fishery offal 12 20.69 194.7 9.63Leuroglossus schmidti (northern smoothtongue) 1 1.72 9.0 0.44Myctophidae gen. sp. (unidentified myctophids) 1 1.72 2.5 0.12Octopoda (octopi) 1 1.72 2.5 0.12Paguridae (hermit crabs) 10 17.24 182.0 9.00Pandalopsis dispar (sidestriped shrimp) 3 5.17 53.5 2.65Pandalus goniurus (humpy shrimp) 16 27.59 187.4 9.27Pleurogrammus monopterygius (Atka mackerel) 1 1.72 90.0 4.45Stenobrachius nannochir (garnet lampfish) 1 1.72 6.0 0.30Unidentified fish 3 5.17 65.0 3.22Unidentified organic material 2 3.45 5.0 0.25Unidentified pandalid shrimps 2 3.45 0.3 0.01Unidentified Tanner crabs 12 20.69 227.5 11.27

Total food weight (g) 2020.9Number of stomachs analyzed 68Number of stomachs contained food 58Total length range (cm) 51-78Mean length (cm) ± standard error 69.82±0.56Body weight range (kg) 0.65-2.45Mean body weight ± standard error 1.94±0.04

skate size, from 24.0 %W (TL < 65 cm) to 4.5 % (71-75cm TL). Fish was most intensively consumed by white-brow skates 66-70 cm TL (37.8 %W), and the minimum(14.9 %W) occurred in 71-75 cm TL individuals.

Smaller Alaska skates (TL < 60 cm) fed on of fal(32.4 %W), cephalopods (28.5 %W), shrimps(13.9 %W), fish (9.7 %W), crabs (8.4 %W), and smallcrustaceans (7.0 %W). Increasing size in Alaskaskates was accompanied by declining proportions ofsmall crustaceans and shrimp in the diet. The oppo-site trend was found for fish consumption (Fig. 1 1),with a maximum (84.5%W) in the 91-100 cm TLgroup. Crabs played an important role in the diet of61-70 cm TL (20.8 %W) and 71-80 cm TL (14.2 %W)skates. Fishery of fal was the most important dietarycomponent (36.9 %W) of 61-70 cm TL skates.

Bering skates, TL < 30 cm, ate mainly small crus-taceans (67.7 %W), shrimp (15.7 %W), and worms(10.3 %W) (Fig. 12). With increasing size, worms,small crustaceans, and shrimp became less importantin the diet of this species. The consumption of crabsand cephalopods rose with increasing skate size. Thediet of larger individuals (71-80 cm TL) consistedmainly of crabs (69.0 %W), cephalopods (8.5 %W),and shrimps (6.2 %W). Fishes occurred in Okhotskskate stomachs only occasionally and were not impor-tant by weight.

Food preference by gender: Considerable dif fer-ences in the diets of male and female skates were

detected for all species (T able VII). Male Aleutianskates ate more fish (63.3 vs. 51.0 %W), cephalopods(15.2 vs. 8.2 %W), crabs (8.3 vs. 3.2 %W), and smallcrustaceans (3.0 vs. 1.7 %W) than females, whereasfemales ate more fishery offal (26.4 vs. 4.4 %W), andshrimp (9.0 vs. 4.0 %W). Male Matsubara skates fedmore on crabs (63.8 vs. 3.0 %W), fishery of fal (18.1vs. 0.0 %W), and shrimp (4.5 vs. 0.7 %W), butfemales ate more cephalopods (73.6 vs. 1 1.3 %W)and fishes (22.3 vs. 2.3 %W). Male white-blotchedskates consumed fishery of fal only , while the foodspectrum of the females was broader (besides of falthey ate crabs, worms, small crustaceans, shrimps,cephalopods, and fish). Male white-brow skates con-sumed more Tanner crabs (56.6 vs. 28.9 %W) andcephalopods (14.2 vs. 5.2 %W), while fishes (44.8 vs.10.7 %W) and fishery of fal (6.7 vs. 1.7 %W) weremore important in the female diet. More cephalopods(13.1 vs. 6.4 %W), crabs (8.8 vs. 4.1 %W) and shrimp(4.9 vs. 1.0 %W) were consumed by male Alaskaskates, and females fed more on fishery offal (22.9 vs.9.1 %W). Male Bering skates consumed morecephalopods (8.1 vs. 4.7 %W) and fishery of fal (12.2vs. 1.2 %W), and females consumed more crabs(66.2 vs. 56.0 %W).

Diet overlap: The spectrum of food being con-sumed by rajid skates is broad, indicating that, as agroup, they make full use of the forage resources inthe study area. The dietary similarity indices showed

7(2)Imp/ok 16-06-2003 12:10 Pagina 53

aqua vol. 7 no. 2 - 2003 54


Table V. Diet composition of Alaska skate Bathyraja parmifera (Fig. 6) in the western Bering Sea, summer 1997.


Number % g %

Berryteuthis magister (red squid) 15 17.44 786.0 8.65Bivalvia (bivalves) 1 1.16 6.0 0.07Caprellidae (caprellids) 1 1.16 2.0 0.02Chionoecetes angulatus (triangle Tanner crab) 8 9.30 296.0 3.26Ch. opilio (snow crab) 2 2.33 165.0 1.82Clupea pallasoii (Pacific herring) 20 23.26 3195.0 35.15Crangonidae (crangonid shrimps) 2 2.33 5.5 0.06Fishery offal 17 19.77 5.0 17.83Gammaridea (gammarids) 5 5.81 8.9 0.10Icelus canaliculatus (porehead sculpin) 1 1.16 30.0 0.33Lumpenella longirostris (longsnout prickleback) 2 2.33 85.0 0.94Lycodes brevipes (shortfin eelpout) 1 1.16 75.0 0.83Malacocottus zonurus (darkfiin sculpin) 1 1.16 10.0 0.11Octopoda (octopi) 1 1.16 20.0 0.22Paguridae (hermit crabs) 5 5.81 32.0 0.35Pandalopsis dispar (sidestriped shrimp) 1 1.16 9.0 0.10Pandalus goniurus (humpy shrimp) 16 18.60 186.5 2.05Stenobrachius nannochir (garnet lampfish) 1 1.16 14.0 0.15Sebastes borealis (shortraker rockfish) 1 1.16 70.0 0.77Stenobrachius leucopsarus (northern lampfish) 1 1.16 6.0 0.07Theragra chalcogramma (walleye pollock) 9 10.47 2180.0 23.98Unidentified fish 2 2.33 218.0 2.40Unidentified organic material 1 1.16 10.0 0.11Unidentified pandalid shrimps 3 3.49 21.0 0.23Unidentified Tanner crabs 3 3.49 36.0 0.40


0%

20%

40%

60%

80%

100%

<30 (12) 31-50 (29) 51-70 (17) 71-90 (21) 91-110 (16) 111-130 (17) >130 (11)

Length categories of Aleutian skates (cm)

Com

posi

tion

by

wei

ght

worms small crustaceans shrimps crabscephalopods fish offal misc. preys

Fig. 9. Variations in the main food items of Aleutian skate, by predator size, in the western Bering Sea, summer 1997(sample size shown in parentheses).

7(2)Imp/ok 16-06-2003 12:10 Pagina 54

aqua vol. 7 no. 2 - 200355

Alexei M. Orlov

Table VI. Diet composition of Bering skate Rhinoraja interrupta (Fig. 7) in the western Bering Sea, summer 1997.


Number % g %

Berryteuthis magister (red squid) 16 8.47 272.4 6.35Chionoecetes angulatus (triangle Tanner crab) 21 11.11 862.0 20.10Ch. tanneri (grooved tanner crab) 1 0.53 50.0 1.16Ch. opilio (snow crab) 36 19.05 1136.0 26.49Clupea pallasii (Pacific herring) 1 0.53 69.0 1.61Crangonidae (crangonid shrimps) 19 10.05 66.7 1.55Cumacea (cumaceans) 3 1.59 0.3 0.01Fish eggs 1 0.53 35.0 0.82Fishery offal 18 9.52 277.3 6.46Gammaridea (gammarids) 90 47.62 422.8 9.86Leuroglossus schmidti (northern smoothtongue) 1 0.53 4.8 0.11Myctophidae gen. sp. (unidentified myctophids) 1 0.53 6.3 0.15Mysidae (mysids) 4 2.12 6.3 0.15Nematoda (roundworms) 8 4.23 30.5 0.71Pandalus hypsinotus (coonstriped shrimp) 1 0.53 3.0 0.07Paguridae (hermit crabs) 19 10.05 367.0 8.55Pandalopsis dispar (sidestriped shrimp) 1 0.53 5.0 0.12Pandalus goniurus (humpy shrimp) 14 7.42 277.7 6.47Polychaeta (polychaete worms) 18 9.52 92.9 2.17Stenobrachius nannochir (garnet lampfish) 1 0.53 5.0 0.12Theragra chalcogramma (walleye pollock) 2 1.06 35.0 0.82Unidentified fish 5 2.64 25.0 0.58Unidentified organic material 4 2.12 15.5 0.36Unidentified pandalid shrimps 5 2.64 15.5 0.36Unidentified Tanner crabs 15 7.94 208 4.85


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

<65 (8) 66-70 (24) 71-75 (23) >75 (3)

Length categories of whitebrow skates (cm)

Com

posi

tion

by

wei

ght

shrimps crabs cephalopods fish offal misc. preys

Fig. 10. Variations in the main food items of white-brow skate, by predator size, in the western Bering Sea, summer 1997(sample size shown in parentheses).

7(2)Imp/ok 16-06-2003 12:10 Pagina 55

1974): (1) herbivores, which consume phytoplankton,algae, detritus, etc.; (2) carnivores, which include zoo-planktophages, benthophages and predators; and (3)omnivores, which consume both plants and animals.

Stomach content analysis of the six skate speciesconsidered here showed the presence of dif ferentfeeding modes, which may change with increasingbody size. The Aleutian skate, Alaska skate, Matsub-ara skate, white-blotched skate, and white-brow skateare predators. Adults consumed mainly fishes,cephalopods, large crustaceans, and fishery of fal.

aqua vol. 7 no. 2 - 2003 56


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

<60 (10) 61-70 (12) 71-80 (14) 81-90 (18) 91-100 (19) 101-110 (12)

Length categories of Alaska skates (cm)

Com

posi

tion

by

wei

ght

small crustaceans shrimps crabs cephalopodsfish offal misc. preys

Fig. 11. Variations in the main food items of Alaska skate, by predator size, in the western Bering Sea, summer 1997 (sample size shown in parentheses).

Table VII. Diet composition of male (M) and female (F) skates in the western Bering Sea, summer 1997.

Dietary component Aleutian Matsubara whiteblotched whitebrow Alaska Okhotsk

M F M F M F M F M F M F

Cephalopods 15.21 8.23 11.31 73.58 - 1.27 14.23 5.25 13.07 6.43 8.12 4.73(squids & octopi)Crabs (Tanner crabs, 8.32 3.24 63.81 2.96 - 29.27 56.59 28.90 8.79 4.10 56.02 66.18hermit crabs, etc.)Fish 63.32 50.97 2.26 22.27 - 1.70 10.75 44.83 63.78 65.30 4.21 4.19Fishery offal 4.42 26.39 18.10 - 100.0 64.92 1.68 6.68 9.10 22.89 12.19 1.23Miscellaneous preys 1.29 0.17 - 0.42 - - 0.46 0.05 - 0.28 0.56 0.18Shrimps 4.00 9.05 4.52 0.74 - 0.51 16.29 14.29 4.93 1.00 6.27 10.69Small crustaceans 3.04 1.67 - 0.03 - 1.48 - - 0.33 - 10.37 9.36(amphipods, etc.)Worms 0.40 0.28 - - - 0.85 - - - - 2.26 3.44Sampled size 72 67 5 14 3 5 40 28 66 47 103 86Total food weight (g) 3611.6 4438.1 221.0 947.3 56.0 235.7 981.6 1048.3 3334.9 5752.5 2049.1 2239.9Mean body lenght (cm) 73.00 77.93 74.20 79.86 46.00 56.20 70.65 68.64 76.61 84.77 54.98 54.44± SE ±3.97 ±4.48 ±4.18 ±2.43 ±7.23 ±12.00 ±0.70 ±0.87 ±2.16 ±2.78 ±1.61 ±1.95Mean body weight (kg) 3.86 5.38 2.43 3.55 0.59 1.69 2.02 1.81 3.64 5.97 1.12 1.27± SE ±0.50 ±0.83 ±0.38 ±0.30 ±0.22 ±0.83 ±0.05 ±0.05 ±0.26 ±0.52 ±0.07 ±0.10

that the diets of these skate species were generallydissimilar (Table VIII). The degree of dietary similarityranged from 12.3 % for white-blotched and Matsubaraskates to 64.8 % for Aleutian and Alaska skates. Onlythree species pairs had a medium level of dietary sim-ilarity: Aleutian and Alaska skates, Alaska and white-brow skates, and white-brow and Bering skates.

DiscussionFishes c an be divided i nto three basi c groups

according to their feeding characteristics (Nikol’ sky,

7(2)Imp/ok 16-06-2003 12:10 Pagina 56

The Bering skate is a benthophage; it is primarily acrustacean specialist that feeds predominately onTanner crabs, shrimp, and gammarid amphipods.

Adult rajid skates consumed a broad spectrum ofbenthic food items but the low level of dietary overlap(Table VIII) would indicate low feeding competitionbetween the species. On the other hand, juvenileskates (except Matsubara skate) all consumeamphipods and worms (Orlov, 1998a). Competitionamong the specie s is probably strongest duringyounger life stages.

Rajid skate diets in other oceans show patterns sim-ilar to those found in this study . In other rajid skatecommunities, the diets also consist of the same groupsof forage organisms: worms, isopods, amphipods,shrimp, Tanner crabs, hermit crabs, cephalopods,fishes, and fishery of fal (Holden and Tucker, 1974;Ajayi, 1982; Abdel-Aziz, 1986; Gordon and Duncan,1989; Ebert et al. , 1991; Smale and Cowley , 1992;Dolganov, 1998c; Orlov , 1998a,b). Likewise, in otherregions, prey is influenced by skate size. Larger skatespecies generally prey more on fishes; smaller skate

aqua vol. 7 no. 2 - 200357

Alexei M. Orlov

0%

20%

40%

60%

80%

100%

<30 (10) 41-40 (27) 41-50 (20) 51-60 (17) 61-70 (58) 71-80 (27)

Length categories of Bering skates (cm)

Com

posi

tion

by

wei

ght

worms small crustaceans shrimps crabscephalopods fish offal misc. preys

Fig. 12. Variations in the main food items of Okhotsk skate, by predator size, in the western Bering Sea, summer 1997(sample size shown in parentheses).

Table VIII. Dietary similarity among western Bering Sea skates (%) during summer 1997: ALT – Aleutian skate, MSB –Matsubara skate, WBL – white-blotched skate, WBR – white-brow skate, ALS – Alaska skate, BRN – Bering skate.

7(2)Imp/ok 16-06-2003 12:10 Pagina 57

species are benthophagic, c onsuming worm s,amphipods, mysids, isopods, and etc. Middle-sizedskates consume both small and large crustaceans andoccasionally cephalopods and fishes.

The feeding behavior of skates is of special interest.Skates are typical representatives of the benthicichthyofauna and their diets consist mainly of benthicprey. However , I occasionally found mesopelagicfishes (northern smoothtongue Leuroglossusschmidti, garnet lampfish Stenobrachius nannochir ,northern lampfish S. leucopsarus , and unidentifiedmyctophids) in their stomachs. Most mesopelagicprey were in a slightly digested condition making itunlikely that they were consumed as the trawl wasbeing retrieved. The continental slope is very steep inthis study area and mesopelagic fishes may swimclose to it during diurnal feeding migrations. I there-fore believe that skates are able to feed some dis-tance from the bottom, sometimes preying onmesopelagic fishes.

Berestovsky (1989) also found some pelagic fishesin skate stomachs from the north Atlantic. However,he concluded that skates could not feed in the watercolumn because of their morphology and suggestedthat pelagic fishes traumatized by trawls in the fishinggrounds were subsequently preyed upon by skates. Idoubt whether this conclusion is correct. The ability ofskates to hunt in the water column and even reach thesurface is well known (Parin, 1971). Moreover, I find itimpossible to consider pelagic fishes as a casualcomponent of skate diets because neritic, epipelagic,and mesopelagic fishes can play an essential role inthe feeding of rajid skates in many regions of theworld. For example, in the Black Sea, sprat, horsemackerel, and anchovy are important components ofthe diet of Raja clavata (Lushnikova and Kirnosova,1990). In the north-west Atlantic, myctophids, herring,and mackerel frequently occur in the diet of the thornyskate R. radiata (Templeman, 1982; Robichaud et al.,1991). The diets of many skates in South Africanwaters consist of myctophids, anchovy , and pilchard(Ebert et al., 1991; Smale and Cowley , 1992). Someskates in the Irish Sea and Bristol Channel eat sprat,herring, and sardine (Holden and Tucker, 1974). Theprey of pelagic fishes is also known to include rajidskates as well as other benthic batoid fishes, includ-ing some stingrays (Devadoss, 1978) and guitarfishes(Abdel-Aziz et al. , 1993). Consumption of meso-pelagic fishes and squid by rajid skates was previ-ously also reported in the Pacific waters off the north-ern Kuril Islands and south-eastern Kamcha tka(Orlov, 1998a, b).

Changes in the diet composition of skates withchanges in size are common to all species of the fam-ily Rajidae. These changes are most evident whencomparing juveniles, which eat mainly small benthicfood items, and adults, which feed mainly on largecrustaceans, cephalopods, and fishes. Similar diets

among various size groups of rajid skates have beenreported from other regions of the world’ s oceans(Holden and Tucker, 1974; Ajayi, 1982; Templeman,1982; Abdel-Aziz, 1986; Ezzat et al., 1987; Ebert etal., 1991; Smale and Cowley , 1992; Pedersen, 1995;Dolganov, 1998c; Orlov 1998a,b).

There are few studies on the dif ferences betweenthe diets of male and female skates. Ezzat et al.(1987) showed the existence of such dif ferences forR. miraletus in Egyptian Mediterranean waters. Ingeneral, these dif ferences appeared as a higher fre-quency of occurrence of the crustaceans and fishes infemale stomachs. Males consumed worms and mol-lusks more frequently . Similar sex-dependent dif fer-ences have been found in the diets of skates inhabit-ing the Pacific waters of the northern Kuril Islands andsouth-eastern Kamchatka (Orlov 1998b). These dietdistinctions were explained mostly by sexual dimor-phism in the sizes of males and females. The presentstudy also found considerable dif ferences in bodylength and weight between most of the westernBering Sea skates considered (T able VII). Thus, thefemales of Aleutian, Matsubara, white-blotched, andAlaska skates were essentially larger than the males.Differences in length and weight between male andfemale white-brow and Bering skates were not so sig-nificant. Despite considerable size dif ferencesbetween males and females there was no pattern intheir consumption of various prey . Thus, most maleskates ate more crab, except for white-blotched andBering skates. Cephalopods were also most impor-tant in male skate diets, except for Matsubara andwhite-blotched skates. Fishes were more important inthe diet of female Matsubara and white-brow skatesthan in that of the males, but were the most importantprey item in the case of male Aleutian skates. Malesof Matsubara, white-blotched and Bering skates, andfemales of Aleutian, white-brow , and Alaska skatesconsumed fishery offal in larger amounts. Therefore Isuggest that the diet differences found between malesand females of western Bering Sea skates serve todecrease intraspecific feeding competition.

Trophic relations between north-western Pacificskates are poorly understood. Diet similarity amongrajid skates inhabiting the Pacific waters off the north-ern Kuril Islands and south-eastern Kamchatka, hasonly been reported by Orlov (1998b). In that area,most of the skates examined had medium levels ofdiet similarity . Maximum values of diet similarityindices were noted for Bering R. interrupta andOkhotsk skates (64.6 %), white-brow and Okhotskskates, and Alaska and white-blotched skates (60.1 %for both pairs). This study showed considerably differ-ent diet similarity indices for the same species pairs.Values of these indices from Orlov (1998b) and thisstudy were, respectively, 46.0% and 64.8% for Alaskaand Aleutian skates, 24.0% and 42.6% for Alaska andwhite-brow skates, and 40.2% and 49.3% for

aqua vol. 7 no. 2 - 2003 58


7(2)Imp/ok 16-06-2003 12:10 Pagina 58

white-brow and Bering skates. These differences areprobably due to the use of different indices of dietoverlap. Orlov (1998b) used normalized frequency ofoccurrence, not percentage by weight.

AcknowledgementsI would like to thank my friend and colleague Dr .

Sergei I. Moiseev (Russian Federal Research Insti-tute of Fisheries and Oceanography , Moscow, Rus-sia) who assisted me on this research cruise aboardthe Japanese trawler Kayo Maru No. 28 during thesummer of 1997. I greatly appreciate the assistanceof Dr. Troy Buckley (NMFS/NOAA, Alaska FisheriesScience Center, 7600 Sand Point W ay NE, Seattle,WA 98115-0070, USA) who improved the manuscriptand reviewed the early draft.

ReferencesAbdel-Aziz, S. H. 1986. Food and feeding habits of

Raja species (Batoidei) in the Mediterranean watersof Alexandria. Bulletin of Institute of Oceanographyand Fisheries of ARE, 12: 265-276.

Abdel Aziz, S. H., Khalil A. N. & S. A. Abdel Maguid.1993. Food and feeding habits of the common gui-tarfish, Rhinobatos rhinoatos in the EgyptianMediterranean waters. Indian Journal of Marine Sci-ences, 22: 287-290.

Ajayi, T. O. 1982. Food and feeding habits of Rajaspecies (Batoidei) in Carmarthen Bay, Bristol Chan-nel. Journal of Marine Biological Association of theU.K., 62: 215-223.

Berestovsky, E. G. 1989. Feeding habits of Raja radi-ata and R. fyllae in the Barents and Norwegian Seas.Voprosy Ikhtiologii, 29: 994-1002 (In Russian).

Brodeur, R. D. & P. A. Livingston. 1988. Food habitsand diet overlap of various Eastern Bering Seafishes. U.S. Department of Commerce, NOAA Tech-nical Memorandum NMFS F/NWC, 127: 1-76.

Chuchukalo, V. I., Lapko V. V. & N. A. Kuznetsovaet al. 1999. Feeding of groundfishes at the shelf andcontinental slope of the northern Sea of Okhotsk.Izvestiya TINRO, 126: 24-57 (In Russian).

Devadoss, P. 1978. On the food of rays, Dasyatis uar-nak (Forskal), D. alcocki (Annadale) and D. sephen(Forskål). Indian Journal of Fisheries, 25: 10-13.

Dolganov, V. N. 1983. Guide to the diagnostic char-acters of cartilaginous fishes from the Far East Seasof the U.S.S.R. and neighboring waters . TINRO:Vladivostok. 92 pp. (In Russian).

Dolganov, V . N. 1998a. Reproduction of skates offamily Rajidae, of the Far-Eastern Seas of Russia.Izvestiya TINRO, 124: 425-428 (In Russian).

Dolganov, V . N. 1998b. Distribution and migration of skates of family Rajidae, of the Far Eastern Seas of Russia. Izvestiya TINRO, 124: 433-437 (InRussian).

Dolganov,, V. N. 1998c. Feeding of skates of familyRajidae, and their role in ecosystems of the

Far-Eastern Seas of Russia. Izvestiya TINRO, 124: 417-424. (In Russian).

Dolganov, V. N. 1999. Geographic and bathymetricdistribution of skates of the family Rajidae, in theRussian Far East Seas and adjacent waters.Voprosy Ikhtiologii, 39: 428-430. (In Russian).

Dolganov, V. N. & V. N. Tuponogov. 1999. Identifica-tion s heets o f s kates o f g enera Bathyraja andRhynoraja (family Rajidae), of the Russian Far EastSeas. Izvestiya TINRO, 126: 657-664 (In Russian).

Ebert, D. A. Cowley, P. D. & L. J. V . Compagno.1991. A preliminary investigation of the feeding ecol-ogy of skates (Batoidea: Rajidae), off the west coastof southern Africa. South African Journal of MarineScience, 10: 71-81.

Ezzat A., Abdel-Aziz, S. H., El-Gharabawy, M. M. &M. O. Hussein. 1987. The food of Raja miraletusLinnaeus, 1758 in Mediterranean waters of f Alexan-dria. Bulletin of Institute of Oceanography and Fish-eries of ARE, 13: 59-74.

Fatykhov, R. N., Poltev Yu. N., Mukhametov, I. N. etal. 2000. Spatial distribution of skate mass species,Bathyraja, in the region of the Northern Kuril Islandsand Southeastern Kamchatka in different seasons of1986-1994. Commercial and biological studies offishes in the Pacific waters of the Kurils Islands andadjacent areas of the Okhotsk and Bering Seas in1992-1998. VNIRO: Moscow.: 104-120 (In Russian).

Glubokov, A. I. & A. M. Orlov. 2000. Some morpho-physiological indices and feeding peculiarities of theAleutian skate Bathyraja aleutica from the westernBering Sea. Voprosy Rybolovstva , 1: 126-149 (InRussian).

Gordon, J. D. M., & J. A. R. Duncan. 1989. A note ofthe distribution and diet of deep-water rays (Raji-dae), in an area of the Rockall Trough. Journal ofMarine Biology Association of the U.K., 69: 655-658.

Holden, M. J. & R. N. Tucker. 1974. The food of Rajaclavata Linnaeus 1758, Raja montagui Fowler 1910,Raja naevus Muller and Henle 1841 and Rajabrachyura Lafont 1873 in British waters. Journal duConseil International pour L’exploration de la Mer,35: 189-193.

Ishihara, H. 1990. The skates and rays of the west-ern North Pacific: an overview of their fisheries, uti-lization, and classification. U.S. Department of Com-merce, NOAA Technical Report NMFS, 90: 485-497.

Ishihara, H., & R. Ishiyama. 1985. Two new NorthPacific s kates ( Rajidae), a nd a r evised k ey t oBathyraja in the area. Japan Journal of Ichthyology,32: 143-179.

Ishiyama, R. 1958. Studies on the Rajid fishes (Raji-dae) found in the waters around Japan. Journal ofShimonoseki College of Fisheries, 7: 1-202.

Livingston, P. A. & Y. de Reynier. 1996. Groundfishfood habits and predation on commercially importantprey species in the Eastern Bering Sea from 1990 to1992. U.S. Department of Commerce, NOAA/

aqua vol. 7 no. 2 - 200359

Alexei M. Orlov

7(2)Imp/ok 16-06-2003 12:10 Pagina 59

NMFS, Alaska Fisheries Science Center ProcessedReport, 96-04: 1-214.

Lushnikova, V. P. & I. P. Kirnosova. 1990. Feedingand feeding necessities of thornback ray Rajaclavata in the Black Sea. Biological resources of theBlack Sea. VNIRO: Moscow.: 58-64 (In Russian)

McEachran, J. D. & T. Miyake. 1990. Zoogeographyand bathymetry of skates (Chondrichthyes,Rajoidei). U.S. Department of Commerce, NOAATechnical Report NMFS, 90: 305-326.

Masuda, H., Amaoka, H., Araga C. et al. 1984. Thefishes of the Japanese Archipelago. Tokai UniversityPress: Tokyo. 437 pp.

Mito, K. 1974. Food relationships among benthic fishpopulations in the Bering Sea on the Theragrachalcogramma fishing grounds in October andNovember o f 1 972. Master of Science Thesis.Hokkaido University Graduate School: Hakodate.135 pp.

Nakaya, K. & S. Shirai. 1992. Fauna and zoogeo-graphy of deep-benthic chondrichthyan fishesaround the Japanese Archipelago. Japan Journal ofIchthyology, 39: 37-48.

Nikol’sky, G. V . 1974. Ecology of fish. V ysshayashkola: Moscow. 367 pp. (In Russian)

Orlov, A. M. 1998a. The diets and feeding habits ofsome deep-water benthic skates (Rajidae) in thePacific waters of f the northern Kuril Islands andsoutheastern Kamchatka. Alaska Fishery ResearchBulletin, 5: 1-17.

Orlov, A. M. 1998b. On feeding of mass species ofdeep-sea skates ( Bathyraja spp., Rajidae) from thePacific waters of the northern Kuril Islands andsouth-eastern Kamchatka. Voprosy Ikhtiologii , 38:659-668 (In Russian).

Orlov, A. M. 1998c. Demersal ichthyofauna of Pacificwaters off the northern Kuril Islands and south-east-ern Kamchatka. Biologiya Morya , 24: 146-160 (InRussian).

Parin, N. V . 1971. Order Rajiformes. W ildlife. Vol. 4,Part 1. Prosveshcheniye: Moscow: 56-57 (In Russian)

Pedersen, S. A. 1995. Feeding habits of starry ray(Raja radiata) in west Greenland waters. ICES Jour-nal of Marine Science, 52: 43-53.

Robishaud, D. A., Elner, R. W ., & R. F. J. Bailey .1991. Dif ferential selection of crab Chionoecetesopilio and Hyas spp. as prey by sympatric codGadus morhua and thorny skate Raja radiata. U.S.Fishery Bulletin, 89: 669-680.

Schoener, T. W. 1970. Nonsynchronous spatial over-lap of lizards in patchy habitats. Ecology, 51: 408-418.

Smale M. J. & P. D. Cowley. 1992. The feeding ecol-ogy of skates (Batoidea: Rajidae), off the cape SouthCoast, South Africa. South African Journal of MarineScience, 12: 823-834.

Templeman, W. 1982. S tomach c ontents o f t hethorny skate, Raja radiata , from the Nort hwestAtlantic. Journal of Northwest Atlantic Fisheries Sci-ence, 3: 123-126.

aqua vol. 7 no. 2 - 2003 60


*********************************************************************************************************************************ERRATUMaqua 6(4): Description of six new Caribbean fish species in the genus Starksia (Labrisomidae) by Jef frey T. Williams and Julie H. Mounts: the correct photo for Fig. 7 should be Starksia sella n. sp., as shown below.

7(2)Imp/ok 16-06-2003 12:10 Pagina 60

Keywords St. Pauls Rocks, zoogeography , reef fishes, fish

assemblages, dispersal

AbstractSt. Paul’ s Rocks is a very small group of rocky

islands located on the mid-Atlantic Ridge just north ofthe Equator, about 1000 km from the Brazilian coast.The aim of this work is to add new information on theabundance, biology, zoogeography and taxonomy ofits reef fishes. In the course of four expeditions thefish fauna was surveyed in tide pools and over reefsat depths down to 62 m using a number of dif ferentmethodologies. Seventy-five fish species (25 newrecords) were recorded, of which 58 are reef inhabi-tants and 17 are pelagic. The most speciose familieswere Muraenidae (seven species), Carangidae (five),Pomacentridae (five), Labridae (four), Serranidae(three), and Scaridae (three). Stegastes sanctipauli(Pomacentridae), Chromis multilineata (Pomacentri-dae), Melichthys niger (Balistidae) and Caranxlugubris (Caranagidae) were the most visually abun-dant fishes. Despite being recorded in prior surveys,Carcharhinus galapagensis and Anthias salmopunc-tatus were not observed by our team. It was observedthat 60.3% of the reef fish species are carnivores,15.5% planktivores, 8.6% omnivores, 8.6% territorialherbivores, and 6.9% non-territorial herbivores. Of the58 reef fishes recorded, four are endemic to St. Paul’sRocks and about 80% also occur of f the coast ofBrazil. It is thought therefore that St. Paul’ s Rocksshould be regarded as an impoverished outpost of theBrazilian province.

ResumoO Arquipélago de São Pedro e São Paulo é um con-

junto muito pequeno de ilhotas rochosas localizado

logo acima do Equador, distante cerca de 1000 km dacosta brasileira. O objetivo do presente estudo foi adi-cionar novas informações acerca da abundância,biologia, zoogeografia e taxonomia dos seus peixesrecifais. Durante quatro expedições, a ictiofauna foilevantada em poças de maré e em recifes até 62 mde profundidade através de várias metodologias.Setenta e cinco espécies de peixes (25 novos reg-istros) foram encontradas na área, das quais 58 sãohabitantes dos recifes e 17 são pelágicos. As famíliasmais ricas quanto ao número de espécies foramMuraenidae (sete espécies), Carangidae (cinco),Pomacentridae (cinco), Labridae (quatro), Serranidae(três), and Scaridae (três). Stegastes sanctipauli(Pomacentridae), Chromis multilineata (Pomacentri-dae), Melichthys niger (Balistidae) e Caranx lugubris(Carangidae) foram os peixes visualmente maisabundantes. Carcharhinus galapagensis e Anthiassalmopunctatus, registrados em levantamentos ante-riores, não foram observadas pela nossa equipe. Foiconstatado que 60,3% das espécies de peixes reci-fais são carnívoras, 15,5% planctívoras, 8,6% onívo-ras, 8,6% herbívoras territoriais e 6,9% herbívorasnão territoriais. Dos 58 peixes recifais registrados,quatro são edêmicos do Arquipélago São Pedro eSão Paulo e cerca de 80% ocorrem também na costado Brasil. Acredita-se, portanto, que o Arquipélago deSão Pedro e São Paulo deve ser considerado comoum ponto externo empobrecido da Provínciabrasileira.

ZusammenfassungDie St.Paul’ s Rocks sind eine sehr kleine Gruppe

felsiger I nseln, d ie e ntlang d er m ittelatlantischenKammlinie – nur wenig nördlich des Äquators –, etwa1000 Km vor der brasilianischen Küste, liegen. DerZweck dieser Untersuchung war die Erfassung neuer

aqua vol. 7 no. 2 - 200361


Reef fishes of St. Paul’s Rocks: new records and notes on biology and zoogeography

Bertran M. Feitoza1, Luiz A. Rocha2, Osmar J. Luiz-Junior3, Sergio R. Floeter4 and João L. Gasparini5

1) Universidade Federal da Paraíba, CCEN, Depto. de Sistemática e Ecologia, João Pessoa, PB, 58059-900, Brasil. E-mail: [email protected]

2) University of Florida, Dept. of Fisheries and Aquatic Sciences, 7922 NW, 71st Street, Gainesville, FL 32653, USA;

3) Universidade Metodista de São Paulo, Núcleo e Agência Ambiental, São Bernardo do Campo, SP, 09640-000, Brasil;

4 & 5) Universidade Federal do Espírito Santo, Depto. de Ecologia e Recursos Naturais, Vitória, ES, 29060-900, Brasil.


7(2)Imp/ok 16-06-2003 12:10 Pagina 61

Informationen über Artenreichtum, Biologie, Zoo-geografie und Taxonomie ihrer Rif fische. Im Verlaufevon vier Expeditionen wurden die entsprechendenEinzelheiten der Fischfauna in Tidentümpeln sowieüber den Riffen, bis hinunter zu Tiefen von 62 m, mitverschiedenartiger Methodik erfasst. FünfundsiebzigFischarten (25 davon als Neuaufzeichnungen) wur-den verzeichnet. Davon waren 58 Arten Riffbewohnerund 17 Arten kamen pelagisch vor. Die artenreichstenFamilien waren: Muraenidae (7 Arten) Carangidae (5Arten), Pomacentridae (5 Arten), Labridae (4 Arten),Serranidae (3 Arten). Stegastes sanctipauli (Poma-centridae), Chromis multilineata (Pomacentridae) undMelichthys niger (Balistidae) waren die am meistengesehenen Fischarten. Die in früheren Berichtenangeführten Arten Carcharhinus galapagensis undAnthias salmopunctatus, wurden von unserem Teamnicht gefunden. Es wurde beobachtet, dass unter denFischarten dieser Inseln 60.3% Fleischfresser, 15.5%Planktonfresser, 8.5% Allesfresser, 8.6% territorialePflanzenfresser und 6.9% nicht-territoriale Pflanzen-fresser sind. V on den 58 erfassten Rif fischartenwaren vier für die St.Paul’ s Rocks endemisch; etwa80% kommen ebenfalls entlang der brasilianischenKüste vor . Daher ist es zu vermuten dass man die St. Paul’ s Rocks als einen fischartenverarmten Vorposten der brasilianischen Provinz betrachtensollte.

RésuméSt Paul's Rocks est un minuscule groupe d'îles

rocheuses sises sur la dorsale médiane de l'Atlan-tique, juste au nord de l'Equateur , à environ 1000 kmde la côte brésilienne. L'objectif de ce travail est defournir des informations nouvelles sur l'abondance, labiologie, la zoogéographie et la taxonomie de sespoissons de récifs. Au long de quatre expéditions, lafaune piscicole a été relevée dans les mares tidales etsur les récifs jusqu'à des profondeurs de 62 m. en util-isant plusieurs méthodologies. Soixante-quinzeespèces de poissons ont été collectées (25 sont nou-velles), dont 58 inféodées aux récifs et 17 pélagiques.Les familles comprenant le plus d'espèces étaient lesMuraenidae (sept espèces), les Carangidae (cinq),les Pomacentridae (cinq), les Labridae (quatre), lesSerranidae (trois) et les Scaridae (trois). Stegastessanctipauli (Pomacentridae), Chromis multilineata(Pomacentridae), Melichthys niger (Balistidae) etCaranx lugubris (Caranagidae) étaient les espècesles plus souvent visibles. Malgré leur présence dansdes relevés précédents, Carcharhinus galapagensiset Anthias salmopunctatus n'ont pas été observéespar notre équipe. L'analyse a révélé que 60,3 % desespèces récifales sont carnivores, 15,5 % planctoni-vores, 8,6 % omnivores, 8,6 % herbivores territorialeset 6,9 % herbivores non territoriales. Sur les 58 pois-sons récifaux collectés, quatre sont endémiques à StPaul's Rocks et 80 % environ figurent aussi au large

du Brésil. D'où la conclusion que St Paul's Rockdevrait être considéré comme un poste avancé pluspauvre en espèces de la province brésilienne.

SommarioSt. Paul’ s Rocks è un piccolo gruppo di isole roc-

ciose localizzate lungo la dorsale Atlantica, a nord del-l’equatore e a 1000 km dalla costa del Brasile. Loscopo di questo lavoro è quello di fornire nuovi datisull’abbondanza, la biologia, la zoogeografia e la tas-sonomia dei pesci che abitano le coste di questeisole. Nel corso di quattro spedizioni, utilizzandodiverse metodologie, è stata censita la fauna itticamarina delle zone costiere dalla fascia delle mareealla barriera fino alla profondità di 62 m. Sono stateregistrate complessivamente 75 specie (incluse 25nuove segnalazioni), 58 delle quali sono pesci di bar-riera, mentre 17 sono pelagici. Le famiglie presenticon il maggior numero di specie sono quelle deiMuraenidae (7 specie), dei Carangidae (5), Poma-centridae (5), Labridae (4), Serranidae (3) e Scaridae(3). Stegastes sanctipauli (Pomacentridae), Chromismultilineata (Pomacentridae), Melichthys niger (Balis-tidae) e Caranx lugubris (Caranagidae) erano lespecie più abbondanti. Malgrado fossero state regis-trate in precedenti spedizioni, le due specie Car-charhinus galapagensis e Anthias salmopunctatusnon sono invece state osservate in questo studio. Dalcensimento eseguito risulta che il 60,3% delle speciedi barriera sono carnivore, il 15,5% planctivore, l’8,6%onnivore, l’8,6% erbivore territoriali e il 6,9% erbivorenon territoriali. Delle 58 specie di barriera registrate,quattro sono endemiche a St. Paul’ s Rocks, mentrecirca l’80% sono presenti anche lungo le coste delBrasile. Si ritiene pertanto che St. Paul’s Rocks debbaessere considerato un avamposto impoverito dellaregione brasiliana.

IntroductionSt. Paul’s Rocks (Arquipélago de São Pedro e São

Paulo) is a very small group of rocky islands locatedon the mid-Atlantic Ridge, just north of the Equator(00°55’N; 29°21’W), 1000 km from the Braziliancoast, and 1890 km from Senegal, Africa (Fig. 1). It isone of the smallest, most isolated groups of oceanicislands in the world.

The Rocks are particularly interesting from the pop-ulation biology and biogeographical perspectivesbecause of their very small size and isolation. Theyare uniquely influenced by both the Equatorial Under-current – facilitating eastward dispersal – and theSouthern Equatorial Current – directing flow from thecentral-eastern Atlantic. The area has been visited byscientific expeditions since 1799 (see Lubbock &Edwards, 1981, for a review). However , the first sur-vey involving scuba diving to a depth of 60 m was onlycarried out in 1979 (Lubbock & Edwards, 1981). In thepast, the inhospitable nature and inaccessibility of St.

aqua vol. 7 no. 2 - 2003 62


7(2)Imp/ok 16-06-2003 12:10 Pagina 62

Paul’s Rocks had prevented detailed biological stud-ies. However, since the establishment of a scientificstation by the Brazilian Navy in July of 1998, ichthyol-ogists have been able to visit the island periodically toreassess the population status of reef fishes (theRocks, now called ‘Ar chipelago’ are perm anentlyinhabited).

The present study adds to the knowledge of the biol-ogy of the reef fishes of St. Paul’ s Rocks obtained bythe 1979 Cambridge Expedition (Lubbock & Edwards,1981).

MethodsStudy area: the Archipelago rises from the 4000 m

deep ocean floor close to the Mid-Atlantic Ridge, andtwo putative ages are given to it: 9.5 MYBP (millionyears before present) if it originated from a nearbyridge, or 35 MYBP if it originated from a farther

oceanic ridge (Melson, 1972). It consists of five smallrocky islets and four larger islets covering an area ofabout 16,000 m2 (Fig. 1). Tide pools are present onmost of the islets, which are generally flushed withseawater at high tide (Fig. 2). A small shallow bay (2to 21 m depth) is formed by the encirclement of threemajor islets (Fig. 3). Other reef habitats of St. Paul’ sRocks consist almost entirely of nearly vertical clif fsextending beyond 60 m depth (Fig. 4). Robertson(2001) noted that this archipelago has one of the mostlimited areas of shallow habitats (<50 m deep) amongoceanic islands, with less than 0.2 km 2. Most of thesublittoral zone is dominated by the soft coralPalythoa caribeorum (from 3 to 8 m depth), and thealgae Caulerpa sp. (from 3 to about 30 m) (Fig. 5).The hermatipic corals Madracis decactis (Lyman) andScolymia wellsi Laborel appear where the Caulerpastops at about 30 m, and occur down to at least 45 m

aqua vol. 7 no. 2 - 200363

Bertran M. Feitoza, Luiz A. Rocha, Osmar J. Luiz-Junior, Sergio R. Floeter and João L. Gasparini

Fig. 1. Map of St. Paul’s Rocks.

7(2)Imp/ok 16-06-2003 12:10 Pagina 63

aqua vol. 7 no. 2 - 2003 64


Fig. 2. Tide pool at the Belmont Islet, it is flushed with fresh seawater at high tide. Photo by B. M. Feitoza.

Fig. 3. Bay situated between the Belmont, Challenger and Cabral Islets. Photo by B. M. Feitoza.

7(2)Imp/ok 16-06-2003 12:10 Pagina 64

aqua vol. 7 no. 2 - 200365


Fig. 4. Vertical cliff, the typical reef habitat of St. Paul’ s Rocks. Photo by O. J. Luiz-Junior .

Fig. 5. Underwater view at St. Paul’s Rocks, with the green algae Caulerpa sp. dominating most of the sublittoral zone.Photo by O. J. Luiz-Junior.

7(2)Imp/ok 16-06-2003 12:10 Pagina 65

where they are quite abundant (Amaral, in press).Two black corals (Antipathes spp.) occur from a depthof 45 m to at least 60 m (Edwards & Lubbock, 1983a;Amaral, in press). Edwards & Lubbock (1983a),recorded 14 alga species in their study.

Data collection: four expeditions have been under-taken since 1999 (May and November 1999, Septem-ber 2000, and August 2001) comprising 47 days offieldwork and about 124 hours of underwater activity(54 scuba dives to depths of 62 m – including twonight dives, and 39 snorkelling dives). The water tem-perature ranged from 23 to 26.5 ºC and visibility from12 to 30 m. The fish fauna was surveyed in tide poolsand over reefs down to a depth of 62 m, throughunderwater observations, collections and pho-tographs. Three small clove oil stations were con-ducted aiming to survey cryptic fish not collectableusing other methods. Six hours of underwater videoswere filmed with a view to investigating fish behaviour.Collected specimens were deposited in the fish col-lections of the followings institutions: UniversidadeFederal da Paraíba, João Pessoa, Paraíba, Brazil(UFPB); and Museu de Biologia Professor MelloLeitão, Santa Tereza, Espírito Santo, Brazil (MBML).Data on voucher specimens is appended.

Species list, populational status and abundancedata: the species list is based on the fishes observed,photographed and collected during the four expedi-tions, as well as on data from the literature (Lubbock& Edwards, 1981) and from fisheries run by commer-cial fishing boats. Bony fishes are listed in the phylo-genetic order of families, following Nelson (1994);elasmobranchs are listed following Compagno(1999). Within the families, species are organised inalphabetical order. We have also included the follow-ing information for each species:

1979 population status – a rough indication of rela-tive abundance in 1979, based on Lubbock &Edwards (1981);

Current population status – an indication of relativeabundance in 1999 – 2001 based on a diver ’s likeli-hood of observing a species in its normal habitat anddepth range on any given dive (adapted from Humann& DeLoach, 2002), where: AB = abundant (at leastseveral sightings of many individuals – at least 50 –can be expected on nearly every dive), VC = verycommon (at least several sightings can be expectedon nearly every dive, but not necessarily of many indi-viduals), CM = common (sightings are frequent, butnot necessarily expected on every dive), OC = occa-sional (sightings are not unusual, but are notexpected on a regular basis), UN = uncommon (sight-ings are unusual), and RA= rare (sightings are excep-tional);

Habitat – where the species has usually been found(adapted from Edwards & Lubbock, 1983a), where: 1= tide pools (either frequently or infrequently flushedby fresh seawater), 2 = littoral zone (spring-tidal

range), 3 = Palythoa and Caulerpa zone (dominatedby Palythoa caribeorum, from the bottom of the littoralzone down to 8 m, and by Caulerpa, from 3 to about30 m), 4 = sub-Caulerpa zone (from where Caulerpastops, at about 30 m, to at least 60 m), 5 = slope andbay (gently sloping areas with patches of coarsesand, rubble and isolated loose rocks), and 6 = watercolumn (offshore and over reefs, pelagic habitat);

Depth range – range commonly seen in underwaterobservations;

Geographic range of the species;Trophic category – determined from direct behav-

ioural observations and available literature (Randall,1967; 1996), where: TH = territorial herbivores, NT =non-territorial herbivores, C = carnivores, P = plankti-vores, and O = omnivores.

Record status – how the species was recorded.We consider ’reef fishes’ to be species either asso-

ciated with hard substrate ( sensu Thresher, 1991) orepipelagic forms that regularly associate with thereefs (such as carangids, belonids, sharks andpelagic rays). Surveys of the abundance and theoccurrence of juveniles and adults of various sizeswere used to estimate which members of the fishfauna are residents, i.e. have self-sustaining popula-tions, or vagrants, i.e. exceedingly rare and probablyarriving from other sites.

Results and discussionNew records and population reassessment: Lubbock

and Edwards (1981) recorded 50 fish species belong-ing to 29 families, of which 34 are associated withrocky-reef habitats. Our team recorded a total of 75fish species (25 new records) belonging to 36 fami-lies. Fifty-eight species were recorded over reef areas(referred to as “reef fishes”), eleven of which are mid-water species that are regularly observed on reefs,and 47 are dependent on rocky-reef habitats (Table I).Seventeen species are pelagic and are not includedin Table I (new records are in bold): Rhincodon typusSmith, 1829; Carcharhinus falciformis (Bibron inMüller & Henle, 1839); Prionace glauca Linnaeus,1758; Isurus oxyrinchus Rafinesque, 1810; Cypselu-rus cyanopterus (Valenciennes, 1847); Exocetusvolitans Linnaeus, 1758; Paraexocoetus sp.;Remora brachyptera (Lowe, 1839); R. osteochirCuvier, 1 829; Remorina albescens (Temminck &Schlegel, 1845); Coryphaena hippurus Linnaeus,1758; Acanthocybium s olandri (Cuvier, 1 832);Scomberomorus cavalla (Cuvier 1829); Thunnusalbacares (Bonnaterre, 1788); T. obesus (Lowe,1839); Makaira nigricans Lacepède, 1802; and Molasp.

Among the 58 reef fishes recorded, the most spe-ciose families were the Muraenidae (seven species),Carangidae ( five), P omacentridae ( five), L abridae(four), Serranidae (three), and Scaridae (three). Six-teen species (27.6%) were rare, five (8.6%) uncom-

aqua vol. 7 no. 2 - 2003 66


7(2)Imp/ok 16-06-2003 12:10 Pagina 66

aqua vol. 7 no. 2 - 200367


mon, nine (15.5%) occasional, 13 (22.4%) common,seven (12.1%) very common, and six (10.3%) abun-dant (see Table I). Nine of the 16 rare species(Cephalopholis fulva , Lutjanus jocu , Stegastesrocasensis, Clepticus brasiliensis, Thalassoma noron-hanum, Sparisoma amplum , S. axillare , S. frondo-sum, and Bathygobius soporator) do not seem tohave a self-sustaining population and probably comefrom other sites where they are common (e.g. Fer-nando de Noronha Archipelago).

The p opulation s tatus o f m ost o f t he s peciesbetween 1999 and 2001 seems to be nearly the sameas that observed by Lubbock & Edwards (1981). Twospecies previously recorded by Lubbock & Edwards(1981) were not observed by our team: the Galapagosshark Carcharhinus galapagensis and the St. Paul’ santhias Anthias salmopunctatus . The abundance ofsharks at St. Paul’ s Rocks has been noted by mostearly visitors and partly attributed to the lack of fishingactivity (Lubbock and Edwards, 1981). In the past twodecades however, fishing pressure has increasedgreatly, and sharks are now targeted due to the highcommercial value of their fins. The pelagic fishes onwhich sharks feed are also targeted by the fishingindustry and this may also have contributed to anapparent population decline of C. galapagensis .Anthias salmopunctatus is endemic to St. Paul’ sRocks and was listed as vulnerable by IUCN (Hilton-Taylor, 2000). This species was common on rockfaces below 30 m, as reported by Lubbock & Edwards(1981), but was not seen by our team.

The St. Paul’ s Gregory Stegastes sanctipauli, the

brown chromis Chromis multilineata, the black durgonMelichthys niger and the black jack Caranx lugubriswere the most visually abundant fishes in St. Paul’ sRocks and certainly account for the most importantpart of the fish biomass. The latter two species areusually found up to at least 150 m from the Rocks,forming large aggregations from just below the sur-face down to about 30 m. Melichthys niger appears tobe common around isolated oceanic islands. Thereare reports of the same abundance for AscensionIsland (Lubbock, 1980), Clipperton Atoll (Robertson &Allen, 1996), Trindade Island (Gasparini & Floeter ,2001), and to a minor degree in the vicinity of RocasAtoll (Rosa & Moura, 1997) and Fernando deNoronha Archipelago (B. M. Feitoza pers. obs.).

Almost two-thirds (60.3%) of the reef fish speciesare carnivores, 15.5% planktivores, 8.6% omnivores,8.6% territorial herbivores, and 6.9% non-territorialherbivores. Stegastes sanctipauli is primarily consid-ered to be a territorial herbivore, but can also beopportunistic, sometimes preying upon fish eggs andsmall benthic invertebrates. The same appears to betrue of the sergeant major Abudefduf saxatilis (pri-marily treated as a ‘planktivore’) since it has mostlybeen seen in mid-water, clearly feeding on zooplank-ton. According to Randall (1967), A. saxatilis has oneof the most diversified food habits known, and may beobserved in aggregations well above reefs, feeding onzooplankton, or grazing on benthic algae, or on ses-sile animal life on the bottom. This feeding flexibilityprobably enables opportunistic planktivores (e.g. S.sanctipauli and A. saxatilis) and the classic omnivores

Fig. 6. Geographic distribution of St. Paul’s Rocks reef fishes.

7(2)Imp/ok 16-06-2003 12:10 Pagina 67

aqua vol. 7 no. 2 - 2003 68


Table I. Reef fishes from St. Paul’s Rocks. Population status, habitat, depth and geographical ranges, trophic categoriesand record status are shown indicated. New records are in bold.

Family / Species Population Population Depth Geographic Trophic Record Status Status Habitat range

Range category Status(1979) (2001) (m)

CARCHARHINIDAECarcharhinus galapagensis(Snodgrass & Heller, 1905) CM – 3,4,5,6 8 – 36 CT C L

SPHYRNIDAESphyrna sp. UN UN 6 0 – 40 CT C SR, L

MOBULIDAEMobula tarapacana(Philippi, 1893) CM CM 6 0 – 30 CT P P, V

MURAENIDAEChannomuraena vittata(Richardson, 1845) – RA 3,4,5 15 – 30 CT C PEnchelycore anatina(Lowe, 1841) – OC 3,4,5 3 – 60 EA+CA+FN C VSEnchelycore nigricans(Bonnaterre, 1788) OC CM 1,3,4,5 2 – 60 PA C VS, LGymnothorax funebrisRanzani, 1840 – RA 3,5 0 – 50 PA C VGymnothorax miliaris(Kaup, 1856) UN CM 3,4,5 2 – 40 PA C P, LMuraena melanotis(Kaup, 1859) – OC 3,4,5 3 – 60 EA+CA+FN C VSMuraena pavoninaRichardson, 1844 CM CM 1,3,4,5 2 – 60 CA+BR C P, V, L

BELONIDAEAblennes hians(Valenciennes 1846) – RA 6 0 – 3 CT C SRStrongylura timucu(Walbaum 1792) – UN 6 0 – 3 WA C P

HOLOCENTRIDAEHolocentrus ascensionis(Osbeck, 1765) OC UN 1,3,4,5 2 – 60 PA C VS, LMyripristis jacobusCuvier, 1829 CM VC 3,4,5 2 – 30 PA P P, V, L

AULOSTOMIDAEAulostomus aff. strigosusWheeler, 1955 CM VC 3,4,5 2 – 30 PA C VS, L

DACTYLOPTERIDAEDactylopterus volitans(Linnaeus, 1758) – RA 3,5,6 0 – 30 PA C P

SCORPAENIDAEScorpaena sp. – RA 3,4,5 25 – 30 ? C PScorpaenodes insularisEschmeyer, 1971 UN UN 3,4,5 5 – 35 CA C VS, L

SERRANIDAEAnthias salmopunctatusLubbock & Edwards, 1981 CM – 4 >30 End P LCephalopholis fulva(Linnaeus, 1758) – RA 3,5 2 – 35 WA C SRRypticus saponaceus(Bloch & Schneider, 1801) CM OC 3,4,5 2 – 62 PA C P, L

APOGONIDAEApogon americanusCastelnau, 1855 CM CM 1,3,4,5 0 – 40 BR P VS, L

CARANGIDAECarangoides bartholomaei(Cuvier, 1833) UN UN 3,4,5,6 0 – 40 WA C SR, LCarangoides crysos(Mitchill, 1815) CM OC 3,5,6 0 – 40 PA C P, LCaranx latusAgassiz, 1829 OC OC 3,5,6 1 – 30 WA C P, LCaranx lugubrisPoey, 1860 VC AB 3,4,5,6 0 – 70 CT C VS, LElagatis bipinnulata(Quoy & Gaimard, 1824) OC OC 6 0 – 40 CT C P, L

LUTJANIDAELutjanus jocu(Bloch & Schneider, 1801) OC RA 3,4,5 2 – 40 WA+CA C P, V, L

CHAETODONTIDAEChaetodon obliquusLubbock & Edwards, 1980 CM CM 4 30 – 70 End C VS, LChaetodon striatusLinnaeus, 1758 CM CM 3,4,5 2 – 55 WA C P, L

7(2)Imp/ok 16-06-2003 12:10 Pagina 68

aqua vol. 7 no. 2 - 200369


Family / Species Population Population Depth Geographic Trophic Record Status Status Habitat range

Range category Status(1979) (2001) (m)

POMACANTHIDAEHolacanthus ciliaris(Linnaeus, 1758) CM CM 3,4,5 2 – 60 WA O VS, LBlue morph UN OC 3,4,5 2 – 60 End O P, V, LWhite morph UN RA 4 30 – 50 End O P, V, LOther colour morphs UN UN 3,4,5 2 – 60 End O P, V, LPomacanthus paru(Bloch, 1787) UN UN 3,4,5 2 – 30 WA+CA O P, V, LKYPHOSIDAEKyphosus sectatrix(Linnaeus, 1766) CM VC 3,4,5,6 0 – 25 PA NH P, V, LPOMACENTRIDAEAbudefduf saxatilis(Linnaeus, 1758) AB AB 1,3,4,5,6 0 – 20 PA P P, V, LChromis aff. enchrysuraJordan & Gilbert, 1882 CM CM 4 40 – 70 WA P VS, LChromis multilineata(Guichenot, 1855) AB AB 3,4,5,6 0 – 60 WA+CA P P, V, LStegastes rocasensis(Emery, 1972) – RA 5 2 – 10 FN TH VSStegastes sanctipauli Lubbock & Edwards, 1981 AB AB 1,3,4,5 0 – 60 End TH VS, LLABRIDAEBodianus insularisGomon & Lubbock, 1980 CM CM 3,4,5 6 – 60 CA C VS, LClepticus brasiliensisHeiser, Moura & Robertson, 2000 – RA 3,5,6 5 – 25 BR P P, VHalichoeres radiatus(Linnaeus, 1758) VC VC 3,4,5 2 – 30 NWA+FN C P, LThalassoma noronhanum(Boulenger, 1890) RA RA 1,3,5 2 – 10 BR P PSCARIDAESparisoma amplum(Ranzani, 1842) – RA 3,4 15 – 30 BR NH PSparisoma axillare(Steindachner, 1878) RA RA 3,4,5 10 – 30 BR NH SRSparisoma frondosum(Agassiz, 1831) RA RA 3,4,5 10 – 30 BR NH P, LTRIPTERYGIIDAEEnneanectes smithiLubbock & Edwards, 1981 CM CM 1,3,5 2 – 25 End C VS, LLABRISOMIDAEMalacoctenus aff. triangulatusSpringer, 1958 CM VC 1,3,4,5 0 – 40 NWA C VS, LStarksia aff. sluiteri(Metzelaar, 1919) CM OC 3,4,5 2 – 40 NWA C VS, LCHAENOPSIDAEEmblemariopsis sp. – VC 3,4,5 2 – 60 End (?) C VSBLENNIIDAEEntomacrodus vomerinus(Valenciennes, 1836) AB AB 1,2 0 – 1 BR TH VS, LOphioblennius trinitatisMiranda-Ribeiro, 1919 VC VC 1,3,4,5 0 – 50 PA TH VS, LGOBIIDAEBathygobius soporator(Valenciennes, 1837) – RA 1 0 – 1 PA TH VSSPHYRAENIDAESphyraena barracuda(Walbaum, 1792) CM CM 3,4,5,6 0 – 60 CT C P, V, LBALISTIDAECanthidermis sufflamen(Mitchill, 1915) OC OC 3,4,5,6 5 – 60 WA+CA C P, V, LMelichthys niger(Bloch, 1786) AB AB 3,4,5,6 0 – 70 CT O VS, LMONACANTHIDAEAluterus scriptus(Osbeck, 1765) UN OC 3,4,5 2 – 40 CT O P, LCantherhines macrocerus(Hollard, 1854) UN CM 3,4,5 2 – 40 WA O P, LDIODONTIDAEDiodon hystrixLinnaeus, 1758 RA RA 3,5 2 – 25 CT C VS, L

Population status: AB = Abundant, VC = Very common, CM = Common, OC = Occasional, UN = Uncommon, RA = Rare or V agrant. Habitat: 1 = tide pools, 2 = littoral zone, 3 = Palythoa and Caulerpa zone, 4 = sub-Caulerpa zone, 5 = slope and bay, and 6 = water column. Geographic Range: CT = Circumtropical, PA = Pan-Atlantic, EA = Eastern Atlantic,WA = Western Atlantic, NWA = North-western Atlantic, BR = Brazilian province (including F. Noronha Ridge Islands), CA= Central Atlantic Islands (Ascension, St. Helena and St. Paul’s),FN = Fernando de Noronha Ridge Islands, End = Endemic to St. Paul’ s Rocks. Trophic category: TH = territorial herbivores, NT = non-territorial herbivores, C = carnivores, P = planktivores, O = omnivores. Record Status: VS = Voucher Specimen, SR = Sight Record, P = Photography, V = video record, F = Fishery, and L = Literature.? = Not known.

7(2)Imp/ok 16-06-2003 12:10 Pagina 69

aqua vol. 7 no. 2 - 2003 70


Fig. 7a-f. Endemic fishes from the Central Atlantic Islands: a-d) St Paul’s; e-f) St. Paul’s, Ascension and St. Helena. a) Chaetodon obliquus; b) Enneanectes smithi; Stegastes sanctipauli, c) juvenile and d) adult; e) Bodianus insularis;and f) Scorpaenodes insularis. Photos by B. M. Feitoza.

a

b

c

(e.g. M. niger) to numerically dominate harsh environ-ments around oceanic islands.

Zoogeography and endemism: of the 58 reef fishesrecorded at St. Paul’ s Archipelago, 20 occur in thewestern Atlantic, seven of which are endemic to theshores of the Brazilian mainland and one to the Fer-nando de Noronha Ridge islands. Thirteen are pan-Atlantic, 11 circumtropical, and five are known primar-ily from the central Atlantic islands, two of which alsooccur in the eastern Atlantic coast and one in theBrazilian Province. Three are north-western Atlanticspecies, one of which also occurs around the Fer-nando de Noronha Ridge islands (Fig. 6; see alsoTable I).

Because of the prevailing currents, St. Paul’ s reeffish fauna more closely resembles that of the BrazilianProvince than of the other mid-Atlantic Ridge islands

of Ascension and St. Helena, with about 80% of itsreef fishes occurring in the Brazilian Province. Thus,we concur with Edwards & Lubbock (1983b), Briggs(1995) and Floeter & Gasparini (2000) that St. Paul’ sshould be regarded as an impoverished outpost of theBrazilian Province.

St Paul’s Rocks supports four endemic fish speciespreviously recorded by Lubbock and Edwards (1981)(Fig. 7 a-d). Our survey revealed the presence of apossible fifth endemic species of the genus Emble-mariopsis from St. Paul’s Archipelago (currently beinginvestigated by the senior author) (Fig. 8). This is thefirst record of a chaenopsid in the area, but a largepopulation of Emblemariopsis sp. has been observedat depths between 3 and 45 m. This species had notbeen recorded previously , probably because of itscryptic habits.

7(2)Imp/ok 16-06-2003 12:10 Pagina 70

aqua vol. 7 no. 2 - 200371


d

e

f

One of the most remarkable features of St. Paul’ sRocks is the occurrence of dif ferent colour morphs ofthe queen angelfish Holacanthus ciliaris . There arethree basic colour morphs, yellow , blue and white(Fig. 9 a-c), and several variations and mixtures (Fig.9 d-h; see also Debelius, 1997: p.143). Moreover, allcolour morphs differ from those in all other H. ciliarispopulations by having shorter dorsal and anal fin fila-ments (see Figs. 9 and 10 for comparison). The yel-low morph was the most abundant pattern observedat the Rocks, accounting for about 95% of allobserved morphs. Colour variations occurring in theH. ciliaris population of St. Paul’ s Rocks were attrib-uted to the effects of inbreeding in a small, isolatedpopulation (Edwards & Lubbock 1983b). It suggeststhat no (or very few) recruits are arriving from othersites and the population of H. ciliaris at St. Paul’s is

maintaining itself by self-recruitment, a process morecommon than previously thought (Swearer et al.1999; Jones et al. 1999; Robertson, 2001). No suchcolour variation is observed across the remainingrange of H. ciliaris in the W estern Atlantic (Rocha etal. 1998; Humann & DeLoach, 2002). Joyeux et al.(2001) suggested a possible on-going dif ferentiationfor H. ciliaris at the Rocks. Genetic and morphologicalcomparisons of H. ciliaris populations across theAtlantic are needed to better assess the inbreedingand taxonomic status of the queen angelfish popula-tion at St. Paul’s Rocks.

Since Lubbock & Edwards’ survey report in 1981, afew presumed albinotic or semi-albinotic Chromismultilineata have b een recorded f rom S t. P aul’sRocks. The supposed ‘albinism’ was also related toinbreeding in a small population by Lubbock &

7(2)Imp/ok 16-06-2003 12:10 Pagina 71

Edwards (1981). However , C. multilineata is one ofthe most abundant fish at the Rocks since 1979.Despite the apparently large population, one pre-sumed ‘semi-albinotic’ specimen was observed andphotographed by our team (Fig. 11).

Our survey revealed the presence at the Rocks of atypical eastern Atlantic species: the honeycombmoray Muraena melanotis. This species is very simi-lar to M. pavonina with small but consistent dif fer-ences in colouration (which remain even after preser-vation) and the size of the posterior nostril (Böhlke etal., 1989). Both species are frequently misidentified(e.g. the M. melanotis photo presented in Debelius(1997: p 75) is actually a photo of the flagged morayM. pavonina ), and records of M. melanotis from thenorth-eastern Brazilian mainland (Böhlke et al., 1989)are probably misidentifications of M. pavonina. Duringa six-year study of f the north-eastern Brazilian coast(B. M. Feitoza, unpublished), M. melanotis has notbeen observed, whereas M. pavonina was found atseveral sites. However, the record of M. melanotis atFernando de Noronha Archipelago and Rocas Atollappears to be correct. Adults of the two species canbe readily distinguished by their colour patterns: darkbackground with a white honeycomb-like pattern(absent or indistinct on the belly), with head spotsbecoming more closely spaced (even fusing) towardsthe snout in M. melanotis (Fig. 12); and dark back-ground with round white spots randomly placed(including belly), with more widely-spaced head spots,becoming almost absent towards the snout in M. pavonina (Fig. 13).

As the zoogeographical analysis implies, the fishfauna at St. Paul’ s Rocks is derived from that of theBrazilian coast and/or Fernando de Noronha Archipel-

ago. Eventual dispersal of larvae through the equato-rial undercurrent (Bowen, 1966; Edwards & Lubbock,1983b) may be presumed by the presence ofvagrants of species probably coming from Fernandode Noronha Archipelago, where they are very com-mon (e.g. Cephalopholis fulva , Lutjanus jocu , Ste-gastes rocasensis , Clepticus brasiliensis , Thalas-soma noronhanum, Sparisoma spp., and Bathygobiussoporator). A notable case was observed during Sep-tember 2000, when about ten juveniles of Stegastesrocasensis were seen at the bay (Fig. 14a). In thelong run, monitoring programs should be imple-mented in order to provide information on howspecies turnover occurs, the extent to which vagrantsarrive from distant sources, and if they establish resi-dent populations.

St. Paul’ s seems to be the only tropical oceanicisland that does not have a resident population of sur-geonfishes (Acanthuridae). These fish have a veryhigh dispersal potential and can maintain genetichomogeneity across long distances (Planes & Fau-velot, 2002; Rocha et al., 2002) suggesting that dis-persal limitation could not be the main cause of theirabsence. Surgeonfishes are mainly herbivores and/ordetritivores (Randall, 1967, 1996; Dias et al., 2001),thus ecological limitations such as the relatively lowalgal diversity (with Caulerpa dominating most of theshallow habitats), the lack of sandy and/or fine sedi-ment habitats (i.e. organic detritus) could be reasonsfor their absence, as well as for the very low densitiesof scarids. Only two of the 27 algae consumed by thesouth-western Atlantic surgeonfishes (Acanthurusspp.) off the Paraíba coast, north-eastern Brazil (Diaset al., 2001) are known to occur at the Rocks. In addi-tion, Dias et al. (2001) found that fine sediment, pre-

aqua vol. 7 no. 2 - 2003 72


Fig. 8. Emblemariopsis sp., a possible fifth endemic species from St. Paul‘s Archipelago. Photo by B. M. Feitoza.

7(2)Imp/ok 16-06-2003 12:10 Pagina 72

aqua vol. 7 no. 2 - 200373


sumably rich in organic matter (e.g. detritus), is one ofthe most important food items of the ocean surgeon-fish A. bahianus and the doctorfish A. chirurgus. Thisfood resource is virtually absent from the Rocks.Crossman et al. (2001) showed that detritus is a valu-able nutrient source for grazing reef fishes, and thatthe biomass of algae and detritus decreases fromsheltered mid-shelf reefs to highly exposed outerreefs. Goatfishes (Mullidae) and flounders (Bothidae),which are closely associated with unconsolidatedsubstrate, are also missing at the Rocks.

Inter- and intraspecific associationsReef fishes are known to interact in a complex man-

ner (Sale, 1991; Moyle & Cech, 1996; DeLoach,1999). Common interactions involve interspecificfeeding associations, such as cleaning (Sazima et al.,1998; Grutter, 1999; Feitoza et al., 2002), followingbehaviour (Diamant & Shpigel, 1985; Strand, 1988),camouflage (Aronson, 1983), and intraspecificaggression, such as territorial defence (Snyderman &Wiseman, 1996; Rocha, 2000). These four associa-tions were observed, filmed and photographed at St.Paul’s Rocks.

Cleaning involves a cleaner species that removesectoparasites and dead or diseased tissue from theclients (Losey , 1971; DeLoach, 1999). Although nofish were seen acting as cleaners at the Rocks, theAtlantic White-Striped Cleaner Shrimp Lysmata grab-hami (Gordon, 1935), was seen in action. Cleaningstations were located either under rocks or increvices, at depths of 6 to 60 m, and contained one ortwo cleaner shrimps, always accompanied by a vipermoray Enchelycore nigricans . Two client fishes,Chromis multilineata and E. nigricans were seenbeing cleaned by the shrimps (Fig. 15). Cleaningevents usually lasted for five to ten seconds.

Following behaviour is an opportunistic strategy thatallows small generalised predators (the followers) tocapitalise upon displacement or uncovering preyitems, when potential predators, grazers or sand-flatfeeders (the nuclear species) cause habitat distur-bances (Strand, 1988). Following behaviour involvingtwo labrids (the island hogfish Bodianus insularis andthe puddingwife Halichoeres radiatus ) and three fol-lower carangids (the horse-eye jack Caranx latus, theblack jack C. lugubris and the blue runnerCarangoides crysos ), was recorded from St. Paul’ s(Fig. 16). All three carangid species were seen follow-ing both B. insularis and H. radiatus. Following behav-iour involving labrids and carangids in the W esternAtlantic has also been recorded: Halichoeres radiatusvs. Carangoides ruber (Bloch, 1793) (see Baird,1993); and the Spanish hogfish Bodianus rufus (Lin-naeus, 1758), the spotfin hogfish B. pulchellus (Poey,1860) and the blackear wrasse Halichoeres poeyi(Steindachner, 1867) vs. Caranx latus (see Silvano,2001).

Various forms of camouflage are widely used amongreef fishes as a means of obtaining food (Moyle &Cech, 1996). The Atlantic cornetfish Aulostomusstrigosus was seen using one of two forms of camou-flage: solitarily , making itself “invisible” both driftingvertically orientated through the water column, andimmobile near Caulerpa turfs; or hiding itself, aligningwith other fish. On the former occasion, A. strigosusdrifted through the water column about 0.6 m or lessabove the substrate close to rocks or remained stillnear Caulerpa turfs, striking approaching small fisheswith a sudden lunge. A. strigosus was observed sev-eral times aligning with and swimming close to thewhitespotted filefish Cantherhines macrocerus, but noattack was recorded. It also presented various colourpatterns and was seen changing colour according tothe background, becoming yellowish, greenish orstriped when approaching Caulerpa turf, or dark whenswimming close to the filefish. Similar behaviour hasbeen described for its congener , the trumpetfish A.maculatus Valeciennes, 1837 (Aronson, 1983).

Intraspecific aggression appears to be commonamong labrids and aggressive encounters are fre-quent (Snyderman & Wiseman, 1996; DeLoach,2000; Rocha, 2000). Two initial phase coloured Hali-choeres radiatus were seen and photographed per-forming agonistic behaviour; they positioned them-selves mouth-to-mouth with their dorsal and anal finserected (Fig. 17), losing interest and separating afterabout a minute.

Most morays are known to live in crevices in reefs,usually hiding alone with only the head protruding dur-ing the day, and foraging at night (Böhlke et al., 1989;Randall, 1996; DeLoach, 1999; Humann & DeLoach,2002). Some species, such as Gymnothorax miliarisand Muraena pavonina forage in the open during theday (Debelius, 1997; Humann and DeLoach, 2002).The Muraenidae are the most speciose family at theRocks and a large population has been observedmainly at the bay and other gently-sloping areas.Some species (G. miliaris, Muraena melanotis and M.pavonina) were frequently observed performing bothan intra and interspecifc ‘friendly’ behaviour, stayingtogether in the same hole or even interlacing one witheach other (Fig 18 a-c). Similar behaviour has beenobserved only a few times at the coast of ParaíbaState, in northeastern Brazil, where two specimens ofGymnothorax vicinus (Castelnau, 1835) sporadicallyoccupied the same hole (L. A. Rocha, pers. obs.).

Taxonomic commentsThe man ta ray tentative ly identified as Mobula

hypostoma (Bancroft, 1831) by Lubbock & Edwards(1981), is probably M. tarapacana (Philippi, 1893),since the latter was frequently observed in the vicinityof the Rocks.

The trumpetfish from St. Paul’s was previously iden-tified as Aulostomus maculatus Valenciennes, 1842

7(2)Imp/ok 16-06-2003 12:10 Pagina 73

aqua vol. 7 no. 2 - 2003 74


d

e

fFig. 9a-h. Colour variations observed in the queen angelfish Holacanthus ciliaris at St. Paul’s Rocks. a) Yellow morph; b) blue morph; c) white morph; d-h) variations and mixtures between blue, yellow, orange and white. Photos a, d, e andh by B. M. Feitoza; b, c, and g by O. J. Luiz-Junior; and f by E. Fritzche.

a

b

c

7(2)Imp/ok 16-06-2003 12:11 Pagina 74

by Lubbock & Edwards (1981) presumably becauseof its morphological similarities with that species.Genetically, however, it is more similar to the EasternAtlantic and coastal Brazilian A. strigosus (Bowen etal., 2001).

The blue runner Caranx fusus (St Hilaire, 1809) citedby Lubbock & Edwards (1981) is now valid asCarangoides crysos (Mitchill, 1815). The Brazilianchromis referred to as Chromis sp. by Lubbock &Edwards (1981) is the brown chromis C. multilineata(Guichenot, 1853), according to L. A. Rocha (basedon an ongoing genetic investigation).

The parrotfish referred to as Sparisoma sp. by Lub-bock & Edwards (1981) is the saddled parrotfish S. frondosum (Agassiz, 1 831), a ccording t o t hedescription provided by these authors and field obser-vations made by our team.

A recent genetic analysis by Muss et al. (2001)demonstrated that the Ophioblennius species at St.Paul’s Rocks is distinct from the Caribbean speciesand identical to that from the Brazilian coast andTrindade island. The available name for this speciesis Ophioblennius trinitatis Miranda-Ribeiro, 1919, andit will be used here.

Three species do not have their taxonomic statuswell defined: Chromis aff. enchrysura, Starksia aff.sluiteri and Malacoctenus aff. triangulatus. The seniorauthor and other Brazilian ichthyologists are currentlytrying to determine their taxonomic status.

Conservation issuesDespite being sporadically replenished with larvae

from elsewhere, St. Paul’ s Rocks also containsunique, self-sustaining populations and endemicspecies. It is now clear that marine species are notexempt from the effects of human impact and the riskof extinction (Roberts & Hawkins, 1999; Hawkins etal., 2000). Some characteristics could impose risks toSt. Paul’s reef fish populations, such as: a) Restricted

geographic range – the only reported case of extinc-tion of a reef fish was an island-endemic species(Roberts & Hawkins, 1999), at St. Paul’ s, endemicspecies are at risk due to their limited distribution, andaccording to Robertson (2001) genetically distinct,isolated populations should be treated as endemicspecies for conservation purposes; b) Aquarium trade– the isolation of St. Paul’s Rocks is not an obstaclefor the harvesting of high-priced, rare fishes (espe-cially the white and blue colour morphs of H. ciliaris)for the aquarium trade. The collection of some speci-mens was recently observed (B. M. Feitoza pers.obs.); and c) Fisheries – shark fin fisheries could notbe sustainable in such a small location as demon-strated by the apparent decrease in shark populationsin the past two decades, coinciding with increasingfishing pressure. By-catch in the lobster fishery is alsoa problem; some fishes (mainly morays, M. niger andH. ciliaris) were continually found in the lobster trapsutilised in commercial fisheries (O. J. Luiz-Junior andB. M. Feitoza pers. obs.) (Fig. 19, on last cover page).

We thereby recommend the establishment of amarine protected area in the Rocks, due to the vul-nerability of its isolated fauna.

AcknowledgementsThis study could not have been carried out without

the essential logistic support of the Brazilian Navy(Marinha do Brasil) which provided transportation andlodging for B. M. Feitoza and L. A. Rocha at theRocks. We also thank: B. P. Ferreira, F. Hazin and F.D. Amaral for making our field trips possible; the diveschools Mar Aberto and Águas Claras for supplyingSCUBA gear; Captain J. C. Marenga and the crew ofthe sailboat ‘Aussteiger’ for transportation and lodgingfor O. J. Luiz-Junior; the crews of the fishing boats‘Transmar I’ and ‘Argus’ for making fish available forstudy; R. Stangorlini for the video records; B. Muniz,C. Buitron, C. Rocha, F . C. Moraes, M. M. Hudson

aqua vol. 7 no. 2 - 200375


g h

7(2)Imp/ok 16-06-2003 12:11 Pagina 75

aqua vol. 7 no. 2 - 2003 76


Fig. 10. Normal colour and morphological pattern of Holacanthus ciliaris from Rio Grande do Norte coast, north-easternBrazil. Photo by B. M. Feitoza.

Fig. 11. A presumed semi-albinotic specimen of Chromis multilineata of St. Paul’s Rocks. Photo by B. M. Feitoza.

7(2)Imp/ok 16-06-2003 12:11 Pagina 76

aqua vol. 7 no. 2 - 200377


Fig. 12. The honeycomb moray Muraena melanotis. Photo by B. M. Feitoza.

Fig. 13. The flagged moray Muraena pavonina. Photo by O. J. Luiz-Junior.

7(2)Imp/ok 16-06-2003 12:11 Pagina 77

aqua vol. 7 no. 2 - 2003 78


Fig. 14. The Rocas Gregory Stegastes rocasensis. a) Vagrant juvenile from St. Paul’ s; b) Juvenile from Fernando deNoronha Archipelago; and c) adult from Rocas Atoll. Photos a and c by B. M. Feitoza, and b by L. A. Rocha.

Fig. 15. Lysmata grabhami cleaning station located at about 60 m depth. Photo by B. M. Feitoza.

a

b c

7(2)Imp/ok 16-06-2003 12:11 Pagina 78

aqua vol. 7 no. 2 - 200379


Fig. 16. Following behaviour between Halichoeres radiatus (the nuclear species) and Caranx latus (the follower species).Photo by B. M. Feitoza.

Fig. 17. Aggression between two Halichoeres radiatus males. Photo by B. M. Feitoza.

7(2)Imp/ok 16-06-2003 12:11 Pagina 79

aqua vol. 7 no. 2 - 2003 80


Fig. 18a-c. ‘Friendly’ behaviour between morays: a) Muraena pavonina and M. pavonina; b) M. pavonina and Gymnothorax miliaris; and c) M. pavonina and M. melanotis. Photos a and c by O. Luiz-Junior; and b by B. M. Feitoza.

a

b

c

7(2)Imp/ok 16-06-2003 12:11 Pagina 80

aqua vol. 7 no. 2 - 200381


and M. Hof fmann for helping in field and laboratorywork; C. L. S. Sampaio, I. L. Rosa, R. S. Rosa, T. L.P. Dias and W . F. Smith-Vaniz for the loan of litera-ture; E. Fritzche for donating a photograph (Fig. 9-f);and R. Robertson and A. Edwards for critically read-ing the manuscript. Funding for L. A. Rocha was pro-vided by CAPES, Brazilian Ministry of Education.

Appendix – Voucher specimens from St. Paul’s Rocks arranged in alphabetic order

Apogon americanus – MBML 612, UFPB 5245;Aulostomus aff. Strigosus – UFPB 4482;

Bodianus insularis – UFPB 4481, 4586, 4587, 4588,4589; Caranx lugubris – UFPB 4485;

Chaetodon obliquus – UFPB 5249; Chromis aff. enchrysura – UFPB 5248; Diodon hystrix – UFPB 4483; Emblemariopsis sp. – UFPB 5237, 5239; Enchelycore anatina – UFPB 4480; Enneanectes smithi – MBML 613 and UFPB 5236,

5240, 5242;Entomacrodus vomerinus –UFPB 5282; Holacanthus ciliaris – UFPB 4585; Holocentrus ascensionis – UFPB 4484; Malacoctenus aff. triangulatus – MBML 614 and

UFPB 5238; Melichthys niger – UFPB 5246; Ophioblennius trinitatis – MBML 615 and UFPB 5243; Remora brachyptera – UFPB 5247; Remora osteochir – UFPB 5250; Scorpaenodes insularis – UFPB 5251; Sparisoma axillare – UFPB 4590; Sparisoma frondosum – UFPB 4591; Starksia sluiteri – MBML 616 and UFPB 5241; Stegastes rocasensis – UFPB 5234; Stegastes sanctipauli – UFPB 5235, 5244.

ReferencesAmaral, F. D., Hudson, M. M., Silveira, F. L. & A. E.

Migotto. (in press). Cnidarians of Saint Peter andSt. Paul Archipelago, Northeast Brazil. Proceedingsof the Biological Association of Washington.

Aronson, R. B. 1983. Foraging behavior of the westAtlantic trumpetfish, Aulostomus maculatus: use oflarge, herbivorous reef fishes as camouflage. Bulletin of Marine Science, 33 (1): 166-171.

Böhlke, E. B., McCosker, J. E. & J. E. Böhlke. 1989.Family Muraenidae. In. Fishes of the Western NorthAtlantic (Ed. E. B. Böhlke): 104-206. Sears Founda-tion for Marine Research, Yale University. 665pp.

Bowen, V. T . 1966. St. Paul’s on t he subway.Oceanus, 12 (4): 2-4.

Bowen, B. W., Bass, A. L., Rocha, L. A. Grant, W.S. & D. R. Robertson. 2001. Phylogeography of thetrumpetfish (Aulostomus): Ring species complex in aglobal scale. Evolution, 55 (5): 1029-1039.

Briggs, J. C. 1995. Global Biogeography, Develop-

ments in Paleontology and Stratigraphy , 14 . Else-vier, Amsterdam. 452pp.

Compagno, L. J. V. 1999. Checklist of living elasmo-branchs. In. Sharks, Skates, and Rays. The Biologyof Elasmobranch Fishes. (Ed. W. C. Hamlett): 471-498. The Johns Hopkins University Press, Baltimoreand London.

Crossman, D. J., Choat, J. H., Clements, K.D.,Hardy, J. & J. McConochie. 2001 Detritus as foodfor grazing fishes on coral reefs. Limnology andOceanography, 46: 1596-1605.

Debelius, H. 1997. Mediterranean and Atlantic FishGuide. IKAN-Unterwasserarchiv, Frankfurt, 305 pp.

DeLoach, N. 1999. Reef fish behavior: Florida,Caribbean, Bahamas. New W orld Publications,Jacksonville, Florida, 359 pp.

Diamant, A. & M. Shpigel. 1985. Interspecific feedingassociations of groupers (Teleostei: Serranidae) withoctopuses and moray eels in Gulf of Eilat (Aqaba).Environmental Biology of Fishes, 13 (2): 153-159.

Dias, T. L. P., Rosa, I. L. & B. M. Feitoza. 2001. Foodresource and habitat sharing by the three W esternAtlantic Surgeonfishes (T eleostei: Acanthuridae:Acanthurus) off Paraíba coast, North-eastern Brazil.aqua, Journal of Ichthyology and Aquatic Biology , 5 (1): 1-10.

Edwards, A. J. & R. Lubbock. 1983(a). The ecologyof Saint Paul’s Rocks (Equatorial Atlantic). Journal ofZoology, London, 200: 51-69.

Edwards, A. J. & R. Lubbock. 1983(b). Marine Zoo-geography of St. Paul’ s Rocks. Journal of Biogeog-raphy, 10: 65-72.

Feitoza, B. M., Dias, T . L. P ., Rocha, L. A. & J. L.Gasparini. 2002. First record of cleaning activity inthe slippery dick Halichoeres bivittatus (Perciformes:Labridae), off northeastern Brazil. Aqua, Journal ofIchthyology and Aquatic Biology, 5 (2): 73-76.

Floeter, S. R. & J. L. Gasparini. 2000, The south-western Atlantic reef fish fauna: composition andzoogeographic patterns. Journal of Fish Biology, 56:1099-1114.

Gasparini, J. L. & S. R. Floeter . 2001. The shorefishes of Trindade Island, western South Atlantic.Journal of Natural History, 35: 1639-1656.

Grutter, A. S. 1999. Cleaner fish really do clean.Nature, 398: 672-673.

Hawkins, J. P., Roberts, C. M. & V. Clark. 2000. Thethreatened status of restricted-range coral reef fishspecies. Animal Conservation, 3: 81-88.

Hilton-Taylor, C. (Compiler). 2000. 2000 IUCN RedList of Threatened Animals. IUCN, Gland, Switzer-land a Cambridge, UK. xviii + 61 pp.

Humann, P. & N. Deloach. 2002. Reef Fish Identifica-tion - Florida, Caribbean, Bahamas. 3rd Edition, NewWorld Publications, Jacksonville, Florida, 481pp.

Jones, G. P., Milicich, M. J., Emslie, M. J & C.Nunow. 1999. Self-recruitment in a coral reef fishpopulation. Nature, 402: 802-804.

7(2)Imp/ok 16-06-2003 12:11 Pagina 81

Joyeux, J. C., Floeter , S. R., Ferreira, C. E. L. & J.L. Gasparini. 2001. Biogeography of tropical reeffishes: the South Atlantic puzzle. Journal of Bio-geography, 28: 831-841.

Losey, Jr ., G. S. 1971. Communication betweenfishes in cleaning symbiosis. In: Aspects of the biol-ogy of symbiosis (Ed. T. C. Cheng.): 45-76. Univer-sity Park Press, Baltimore, Maryland.

Lubbock, R. & A. Edwards. 1981. The fishes of SaintPaul’s Rocks. Journal of Fish Biology , 18: 135-157.

Lubbock, R. 1980. The shore fishes of AscensionIsland. Journal of Fish Biology , 17: 283-303.

Melson, W. G., Hart, S. R. & G. Thompson. 1972. StPaul’s Rocks, equatorial Atlantic; petrogenesis,radiometric ages, and implications on sea-floorspreading. Memoirs of the Geological Society ofAmerica, 132: 241-272.

Muss, A., Robertson, D. R., Stepien, C. A., Wirtz, P. & B. W . Bowen. 2001. P hylogeography o fOphioblennius: the role of ocean currents and geog-raphy in reef fish evolution. Evolution, 55 (3): 561-572.

Moyle, P. B. & J. J. Cech. 1996. Fishes: an introduc-tion to ichthyology. Third Edition. Prentice Hall, Inc.,590 pp.

Nelson, J. S. 1994. Fishes of the world. 3rd Edition,John Wiley & Sons, Inc., New York. 600 pp.

Planes, S. & C. Fauvelot. 2002. Isolation by distanceand vicariance drive genetic structure of a coral reeffish in the Pacific Ocean. Evolution, 56: 378-399.

Randall, J. E. 1967. Food habits of reef fishes of theWest Indies . Studies in T ropical Oceanography, 5:665-847.

Randall, J. E. 1996. Caribbean Reef Fishes. ThirdEdition. T. F. H. Publications: Hong Kong, 368 pp.

Roberts, C. M. & Hawkins, J. P. 1999. Extinction riskin the sea. Trends in Ecol. Evol., 14: 241-246.

Robertson, D. R. & G. R. Allen. 1996. Zoogeographyof the shorefish fauna of Clipperton Atoll, CoralReefs, 15: 121-131.

Robertson, D. R. 2001. Population maintenanceamong tropical reef fishes: Inferences from small-island endemics. Proceeding of the National Acad-emy of Sciences 98 (10): 5667-5670.

Rocha, L. A. 2000. Interspecific aggression in Span-ish Hogfish es ( Bodianus rufus ) in North easternBrazil. Coral Reefs, 19: 184.

Rocha, L. A., Rosa I. L. & R. S. Rosa. 1998. PeixesRecifais da Costa da Paraíba, Brasil. RevistaBrasileira de Zoologia, 15 (2): 553-566.

Rocha, L. A., Bass, A. L., Robertson, D. R. & B. W.Bowen. 2002. Adult habitat preferences, larval dis-persal, and the comparative phylogeography ofthree Atlantic surgeonfishes (Teleostei: Acanthuri-dae). Molecular Ecolology, 11: 243-252.

Rosa, R. S. & R. L. Moura. 1997. Visual assessmentof reef fish community structure in the Atol dasRocas Biological Reserve, of f Northeastern Brazil.

Proceedings of the 8th International Coral ReefSymposium, 1: 983-986.

Sale, P. F. 1991. The Ecology of Fishes on CoralReefs. Academic Press: San Diego, 754 pp.

Sazima, I.; Moura, R. L. & J. L. Gasparini. 1998. Thewrasse Halichoeres cyanocephalus (Labridae) as aspecialized cleaner fish. Bulletin of Marine Science,63 (3): 605-610.

Silvano, R. A. M. 2001. Feeding habits and interspe-cific feeding associations of Caranx latus (Carangi-dae) in a subtropical reef. Environmental Biology ofFishes, 60: 465-470.

Snyderman, M. & C. W iseman. 1996. Guide toMarine Life: Caribbean, Bahamas, Florida. AquaQuest Publications, New York, 284pp.

Strand, S. 1988. Following behavior: interspecific for-aging associations among Gulf of California reeffishes. Copeia, 1988 (2): 351-357.

Swearer, S. E., Caselle, J. E., Lea, D.W . & R.R.Warner. 1999. Larval retention and recruitment in anisland population of coral-reef fish. Nature, 402: 799-802.

Thresher, R. E. 1991. Geographic variability in theecology of coral reef fishes: evidence, evolution andpossible implications. In The Ecology of Fishes onCoral Reefs (Sale, P. F . ed.): 401-436. AcademicPress, San Diego, 754 pp.

aqua vol. 7 no. 2 - 2003 82


7(2)Imp/ok 16-06-2003 12:11 Pagina 82

aqua vol. 7 no. 2 - 200383

Keywords Gloved snailfish, Palmoliparis beckeri , Liparidae,

spatial-bathymetric distribution, size-weight composi-tion, age, feeding, fecundity, northern Kuril Islands

AbstractThe spatial and bathymetric distribution, size, weight

composition, age, fecundity , and diet composition ofthe rare, little-studied gloved snailfish Palmoliparisbeckeri Balushkin, 1996 (Liparidae) are considered,based on data obtained during expeditions between1995 and 2001 in the Pacific, of f the northern KurilIslands, Russia.

ZusammenfassungDie räumliche-und bathymetrische V erteilung, die

Zusammensetzung von Größe und Gewicht, dasAlter, sowie Fruchtbarkeit und Nahrungszusam-mensetzung des seltenen und wenig-untersuchtenScheibenbauches Palmoliparis beckeri Balushkin,1996 (Liparidae) werden anhand von Daten, diewährend Expeditionen zwischen 1995 und 2001 imPazifik, vor den nördlichen Kurilen (Russland) gesam-melt wurden, ausgewertet.

RésuméOn examine ici la distribution spatiale et

bathymétrique, le rapport taille-poids, l'âge, la fécon-dité et le régime de la limace de mer , rare et peuétudiée, Palmoliparis beckeri Balushkin, 1996 (Lipari-dae), sur base de données fournies par des expédi-tions, échelonnées de 1995 à 2001, dans le Paci-fique, au large du nord des îles Kouriles, Russie.

SommarioIn questo lavoro vengono presentati nuovi dati sulla

distribuzione spaziale e batimetrica, il peso, l’età, lafecondità e la composizione della dieta della rara epoco studiata specie di limaccia di mare (Liparidae)Palmoliparis beckeri Balushkin, 1996. I dati sono stati

raccolti durante spedizioni condotte tra il 1995 e il2001 nel Pacifico settentrionale, al largo delle IsoleKurili, Russia.

IntroductionDuring the summer expedition of 1995 aboard the

Tora-Maru 58, a Japanese trawler , in the Pacificwaters off the northern Kuril Islands, two specimens ofan unknown snailfish (Liparidae) were collected andstudied by A. V. Balushkin of the Zoological Institute ofthe Russian Academy of Sciences. Detailed study ofthese specimens had shown that they belonged to anew genus and species of liparids. The new fish wasnamed Palmoliparis beckeri (Fig. 1) in honour of V. E.Becker, a Russian ichthyologist (Balushkin, 1996).The new species received a common Russian name“perchatochnik Bekkera ,” which means “Becker ’sgloved fish.” The species has since been collectedduring each expedition in that area. This liparid ischaracterized as a rare western Pacific species with awide boreal distribution in the Pacific waters off south-eastern Kamchatka and the northern Kuril Islands(Borets, 2000; Fedorov , 2000; Sheiko, Fedorov ,2000), although all known specimens of this snailfish(over 40) were caught only in Pacific waters of f thenorthern Kuril Islands (not of f south-eastern Kam-chatka) from the Krusenstern Strait to the Forth KurilStrait (Balushkin, 1996; Chernova, 1998; Orlov, 1998;Balushkin, Prirodina, 2000; Tokranov, 2000a; Tokra-nov, Orlov, 2001).

In this paper, a new English common name is pro-posed for Palmoliparis beckeri, its spatial-bathymetricdistribution and some biological characteristics aredescribed, and two colour photographs of the speciesare published for the first time.

Materials and methodsThe paper is based on data collected between April

and December, from 1995 to 2001 during bottom trawlsurveys and exploratory fishing aboard the Japanese


Some biological characteristics of the rare, little-studied gloved snailfishPalmoliparis beckeri Balushkin, 1996 (Liparidae, Teleostei),

in the Pacific off the Northern Kuril Islands

Alexei M. Tokranov1 and Alexei M. Orlov2

1) Kamchatka Branch of Pacific Institute of Geography Far-Eastern Department RAS, KBPIG, Partizanskaya, 6, 683000, Petropavlovsk-Kamchatsky, Russia. E-mail: [email protected]

2) Russian Federal Research Institute of Fisheries and Oceanography , VNIRO, V, Krasnoselskaya17, 107140, Moscow, Russia. E-mail: [email protected] (corresponding author).


7(2)Imp/ok 16-06-2003 12:11 Pagina 83

trawlers «Tora-Maru-58», «Tomi-Maru-53» and «Tomi-Maru-82» (about 8,000 bottom trawl hauls in depthsranging from 100 to 850 m) conducted in the Pacificwaters off the northern Kuril Islands and south-easternKamchatka (47°50´ - 52°00´ N) under the aegis of theRussian Federal, Kamchatka, and Sakhalin ResearchInstitutes of Fisheries and Oceanography (VNIRO,KamchatNIRO, and SakhNIRO, respectively).

Trawling was carried out around the clock using abottom trawl with an opening 5-6 m high and 25 mwide. The average towing speed was 3.6 knots. Thebottom temperature was measured on most of thesurveys. Since the duration of hauls during trawlingoperations varied between 0.5 and 10 hours, all thecatches were subsequently recalculated to CPUE

(catch per unit ef fort), expressed in individuals perhour of trawling. The distribution of species, whichdepended on trawling depth and bottom temperature,was analyzed accordingly to occurrence (%), calcu-lated using an average CPUE. 30 individuals weremeasured and weighed, and the sexes of 10 individu-als were also examined. Age determinations weremade for eight gloved snailfish using the “break-and-burn” technique. Stomach content analyses were car-ried out on board the research vessel on 10 speci-mens between August and December , 1997- 2000.Fecundity was determined using the mature ovariestaken from three females in April-May 2001. Individualfecundity was based on the number of eggs counted in20-25% of each ovary.

aqua vol. 7 no. 2 - 2003 84

Some biological characteristics of the rare, little-studied gloved snailfish Palmoliparis beckeri Balushkin, 1996

Fig. 1. Two specimens of gloved snailfish Palmoliparis beckeri caught off the northern Kuril Islands. Photo by A. M. Orlov.

7(2)Imp/ok 16-06-2003 12:11 Pagina 84

were only caught in the Pacific waters off the northernKuril Islands from Krusenstern Strait (47°50´ N) to theForth Kuril Strait (49°21´5 N). However , its maximumabundance (CPUE over 3 specimens per hour) wasmostly recorded on underwater plateau slopes in thesouthern part of the study area (Fig. 2).

According to data from Sheiko and Fedorov (2000),the gloved snailfish is a mesobenthic species inhabit-ing depths ranging from 200 to 800 m. Data obtainedbetween April and December from 1995 to 2002 in the

Results and discussionAccording to the frequency of occurrence and catch

rates, the abundance of gloved snailfish Palmoliparisbeckeri in the Pacific waters off the northern KurilIslands was very low (T able I). This liparid usuallyoccurred in catches along with more abundant andtypical ichthyofaunal representatives of the study area(Orlov, 1998), and were usually taken in the investi-gated bathymetric range (T able II). Data analysisshowed that during the study period gloved snailfish

aqua vol. 7 no. 2 - 200385

Alexei M. Tokranov and Alexei M. Orlov

Table I. Some quantitative data on the occurrence of gloved snailfish, Palmoliparis beckeri, in catches in the Pacificwaters off the northern Kuril Islands, 1995-2002.

Table II. Frequency of occurrence of species in trawls containing gloved snailfish Palmoliparis beckeri from the Pacificwaters off the northern Kuril Islands, 1995-2001.

Proportion Specimens Number per Total Weight Number in catch hour of fish per hour of hauls

(% weight) trawling weight, (kg) trawling, (kg) with species

Range 0-0.12 1-5 0-3 0-3 0-3 33Average 0.03 1.33 0.85 0.73 0.48

Species * Percent occurrence

Darkfin sculpin Malacocottus zonurus 100.0Whiteblotched skate Bathyraja maculata 91.3Pacific ocean perch Sebastes alutus 91.3Broadbanded thornyhead Sebastolobus macrochir 91.3Shortraker rockfish Sebastes borealis 87.0Forktail snailfish Careproctus furcellus 87.0Kamchatka flounder Atheresthes evermanni 87.0Dimdisc snailfish Elassodiscus tremebundus 82.6Snailfish Careproctus cf. cyclocephalus 78.3Aleutian skate Bathyraja aleutica 69.6Rougheye rockfish Sebastes aleutianus 65.2Scaly-belly sculpin Icelus perminovi 60.9Round snailfish Careproctus roseofuscus 60.9Giant grenadier Albatrossia pectoralis 56.5Sawback poacher Sarritor frenatus 56.5Matsubara skate Bathyraja matsubarai 52.2Gloved snailfish Palmoliparis beckeri <0.1

* - only includes species (except for gloved snailfish) with an occurrence of 50% or more.

Age in years6 7 8

Length, cm 25.0-26.5 28.0-30.5 31.0

Weight, g 220-310 290-480 540

Number of fish 4 3 1

Table III. Length and weight of gloved snailfish Palmoli-paris beckeri of different estimated age groups (August-October, 2000).

Table IV. Diet composition of gloved snailfish Palmoli-paris beckeri in the Pacific waters of f the northern KurilIslands, August-December 1997-2000.

Taxon Percent frequency of occurrence

Ostracoda 10.0Amphipoda 10.0Decapoda 90.0Pisces 10.0

Number of fish 10

7(2)Imp/ok 16-06-2003 12:11 Pagina 85

aqua vol. 7 no. 2 - 2003 86


Fig. 2. Map of distribution and relative abundance of gloved snailfish Palmoliparis beckeri off the northern Kuril Islands,April-December 1995-2001. Dashed lines are isobaths.

Pacific waters of the northern Kuril Islands confirmpreviously published information. The bottom temper-ature at capture sites ranged from 2.0 to 3.8°C, andmost gloved snailfish were caught at depths of 300-500 m (over 65%) and at bottom temperatures ofbetween 2.7 and 3.2°C (Fig. 3, 4).

According to the published data (Balushkin, 1996;Tokranov, Orlov , 2001), the maximum body length(total length) and weight of the gloved snailfish are 38cm and 1 kg respectively. Trawl catches in the Pacificwaters of f the northern Kuril Islands between 1995and 2002 contained individuals measuring 15 to 42cm in length (average 29.6 cm) with body weightsbetween 60 and 1080 g (average 492 g) (Fig. 4, 5).Specimens with a length of 24-36 cm (over 83%) anda weight of 100-500 g (some 67%) were most com-mon amongst the specimens collected.

The length-weight relation for gloved snailfish isdescribed by the following equation (R 2 = 0.846):

W = 0.0349 TL2.789, where W equals weight (g) and TL equals total

length (cm).

The theoretical regression graph calculated usingthe above equation coincided quite well with empiricdata (Fig. 6) and can therefore be used for the recal-culation of the body weight of gloved snailfish bylength. Due to insufficient data, no analysis was madeof weight differences between sexes.

Only a few studies of length-weight relationships forother species of snailfish are known. Those studiedwere Liparis pulchellus (snowy snailfish), Elassodiscustremebundus (dimdisc snailfish), Careproctus roseo-fuscus (round snailfish), and an undescribed snailfishCareproctus cf. cyclocephalus (Johnson, 1969; Orlov ,Pitruk, 1996; Nesin, Orlov , 2001). The linear coef fi-cients of the equation were similar for all the liparidspecies considered: 0.1254-0.1273 for L. pulchellus ,0.0787 for E. tremebundus, 0.0927 for C. roseofuscus,and 0.0977 for C. cf. cyclocephalus. The exponentialcoefficients of the relation considered for these liparidsare close to three (3.26-3.29 for L. pulchellus, 3.13 forE. tremebundus, 3.19 for C. roseofuscus, and 3.21 forC. cf. cyclocephalus). This indicates isometric growth inthese species (Zotina & Zotin, 1967).

7(2)Imp/ok 16-06-2003 12:11 Pagina 86

aqua vol. 7 no. 2 - 200387

Alexei M. Tokranov and Alexei M. Orlov

Examination of a limited number of otoliths suggeststhat the largest specimen examined was about 12 to13 years old. This is similar to longevity estimates forother liparids in the study area (T okranov, 2000b).

During the study period, trawl catches in the Pacificwaters of f the northern Kuril Islands most frequentlycontained individuals aged over 6 years (Table III).Limited age estimations exclude a more detailedanalysis at this stage.

Gloved snailfish, similar to some liparid species(Andriashev, 1950; Rass, 1950), have large, yellowisheggs. Spawning in this species appears to be a singu-lar event judging by the predominant presence of ripeoocytes 0 =5.6 mm (4.0-6.8) in April/May and a reserveof immature oocytes 0=0.9 mm (0.5-1.4) in the ovaries.The individual egg counts for the three females exam-ined (31-36 cm TL) were 328, 395 and 552.

According to our data, gloved snailfish is primarily abenthophagic species feeding on small benthic andnektonic organisms, mostly crustaceans (T okranov,Orlov, 2001). This liparid species is characterized bya relatively narrow food spectrum comprising repre-sentatives of only fishes and three large taxa of inver-tebrates (Table IV). However, its main prey items (fre-quency of occurrence 90%) are dif ferent smallshrimps (mainly of the Hippolytidae family).

Fig. 3. Occurrence of gloved snailfish Palmoliparis beck-eri in the Pacific waters of f the northern Kuril Islandsdepending on capture depth, April-December 1995-2001.

Fig. 4. Occurrence of gloved snailfish Palmoliparis beck-eri in the Pacific waters of f the northern Kuril Islands indifferent ranges of bottom temperature, April-December1995-2001.

Fig. 5. Size composition of gloved snailfish Palmoliparisbeckeri in the Pacific waters of f the northern KurilIslands, April-December 1995-2002.

Fig. 6. Weight composition of Palmoliparis beckeri in thePacific waters of f the northern Kuril Islands, April-December 1995-2002.

Fig. 7. Length-weight relationship for gloved snailfishPalmoliparis beckeri in the Pacific waters off the northernKuril Islands, April-December 1995-2001.

7(2)Imp/ok 16-06-2003 12:11 Pagina 87

Summary According to our data, the gloved snailfish, Palmoli-

paris beckeri, is a rare mesobenthic liparid species. Allof the specimens concerned in this study were foundonly in the Pacific waters off the northern Kuril Islandsfrom the Krusenstern Strait to the Forth Kuril Strait atdepths between 200 and 800 m. However , maximumcatches of the species (over 2 specimens per hour oftrawling) were recorded between April and Decemberfrom 1995 to 2002 on the slopes of an underwaterplateau in the southern part of the study area, atdepths of 300 and 500 m and at temperatures from2.7 to 3.2°C.

The maximum total length and body weight of glovedsnailfish recorded in this study were 42 cm and 1080g, respectively. Individuals with lengths of 24-36 cmweighing 100-500 g were the most numerous. In ouropinion, the estimated maximum age of the species is12-13 years, similar to that reached by the otherliparid species above.

This l iparid s pecies i s probably a s ingle-batchspawner. Three females 31-36 cm in length hadcounts of 328, 395 and 552 eggs.

The gloved snailfish is primarily benthophagic, with arather narrow food spectrum. Its diet consisted of var-ious small benthic and nektonic organisms (mostlyshrimps).

AcknowledgementsWe greatly appreciate the assistance of our col-

leagues from KamchatNIRO (Petropavlovsk-Kam-chatsky, R ussia), V NIRO ( Moscow, R ussia), a ndSakhNIRO (Y uzhno-Sakhalinsk, Russia), especiallyA. V. Vinnikov and A. I. Varkentin (KamchatNIRO) indata collecting during 1995-2001. Special thank goesto Allen Hia Andrews (Moss Landing Marine Labora-tories, 8272 Moss Landing Road, Moss Landing, Cal-ifornia 95039, USA) who significantly improved theearly draft of the manuscript.

ReferencesAndriashev, A. P. 1954. Fishes of northern seas of

the USSR. Academy of Sciences of USSR, Moscow-Leningrad, 566 pp. (In Russian).

Balushkin, A. V. 1996. New genus and species ofsnailfish Palmoliparis beckeri (Scorpaeniformes,Liparidae) from the Pacific waters of f northern KurilIslands with remarks about the phylogeny of the fam-ily. Voprosy Ikhtiologii, 36 (3): 293-299 (In Russian).

Balushkin, A. V. & V. P. Prirodina. 2000. Secondoccurrence of snailfish Palmoliparis beckeri (Lipari-dae) in the Pacific waters of f northern Kuril Islands.Voprosy Ikhtiologii, 40 (1): 97-99 (In Russian).

Borets, L. A. 2000. Annotated list of fishes of the FarEast seas. TINRO-Center, Vladivostok, 192 pp. (InRussian).

Chernova, N. V. 1998. Catalogue of standard speci-mens of liparids (Liparidae, Scorpaeniformes) in col-

lection of Zoological Institute of Russian Academy ofSciences. Voprosy Ikhtiologii, 38 (6): 760-775 (InRussian).

Fedorov, V. V. 2000. Species composition, distribu-tion and habitation depths of the northern KurilIslands fish and fish-like species. In: Commercialand biological studies of fishes in the Pacific watersof the Kuril Islands and adjacent areas of theOkhotsk and Bering Seas in 1992-1998. (Ed. B.N.Kotenev): 7-41. VNIRO, Moscow (In Russian).

Nesin, A. V. & A. M. Orlov . 2001. New data on thebiology of the snailfish Careproctus cf. cyclo-cephalus (Liparidae, Scorpaeniformes) from thePacific waters off the northern Kuril Islands. VoprosyIkhtiologii, 41 (6): 777-783 (In Russian).

Orlov, A. M. 1998. Demersal ichthyofauna of Pacificwaters off the northern Kuril Islands and southeast-ern Kamchatka. Biologiya Morya, 24 (3): 146-160 (In Russian).

Orlov, A. M. & D. L. Pitruk. 1996. Materials on thefeeding o f Polypera simushirae (Liparidae) a ndremarks on its distribution in the region of the north-ern Kuril Islands. Voprosy Ikhtiologii, 36 (6): 821-826(In Russian).

Rass, T. S. 1950. Wonderful case of biological rela-tion of fish and crab. Priroda, 7: 68-69 (In Russian).

Sheiko, B. A. & V. V. Fedorov. 2000. Chapter 1.Class Cephalaspidomorphi – Lampreys. ClassChondrichthyes – Cartilaginous Fishes. Class Holo-cephali – Chimaeras. Class Osteichthyes – BonyFishes. In: Catalogue of vertebrates of Kamchatkaand adjacent waters. (Eds. R.S. Moiseev & A.M.Tokranov.): 7-69. Kamchatskii Pechatnyi Dvor ,Petropavlovsk-Kamchatsky (In Russian).

Tokranov, A. M. 2000a. Species composition andspatial-bathymetric distribution of liparids (Liparidae)in the Pacific waters of f Southeastern Kamchatkaand northern Kuril Islands. Voprosy Ikhtiologii,40 (2): 176-186 (In Russian).

Tokranov, A. M. 2000b. Size-age composition ofliparids (Liparidae) in the Pacific waters of f South-eastern Kamchatka and northern Kuril Islands.Voprosy Ikhtiologii, 40 (3): 347-352 (In Russian).

Tokranov, A. M. & A. M. Orlov. 2001. Some biologi-cal features of rare liparid species (Liparidae) in thePacific waters of northern Kuril Islands and south-eastern Kamchatka. In: Conservation of Biodiversityof Kamchatka and Coastal W aters. Materials of theII Scientific Conference, Petropavlovsk-Kamchatsky,April 9-10, 2001. (Eds. Korostelev et al.): 187-190.Kamshat, Petropavlovsk-Kamchatsky (In Russian).

Zotina, R. S. & A. I. Zotin. 1967. Quantitative rela-tionships between weight, length, age, egg size, andfecundity in animals. Zhurnal Obshchei Biologii,28 (1): 82-92 (In Russian).

aqua vol. 7 no. 2 - 2003 88


7(2)Imp/ok 16-06-2003 12:11 Pagina 88

Instructions to Authorsaqua is an international journal which publishes original sci-

entific articles in the fields of systematics, taxonomy , ethology ,ecology, biogeography, and general biology of fishes, amphibians,aquatic invertebrates and plants. Papers dealing with freshwater ,brackish, and marine organisms will be considered for publication.Scientific articles of interest to a wide readership are especiallywelcome. Full length research papers and short notes will also beconsidered for publication.

1. Manuscript preparation : manuscripts must be submitted inEnglish. In exceptional cases aqua may provide translations ofmanuscripts written in French, German, Italian, or Spanish.

Manuscripts must be word-processed, preferably in W ord orWordPerfect format, double-spaced throughout. Pages should benumbered consecutively. Generic, specific, and subspecific namesmust be italicised. All papers must conform to the latest edition ofthe “International Code of Zoological Nomenclature".

2. Title: the title must be short and should precisely identify themain topic of the article. If the name of a genus or species isincluded, the name of the systematic group to which it belongsshould follow in parentheses. Author name(s) should be given infull immediately beneath the title.

3. Abstract: the abstract should be concise and intelligible, andshould draw attention to the significant contents of the paper andprincipal conclusions. It should not exceed 250 words nor containany uncommon abbreviations or literature citations. The inclusionof summaries in other languages is optional.

4. Keywords: up to eight keywords should be suggested by theauthor(s).

5. Subject matter: the text of the manuscript is usually arrangedin four main sections: introduction, materials and methods (includ-ing a key to abbreviations used in the text), results, and discus-sion. Other subdivisions may be chosen depending on the mater-ial presented. Acknowledgements should be placed between thetext and references.

Scientific names of genera, species, and subspecies should begiven in full on first mention and should be followed by the name(s)of author(s) and the year of publication.

When the name of a taxon proposed as new to science is given,it must be followed by the abbreviation n. gen., n. spec., or n. ssp.The description must contain the following sections: Material,Diagnosis, Description, and Affinities. Holotype and paratypesmust be clearly identified, the museum or institution in which thetype material has been deposited named, and the catalogue num-bers given. Author's collections are not acceptable as repositoriesfor holotypes.

Synonyms should be arranged in chronological order.Authors may choose either to use “telegraphic style” when

describing taxa, or use conventional descriptions which include theuse of indefinite and definite articles and participles. A mix of con-ventional and telegraphic styles will not be accepted.

Identification keys should be dichotomous.The metric system should be used for measures and weights. SI

units and symbols should be used. Temperatures should be givenin degrees Celsius. Only decimal notation is acceptable: fractionsshould not be used.

Footnotes should be avoided unless thought to be absolutelynecessary.

6. References to literature : In both the text and the referencelist, the name-year system must be used. The list of referencesshould be placed at the end of the paper , alphabetically arrangedaccording to author name. Only those publications cited in thepaper may be included. Titles of journals should be given in full.

Examples of correct reference formats:Blaber, S. J. M. 1980. Fish of the Trinity Inlet System of North

Queensland, with Notes on the Ecology of Fish Fauna of Tropic-al Indo-Pacific Estuaries. Australian Journal of Marine andFreshwater Research 31:137-46.

Day, J. H., Blaber , S. J. M., & J. H. W allace. 1981. EstuarineFishes. In: Estuarine Ecology with Particular Reference to South-ern Africa. (Ed. J.H. Day .) : 197-221. A. A. Balkema, Rotterdam.

Dimmich, W. W. 1988. Ultrastructure of North American cyprinidmaxillary barbels. Copeia 1988 (1): 72-79.

Trewavas, E. 1983. Tilapiine Fishes of the Genera Sarotherodon,Oreochromis and Danakilia . British Museum (Natural History),London, 583 pp.7. Author details: these should be placed at the beginning of the

manuscript, immediately after the title, and contain: full name(s) ofauthor(s), place(s) of work, and address(es) (including e-mail) forcorrespondence.

8. Submission of manuscripts and illustrative material: allmaterial except original photographs (see below) must be submit-ted to the Scientific Editor:

Dr. Walter lvantsoff, Scientific Editor, aqua - Journal of Ichthyology and Aquatic Biology, Department of Biological Sciences, Macquarie University, N.S.W. 2109, Australia e-mail: [email protected]; Phone: +61 2 9850 8167; Fax: +61 2 9869 8886

to whom all subsequent correspondence should be addressed. Unless otherwise agreed with the Scientific Editor , all texts,

tables, graphs, and drawings must be submitted in Microsoft-com-patible electronic form, preferably as email attachments (this willconsiderably speed up publication time) but alternatively on CD or3.5" diskette. All electronic material must be checked for virusesbefore transmission. Texts should be in Word or WordPerfect form-at; tables submitted as Excel (or Excel-compatible) spreadsheetfiles; graphs and drawings as graphics files (JPEG, TIF, etc).Authors are encouraged to submit quality colour photographswhich will be published free of charge. These must be clear andwithout too much contrast, and if possible should be submitted ashigh-resolution scans, again using graphics files, but hard-copyphotographs (prints or transparencies) will also be accepted ifscans are not feasible. In this case three copies will be required(for referees).

Original photographs (ideally transparencies; otherwise glossyprints, preferably in the size in which they are eventually to appear- the type area of aqua is 158 x 224 mm, one column is 76 mmwide) must be sent by registered mail to:

Aquapress, The Managing Editor Via G. Falcone 11, I-27010 Miradolo Terme (Pavia), Italy

Authors should retain a copy of all material for reference.A fax number must be provided for the senior author, to

which proofs of accepted papers will be sent for approval.9. Labelling of figures and tables: captions for photographs,

drawings, and graphs should be included at the end of themanuscript file, in the order in which they are to appear , andlabelled Fig. 1, Fig. 2a, etc. Hard copy illustrations and/or graph-ics files should be labelled/titled accordingly, to avoid any poss-ibility of confusion; authors should also indicate correct orientat-ion for their illustrations (including from which side transparenc-ies are to be viewed) if there is any room for doubt. Table head-ings should be labelled Table I, etc, and should be included atthe head of the relevant spreadsheet files, which should in turnbe titled Table I, etc.

The author(s) may indicate approximate positions for illustrativematerial in the text by means of a note, clearly recognisable assuch, ideally in parentheses and including the initials of the (senior)author, eg "(Note: Fig. 1 here. AZ)".

10. Evaluation of manuscripts: manuscripts submitted to aquawill be evaluated by the editors and referees on the basis of theircontents. Papers are accepted on the understanding that theyhave not and will not be published elsewhere.

11. Reprints: 50 reprints of each paper will be provided free ofcharge. Additional reprints may be ordered from Aquapress.

7(2)Imp/ok 16-06-2003 12:11 Pagina 89

aquaJournal of Ichthyology and Aquatic Biology

Vol. 7 (2), June 2003

Contents

Alexei M. Orlov: Diets, feeding habits, and trophic relations of six deep-benthic skates (Rajidae) in the western Bering Sea ..................................................................................................................45-60

Bertran M. Feitoza, Luiz A. Rocha, Osmar J. Luiz-Junior, Sergio R. Floeter and João L. Gasparini :

Reef fishes of St. Paul’s Rocks: new records and notes on biology and zoogeography ..................................61-82

Alexei M. Tokranov and Alexei M. Orlov: Some biological characteristics of the rare, little-studied gloved snailfish Palmoliparis beckeri Balushkin, 1996 (Liparidae, Teleostei), in the Pacific off the Northern Kuril Islands .......................................................................................................83-88

Papers appearing in this journal are indexed in: Zoological Record; Biolis - Biologische Literatur Information Senckenberg;

www.aquageo.com; www.Joachim-Frische.com

Cover photo: Alaska skate (Bathyraja parmifera) caught in the western Bering Sea. Photo by Alexei M. Orlov

Fig. 19. Lobster trap at St. Paul’s Rocks. Photo by O. J. Luiz-Junior . (See page 75)

7(2)Imp/ok 16-06-2003 12:12 Pagina 90

Documents

7(2)Imp/ok 16-06-2003 12:10 Pagina 1 aqua2).pdf · 7(2)Imp/ok 16-06-2003 12:10 Pagina 47 aqua vol. 7 no. 2 - 2003 48 Diets, feeding habits, and trophic relations of six deep-benthic