batoid fishes - skates, rays, and guitarfishes mhabitat and biology: a demersal species, from...

BATOID FISHES - SKATES, RAYS, AND GUITARFISHES

Mostly from the work of Compagno and collaborators (1989 and 1991) and our collections, we count 28species in 7 families and 3 orders of batoid fishes from Namibia. A checklist of batoid fishes is included

in the Appendix in order to serve as an aid to a more accurate assessment of the batoid resources of Namibia.Although not actively fished, they are consistently caught in the bottom trawls of the hake fishery andconstitute a substantial biomass in the demersal community.

TECHNICAL TERMS AND MEASUREMENTS

Guide to Orders and Families 89

length of disc

1st dorsalfin

dorsal view

spiracle

orbit

alar spines (in males)

thorns of median row

pelvic fin, anterior lobe

pelvic fin, posterior lobe

clasper of males

2nd

dorsalfin

caudalfin

lateral tail fold

length ofsnout,

preorbitalaxil of

pectoralfin

length ofsnout,

preorbital

ventral view

width of disc

nasal apertures

mouth

gill slits

anus

length of tail

click for previous page

Order TORPEDINIFORMES - Electric RaysA large electric organ on each side of head but no sting on tail; body not elongate and shark-like but tail isstout and caudal fin large. Two families found in Namibia.

TORPEDINIDAE Page 92

Electric raysOne species found in Namibia, included inthe “Guide to Species.” Pelagic fromdepths between 10 to 560 m. Size to1.8 m total length.

NARKIDAE Page 92

NumbfishA single species found in Namibia, in-cluded in the “Guide to Species.”Demersal in shallow depths to 183 m.Size to 38 cm total length.

Order RAJIFORMES - Guitarfishes and SkatesNo electric organs on head or sting on tail; body elongate and shark-like (guitarfish family) or, with enlargedpectoral fins forming a disc and the rear margin of the pelvic fin deeply notched forming 2 distinct lobes andwith a slender tail (skate family). Two families found in Namibia.

RHINOBATIDAE Page 92

GuitarfishesTwo species in 1 genus reported fromNamibia, both in the “Guide to Species.”Coastal in shallow water to depths ofaround 70 m. Size to 1.4 m total length.

90 Skates, Rays, and Guitarfishes

STOUT TAIL

NO STING ON TAIL

BODY NOT ELONGATE

ELECTRIC ORGAN ONEACH SIDE OF HEAD

2 dorsal fins

1 dorsal fin

NO ELECTRICORGANS

body elongate and shark-like NO STINGON TAIL

RAJIDAE Page 93

SkatesPerhaps 17 species in 3 genera fromNamibia, all in the “Guide to Species” ex-cept 2 whose presence in Namibia isdoubtful. Demersal from shallow depthsto nearly 2 000 m. Size to 1.3 m disc width.

Order MYLIOBATIFORMES - StingraysNo electric organs on head but sting on tail usually present; pectoral fins enlarged to form a disc; tail slen-der or whip-like; pelvic fins not deeply indented, each with only a single lobe. Three families reported fromNamibia.

DASYATIDAE Page 98

StingraysA single genus and possibly 3 species inNamibia; the record of 1 species,Dasyatis pastinaca, is questionable and itis not included in the “Guide to Species.”Neritic and pelagic. Size to 80 cm discwidth.

GYMNURIDAE Page 99

ButterflyraysA single genus and possibly 2 species re-ported from Namibia; Gymnura altavelaisa questionable record from Namibia andnot included in the “Guide to Species.”Demersal in shallow depths to 75 m. Sizeto 2.5 m disc width.

MYLIOBATIDAE Page 99

Eagle raysTwo species in 2 genera reported fromNamibia, both in the “Guide to Species.”Coastal to depths of around 100 m. Sizeto 1.8 m disc width.

Guide to Orders and Families 91

BODY NOT ELONGATE

NO ELECTRIC ORGANS

disc width not much differentfrom disc length

head not distinct from disc,eyes well behind forward

margin of disc

STING USUALLYPRESENT ON TAIL

head not distinct from disc,eyes well behind forward

margin of disc

disc about twiceas wide as long

body not elongate

head elevated and distinct fromdisc, eyes in front of or near

front of forward margin of disc

Torpedo nobilianaBonaparte, 1835 (plate III, 20) TORPEDINIDAE

FAO names : En - Electric ray; Fr - Torpillenoire; Sp - Tremolina negra.Local names : Atlantic electric ray; Atlantiesedrilvis (Ak); Schwarzer Zitterrochen (Gr).Size: Maximum recorded, 1.8 m total length.Fisheries : Caught occasionally with bottomtrawls and line gear.Habitat and biology : Young are known tobe demersal on soft bottoms, from 10 to150 m, sometimes as deep as 560 m. Adultsare pelagic or semi-pelagic, migrating longdistances. Feeds mainly on bony fishes.

Narke capensis(Gmelin, 1789) NARKIDAE

FAO names : En - Cape numbfish; Fr - Poissonengourdeur du Cap; Sp - Pez temblador delCabo.Local names : Onefin electric ray; Eenvin-drilvis(Ak).Size: To about 38 cm total length.Fisheries : None at present.Habitat and biology : Found in shallow watersdown to a depth of 180 m. A small ray that candeliver a very powerful shock.Remarks : Only a single recorded specimencollected in Namibia thus far, 1 caught by ashore angler in Meob Bay. Unofficial report ofthis species from Walvis Bay.

Rhinobatos annulatusSmith, 1841 RHINOBATIDAE

FAO names : En - Lesser guitarfish; Fr - Pois-son-guitare du Cap; Sp - Guitarra del Cabo.Local names : Kleiner sandkruiper (Ak).Size: To about 1.4 m total length.Fisheries : Occasionally caught in bottom trawlsand by hook-and-line from the beach.Habitat and biology : Mainly in inshore watersand down to a depth of 70 m; also entering estuar-ies. Feeds mainly on small invertebrates includingcrustaceans, bivalves, and polychaete worms,and small bony fishes.Remarks : Confirmed reports for localities inNamibia are needed.


2 dorsal fins

1 dorsal fin

numerous small spots on backsnout sharply

pointed

Rhinobatos blochiiMüller and Henle, 1841 RHINOBATIDAE

FAO names : En - Bluntnose guitarfish;Fr - Poisson guitare épointé; Sp - Guitarraembotada.Local names : Stompneus-sandkruiper (Ak).Size: To about 95 cm.Fisheries : Occasionally caught in bottomtrawls.Habitat and biology : Demersal, near shore inshallow sandy areas. Rare. In Namibia, southof Walvis Bay.

Bathyraja smithii (Müller and Henle, 1841) (plate IX, 72) RAJIDAE

FAO names : En - African softnose skate; Fr - Raiede Smith; Sp - Raya de Smith.Local names :Size: Up to 85 cm disc width.Fisheries : Occasionally caught in deep-waterbottom trawls.Habitat and biology : A demersal species of theupper continental slope, from depths of 440 to1 020 m. Feeds on bony fishes such as hake,barracudinas, and dragonets, and invertebratessuch as squid, octopus, crabs, and shrimps.

Cruriraja parcomaculataVon Bonde and Swart, 1923 RAJIDAE

FAO names : En - Roughnose legskate; Fr - Raiaá nez hérissé; Sp - Raya nariz áspera.Local names : Rog (Ak).Size: To about 35 cm disc width.Fisheries : Regularly caught by hake trawlers.Habitat and biology : Known to occur on thebottom, at depths from 200 to 620 m. Feedsmainly on invertebrates such as crabs, shrimps,hermit crabs, squid, and polychaete worms.

Guide to Species 93

colour whitish grey, sometimes with white spots; white ventrally,with black blotches between gill slits and around vent

angular

snout soft

a single row oflarge thorns,14-19 from

above vent to1st dorsal-fin

origin

colour uniform brown (sometimes withirregular patches); underside white

thorns on tip ofsnout

margin of pelvicfin confluentwith posteriormargin of disc

long leg-likeanterior lobe

snoutblunt

Raja albaLacepède, 1803 RAJIDAE

FAO names : En - White skate; Fr - Raieblanche; Sp - Raya bramante.Local names : Spearnose skate; Spiesneus(Ak); Bandrochen, Spitzrochen (Gr).Size: To at least 180 cm disc width.Fisheries : Caught in bottom trawls, pelagictrawls, and by shore anglers.Habitat and biology : A demersal species, fromintertidal coastal waters to the upper continentalslope, from shallow depths to about 500 m. Abottom predator, feeding on a wide range ofspecies, including bony fishes such as hake,kingklip, anchovy, gobies, sardines, and horsemackerel, and other sharks, rays, and variouscephalopods and crustaceans.

Raja caudaspinosavon Bonde and Swart, 1923 RAJIDAE

FAO names : En - Munchkin skate; Fr - Raie áqueue épineuse; Sp - Raya cola espinosa.Local names : Rog (Ak).Size: To at least 32 cm disc width.Fisheries : Only occasionally caught in bottomtrawls.Habitat and biology : Recorded from depths of310 to about 700 m, mostly south of Lüderitz.Feeds on mysids, lightfish, and polychaetes.

Raja clavataLinnaeus, 1758 (plate III, 21) RAJIDAE

FAO names : En - Thornback ray; Fr - Raiebouclée; Sp - Raya de clavos.Local names : Thornback skate; Doringrug-rog(Ak); Keulenrochen, Nagelrochen, Steinrochen(Gr).Size: To 60 cm disc width.Fisheries : Occasionally caught in bottomtrawls.Habitat and biology : A demersal speciesfound from shallow inshore waters to the uppercontinental slope to a depth of at least 700 m.Feeds on crustaceans, fish, and cephalopods.Remarks : Reports of R. clavata andR. straelenimay represent a single species.


dorsal surface of disc sometimes with dark spots; paleventrally with margins of disc greyish.

eyespot, if present,strongly ovate

strong thorns present

snout bluntlypointed

tail with 5-7 rowsof thorns

tail long, distance from vent to 1st

dorsal-fin origin longer thandistance from vent to tip of snout

snout short,pointed

adults and large juvenileswith small white spots

narrow-tipped snoutangular

3 rows of largethorns on tail

upper side of disc covered withsmall sharp thorns, no large

thorns on nape or back

Raja confundensHulley, 1970 (plate X, 73) RAJIDAE

FAO names : En - Bigthorn skate; Fr - Raiegrand épine; Sp - Raya de grande espina.Local names :Size: To about 45 cm disc width.Fisheries : Commonly caught in bottom trawls.A bycatch of the deep-water fishery.Habitat and biology : Found in the deeper partof the shelf and on the upper slope, from depthsof about 170 m to 900 m. Feeds mainly on inver-tebrates such as crustaceans, squid, andpolychaete worms.Remarks : Considered a junior synonym of Rajabarnardi Norman, 1935 by some authors.

Raja doutreiCadenat, 1960 (plate III, 22) RAJIDAE

FAO names : En - Javelin skate; Fr - Raieviolette; Sp - Raya violeta.Local names :Size: To over 95 cm disc width.Fisheries : Occasionally caught in bottomtrawls. A bycatch of the deep-water fishery.Habitat and biology : Found on the slope be-tween depths of 450 and 600 m.

Raja leopardusvon Bonde and Swart, 1923 RAJIDAE

FAO names : En - Leopard skate; Fr - Raieléopard; Sp - Raya leopardo.Local names :Size: To 65 cm disc width.Fisheries : Occasionally caught in bottomtrawls.Habitat and biology : A rather common spe-cies, found on the upper continental slope, fromdepths of about 300 to 900 m. Feeds on bottomcrustaceans, bony fishes, cuttlefish, andpolychaete worms.

Guide to Species 95

pigmented pores on underside of disc

long stiffpointedsnout

tips rounded

median row ofthorns

snout moderatelylong

small thorns onupper surface

often with blackishspots

adults with 4-5 rows of thornsincluding a median row

short, obtusesnout

large white thorns on uppersurface and snout

5 rows of thorns on tail,including median row

Raja miraletusLinnaeus, 1758 RAJIDAE

FAO names : En - Brown ray; Fr - Raie miroir;Sp - Raya de espejos.Local names : Twineye skate; Tweeoog-rog(Ak); Vieräugiger Spiegelrochen (Gr).Size: To 35 cm disc width.Fisheries : Occasionally caught in bottom trawlsand by anglers.Habitat and biology : Found from shallow in-shore waters to a depth of 500 m, most commonbetween 50 and 150 m. Feeds on crustaceans,bony fishes, and cephalopods.

Raja pullopunctataSmith, 1964 RAJIDAE

FAO names : En - Slime skate; Fr - Raiebaveuse; Sp - Raya limosa.Local names : Rog (Ak).Size: To 70 cm disc width.Fisheries : Caught in bottom trawls. Commonbycatch in hake fisheries.Habitat and biology : Found on soft substrateof the outer shelf and upper slope, from depthsof about 50 to 450 m. A common species, feed-ing on various bony fishes, crustaceans, andmolluscs.

Raja ravidulaHulley, 1970 RAJIDAE

FAO names : En - Smoothback skate; Fr - Raielisse; Sp - Raya suave.Local names : Rog (Ak).Size: To 36 cm disc width.Fisheries : Incidentally caught in bottom trawls.A bycatch of the deep-water fishery.Habitat and biology : Upper slope from depthsof about 500 to 1 000 m. Common in centralNamibia.


long snout

no mental pores onunderside of disc

juvenile

large brown blotch

median row of thorns

long snout

2 prominent rows of thorns,no median row

snout short, bluntlypointed

eyespots with3 rings of

colour, centrebright blue in

life

often with small dark spots

Raja spinacidermisBarnard, 1923 RAJIDAE

FAO names : En - Roughskin skate; Fr - Raiepeau hérissée; Sp - Raya piel áspera.Local names : Ruwevel-rog (Ak).Size: To 45 cm disc width.Fisheries : Caught ocasionally in bottom trawls.Habitat and biology : Found on the slope, fromdepths of about 800 to 1 400 m.

Raja springeriWallace, 1967 RAJIDAE

FAO names : En - Roughbelly skate; Fr - Raiede Springer; Sp - Raya de Springer.Local names :Size: To 130 cm disc width.Fisheries : Rarely caught in bottom trawls.Habitat and biology : Found on the outer shelfand upper slope, on the bottom, at depths be-tween about 80 and 750 m. Feeds on bonyfishes such as round herring and macrourids,and on crabs and squids.

Raja straeleniPoll, 1951 RAJIDAE

FAO names : En - Biscuit skate; Fr - Raietachetée; Sp - Raya manchada.Local names : False thornback skate; Valsdoringrug-rog (Ak).Size: To 68 cm disc width.Fisheries : Occasionally caught in bottomtrawls; pectoral fins used for human consump-tion.Habitat and biology : A very common skate,found from inshore waters to the upper slope toa depth of about 350 m. Feeds mainly oninvetebrates such as shrimps, hermit crabs,mantis shrimp, and cephalopods, and bonyfishes such as hake, sardine, and lanternfishes.Remarks : See remarks under R. clavata.

Guide to Species 97

pigmented pores onunderside of disc

long stiff pointedsnout

angular tips

median row ofthorns

strong thorns

oblong eyespotoften present

snout angular

usually with black,irregular spots

lateral caudalthorns

a median row of thorns

large juveniles andadults without

thorns on disc ortail

snout bluntlypointed and

flexible

Raja wallaceiHulley, 1970 RAJIDAE

FAO names : En - Yellow spotted skate; Fr - Raiede Wallace; Sp - Raya de Wallace.Local names : Blancmange skate; Witpoeding-rog(Ak).Size: To 53 cm disc width.Fisheries : Rarely caught in bottom trawls.Habitat and biology : Found at depths of 90 to440 m. Preys on crustaceans and small fish,and is also scavenger.

Dasyatis chrysonota(Smith,1828) DASYATIDAE

FAO names : En - South African blue stingray;Local names : Blue stingray; Blou pylstert (Ak).Size: To 75 cm disc width.Fisheries : Occasionally caught by shore an-glers.Habitat and biology : A common inshore sting-ray, often in shallow bays and sheltered sandybeaches, especially in summertime, moving todeeper waters to a depth of about 100 m duringwinter. Feeds on crustaceans such as crabs,shrimps, and mantis shrimps, and on smallbony fishes.Remarks : Previously confused with D.pastinacaand D. marmoratawhich do not oc-cur in the area.

Dasyatis violacea(Bonaparte, 1832) DASYATIDAE

Synonyms : Pteroplatytrygon violacea(Compagno et al., 1989).FAO names : En - Blue stingray;Fr - Pastenague violette; Sp - Raya látigovioleta.Local names : Pelagic stingray; Pelagiesepylstert (Ak); Violetter Stechrochen (Gr).Size: To 80 cm disc width.Fisheries : Caught by pelagic offshorelonglines.Habitat and biology : This is the only pelagicand oceanic stingray.


anterior contour of discbroadly arched

colour violet purple above and below

short broadblunt snout

bright yellow or whiteirregular spots

2-4 rows of thorns

conspicuous bright blueblotches and branching

lines on a goldenbackground

Gymnura natalensis(Gilchrist and Thompson, 1911) GYMNURIDAE

FAO names : En - Backwater butterflyray;Fr - Raia-papillon de Natal; Sp - Rayamariposa de Natal.Local names : Rem-vinderrog (Ak).Size: Up to 250 cm disc width.Fisheries : Rarely caught by offshore trawlersand rarely by shore anglers.Habitat and biology : Close inshore offsandy beaches, on offshore banks to a depthof 75 m. Feeds mainly on bony fishes such asflatfishes, sardines, and gurnards, and oncrabs and polychaete worms.

Myliobatis aquila(Linnaeus, 1758) MYLIOBATIDAE

FAO names : En - Common eagle ray; Fr - Aiglecommun; Sp - Aguila marina.Local names : Eagle ray; Arendrog (Ak);Adlerrochen, Gewöhnlicher Adlerrochen (Gr).Size: To about 150 cm disc width.Fisheries : Rarely caught with bottom trawls,purse seines, longlines, and shore anglers.Habitat and biology : Found in coastal waters toa depth of about 100 m, mainly on soft bottoms;enters lagoons and estuaries. Often found ingroups. Feeds on invertebrates such as bivalvesand crabs, and on small fish.

Pteromylaeus bovinus(Saint-Hilaire, 1817) MYLIOBATIDAE

FAO names : En - Bull ray; Fr - Aigle vachette;Sp - Chucho vaca.Local names : Bulrog (Ak); AfrikanischerAdlerrochen (Gr).Size: To about 180 cm disc width.Fisheries : Rarely caught with bottom trawls.Habitat and biology : A coastal species, todepths of about 100 m; often found close tosoft bottoms. Feeds mainly on invertebratessuch as crabs, bivalves, and squid, and smallfish. Possibly present only along the northerncoast of Namibia (absent in the cold upwellingwaters).

Guide to Species 99

mouth

colour grey-green or brownish withdarker mottling, but changing to

match substrate

black and white bands on tail

ventral view of head

head marked off from rest of disc

sting

head marked off from rest of disc

pointed

blue-grey crossbars

sting

CHIMAERAS

There are 6 species of chimaeras in Namibia. They are usually caught incidentally in bottom trawls and arenot normally found in great numbers. However, in some places they are considered a delicacy and

represent a potential resource for further exploitation.

TECHNICAL TERMS AND MEASUREMENTS

Order CHIMAERIFORMES - ChimaerasA cartilagenous skeleton; a simple external gill opening on each side of head; naked skin; 2 dorsal fins, thefirst with a long spine; elongate tapering tail. Three families found in Namibia.

CALLORHINCHIDAE Page 101

ElephantfishA single species reported from Namibia,included in the “Guide to Species.”Demersal, from shallow depths to 370 m.Size to 1.2 m total length.

CHIMAERIDAE Page 101

Shortnose chimaerasTwo species in Namibia, both included inthe “Guide to Species” and both possiblyundescribed. Demersal in depths be-tween 400 and 1 200 m. Size to 1.0 m totallength.

RHINOCHIMAERIDAE Page 102

Longnose chimaerasThree species in 3 genera from Namibia,all included in the “Guide to Species.”Demersal in depths between 200 and1 100 m. Size to 1.3 m total length.

100 Chimaeras

soft gillcover

mouth

frontal tentaculum

nostril

pelvicfin

caudalfilament

caudalfin

anal finclasper

prepelvictentaculum

pectoralfin

gill opening

length to 2nd dorsal base

head

snout

lateral-line

fin spine

1st dorsal fin

2nd dorsal fin

total length

diagram of a male chimaera(Chimaera)

2nd dorsal fin long and low

caudal fin on horizontalaxis or slightly arched

snout long, pointed

snout short, blunt

2nd dorsal finlong and low

caudal fin ona horizontal

axis

caudal fin archedupward

2nd dorsal fin shortand high

snout hoe-shaped

Callorhinchus capensisDuméril, 1865 (plate III, 23) CALLORHINCHIDAE

FAO names : En - Cape elephantfish;Fr - Masca du Cap; Sp - Pejegallo delCabo.Local names : Elephantfish; Josef (Ak);Totenkopfchimäre (Gr).Size: To 1.2 m total length.Fisheries : Caught with bottom trawlsand commonly by shore anglers.Habitat and biology : A demersal speciesof the continental shelf, from shallowcoastal waters to a depth of 370 m. Feedson a wide variety of invertebrates such seaurchins, bivalves, shrimp, crabs, gastro-pods, and small fish. Produces egg-casesthat are spindle shaped, with broad hori-zontal flanges.

Chimaerasp. CHIMAERIDAE

FAO names : En - Cape chimaera;Fr - Chimère du Cap; Sp - Quimera delCabo.Local names : Kaapse chimaera (Ak).Size: To 1 m total length.Fisheries : Occasionally caught in bottomtrawls. A bycatch of the deep-water fish-ery.Habitat and biology : A demersalspecies found on the continental slopefrom depths of 680 to around 1 000 m.

Hydrolagussp. CHIMAERIDAE

FAO names : En - Brown chimaera;Fr - Chimère brunette; Sp - Quimeracastaña.Local names :Size: To about 70 cm total length.Fisheries : Occasionally caught in bottomtrawls. A bycatch of the deep-water fish-ery.Habitat and biology : Demersal indepths between 400 and 1 200 m.Remarks : This species is probably H. africanus(Gilchrist, 1992).

Guide to Species 101

colour silvery with dusky marking

recurved projection

caudal fin withraised axis

blunt and short

small anal fin

blunt and short

no anal fin

Harriotta raleighanaGoode and Bean, 1895 RHINOCHIMAERIDAE

FAO names : En - Narrownosechimaera; Fr - Chimère de Raleigh;Sp - Quimera de Raleigh.Local names :Size: To 1 m total length.Fisheries : Rarely caught in bottomtrawls.Habitat and biology : A bottom livingspecies of the upper slope, found fromdepths of about 850 to 1 100 m.

Neoharriotta pinnata(Schnakenbeck, 1931) (plate III, 24)

FAO names : En - Sicklefin chimaera;Fr - Chimère faucillée; Sp - Narigónaletas de haz.Local names :Size: To 1.3 m.Fisheries : Caught occasionally in bottomtrawls.Habitat and biology : A demersal spe-cies of the upper slope, from depths of200 to 470 m. Feeds on swimming crabs.Egg cases spindle-shaped, with broadhorizontal flanges.

Rhinochimaera atlanticaHolt and Byrne, 1909 RHINOCHIMAERIDAE

FAO names : En - Spearnose chimaera;Fr - Chimère nez lance; Sp - Narigón si-erra.Local names :Size: To 1.3 m.Fisheries : Rarely caught in bottom trawls.A bycatch of the deep-water fishery.Habitat and biology : Found on the conti-nental slope, from depths of about 550 to1 100 m.

102 Chimaeras



colour whitish to light brownno anal fin

spine smooth

upper margin of caudal fin with series ofenlarged denticles in males

colour dark brown or blackish

spine serrated

no anal fin

colour chocolate brown


large anal fin

spine smooth anteriorly,serrated posteriorly

click for next page

batoid fishes - skates, rays, and guitarfishes mhabitat and biology: a demersal species, from...

Documents