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ACANT 3

1983 FAO IDENTIFICATION SHEETS

FAMILY: FISHING AREA 51 (W. Indian Ocean)

Naso unicornis (Forsskål, 1775)

OTHER SCIENTIFIC NAMES STILL IN USE: None

VERNACULAR NAMES:

FAO : En - Fr - Nason à épérons bleus Sp - Barbero de aguijón azul

NATIONAL:

DISTINCTIVE CHARACTERS:

Body deep and compressed, the depth 1.8 to 2.6 times in standard length. Adults with a median horn-like projection anterior to eyes which does not extend in front of mouth; dorsal profile of snout forming an angle of about 45°; mouth small; about 40 to 60 pointed compressed teeth in jaws, the tips serrate (serrae absent on teeth of large adults). A continuous unnotched dorsal fin with 6 spines and 27 to 30 soft rays; anal fin with 2 spines and 27 to 30 soft rays; pelvic fins with 1 spine and 3 rays; caudal fin emarginate in young, developing long and slender lobes in adults. Caudal peduncle slender, subcylindrical, with 2 fixed bony plates on mid-side which have forward-directed, knife-like keels in adults.

Colour: light olive to yellowish grey, the caudal spines and a small area around each bright blue; edges of lips bluish; dorsal and anal fins with a blue lower tooth margin and alternating narrow bands of light blue and brownish yellow; caudal fin yellowish grey, a little more yellow centro-posteriorly. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

Naso lituratus: no rostral projection on head at any age; yellow and black bands on head; caudal spines orange; caudal fin with black upper and lower edges and a submarginal black band posteriorly.

Naso brachycentron: a concavity in profile of back beneath anterior spinous portion of dorsal fin followed by a bump (giving a humpback appearance); only the males develop a median rostral horn anterior to eyes.

SIZE:

Maximum: 70 cm; common to 50 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: Indo-Pacific; in the Western Indian Ocean, from the Red Sea to the Natal coast of South Africa, the prejuveniles drifting at least as far south as 34° latitude. male female An inshore species associated with coral reefs or rocky substrata. Will enter surprisingly shallow water for such a large in quest of its algal food. Prefers leafy algae such as Sargassum.

PRESENT FISHING GROUNDS:

No specific fishing area.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this

species.

Caught in nets, traps, and by spearing.

Marketed fresh. The flesh is of good quality.

ACANT Zebra 1

1983

FAO SPECIES IDENTIFICATION SHEETS

FAMILY: ACANTHURIDAE FISHING AREA 51 (W. Indian Ocean)

Zebrasoma veliferum (Bloch, 1797)

OTHER SCIENTIFIC NAMES STILL IN USE: desjardinii (Bennett, 1835) -see explanation below

VERNACULAR NAMES: FAO : En - Fr - Chirurgien à voile Sp - Navajón velero

NATIONAL:

DISTINCTIVE CHARACTERS:

A deep-bodied, compressed fish, the depth 1.8 to 2.0 times in standard length. Snout protruding; mouth small; teeth spatulate, close-set, with denticulate edges, at most 16 in upper jaw and 18 in lower. A continuous unnotched dorsal fin of 4 spines and 27 to 31 rays, the fin extremely elevated (longest ray of adults 2.1 to 2.5 times in standard length); anal fin with 3 spines and 22 to 24 rays this fin also elevated); pectoral fin rays 15 to 17 (usually 16); caudal fin truncate to slightly rounded. A lancet-like spine on side of caudal peduncle fitting into a groove; no patch of stiff bristles on side of body anterior to caudal spine. Colour: grey-brown to dark brown (often appearing nearly black underwater) with vertical orange-yellow lines on upper two-thirds of body, small orange-yellow spots on lower third of body and pale yellowish or greenish dots on head; a dark bar through eye and another from origin of dorsal fin to base of pectoral fin; dark and light bars sometimes visible on body; a broad purplish area may be present around caudal spine; dorsal and anal fins brown with numerous broadly curved yellow bands; caudal fin brown with small yellowish to greenish spots. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

Zebrasoma scopas: dorsal fin with 5 spines and 23 to 25 soft rays T-4 spines and 27 to 31 rays in Z. veliferum); anal fin with 3 spines and 19 to 21 soft rays T-3 spines and 22 to 24 rays in Z. veliferum); an oval-shaped patch of bristles post- eriorly on sides of body; colour dark brown with very fine oval patches longitudinal wavy pale blue lines breaking into dots on nape, of bristles chest and head; sheath of caudal spine white.

Zebrasoma xanthurum (Red Sea to the Persian Gulf): dorsal fin with 5 spines and 24 or 25 soft rays; anal fin with 3 spines and 19 or 20 soft rays; an oval patch of bristles posteriorly on sides of body; deep blue with small dark spots anteriorly on body and on head; caudal fin and outer part of pectorals bright yellow. (known only from Mauritius, Réunion Island and Durban, South Africa): dorsal fin with 4 spines and 25 to 28 soft rays; anal fin with 3 spines and 24 or 25 soft rays; dark brown with numerous pale dots or short dashes; caudal fin and posterior caudal peduncle yellow. 5 spines ovalpatches of bristles

Zebrasoma xanthurum SIZE : Zebrasoma gemmatum

Maximum: 40 cm; common to 32 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

Indo-Pacific. Differentiated into two subspecies, Zebrasoma veliferum veliferum in the Pacific and Zebrasoma veliferum desjardinii (Bennett, 1835 in the Indian Ocean and Red Sea. Some authors prefer to regard Z. desjardinii as a full species. The diagnosis above is for this form. Occurs on coral reefs or rocky bottoms, generally in less than 20 m depth.

Feeds on benthic algae.

PRESENT FISHING GROUNDS:

No definite fishing grounds.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION: No separate statistics are reported for this species. Caught mainly in traps or nets. Marketed fresh.

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