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CARCH Rhiz 4

1983

FAO SPECIES IDENTIFICATION SHEETS

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

Rhizoprionodon oligolinx Springer, 1964

OTHER SCIENTIFIC NAMES STILL IN USE : Scoliodon palasorra (Bleeker, 1853)

VERNACULAR NAMES: FAO : En - Grey sharpnose Fr - Requin aiguille gris Sp - Cazón picudo gris

NATIONAL:

DISTINCTIVE CHARACTERS:

A small, slender shark. Snout long and depressed, its length usually greater than width of mouth, its tip narrowly rounded; eyes without a posterior notch; no spiracles; labial furrows very short, much less than eye length, ending well behind eyes; teeth similar in both underside of head jaws, low-crowned, oblique and narrow-cusped, with the outer edges deeply notched and without cusplets, smooth- edged in young but often finely serrated in adults. Origin of first dorsal fin over or posterior to inner corners of pectoral fins, its base length less than 2 times in distance between pectoral and pelvic fin bases, its free rear tip usually anterior to pelvic fin origins but occasionally over them; second dorsal fin smaller than anal fin, its origin far posterior to midlength of anal fin base; anal fin with slightly concave posterior margin and a pair of long preanal ridges.

Colour: grey or grey-brown above, white below, dorsal and anal fins with dusky or blackish edges, fins slightly darker than back. upper and lower lateral teeth DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

Rhizoprionodon acutus: body often more slender, upper labial furrows rather long (about eye length), pre- caudal vertebrae less, 55 to 79 (84 to 91 in R. oligolinx); fresh specimens usually darker and not as bronzy but lighter when preserved. Loxodon macrorhinus: body usually more slender, eyes with posterior notches, origin of first dorsal fin behind pectoral free rear tips, first dorsal fin base over 2 Rhizoprionodon acutus R. oligolinx times in distance between pectoral and pelvic fin bases. underside of head Scoliodon laticaudus: head and snout broader and more flattened, body stouter, free rear tip of first dorsal usually reaching pelvic midbases, pectoral fins broadly triangular, preanal ridges short, and caudal fin not deeply notch on its posteroventral margin. macloti: teeth with more erect cusps, the uppers with strong cusplets, first dorsal fin with longer free rear tip, second dorsal fin origin in front of Loxodon macrorhinus anal midbase, anal fin with very short preanal ridges and with a deeply notched posterior margin.

The combination of characters, including the small size, moderately long snout, absence of spiracles, unnotched eyes, short labial furrows, oblique, narrow- cusped teeth without cusplets and serrations in both jaws, Scoliodon laticaudus second dorsal fin very low, originating about over anal fin insertion, small pectoral fins, slightly concave posterior margin of anal fin, and long preanal ridges, serves to distinguish this shark from other carcharhinids occurring in the area. SIZE: Carcharhinus macloti Maximum: about 61 cm; males may mature at 38 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

In the area, confined to the northeast part from the "Gulf", Pakistan, India and Sri Lanka. Elsewhere, eastward from the area to Thailand, Malaya, Indonesia and Japan.

A common small inshore and offshore shark of coastal tropical waters, ranging down to at least 36 m depth from close inshore. Viviparous, size at birth about 21 to 26 cm. Probably feeds on small fishes and invertebrates; harmless to people.

PRESENT FISHING GROUNDS:

Throughout the area where it occurs. Commonly taken off south- eastern India.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this species. Caught with floating and bottom gillnets, and line gear. Utilized fresh for human consumption; also for fishmeal. CARCH Scol 1

1983

FAO SPECIES IDENTIFICATION SHEETS

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

Scoliodon laticaudus Müller & Henle, 1838

OTHER SCIENTIFIC NAMES STILL IN USE: Physodon muelleri (Valenciennes, in Müller & Henle, 1839) Scoliodon palasorra (Bleeker, 1853) Scoliodon sorrakowa (Bleeker, 1853)

VERNACULAR NAMES: FAO : En - Spaderiose shark Fr - Requin épée Sp - Cazón espadachín NATIONAL:

DISTINCTIVE CHARACTERS: A small shark. Body moderately stout and markedly compressed. Head and snout strongly depressed; snout long. narrowly rounded, its length greater than mouth width; labial underside of head furrows very short; anterior nasal flaps with a short, narrowly triangular lobe; eyes moderately large, without a posterior notch; spiracles absent; teeth similar in both jaws, oblique and narrow-cusped, with the distal edges deeply notched and with- out cusplets or serrations. First dorsal fin moderately large, its origin well behind pectoral free rear tips, its base closer to pelvic than to pectoral fin bases, and its free rear tip over or behind middle of pelvic fin bases; second dorsal fin very small, its height less than a third of that of first dorsal, its inner margin elongated and over twice the fin height, fin origin over or slightly anterior to anal fin insertion; pectoral fins small, broad, triangular, and nol: falcate, originating under or slightly anterior to 5th gill openings, anal fin with a slightly concave posterior margin and relatively short preanal ridges. Upper precaudal pit transverse and crescentic; no keels on caudal peduncle; no interdorsal ridge. upper tooth and lower tooth Colour: bronzy grey above, white below, fins sometimes near centre darker than body; no conspicuous markings.

DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

This species is readily distinguished from all other carcharhinids in the area by the following combination of characters: small size; compressed body; strongly depressed head and snout; long snout; short labial furrows; oblique-cusped, smooth-edged teeth without cusplets in both jaws; posterior position of first dorsal fin with rear tip over or behind pelvic midbases; small, low second dorsal fin with origin over or slightly anterior to end of anal fin base; broadly triangular (not falcate) pectoral fins, with origins about under the 5th gill openings; anal fin with a slightly concave posterior margin and short preanal ridges.

SIZE:

Maximum: about 74 cm, but most individuals smaller.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

In the area, mostly confined to the northeastern part, including "the Gulf", Pakistan, India and Sri Lanka, but recently taken off Tanzania. Elsewhere, in the Eastern Indian Ocean and the Western Central Pacific ranging eastward to Thailand, China, Japan and Borneo, but absent from Oceania or the Australasian Region. Occurs in tropical, coastal waters, often near the bottom in rocky areas. Viviparous, number of young 5 to 14. Size at birth about 13 to 15 cm. A small harmless shark, very abundant where it occurs in the area, and forming large schools. Feeds on shrimps, cuttlefishes, and small schooling fishes including anchovies, bregmacerotids, tripauchenids, and Bombay ducks (Harpodon nehereus).

PRESENT FISHING GROUNDS:

Throughout the northeastern part of the area.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this species. Caught with line gear, including floating longlines, and surface and bottom gillnets.

Utilized fresh for human consumption; offal for fishmeal, and as bait for other fishes.

CARCH Tria 1

1983

FAO SPECIES IDENTIFICATION SHEETS FAMILY: CARCHARHINIDAE FISHING AREA 51 (W. Indian Ocean)

Triaenodon obesus (Rüppell, 1837)

OTHER SCIENTIFIC NAMES STILL IN USE: None

VERNACULAR NAMES: FAO : En - Fr - Requin corail Sp - Cazón coralero trompacorta

NATIONAL:

DISTINCTIVE CHARACTERS: A small to medium-sized shark. Bode moderately stout. Snout very short, broadly rounded, its length much less than mouth width and equal to or less than distance between nostrils; labial furrows underside of head very short; anterior nasal flaps with a short, truncate prominent lobe, formed into a partial tube; spiracles usually absent small ones present in a few specimens; teeth in upper end lower jaws with high, narrow, smooth-edged cusps with strong cusplets on each side, no serrations. First dorsal fin moderately large, with a narrowly rounded apex, its origin well posterior to pectoral free rear tips, its base closer to the pelvic fins than the pectorals, and its free rear tip about over the pelvic fin origins; second dorsal fin very large, about half the surface of first dorsal and over half its height, its inner margin shorter than fin height, its origin over or slightly anterior to anal fin origin; pectoral fins moderately long, moderately narrow, slightly falcate, and with narrow tips; anal fin with posterior margin deeply notched; upper precaudal pit transverse and crescentic. No dermal ridge between dorsal fins, and no keels on caudal peduncle.

Colour: grey-brown above, sometimes with a few or several upper tooth and lower tooth dark spots on sides, first dorsal and dorsal caudal lobe with conspi- cuous white tip, second dorsal and ventral caudal lobe often white- near centre tipped; ventral surface cream-white. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

This species can be readily distinguished from all other carcharhinids in the area by the following combination of characters: snout very short, bluntly rounded; nasal flaps tubular; teeth smooth-edged with strong cusplets in both jaws; relatively posterior position of first dorsal fin (closer to pelvic than to pectoral fins); second dorsal fin large, about half the size of first dorsal; second dorsal fin and upper lobe of caudal fin conspicuously white-tipped.

SIZE:

Maximum: possibly 213 cm, but most adults below 160 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

In the area, wide-ranging from South Africa to the Red Sea, Pakistan, India and Sri Lanka; also Madagascar, Seychelles, Mauritius, Chagos Archipelago, Aldabra and Tromelin Islands. Elsewhere, widespread in the Eastern Indian Ocean and the Western, Central and Eastern Pacific; it has an extensive distribution among islands of the tropical Pacific. Occurs in tropical, coastal clear waters, usually on or around coral reefs; commonly in holes and crevices, often in shallow water near the bottom, but exceptionally at considerable depths down to 330 m. Viviparous, number of young 1 to 5 in a litter. Size at birth about 52 to 60 cm. A common reef shark, feeding on a wide variety of reef fishes including moray eels, squirrelfishes, snappers, damselfishes, parrot- fishes, surgeonfish, triggerfishes, goatfishes; also octopi, lobsters and crabs. A relatively non-aggressive shark to people in the water, and generally considered as not particularly dangerous. In response to exciting stimuli, especially speared fish, this shark has been known to attack divers, but never with serious results. Flesh and liver sometimes toxic in the Western-Central Pacific, but not in Fishing Area 51.

PRESENT FISHING GROUNDS: Known fishing grounds in the area are found off India and Sri Lanka, but probably fished elsewhere. Relatively uncommon as a commercial catch in the area.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this species.

Caught in floating and bottom gillnets and with line gear, including floating longlines.

Utilized fresh for human consumption.

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