click for previous page SIGAN Sigan 1 1983 FAO SPECIES IDENTIFICATION SHEETS FAMILY: SIGANIDAE FISHING AREA 51 (W. Indian Ocean) Siganis rivulatus Forsskål, 1775 OTHER SCIENTIFIC NAMES STILL IN USE : Teuthis rivulata (Forsskål, 1775) VERNACULAR NAMES: FAO : En - Marbled spinefoot Fr - Sigan marbré Sp - Sigano jaspeado NATIONAL: DISTINCTIVE CHARACTERS: Body slender and compressed, its depth contained 2.7 to 3.4 times in standard length. Dorsal profile of head slightly concave above orbit, snout blunt; anterior nostril with a flap shaped like a tall triangle that reaches halfway to posterior nostril. A forward-directed spine present in front of dorsal fin; longest dorsal spine 4th to 7th; last dorsal spine short, subequal to the first, contained about 2.3 times in longest dorsal spine; last anal spine the shortest but only slightly shorter than (0.9 times) first anal spine and contained 1.6 times in longest anal spine; caudal fin only moderately forked, length of median rays two-thirds the length of longest rays. Scales minute; cheeks usually covered with very fine scales; 18 to 21 scale rows between lateral line and bases of leading dorsal spines. Colour: in general, head and body are brown or olive-green, grading to paler below, with horizontal golden lines running the length of the lower two-thirds of sides; lines becoming indistinct after death.
DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA: Siganus argenteus: caudal fin much more deeply forked; last anal spine relatively shorter, contained 2 to 3.2 times in the longest anal spine (contained 1.6 times in S. rivulatus); head and sides either covered with yellow spots, or wavy horizontal yellow lines substituting for the spots, particularly on lower sides. S. luridus: caudal fin truncate; body deeper, 2.2 to 2.8 times in standard length (2.7 to 3.4 in S. rivulatus). Other Siganus species: either deeper bodied, or with cream or pearly-blue spots or lines on sides. S. argenteus SIZE: Maximum: 40 cm; common to 20 cm. GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: In the area, confined to the Red Sea and Gulf of Aden. Elsewhere, only in the eastern Mediterranean to where this species has recently spread through the Suez Canal. S. luridus Lives about rock and coral reefs and over sandy bottoms down to 20 m depth. Feeds on bottom algae. PRESENT FISHING GROUNDS: Shallow coastal waters. CATCHES, FISHING GEAR AND FORMS OF UTILIZATION: Separate statistics are not reported for this species. Caught with beach seines and gillnets, occasionally trawled. Marketed fresh or frozen.
SIGAN Sigan 2 1983 FAO SPECIES IDENTIFICATION SHEETS FAMILY: SIGANIDAE FISHING AREA 51 (W. Indian Ocean) Siganus luridus (Rüppell, 1828) OTHER SCIENTIFIC NAMES STILL IN USE: Teuthis lurida Rüppell, 1828 VERNACULAR NAMES: FAO : En - Dusky spinefoot Fr - Sigan sombre Sp - Sigano nebuloso NATIONAL: DISTINCTIVE CHARACTERS: Body compressed, fairly slender, its depth contained 2.2 to 2.8 times in standard length. Dorsal profile of head strongly concave at nape, snout very blunt; anterior nostril with a long flap reaching to or past posterior nostril. A forward-directed spine present in front of dorsal fin; longest dorsal spine the 3rd to 7th, about 1.5 times the length of last dorsal spine; longest Final spine the 3rd or 4th, up to 1.3 times the length of the last anal spine; caudal fin truncate. Scales minute; cheeks with a few to many fine scales; 15 to 20 scale rows between lateral line and bases of leading dorsal fin spines. Colour: head and sides olive green or a very dark brown; sides often conspicuously marked with pale vermiculating lines, but sometimes pattern very indistinct and disappearing at death; pectoral fins hyaline-yellow.
DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA: Siqanus spinus: very similar in proportions to S. luridus but confined to the eastern part of the area, vermiculate pattern present on both head and sides; a prominent pale bar at base of caudal fin. Other Siganus species: caudal fin forked to emarginate, never truncate. SIZE: Maximum: 30 cm; common to 20 cm. S. spinus GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: Mauritius, Seychelles, tropical east Africa and the Red Sea: recently spread into the eastern Mediterranean. Lives in small schools around coral and rock reefs. Browses on algae growing on rocks and corals. PRESENT FISHING GROUNDS: Shallow coastal waters. CATCHES, FISHING GEAR AND FORMS OF UTILIZATION: Separate statistics are not reported for this species. Caught with set traps, gillnets and beach seines. Marketed fresh.
SIGAN Sigan 3 FAO SPECIES IDENTIFICATION SHEETS FAMILY: SIGANIDAE FISHING AREA 51 (W. Indian Ocean) 1983 Sijanus javus (Linnaeus, 1766) OTHER SCIENTIFIC NAMES STILL IN USE : Teuthis javus: Herre and Montalban, 1928 VERNACULAR NAMES: FAO : NATIONAL: En - Streaked spinefoot. Fr - Sigan ondulé Sp - Sigano ondulado DISTINCTIVE CHARACTERS: Body deep, oval and compressed, its depth contained 2 to 2.3 times in standard length. Dorsal profile of head slightly concave above orbit; snout short and blunt anterior nostril with a small triangular flap reaching halfway to posterior nostril. A forward-directed spine present in front of dorsal fin, imbedded in nape; longest dorsal fin spine the 5th or 6th, 1.25 to 1.5 times the length of last dorsal spine; apart from the short first spine, all anal spines of similar length and subequal to longest dorsal spine; soft part of dorsal and anal fins of moderate height, longest rays subequal to longest spines; caudal fin emarginate. Scales minute; cheeks covered with prominent scales; 30 to 35 scale rows between lateral line and bases of leading dorsal spines. Colour: back dark bronze, to paler below; numerous qun-metal blue spots on head and upper sides, slightly smaller than pupil and coalescing into paler silvery blue undulating lines on mid- and lower sides. Spines and rays of dorsal, anal and pelvic fins golden, membranes dusky or golden; pectoral fins golden hyaline; caudal fin dusky, sometimes with faint vertical bars.
DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA : Siganus lineatus: golden bronze bands covering sides of trunk; bands breaking up into spots at bases of dorsal and anal fins and on caudal peduncle; spots extending onto caudal fin; a prominent blue line running diagonally across cheek from corner of mouth: a bright yellow spot, slightly larger than eye, on sides at base of last few rays of dorsal fin. S. argenteus: some specimens with similar colour pattern but body slender, 2.4 to 3 times in standard length (2 to 2.3 in S. J'a vus) and caudal fin deeply forked. Other Siganus species: have a different colour pattern and less than 30 scale rows (except some S. sutor) between lateral line and dorsal fin (30 to 35 in S. javus). S. lineatus SIZE: Maximum: 45 cm; common to 20 cm. GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: In the area, from the "Gulf", along the coasts of India and Sri Lanka. Elsewhere, from the Indo-Malayan Archipelago to the New Guinea arc and northward to the Ryukyu islands. Occurs in small schools in shallow coastal waters; about rock and coral reefs and in brackish lagoons. S. argenteus Feeds from bottom on encrusting algae. PRESENT FISHING GROUNDS: Coastal lagoons and other shallow waters. CATCHES, FISHING GEAR AND FORMS OF UTILIZATION: Separate statistics are not reported for this species. Caught with trawls, gillnets and traps. Marketed fresh.
SIGAN Sigan 4 1983 FAO SPECIES IDENTIFICATION SHEETS FAMILY: SIGANIDAE FISHING AREA 51 (W. Indian Ocean) Siganus canaliculatus (Park, 1797) OTHER SCIENTIFIC NAMES STILL IN USE : Siganus oramin (Bloch & Schneider, 1801) VERNACULAR NAMES: FAO : En - White-spotted spinefoot Fr - Sigan pintade Sp - Sigano pintado NATIONAL: DISTINCTIVE CHARACTERS: Body compressed, fairly slender, its depth contained 2.4 to 2.8 in standard length. Head profile slightly to markedly concave above eye; snout blunt; anterior nostril with a long flap in juveniles, shortening with age, absent in old fish; tip of flap reaching less than halfway to posterior nostril in specimens larger than 12 cm standard length. A forward-directed spine present in front of dorsal fin; longest dorsal spine 4th to 8th; last dorsal spine the shortest, contained 0.5 to 0.6 times in longest dorsal spine; last anal spine contained 1.2 to 1.5 times in longest anal spine (usually the third); caudal fin almost emarqinate in specimens under 10 cm standard length, forked in larger fish (but median rays never less than half length of longest rays). Scales minute; cheeks scaleless, or with few to many very fine scales; 21 to 27 scale rows between lateral line and bases of leading dorsal spines. Colour: in life highly variable, dependirg on mood of fish and colour of substrate; greenish grey above to silver on belly; numerous pearly blue match-head size spots covering nape and sides, arranged more or less in horizontal rows (about 3 rows above and 10 below lateral line); spots often ovoid or rod shaped. Frightened and injured fish mottled brown; mottling includes dappling with pale cream and dark brown spots which may obscure basic colour pattern. Caudal fin plain grey or irregularly barred with pale and dark grey; pectoral fins hyaline; dorsal, anal and pelvic spines and rays same colour as adjacent areas of sides; fin membranes grey; after death fins usually marbled with pale and dark grey, dorsal fin rays banded.
DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA : Siganus sutor: very similar in proportions but appears to be confined to the western portion of Fishing Area 51: spots round, larger and less numerous; 26 to 31 scale rows between lateral line and bases of leading dorsai spines (21 to 27 in S. canaliculatus). S. rivulatus: body more slender, depth 2.7 to 3.4 in standard length (2.4 to 2.8 in S. canaliculatus); 18 to 21 scale rows between lateral line and bases of leading dorsal spines; colour pattern different, golden horizontal lines present on sides (in fresh specimens). S. argenteus: caudal fin deeply forked; last anal spine contained 2 times or less in longest anal spine (1.2 to 1.5 times in S. canaliculatus). S. argenteus S. luridus and S. spines: caudal fin truncate. Other Siganus species: body deeper, depth contained 2.4 times or less in standard length. SIZE: Maximum: 30 cm; common to 20 cm. GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: From the "Gulf" along the coasts of India to the Indo-Malayan Archipelago. Occurs in schools, in coastal waters to depths of at least 40 m. Feeds by scraping algae from rocks and corals, and by browsing on seaweeds and sea grasses; will take small invertebrates. PRESENT FISHING GROUNDS: Coastal waters, including estuaries. CATCHES, FISHING GEAR AND FORMS OF UTILIZATION: Separate statistics are not reported for this species. Caught mainly with bottom trawls and traps. Marketed mostly fresh. click for next page