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GERR Gerr 3

1983

FAO SPECIES IDENTIFICATION SHEETS

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

Gerres oyena (Forsskål, 1775)

OTHER SCIENTIFIC NAMES STILL IN USE : None

VERNACULAR NAMES: FAO: En - Common silver-biddy Fr - Blanche commune Sp - común

NATIONAL :

DISTINCTIVE CHARACTERS :

Body very slender, its depth contained 3.0 to 3.3 times in standard length. Anterodorsal profile gently convex, ascending at angle of about 35° to horizontal axis. Pectoral fin reaching to just above anus; second anal spine slender and short, equal to or shorter than eye diameter; caudal fin deeply forked, its lobes not exceptionally long, longest ray subequal to pectoral fin and head. Scales on lateral line, 35 to 39 to base of caudal fin and 3 or 4 more pored scales on scaly sheath on caudal fin base; 3.5 scale rows between lateral line and base of 5th dorsal spine.

Colour: pale olive above to silvery below; 7 or 8 faint dusky bars on sides of body, more pronounced in young. Prominent black tip to spinous part of dorsal fin, usually confined to distal part of 2nd to 5th spines but sometimes continuing as black margin along whole of dorsal fin; caudal fin uniformly dusky. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA : oblongus: 44 or 45 lateral line scales, plus 4 or 5 on base of caudal fin (35 to 39 in G. oyena).

G. acinaces: body depth contained 2.5 to 2.9 times in standard length (3 to 3.3 times in G. oyena); longest caudal fin ray distinctly longer than pectoral fin or head; 2nd anal spine much longer than eye diameter.

Pentaprion longimanus: anal fin base longer than base of soft part of dorsal fin (shorter in G. oyena).

Other species of Gerreidae: deeper bodied, body depth contained much less than 3.0 times in standard length.

Species of Leiognathidae: nuchal crest on nape.

SIZE:

Maximum: 25 cm; common to 15 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

In the area, found along the east coast of Africa (possibly including the Seychelles) to the Red Sea and the "Gulf"; also along the southeastern coasts of India and around Sri Lanka. Elsewhere extending to the Western Pacific.

Common along sandy beaches but also said to enter estuaries and brackish lagoons.

Feeds on small organisms living on sandy bottoms.

PRESENT FISHING GROUNDS:

Shallow inshore waters.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this species.

Caught mainly with bottom trawls and seines.

Marketed fresh; also used as fishmeal.

GERR Gerr 6

1983

FAO SPECIES IDENTIFICATION SHEETS

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

Gerres acinaces Bleeker, 1854

OTHER SCIENTIFIC NAMES STILL IN USE: None

VERNACULAR NAMES: FAO : En - Longtail silver-biddy Fr - Blanche gouvernail Sp - Mojarra timonera

NATIONAL:

DISTINCTIVE CHARACTERS:

Body slender, its depth contained 2.5 to 2.9 times in standard length. Anterodorsal profile gently convex, ascending at angle of about 40° to horizontal axis. Pectoral fin reaching past level of anus, as far as level of base of 1st anal spine; second anal spine fairly strong, much longer than eye diameter; caudal fin deeply forked and very long, its longest ray longer than either pectoral fin or head. Scales on lateral line 42 to 44 to base of caudal fin and 3 to 5 more on scaly sheath on caudal fin base; 4.5 to 5.5 scale rows between lateral line and base of 5th dorsal spine. Colour: olive green above to silver below. In young, 7 or 8 dusky bars on sides of body. In older fish, columns of dark ovoid spots below lateral line, as many as 5 spots below highest part of lateral line; above lateral line, rows of dark spots following the course of each scale row. Trailing margin of caudal fin broadly edged in black. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

Gerres oblongus: body more elongate, its depth at least 3 times in standard length (2.5 to 2.4 times in G. acinaces); 44 or 45 lateral line scales (42 to 44 in G. acinaces) (counts exclude pored scales on base of caudal fin). G. oyena: less than 40 lateral line scales (excluding pored scales on base of caudal fin); 3.5 scale rows between lateral line and 5th dorsal fin spine (4.5 to 5.5 in G. oblongus G. acinaces). 3.5 scale rows G. lucidus: on average deeper bodied; lateral line scales 33 to 35; caudal fin short, longest ray subequal to head and pectoral fin; 2nd anal spine very strong.

G. filamentosus: 2nd dorsal fin spine filamentous.

Pentaprion lonqimanus: 5 or 6 spines and 12 to 14 rays in anal fin.

Other species of Gerreidae: much deeper bodied, G. oyena body depth contained less than 2.5 times in standard length.

Species of Leiognathidae: nuchal crest on nape; scales barely visible.

SIZE:

Maximum: 35 cm; common to 15 cm.

G. filamentosus

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: 4.5 to 5.5 scale rows In the area, found from the east coast of Africa to the Red Sea including Madagascar, Comores, Seychelles, Mauritius, Réunion, Maldive and Laccadive Islands; also occurring in the "Gulf", and along the southern coast of India and Sri Lanka. Elsewhere, throughout the tropical Indo-Pacific to the western Pacific islands.

Appears to favour clear shallow waters over sandy bottoms; broadly ranging, from coral reefs to brackish G. acinaces

lagoons.

PRESENT FISHING GROUNDS:

Inshore waters, throughout the year.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this species.

Mainly caught with bottom trawls, down to about 40 m depth.

Marketed fresh; in other fishing areas processed as fishmeal and duck food.

GERR Gerr 7

1983

FAO SPECIES IDENTIFICATION SHEETS

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

Gerres lucidus Cuvier, 1830

OTHER SCIENTIFIC NAMES STILL IN USE: ? Gerres limbatus Cuvier, 1830

VERNACULAR NAMES: FAO : En - Saddleback silver-biddy Fr - Blanche selles Sp - Mojarra ensillada

NATIONAL:

DISTINCTIVE CHARACTERS:

Body fairly deep, its depth contained 2.3 to 2.7 times in standard length. Anterodorsal profile very slightly convex, ascending at an angle of about 40° to horizontal axis; ventral profile of head convex at chin; head length contained 3 to 3.2 times in standard length; orbit contained 2.5 to 2.7 times in head length. Second anal fin spine strong and shorter than anal fin base; pectoral fin short, tip of depressed fin reaching to level of anus but not to level of first anal spine; caudal fin forked, longest rays about 2 times the length of median rays. Only 3 scale rows between lateral line and 5th dorsal spine; lateral line scales 33 to 35 to base of caudal fin and 3 more pored scales on scaly sheath on base of caudal fin. Colour: silvery, dusky dorsally. Four diffuse, dark saddles along back, extending down sides to midline: the first straddles the nape, the second is under the 2nd to 6th dorsal spines, the third lies beneath the beginning of the soft part of dorsal fin, the fourth lies immediately behind the third and extends onto the caudal peduncle. Dorsal fin very faint golden, with a dark patch on the tip of the spinous portion above a line running from middle of 2nd dorsal spine to tip of 6th dorsal spine; caudal fin pale yellow, with a dusky trailing edge; anterior half of anal fin orange, posterior half dusky; pectoral fins pale yellowish, grading to hyaline at tip; pelvic fins orange, with a silvery perimeter. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

Gerres filamentosus: 2nd dorsal fin spine fila- mentous (but often damaged).

G. limbatus: said to differ from G. lucidus mainly in the absence of the black spot on tip of spinous part of dorsal fin, but probably conspecific.

G. oyena: body slender, 3 to 3.3 times in standard length (2.3 to 2.7 times in G. ludicus).

G. abbreviatus, G. acinaces, G. oblonqus, G. poieti, G. rappi and Pentaprion longimanus: more than 3 scale rows between lateral line and 5th dorsal spine. G. filamentosus Species of Leiognathidae: nuchal crest on nape; scales barely visible

5 scale rows

G. oyena only 3 scale rows

G. rappi

SIZE: G. lucidus Maximum: 15 cm; common to 10 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

In the area, from Bombay along the western coasts of India and around Sri Lanka. Elsewhere, from the east coast of India to southeast Asia and the South China Sea.

Inhabits tidal areas of estuaries and very shallow coastal waters.

Feeds on small living on mud-sand bottoms. PRESENT FISHING GROUNDS Tidal areas throughout the year. CATCHES, FISHING GEAR AND FORMS OF UTILIZATION Separate statistics are not reported for this species. Caught with stake, lift, seine and cast nets. Marketed fresh.

GERR Gerr 8

1983

FAO SPECIES IDENTIFICATION SHEETS

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

Gerres oblongus Cuvier, 1830

OTHER SCIENTIFIC NAMES STILL IN USE: None

VERNACULAR NAMES: FAO : En - Slender silver-biddy Fr - Blanche élégante Sp - Mojarra elegante

NATIONAL:

DISTINCTIVE CHARACTERS:

Body compressed and very slender, its depth contained 3.1 to 3.4 times in standard length. Snout pointed; anterodorsal profile scarcely convex, ascending at an angle of less than 30 o to horizontal axis. Spines weak; second anal spine very short, contained about 2 times in base of anal fin, pectoral fins increasing in length with age, reaching to level of anus in small specimens and almost to level of 1st anal spine in older specimens; caudal fin very deeply forked. Number of rows of scales between base of 5th dorsal spine and lateral line scale row 4.5 to 5.5; scales on lateral line 44 or 45 to base of caudal fin and 4 or 5 more on the well developed scaly sheath on the base of the fin. Colour: silvery; lilac brown dorsally. Dusky tip to dorsal fin; other fins pale. DISTINGUISHING CHARACTERS OF SIMILAR SPECIES OCCURRING IN THE AREA:

Gerres oyena: 35 to 39 lateral line scales (plus 3 or 4 on base of caudal fin).

Other species of Gerreidae: deeper bodied, body depth contained less than 3 times in standard length (3.1 to 3.4 times in G. oblonqus).

Species of Leiognathidae: nuchal crest on nape; scales barely visible.

SIZE: Maximum: 30 cm; common to 15 cm.

GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR:

In the area, along the east coast of Africa from Kenya to southern Mozambique, including the Seychelles and off southeast India, Sri Lanka, Maldives and Lacca- dive Islands. Elsewhere, extending eastward through the Indo-Malayan archipelago to the islands of the near western Pacific. Known distribution suggests this species prefers coralline areas.

Feeds on small organisms living on sandy bottoms.

PRESENT FISHING GROUNDS:

Shallow inshore waters.

CATCHES, FISHING GEAR AND FORMS OF UTILIZATION:

Separate statistics are not reported for this species.

Caught with set nets and beach seines.

Flesh is reputed to be excellent if marketed very fresh.

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