Shark Mackerel, Grammatorcynus bicarinatus (Quoy & Gaimard 1825)

Other Names: Couta, Double-lined Mackerel, Large Scale Tuna, Largescale Tunny, Large-scaled Tuna, Large-scaled Tunny, Salmon Mackerel, Scaley Mackerel, Scaly Kingfish, Scaly Mackerel

A Shark Mackerel, Grammatorcynus bicarinatus, at the wreck of the SS Yongala off Townsville, April 2015. Source: Robin Laws-Wall / License: CC By Attribution-NonCommercial


An easily recognised slender mackeral with a metallic bluish-green tinge above, silvery below often with small black spots on the belly, and a double lateral line - one from the gill cover to the caudal fin, the second from the first line running steeply downwards behind the pectoral fin and along the lower side to rejoin the first lateral line near the caudal fin. 

With its oily flesh, this species is not highly regarded at a table fish.

A Shark Mackerel attracted to a pelagic baited remote underwater stereo-video system at Tantabiddi (Ningallo), Western Australia - depth 35 m.

Cite this page as:
Bray, D.J. & Schultz, S. 2017, Grammatorcynus bicarinatus in Fishes of Australia, accessed 24 Jun 2024,

Shark Mackerel, Grammatorcynus bicarinatus (Quoy & Gaimard 1825)

More Info


Houtman Abrolhos Islands to the Dampier Archipelago, Western Australia, Ashmore Reef, Timor Sea, and Cape York, Queensland, to at least Byron Bay, New South Wales. Elsewhere the species occurs in the south-west Pacific (New Guinea, New Caledonia). 

Forms schools around reefs and near bays, moving into shallow water on the high tide to feed over reef flats.


Dorsal fin XI-XIII, 0, 0, 10-12 + 6 finlets; Anal fin 11-13 + 7finlets; Pectoral fin 22-26; Gill rakers 14-15.

Dorsal fins separated by a narrow space. Pectoral fins stout. Body elongate and slightly compressed. Slender conical teeth forming a single series in each jaw, 20-30 in each jaw. Body covered in moderately small scales, no prominent corselet present. Two lateral lines. Caudal peduncle with well-developed keel, flanked on each side by a smaller keel. Swim bladder present.


To at least 110 cm and 13.5 kg in weight.


Metallic blue-green dorsally and on upper sides, fading to silvery-white with golden tinge on belly. Belly with small dark spots (may be absent).


Carnivore - feeds on schools of clupeoid fishes and crustaceans.



Commercially fished and used as bait in Queensland. The species is also targeted by light-gear recreational fishers. The flesh is not highly valued due to the high oil content.



Commonly called the Shark Mackerel due to the ammonia shark-like odour of the flesh.

Similar Species

G. bicarinatus differs from the closely related G. bilineatus in having fewer gill rakers (12-14 vs. 18-24), a smaller eye (3.1-4.6% vs 4.0 to 6.0% FL), small black spots on the lower sides of the body, and reaching a larger size (110cm vs 60cm FL). These species also differ from one another in a number of osteological characters.

Species Citation

Thynnus bicarinatus Quoy & Gaimard 1825, in Freycinet, Voyage autour du Monde: 357, pl. 61 1. Type locality: Shark Bay, Western Australia (as Baie des Chiens-Marins).


Bray, D.J. & Schultz, S. 2017


Australian Faunal Directory

Shark Mackerel, Grammatorcynus bicarinatus (Quoy & Gaimard 1825)


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Allen, G.R. 1997. Marine Fishes of Tropical Australia and South-east Asia. Perth : Western Australian Museum 292 pp. 106 pls. 

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Quick Facts

CAAB Code:37441025

Conservation:IUCN Least Concern

Depth:0-200 m

Fishing:Commercial, recreational fish


Max Size:130 cm FL; 12.3 kg

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Species Maps

CAAB distribution map