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Common Jack Mackerel
Trachurus declivis (Jenyns, 1841)
A school of Common Jack Mackerel at a depth of 14 m, Kangaroo Island, South Australia, April 2001. Photo © J. Lewis. View larger image.
A Common Jack Mackerel from the CSIRO Fish Collection, Hobart (H 3766-02). Photo: G. Yearsley © CSIRO Marine Research.
The Common Jack Mackerel has an elongate body and a forked caudal fin. The scales in both the curved and straight parts of the lateral line are enlarged and scute-like, but may be overgrown by smaller scales in larger individuals. An accessory lateral line runs close to the base of the dorsal fin as far posteriorly as the fifth to tenth dorsal fin ray. The first dorsal fin is shot-based with eight spines. The second dorsal fin is long-based with the terminal ray being enlarged and slightly separated from the rest of the fin.
The species is dark blue-green above and silver to grey below. There is a prominent black blotch on the rear of the operculum.
It grows to at least 60 cm in length.
The Common Jack Mackerel is a pelagic species that occurs in Australia and New Zealand. It is found in inshore waters as well as continental shelf and continental slope waters at depths from the surface to about 500 m.
In Australia it is known from southern Queensland, around the south of the country, and north to the central coast of Western Australia.
View a map of the collecting localities of specimens in the Australian Museum Fish Collection.
It has also been called Cowanyoung, Greenback Horse Mackerel and Scaly Mackerel.
This species looks similar to the Yellowtail Scad. The Common Jack Mackerel is longer and more slender than the Yellowtail Scad and has a longer accessory lateral line (only reaches to below the first or second dorsal fin ray in the Yellowtail Scad).
Related links
- Yellowtail Scad fact sheet
- View the Family Carangidae list
- View the Trevallies list
Further reading
- Gomon, M.F. in Gomon, M.F., Glover, C.J.M. & R.H. Kuiter (Eds). 1994. The Fishes of Australia's South Coast. State Print, Adelaide. Pp. 992.
- Hutchins, B. & R. Swainston. 1986. Sea Fishes of Southern Australia. Complete Field Guide for Anglers and Divers. Swainston Publishing. Pp. 180.
- Smith-Vaniz, W.F. Carangidae. in Carpenter, K.E. & V.H. Niem. 1999. The Living Marine Resources of the Western Central Pacific. Volume 4. Bony fishes part 2 (Mugilidae to Carangidae). FAO. Rome Pp. iii-v, 2069-2790.
