Latin name

Trachurus declivis

Other name

Chows, cowan young, greenback horse mackerel, greenback scad, horse mackerel, common jack mackerel, scad, scaly mackerel 

Identification

Greek, trachys, -eia, -ys = rough + Greek, oura = tail.

The common name comes from the legend that other smaller fish species can travel long distances on their backs. 

Adults are elongated and slightly compressed, with a main lateral line of 71-89 scales and a secondary lateral line extending to 7-9 dorsal fin rays. Vertebrae: 24. 

Features of fish fins

Dorsal spines (total): 9; Dorsal soft rays (total): 29 - 35; Anal spines: 3; Anal soft rays: 24 - 29.

Fish colouring

The fish is dark blue-green on top and silvery or grey underneath.

Distribution

Widespread in the southwest Pacific: from Western Australia to New South Wales, including New Zealand. Principal component analysis of morphometric and meristic characters suggests three distinct subpopulations in the Great Australian Bight, off New South Wales and Tasmania.

Habitat

A marine benthopelagic species that prefers brackish waters and temperate climates. Its usual depth range is 27-460m.

Size

Males of this species reach 64 cm in length. The total length is 42 cm. The reported maximum age is 25 years.

Behavior

Adults are usually found near the bottom, in mid-water and occasionally on the surface in continental shelf waters. They form pelagic schools for most of the year, but may move close to the seabed in winter. They are usually found at depths of less than 300 m when water temperatures are below 16°C. Juveniles inhabit coastal waters and estuaries, although they can sometimes be found offshore. 

Food and feeding habits

Adults feed mainly on krill and other planktonic crustaceans, light fish (Sternoptychidae) and lanternfish (Myctophidae) on the edge of the continental shelf.

Reproduction

Eggs and sperm are caught in schools of fish, possibly deep in the water column near the edge of the continental shelf. Eggs are distributed between the surface and the thermocline, and larvae are carried to the coast by currents.

Fishing

It is an important commercial and recreational fish.  Commercially, it is caught using trawls, purse seines, traps and on-line gear.

Relationship with a person

Harmless. The flesh of these fish has a pleasant flavour.