(Trachurus novaezelandiae). This is a streamlined, blue-green and silver fish reaching 20 in. in length, with large eyes and a prominent row of enlarged scales along the side of the body. Near the tail each scale in this row has a raised, pointed ridge, or scute. The horse mackerel is not a true mackerel, but belongs to the trevally family. It inhabits coastal and offshore waters south to about the Otago Peninsula, being most common off the North Island coast. Horse mackerel are school fish, each school usually containing individuals of similar size. They feed on small fish and crustaceans. There is a second, very similar species of horse mackerel in New Zealand (the mackerel scad, Trachurus declivis), as well as a smaller, related fish, the koheru (Decapterus koheru).
by Lawrence James Paul, B.SC., Fisheries Division, Marine Department, Wellington.