Jack mackerels are marine fishes in the Trachurus genus of the Carangidae family. The name of the genus is derived from the Greek words trachys, meaning “rough”, and oura, meaning “tail”. Some species, such as T. murphyi, are harvested in purse seine nets, and in some cases overfishing occurs (i.e. harvesting beyond sustainable levels). It is often used in Japanese cuisine, where it is called aji.