Greenback horse mackerel, commonly known as "jack mackerel" and cowanyoung, is an important commercial species in the Oceania region, occurring along the Australian coast starting with southern Queensland, throughout southern Australia, and north to the central coast of Western Australia; is also found in the waters of New Zealand. 

The stock structure of jack mackerel is still unclear (Marton and Steven 2019) but there is evidence that the population found in eastern Australia is genetically distinct from the one found in western Australia, with a third distinct population in New Zealand. These conclusions are based on morphological and meristic differences between fish from the Great Australian Bight and eastern Australia, genetic differences between fish from the Great Australian Bight and New Zealand, and a lack of genetic difference between fish from eastern Tasmania and New South Wales (Bulman et al. 2008)(AFMA 2018)​. Eastern and Western assessment units are assumed with respective management measures (Marton and Steven 2019)(AFMA 2020).