Main fisheries are conducted in New Zealand, Australia, NE Atlantic and Namibia, where different regional units are considered for assessment and management purposes. Several studies (e.g. Oke et al. 1997; Varela et al. 2012)) have been conducted using distinct techniques (microsatellites, allozyme or mtDNA analysis, diet and behavior, etc.) in different geographic scales (New Zealand, Australia, Namibia, and Chile, North Atlantic). Genetic comparisons found differences among New Zealand and Australian stocks (Branch 2001) but the worldwide stock structure of orange roughy is still currently unknown and a lack of significant differentiation among far geographic samples is revealed (Varela et al. 2012).

In New Zealand, the presumable biological stock structure is based on the spawning grounds identified but the nine assessment/management units regard the main fisheries operating in the region, not always coincide with the boundaries of the biological stocks (more details in MPI, 2014a). Within the management unit Cape Runaway to Banks Peninsula (ORH 2A, 2B, 3A) there are two biological stocks and correspondent assessment units: East Cape (ORH 2A North) and Mid-East Coast (ORH 2A South, 2B, 3A).