Inhabit waters from 700 m to at least 1400 m, on the continental shelf slope between Port Stephens in New South Wales and Cape Naturaliste in Western Australia. They are also found on the South Tasman Rise, Cascade Plateau and Lord Howe Rise (Ref. 6390).

The stock structure of orange roughy in Australian waters remains uncertain (Ref. 27081). Based on genetic studies, a single population exists, but biological studies imply the existence of separate stocks.

Commercial fishery: Orange roughy were first recorded in Australian waters in trawl surveys off New South Wales conducted in 1972. The first promising catches were taken off Tasmania in 1981 by the research vessell Challenger, but it was not until 1986 that a large (non-spawning) aggregation was discovered off western Tasmania. From 1986 until the discovery of the spawning aggregation off St. Helens in 1989, the fishery was largely based on non-spawning aggregations and small catches from the dispersed population. Orange roughy are caught in the South East Fishery and, to a much lesser extent, in the Great Australian Bight Trawl Fishery, mainly in depths of 800-1200 m. The bulk of the catch is taken off eastern and southern Tasmania. The few attempts to catch orange roughy north of the South East Fishery area have proved largely unsuccessful, although small catches have been made off Port Stephens (Ref. 27024).

Commercial fisheries were based primarily on spawning and non-spawning aggregations of adult fish over 30 cm in length. Most fish in catches from the Cascade Plateau are 35-50 cm long (average 42 cm) with an average weight of 1-2 kg, whereas those from around Tasmania and the Great Australian Bight are 30-46 cm (average 36 cm). The aggregations tend to be highly localised. The 'Hill' east of St. Helens supports a major fishery and minor aggregations, also of spawning fish, have been fished in the Great Australian Bight and off southern Tasmania. Non-spawning aggregations have so far been found on the Cascade Plateau; at Port Davey, Maatsuyker and Pedra Branca (southern Tasmania); off Sandy Cape (western Tasmania); off Beachport, Kangaroo Island and Port Lincoln (South Australia); and off Albany (Western Australia).

The orange roughy catch is sold as frozen, deep-skinned, boned fillets. Most is exported. Orange roughy oil has been used both as lubricant and in the cosmetic, pharmaceutical, leather, and textile industries.

Resource status: The Australian orange roughy fishery has developed relatively recently and the status of the resource as of 1993, was uncertain (Ref. 27083). Available evidence suggests that the long-term sustainable yield is low as orange roughy have a low fecundity, slow growth and a long life. The history of the New Zealand fishery, which has been operating since 1979, supports this view. An acoustic estimate of the St Helens spawning aggregation calculated the virgin biomass as 110,000 t. No biomass estimates (as of 1993), were available elsewhere in this fishery. As of 1993, the maximum sustainable yield estimates for the South East Fishery were in the order of thousands of t rather than tens of thousands.