Distributed throughout southern Australian waters from Cape Moreton in southern Queensland (Ref. 28785) to the continental slope off the central Western Australian coast.

Stock structure: Two distinct Australian stocks are evident from a current study (Ref. 28836). Genetic profiles from this study have shown highly significant differences between eastern and southern/western Australian specimens. The split is at the western end of Bass Strait, with limited mixing off western Tasmania (Ref. 28836). For fisheries management puposes, these eastern and southern/western populations can be considered completely separate breeding stocks (Ref. 28836).

Commercial fishery: Gemfish have a history of commercial exploitation beginning last century in Tasmanian waters. Up until 1880 gemfish was an important commercial species in southern Tasmania, where it was caught inshore at night on lines baited with jack mackerel (Trachurus declivis) or barracouta (Thyrsites atun). The cause of the disappearance of gemfish from the inshore fishery was never established (Ref. 27500).

Juvenile gemfish have been an incidental catch of demersal otter trawlers operating on the continental shelf since 1915 (Ref. 28789). It is only since the early 1970s that fishing effort has been targeted on migrating gemfish on the upper continental slope. The Australian gemfish catch rose from less than 100 t in the 1960s to a peak of more than 5000 t in 1978-79 but has since declined because of the lower availability of fish as well as government regulation of catches.

Gemfish are mainly caught from trawl vessels using demersal otter trawl gear and operating in the South East Fishery. The main trawl grounds are located from Newcastle to eastern Bass Strait in depths of 300 m to 400 m. Most of the catch is taken in June and July when migrating fish are targeted. In the South East fishery, over 80% of the annual gemfish catch is taken during winter. The fish caught from the spawning run are large, mature fish mostly between 60 cm and 90 cm FL.

During spring and autumn, some catches are taken from western Victoria and northwestern Tasmania. Immature gemfish are also caught throughout the year as a bycatch of trawling operations targeted at other species such as redfish (Centroberyx affinis), jackass morwong (Nemadactylus macropterus) and royal red prawns, Haliporoides sibogae. Small amounts of gemfish are caught in the Great Australian Bight Trawl Fishery.

A small dropline fishery exists for spawning gemfish off the coast of northern New South Wales. Catch rates of gemfish by dropline are low in this area except during August and early September. Some gemfish are also caught in bottom set gillnets (for sharks) in eastern Bass Strait (Ref. 28786).

Most of the gemfish catch is sold on the domestic fresh fish market. The Sydney Fish Market is the main wholesale market for gemfish, although in recent years the bulk of the catch has been sent directly to processors. Significant quantities of frozen gemfish fillets were until recently exported to Japan, but catch reductions have limited development of a bigger export market. Gemfish are either headed and gutted on board the catching vessel if catches are small, or sold as whole fish when large catches are made.

Recreational fishery: As they live in deep water, gemfish are rarely caught by anglers. In 1993, the Australian Anglers Association's record for gemfish was a 6.9 kg individual caught off the New South Wales in 1979.

Resource status: A decline in catch rates and changes in mean size for gemfish caught in eastern Australian waters have been observed since the mid 1980s. These changes in the fishery may have been caused by excessive levels of fishing or unknown environmental factors. In any event the stock has been unable to produce sufficient numbers of juvenile fish to replace adults and the result has been a 'recruitment failure' from 1988 onwards. The total allowable catch of 3000 t introduced in 1988 has, of necessity, been greatly reduced in successive years. The present stock size in eastern Australian waters is well below that capable of producing maximum sustainable yields (Ref. 28786, 28795). Given the severely depleted state of the eastern gemfish stock, no guarantee can be given that the stock will recover to former levels, even if the remaining fish are totally protected from exploitation (Ref. 28838, 28843).