Inhabits the southern waters from Marrawah in northwestern Tasmania to latitude 27° S off Western Australia.

No studies have been carried out on stock structure for deepwater flathead. The average size of deepwater flathead from trawl catches is significantly greater from grounds near Kangaroo Island than for the western central Great Australian Bight (Ref. 27192), but it is not known if this size variation indicates the presence of discrete stocks.

Commercial fishery: Deepwater flathead have been trawled sporadically in the Great Australian Bight since the turn of the century. However, only since the Great Australian Bight Trawl Fishery was set up as a developmental fishery in 1988 (Ref. 27194), has a commercial fishery for them become established. The most productive grounds for deepwater flathead are on the Ceduna Plateau in the central Bight and the Eyre Plateau further to the west. Catches are less frequent on continental shelf grounds south of Kangaroo Island, mainly as a result of lower fishing effort in that region. Small quantities of deepwater flathead are caught in the South East Fishery off western Tasmania and western Victoria, and in southern areas of the Western Deepwater Trawl Fishery (Ref. 27124).

Deepwater flathead is the dominant species in the continental shelf component of the Great Australian Bight Trawl Fishery, accounting for 40-50% of landings. Most of the deepwater flathead catch is taken at depths of 100-200 m, and the majority of the fish are between 45 cm and 60 cm TL; very few individuals shorter than 35 cm are caught.

This fishery is worked by stern trawlers of 23-37 overall length using demersal otter trawl nets. Deepwater flathead may be trawled at any time of the day and night (Ref. 27192). The annual catch of deepwater flathead from the Great Australian Bight rose sharply in 1988-89 from previous levels. By 1990-91 it had reached 430 t. However, the average annual trawl catch rates for deepwater flathead have dropped from 127 kg per hour trawled in 1989 to 80-85 kg per hour in 1990 and 1991 (Ref. 27194).

Marketing of the deepwater flathead catch has changed greatly since 1988 when 75% of landings were exported, mainly as frozen fillets. All of the catch is now sold on the domestic market as fresh, chilled, or frozen fillets. Fish heads are sold either for use as rock lobster (Jasus species) bait or to processors producing fish meal.

Resource status: As of 1993, estimates of sustainable yield for deepwater flathead indicated that the resource was under-exploited in the Great Australian Bight. However, Bight redfish (Centroberyx gerrardi) is an unavoidable bycatch of target fishing for deepwater flathead and the annual catch of Bight redfish up to 1993 was within the range of sustainable yield estimates. In other words, and at that time although an increase in the catch of deepwater flathead would not endanger that stock, it would be difficult to take more of them without imposing a risk of over-fishing Bight redfish.

As of 1993, there was no information on the resource status of deepwater flathead stocks outside of the Great Australian Bight.