Spangled emperors are distributed between Rottnest Island (near Perth) and northern New South Wales (Ref. 6390), including the Torres Strait Islands (Ref. 13465). Spangled emperors appear to be more common in outer coastal waters to the west and east of Australia than they are in the north (Ref. 6390). Recorded from Shark Bay (Ref. 115274).

Stock structure: The taxonomic position of blue-spotted (L. choerorynchus), spangled and blue-lined (L. frenatus) emperors has been confused, with reviews (Ref. 2295, 2334) suggesting they are misidentifications for the 1 species. However, surveys and continuing studies consistently reveal morphological and ecological differences between them, and recent electrophoretic study (Ref. 28017) in Western Australia has confirmed that the 3 taxa are reproductively isolated species.

Western Australian populations of blue-spotted emperors and spangled emperors have been shown to be single stocks, yet the relationship of these populations and blue-spotted and spangled emperors from other States is unknown.

Commercial fishery: Emperors in general are caught by handlines, rod-and-line, traps and demersal otter trawling - mainly stern trawling but also semi-pelagic trawling in the Northern Territory.

Emperors are trawled off northwestern and northern Australia. From 1970 (Ref. 28206, 28207) until 1991, Taiwanese and later Thai and Chinese fleets operated pair trawlers and stern trawlers on the North West Shelf and northern Australia. Emperors and butterfly bream (Nemipteridae) dominated catches on the North West Shelf for the 10 years from 1980 (Ref. 27275), peaking at a retained catch of 2200 t of emperor in 1982. Emperors were far less abundant in retained catches in the Timor and Arafura seas for the same period. The trawlers worked in depths between 30 m and 120 m, and concentrated on waters between 115° and 120°E (Ref. 28206).

Domestic fishing interest in trawling in northern Australia commenced in 1985 and increased after 1988 (Ref. 28207). It is focused on grounds on the North West Shelf, the Arafura Sea and in the northern region of the Gulf of Carpentaria (Ref. 28207), and has a large seasonal component caused by prawn trawlers converted to fish trawling during the closed seasons of the Northern Prawn Fishery (Ref. 28207, 27275). Spangled emperors are taken by domestic trawlers near Barrow Island and Glomar Shoal, Western Australia.

Trap fishing began on the North West Shelf in 1984 (Ref. 28206, 27266). Fishing is carried out on hard-bottom areas to the west or inshore from main areas worked in the past by Taiwanese pair trawlers. It first concentrated on the Monte Bello-Barrow Island area mainly near the coastal towns of Onslow, Port Hedland and Point Samson (Ref. 27266, 28209). The main area for trapping is now north of Broome.

Fish traps used in Western Australia are mostly circular ('O' traps) and are baited usually with pilchards (Sardinops neopilchardus).

Spangled emperors are targeted by handline fishers on the west coast. A small quantity of emperors are also taken by dropline.

Spangled emperors are the most abundant emperor caught in the North West Shelf Trap and Line Fishery, followed next in abundance by red-throat emperors, L. miniatus (Ref. 27266).

In the shallow water (10-50 m) fishery in the Northern Territory, spangled emperors comprise up to 50% of the catch.

Spangled and red-throat emperors are the only emperors of significance on the Great Barrier Reef although red-spot emperors are caught in fish traps on the outer slopes of mid-shelf reefs (Ref. 27260). Bottom fishing in Great Barrier Reef shallow lagoons at night catches mainly spangled emperors.

Most fish from the North West Shelf fishery are sent to Perth as whole, chilled fish. Some are gutted and brined before freezing.

Recreational fishery: Anglers also target spangled emperors to a lesser extent than red-throat emperors, both in Western Australia and Queensland. Emperors are caught with either fresh baits or whole or cut fish, crabs, prawns and squid, and tackle ranges from handlines to casting rigs. The largest emperor recorded by the Australian Anglers Association was 9.6 kg. from Queensland.

Spangled emperors are the largest component of recreational angling in the Ningaloo Marine Park, Western Australia. The recreational fishery in that State extends from the Houtman Abrolhos to Dampier Archipelago.

Resource status: Emperors comprised 47% of demersal fish in retained catches taken by Russian survey vessels on the North West Shelf between 1962 and 1973. Emperors and sea perch (Lutjanidae) comprised 40-60% by weight in 1962 but the amount dropped to about 10% in 1983 (Ref. 28206) (the emperor component of the total catch fell from 27.9% in 1967 to 5.4% in 1983 (Ref. 28006). This reduction in yield can partly be attributed to the removal of large epibenthos from the sea floor by the action of trawlers and to over-fishing these groups in the mixed species trawl fishery (Ref. 28206, 28207). The size composition also changed, with emperors (probably blue-spotted emperors) larger than 0.6 kg disappearing from the catch after 8 months of fishing (Ref. 28006). By 1986, the catch per unit of effort for emperors had declined by 65% from a peak in 1973. Whereas the abundance of emperors has continued to decline in trawled areas, the catch rate has increased since 1986 due to concentration of fishing effort on emperors by Taiwanese fleets (Ref. 28207).

As of 1993, there have been no studies on the resource status of emperors on the Great Barrier Reef and inshore areas of northern Australia. Similarly, there is no information on the resource status of emperors in Western Australian fisheries.

Also Ref. 2334, 13465.