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Red Emperor occur throughout the Western Pacific and Indian Oceans [Allen 1985]. The species' Australian distribution encompasses the entire northern coastline, from Cape Naturaliste in WA, around to the east coast, occasionally extending as far south as Sydney. Red Emperor is assessed as sustainable in the Gascoyne, Pilbara, and Kimberley management units. The Timor Sea, Arafura Sea, and Gulf of Carpentaria biological stocks are also sustainable, while the Joseph Bonaparte Gulf biological stock and East Coast Queensland management unit are classified as undefined.

Red Emperor are widely distributed throughout the Western Pacific and Indian Oceans, ranging from western and eastern Australia to southern Japan, and westward to east Africa and the southern Red Sea (Allen 1985). Within Australia, Red Emperor range from Cape Naturaliste (33°30’ S) in Western Australia, north and east across northern Australia and down the east coast to Sydney in New South Wales. Red Emperor is exploited primarily in the North Coast Bioregion of Western Australia [Newman et al. 2020]. Smaller catches are taken in the Northern Territory and Queensland. Red Emperor is one of the indicator species used to assess the status of the demersal resources in the North Coast Bioregion [Newman et al. 2018].

van Herwerden et al. [2009] examined the genetic connectivity of Red Emperor using mitochondrial DNA from samples collected at two locations in Western Australia (Browse Island, Kimberley region; Montebello Islands, Pilbara region) and two locations on the east coast (High Peak Island and Catfish Shoal, East Coast Queensland). The mitochondrial DNA data for Red Emperor did not differ genetically either within or between coasts at the locations examined, suggesting a panmictic population structure with high levels of gene flow among populations. This study indicates that eastern and western Australian populations of Red Emperor form a single inter-breeding genetic stock [van Herwerden et al. 2009] or one biological stock. The results of van Herwerden et al. [2009] confirm those derived by Johnson et al. [1993] using allozymes for Red Emperor in Western Australian waters. Johnson et al. [1993] examined allozyme samples of Red Emperor from the Lacepede Islands, Bedout island, Lowendal Islands, Ningaloo and Shark Bay. This study reported extensive connectivity and gene flow among populations throughout the sampled range of 1 400 km in Western Australia.

Stephenson et al. [2001] examined stable isotopes in sagittal otolith carbonates of Red Emperor from four locations; Shark Bay (Gascoyne), Ningaloo (Gascoyne), Pilbara and Broome (Kimberley). Significant differences in stable isotope ratios provided evidence that there was limited mixing of adult Red Emperor between three broad zones; Shark Bay (Gascoyne), Pilbara, and Broome (Kimberley), a distance of approximately 1 400 km [Stephenson et al. 2001]. Therefore, these broad locations could be managed separately for the purposes of fishery management, if management arrangements were established to harmonise with the spatial patterns of exploitation. Stephenson et al. [2001] reported partial mixing of Red Emperor from Pilbara west and east sites. The overlap in the multivariate analyses of otolith stable isotope signatures between some sites potentially reflects dispersal by a proportion of juvenile or adult fish. This suggests that, in Western Australia, Red Emperor can be managed as a number of separate management units. Additionally, Saunders et al. [2018] used otolith microchemistry and parasitology to identify separate biological Red Emperor stocks in the Joseph Bonaparte Gulf, Timor Sea, Arafura Sea and Gulf of Carpentaria.

Here, assessment of stock status is presented at the management unit level — Gascoyne, Pilbara and Kimberley (Western Australia) and East coast (Queensland); and at the biological stock level for the Joseph Bonaparte Gulf, Timor Sea, Arafura Sea and Gulf of Carpentaria.

Gascoyne

The Gascoyne management unit of Red Emperor is a component of the Gascoyne Demersal Scalefish Managed Fishery (Western Australia) (GDSMF) [Gaughan and Santoro 2020]. Red Emperor is assessed on the basis of the status of the indicator species for other demersal finfish species in the GDSMF (particularly Goldband Snapper [Newman et al. 2018]).

An assessment of fishing mortality derived from representative samples of the age structure of Goldband Snapper was undertaken in the GDSMF in 2017. These fishing mortality based assessments utilise reference levels defined below for the Pilbara management unit. The fishing mortality based assessments and associated uncertainty ranges indicated that the fishing mortality rate on Goldband Snapper was less than the target level, indicating that the level of exploitation experienced by Goldband Snapper in the Gascoyne has been low. Catches of Red Emperor in the GDSMF have been low and stable for the past 10 years (2010–19), ranging from 7–16 tonnes (t), with a mean annual catch of 14.3 t. The above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

Based on the evidence provided above, the Gascoyne (Western Australia) management unit is classified as a sustainable stock.

Kimberley

Red emperor is one of the indicator species used to assess the status of the demersal scalefish resources in the Kimberley subregion of the North Coast Bioregion of Western Australia [Newman et al. 2018]. The major performance measures for the Kimberley management unit of Red Emperor are spawning stock levels and fishing mortality estimated using an integrated age-structured assessment. The target reference level of spawning biomass is 40 per cent of unfished (1980) levels, with a threshold reference level of 30 per cent and limit reference level of 20 per cent. The spawning biomass level of Red Emperor was estimated to be approximately 30 per cent in the Northern Demersal Scalefish Managed Fishery (NDSMF) in 2017 [Newman et al. 2020]. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired.

An assessment of fishing mortality derived from representative samples of the age structure of Red Emperor has also been undertaken for the NDSMF. These fishing mortality based assessments utilise reference levels defined for the Pilbara management unit. The fishing mortality based assessments indicated that the fishing level on Red Emperor is at or below the limit level in 2017 [Newman et al. 2020]. This indicates that fishing is not having an unacceptable impact on the age structure of the population. Catch levels of Red Emperor in the NDSMF over the last 10 years (2010–19) have ranged from 128–192 t, with a mean annual catch of 141 t [Newman et al. 2020]. The above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

Based on the evidence provided above, the Kimberley (Western Australia) management unit is classified as a sustainable stock.

Pilbara

Red emperor is one of the indicator species used to assess the status of the demersal scalefish resources in the Pilbara subregion of the North Coast Bioregion of Western Australia [Newman et al. 2018]. The major performance measures for the Pilbara management unit of Red Emperor landed in the Pilbara Trap Managed Fishery and Pilbara Fish Trawl Interim Managed Fishery are spawning stock levels and fishing mortality estimated using an integrated age-structured assessment. The target reference level of spawning biomass is 40 per cent of unfished (1980) levels, with a threshold reference level of 30 per cent and limit reference level of 20 per cent. Estimates of the relative spawning biomass for the overall stock have fluctuated between the target and threshold levels in the Pilbara Demersal Scalefish Fisheries since the mid-1980s. The spawning biomass level of Red Emperor overall (across all management areas) was estimated to be above the threshold level in the Pilbara Demersal Scalefish Fisheries in 2015, the year the last integrated assessment was undertaken [Newman et al. 2020]. All scenarios evaluated in the assessment model indicate that there is a high probability that the estimate of spawning biomass of Red Emperor is above the threshold level. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired.

An assessment of fishing mortality derived from representative samples of the age structure of Red Emperor in the Pilbara management unit was also undertaken in 2015. These fishing mortality (F)-based assessments utilise the following reference levels based on ratios of natural mortality (M) that are applicable to each species, such that F_target = 2/3M, F_threshold = M and F_limit = 3/2M (DPIRD 2017). The fishing mortality based assessments indicated that the fishing level on Red Emperor in 2011 was generally between the target and the threshold level, but between the threshold and limit levels in some areas. This indicates that fishing was having an impact on the age structure of the population in some management areas.

Effort reductions since 2008 have resulted in decreasing catch levels and the total retained catches of Red Emperor in the Pilbara Demersal Scalefish Fisheries have been stable since trawl effort was reduced in 2009 as part of a stock rebuilding strategy. Recreational catches are a minor component of total catches. These stable annual catch trends and estimates of F that are below the limit level in all areas suggest no evidence of recent stock depletion. The stability in the adjusted fish trawl catch rates since 1998 indicates that stock abundance has remained stable during this period, with some indication of recent increasing abundance in the western area of the fishery. Catch levels of Red Emperor in the Pilbara over the last 10 years (2010–19) have ranged from 103–219 t, with a mean annual catch of 145 t [Newman et al. 2020]. The above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

Based on the evidence provided above, the Pilbara (Western Australia) management unit is classified as a sustainable stock.

Red Emperor biology [McPherson et al. 1992, McPherson and Squire 1992, Newman et al. 2000, 2001, Newman and Dunk 2002, Newman et al. 2010, O'Neill et al. 2011, DAF unpublished data 2018]

Distribution of reported commercial catch of Red Emperor.

Western Australia Active Vessels data is confidential as there were fewer than three vessels in the Pilbara Fish Trawl Interim Managed Fishery, the Pilbara Trap Managed Fishery and the West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery.

Western Australia – Commercial (management methods) Red Emperor forms part of the combined Total Allowable Commercial Catch for other mixed demersal species in the Gascoyne Demersal Scalefish Managed Fishery.

Western Australia – Recreational (Catch) Boat-based recreational catch is from 1 September 2017–31 August 2018. These data are derived from those reported in Ryan et al. 2019.

Western Australia – Recreational (management methods) A Recreational Fishing from Boat Licence is required for the use of a powered boat to fish or to transport catch or fishing gear to or from a land-based fishing location.

Western Australia – Indigenous (management methods) Subject to application of Section 211 of the Native Title Act 1993 (Cth), and the exemption from a requirement to hold a recreational fishing licence, the non-commercial take by Indigenous fishers is covered by the same arrangements as that for recreational fishing.

Northern Territory — Charter (management methods) In the Northern Territory, charter operators are regulated through the same management methods as the recreational sector, but are subject to additional limits on license and passenger numbers.

Northern Territory – Indigenous (management methods) The Fisheries Act 1988 (NT), specifies that “…without derogating from any other law in force in the Territory, nothing in a provision of this Act or an instrument of a judicial or administrative character made under it limits the right of Aboriginals who have traditionally used the resources of an area of land or water in a traditional manner from continuing to use those resources in that area in that manner”.

Queensland – Indigenous (management methods) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Commercial catch of Red Emperor - note confidential catch not shown

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