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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. All stocks of Red Emperor in Australia are considered sustainable.

Red Emperor is 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 in Western Australia is exploited primarily in the North Coast Bioregion [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

Red Emperor in the Gascoyne are caught by commercial line fishers in the Gascoyne Demersal Scalefish Managed Fishery and the recreational/charter sectors. Red Emperor is assessed based on the status of the indicator species, particularly Goldband Snapper, for the Gascoyne Demersal Scalefish Resource (GDSR), that are representative of the inshore demersal species occurring at depths of 30–250 m [Newman et al. 2018]. The inshore demersal indicator species in the Gascoyne have been classified as sustainable. The level of risk associated with the sustainability of Red Emperor in the GDSR is assessed as low. This assessment of Red Emperor is supported by the results of a data-limited Catch-MSY assessment, where recent catches were compared to median model predictions for maximum sustainable yield (MSY).

Total catches of Red Emperor in the Gascoyne over the last 10 years (2013–22) have ranged from 21–38 t (mean annual catch 30 t). This represents a moderate decline in the total catch compared to the previous 10 years (mean annual catch 38 t). The combined recreational and charter catch has been comparable to the commercial catch over the past 10 years, averaging approximately 55% of the total catch. Analyses using a Catch-MSY model applied to annual catches for this species (1976–2022), demonstrated that the annual catches began below the median model prediction for MSY but increased above the upper 95% CI of MSY from 1986–89, then fluctuated within the MSY range, then increased above the 95% CI from 1998–2007, but have since fluctuated around MSY. This is also consistent with the predicted values for biomass declining below BMSY (0.5) in 2004 and having remained between 25% BMSY and BMSY for the remainder of the time series. Fishing mortality has been above FMSY since 2006 but was below in 2022. However, it is important to recognise that Catch-MSY is a data-limited technique with relatively strong assumptions, dependent on user inputs. For this assessment, assumptions included specified ranges for initial depletion (0.5–0.975), based on likely catch prior to the start of the time series, final depletion (0.05–0.5), based on recent catches relative to maximum recorded annual catch, and low resilience (r=0.1–0.6, consistent with species longevity, of approximately 41 years in WA). Given recent catches of this species being around the predicted MSY, and the status of the indicator species for the GDSR, it is considered unlikely that the biomass of Red Emperor in the Gascoyne is depleted.

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 in the Kimberley management unit of the North Coast Bioregion of Western Australia [Newman et al. 2018] and as such the stock status of Red Emperor contributes to determining the risk-level for the biological sustainability of the demersal scalefish resources in the Kimberley management unit. Red Emperor is landed commercially in the Northern Demersal Scalefish Managed Fishery (NDSMF). The major performance measures for the Kimberley management unit of Red Emperor are periodic assessments of spawning stock levels and fishing mortality estimated using an integrated age-structured model relative to standard reference levels and fishing mortality from catch curve analysis derived from representative samples of the age structure. Catch, effort and/or catch rates for the indicator species/fishing sector are also reviewed annually, to determine whether they are consistent with current harvest control rules (HCRs) for the resource [DPIRD 2017]. An assessment was undertaken in 2018 and included age composition collected during fisheries independent sampling in 2016–17.

The spawning biomass level of Red Emperor was estimated to be approximately 30% in the NDSMF in 2017 [Wakefield et al. 2023]. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. The fishing mortality-based assessments indicated that the fishing level on Red Emperor is at or below the limit level (F=3/2M) in 2017 [Wakefield et al. 2023]. This indicates that fishing is not having an unacceptable impact on the age structure of the population. The 2018 assessment resulted in a medium risk to the stock over the next 5 years.

Total catch of Red Emperor in the Kimberley over the last 10 years (2013–22) have ranged from 132–194 t, with a mean annual catch of 147 t. This is consistent with the averages catches across the previous 10 years of 155 t. Recreational and charter catch are very low compared to the commercial catch, in the past 10 years where reliable catches estimates are available, the proportion of the total catch has averaged < 1%. Since 2017, fisheries-dependent catch rates have remained stable with no evidence of a marked decline. 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]. Red Emperor is landed commercially in the Pilbara Trap Managed Fishery, Pilbara Fish Trawl (Interim) Managed Fishery, and the Pilbara Line Fishery. The major performance measures for the Pilbara management unit of Red Emperor are periodic assessments of spawning stock levels and fishing mortality estimated using an integrated age-structured model relative to standard reference levels and fishing mortality from catch curve analysis derived from representative samples of the age structure. Catch, effort and/or catch rates for the indicator species/fishing sector are also reviewed annually, to determine whether they are consistent with current harvest control rules (HCRs) for the resource [DPIRD 2017]. An assessment was undertaken in 2020 and included a representative age composition collected during fishery dependent sampling in 2019.

Estimates of the relative spawning biomass for the overall stock have fluctuated above threshold levels in the Pilbara Demersal Scalefish Fisheries since the mid-1980s, they dropped below threshold levels in about 2006, and based on the 2020 assessment had increased to about the threshold level [Wakefield et al. 2023]. All scenarios evaluated in the assessment model indicated that there is a high probability that the estimate of spawning biomass of Red Emperor is around the threshold level in 2019. This indicates that fishing was having an impact on the age structure of the population.

Total catch of Red Emperor in the Pilbara over the last 10 years (2013–22) has ranged from 114–230 t, with a mean annual catch of 172 t. This is comparable to the average catches across the previous 10 years of 176 t. Recreational and charter catch are relatively low compared to the commercial catch, in the past 10 years where reliable catches estimates are available, the proportion of the total catch has averaged approximately 7%. Trawl effort was reduced in 2009 as part of a stock rebuilding strategy, which resulted in stabilising the total retained catches of Red Emperor in the Pilbara Demersal Scalefish Fisheries at about 127 t per year from 2009 to 2015. These commercial catches increased from 2015 to a peak of 215 t in 2019 but have dropped back to previous levels in the last two years. Adjusted catch rates of Red Emperor from the commercial trawl fishery have followed a similar trend, generally increasing from 2014 to 2019, before declining over the last three years. On the basis of the most recent assessment in 2020, the spawning biomass was estimated to be at the threshold level (BMSY) and thus classified as sustainable [Wakefield et al. 2023]. Since that assessment catch rates have shown a declining trend, thus increasing the level of uncertainty regarding current spawning biomass levels. 

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; Sumpter et al. 2022]

Distribution of reported commercial catch of Red Emperor.

Western Australia. Active Vessels data are 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 2020–31 August 2021. These data are derived from those reported in Ryan et al. 2022.

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: “Unless expressly provided otherwise, nothing in this Act derogates or limits the right of Aboriginal people who have traditionally used the resources of an area of land or water in a traditional manner to continue to use those resources in that area in that manner.”

Queensland – Commercial (Catch). Queensland commercial and charter data have been sourced from the commercial fisheries logbook program.  Further information is available through the Queensland Fisheries Summary Report (https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/data/queensland-fisheries-summary-report)  

Queensland – Recreational Fishing (Catch). Data based at the whole of Queensland level and derived from statewide recreational fishing surveys. Estimates have been converted to weight (tonnes) using best known conversion multipliers. Conversion factors may display regional or temporal variability. 

Queensland – Indigenous (Management Methods). For more information see: https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing.

Queensland – Commercial (Management Methods). Harvest strategies available at: https://www.daf.qld.gov.au/business-priorities/fisheries/sustainable/harvest-strategy

Commercial catch of Red Emperor - note confidential catch not shown

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