*

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.

Arafura Sea

Red Emperor were initially harvested by the foreign trawl fleet operating in this region in the 1970s and 1980s with a peak catch of 69 tonnes (t) recorded in 1989. In 1991 this fleet left Northern Territory waters and only small catches were recorded by trap and line gear in the Demersal Fishery (DF). From 1995 a single trawl vessel in the fishery resulted in a slight increase in catch which was further increased when three additional trawlers commenced fishing in 2012. This catch peaked at 25 t in 2017 before declining to 9 t in 2019.

A preliminary assessment using catch data from all commercial fisheries applied to a modified catch-MSY model (developed by Martell and Froese [2013] and modified by Haddon et al. [2018]), estimated that the 2019 biomass of Red Emperor was 58 per cent of unfished levels [Saunders 2020a] suggesting that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Similarly, the fishing mortality in 2019 was 0.12 which was around the target level and well below the limit reference point  indicating that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, Red Emperor in the Arafura Sea biological stock is classified as a sustainable stock.

Gulf of Carpentaria

Red Emperor in this stock has historically been taken by demersal fish trawl (Gulf of Carpentaria Developmental Fin Fish Trawl Fishery (GOCDFFTF) and Northern Territory Demersal Fishery (DF)).There is no reliable estimate of recreational or Indigenous harvest of Red Emperor in the Gulf of Carpentaria, but it is expected to be minor given the offshore nature of the fishery. This stock was also exposed to historical fishing from foreign fleets during the 1950s to the 1980s [O’Neill et al. 2011]. These catches peaked during the 1970s at approximately 30 t and were only slightly higher than the recent peak catch of 23 t in 2008. Commercial catches were initially dominated by the GOCDFFTF however these have declined markedly since 2012 as a result of transfer of effort to Northern Territory stocks outside the Gulf of Carpentaria. In 2019, the commercial catch increased to 9 t due to the DF substantially increasing its fishing effort in this stock area targeting Saddletail and Crimson Snappers (Lutjanus malabaricus and Lutjanus erythropterus).

A preliminary assessment using catch data from all commercial fisheries applied to a modified catch-MSY model (developed by Martell and Froese [2013] and modified by Haddon et al. [2018]), estimated that the 2019 biomass of Red Emperor was 59 per cent of unfished levels [Saunders and Roelofs 2020] suggesting that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Similarly, the fishing mortality in 2019 was 0.07 which was well below the limit reference point indicating that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, Red Emperor in the Gulf of Carpentaria biological stock is classified as a sustainable stock.

Joseph Bonaparte Gulf

Harvest of this Red Emperor stock was first reported in 1985, and the average catch from trap and line vessels in the Demersal Fishery (DF) to 2011 was very small (average < 1 t) compared to the adjacent Timor Sea stock. From 2012 a trawler entered the fishery and catches increased to a peak of 12 t in 2019. A trawl survey conducted on this stock [Ramm 1994] did not provide an estimate of Red Emperor biomass. Consequently, there is insufficient evidence to classify the status of this stock.

Based on the evidence above, the Joseph Bonaparte biological stock is classified as an undefined stock.

Timor Sea

Red Emperor harvest in this stock began in 1988, and quickly peaked at just over 100 t in 1991 as the Timor Reef Fishery (TRF) quickly developed. However, targeting quickly shifted to the more abundant Goldband Snapper thereafter, and only small annual catches (average <10t) were reported between 1994–1999.  Thereafter, the trap effort in the TRF and  Demersal Fishery (DF) increased substantially and catches of Red Emperor increased to an annual average of 37 t during 2000–2019.

A preliminary assessment using catch data from all commercial fisheries applied to a modified catch-MSY model (developed by Martell and Froese [2013] and modified by Haddon et al. [2018]), estimated that the 2019 biomass of Red Emperor was  62 per cent of unfished levels [Saunders 2020b] suggesting that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Similarly, the fishing mortality in 2019 was 0.07 which was well below the limit reference point  indicating that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, Red Emperor in the Timor Sea biological stock 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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