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Redspot Emperor is found throughout tropical Australia in both coastal and offshore habitats. Stocks In NT and WA are classified as sustainable, while stocks found on the east coast of QLD and in the Gulf of Carpentaria are undefined. 

Photo credit: Matthew Dorter

Redspot Emperor is a widespread Indo-Pacific species, found throughout tropical Australia in both coastal and offshore habitats. This species inhabits northern Australia, with its range extending from approximately Gladstone, Queensland in the east, to Port Headland Western Australia, in the west [Carpenter and Allen 1989].

There is no information on population connectivity for this species in Australian waters and subsequently, this species has been assessed at the jurisdictional level for the Northern Territory and Western Australia. In Queensland, geographic separation caused by Torres Strait most likely results in limited movement between the Queensland east coast and the Queensland side of the Gulf of Carpentaria, consequently, this species has been assessed as two management units in this state.

Here, assessment of stock status is presented at the jurisdictional level–Western Australia and Northern Territory, and the management unit level–Gulf of Carpentaria Queensland and East Coast.

Northern Territory

Redspot Emperor was initially harvested by the foreign trawl fleet operating in this region in the 1970s and 1980s with catches up to 264 t [O'Neill et al. 2011]. In 1991 this fleet left Northern Territory waters and from 1995 a single trawl vessel in the fishery resulted in catches of this species resuming. Catches were initially relatively low (averaging 32 t) but increased when three additional trawlers commenced fishing in 2012. Catch in the last 10 years (2013–22) has ranged from 48 t to 130 t, at an annual average of 85 t. This species is primarily encountered offshore in Northern Territory and consequently recreational and charter catch is minimal [West et al. 2022]. Similarly, indigenous catch is unknown, but given this species offshore distribution, is also assumed to be negligible. 

A fishery independent survey was undertaken in 2021 to estimate the relative biomass of key offshore species in Northern Territory waters. As a result of this work the biomass of Redspot Emperor across the Northern Territory jurisdiction was estimated to be 8,153 t with a coefficient of variation of 0.17 [Knuckey and Koopman 2022]. The commercial harvest in this stock has averaged 85 t in the last 10 years (2013–22), which represents a harvest fraction of 1.05% of the estimated biomass. It is important to note that the survey was designed to obtain a time-series of consistent and robust relative abundance indices and due to uncertainties around assumptions of catchability, herding and escapement, this one-off estimate of absolute abundance should be used with caution [Knuckey and Koopman 2022]. Regardless, this estimate of biomass can assist in understanding the impact fishing has on this stock, with the low level of catch relative to biomass size indicating the stock is unlikely to be depleted and the level of fishing mortality is unlikely to result in the stock becoming recruitment impaired.

On the basis of the evidence provided above, Redspot Emperor in the Northern Territory jurisdiction is classified as a sustainable stock.

Redspot Emperor biology [Currey et al. 2009; Currey et al. 2013; Grandcourt 2002; Johnson unpublished; Mobiha 1991]

Distribution of reported commercial catch of Redspot Emperor – confidential catch is not shown

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

Queensland – Recreational Fishing (Catch). Data with high uncertainty (Residual Error greater than 50 %) has been excluded and listed as unknown. More information available at: https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/monitoring-reporting/statewide-recreational-fishing-surveys

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

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

Western Australia – Recreational (catch). Boat-based recreational catch between 1 September 2020 and 31 August 2021 from Ryan et al. [2022]. Please note that catches of Blue Threadfin are underestimates as shore-based and boat-based fishers that only operated in freshwater were out of scope of the survey.

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.

Commercial catch of Redspot Emperor - note confidential catch not shown

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