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Dusky Flathead is an inshore and estuary fish found in QLD, NSW and VIC. Stocks in QLD and NSW are sustainable, while the VIC stock is undefined.

The biological stock structure of Dusky Flathead populations is unknown.

In the absence of information on biological stock boundaries, assessment of stock status is presented at the jurisdictional level—Queensland, New South Wales and Victoria.

Queensland

In Queensland, approximately 77% of the annual harvest for Dusky Flathead is caught by hook and line within the recreational sector [Yang et al. 2022]. The remaining harvest is predominantly caught by the commercial sector using mesh nets (mainly tunnel and gillnets) within the East Coast Inshore Fishery (ECIF). Most of the harvest in Queensland occurs in shallow coastal and estuarine waters south of Baffle Creek. 

The most recent stock assessment on the Queensland jurisdictional stock of Dusky Flathead (based on 2020 data) estimated the spawning biomass to be at 46% of unfished levels [Yang et al. 2022]. The latest combined commercial and recreational harvest estimate was approximately 135 t; consistent with the harvest recommended to maintain the stock at a target level of 50% unfished biomass (138 t per year), though considerably lower than MSY (189 t) [Yang et al. 2022]. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. 

According to Queensland logbook data, nominal effort in the commercial sector for Dusky Flathead peaked in 2004-05 (6440 boat days) and has gradually declined in the subsequent years. Part of this decline can be attributed to spatial closures within key fishing grounds. In March 2009, the Moreton Bay Marine Park Zoning Plan (2008) converted 16% of previously fishable waters to no-take zones and closed a further 8% to net fishing (van de Geer et al. 2013). A series of subsequent license buybacks by the Government substantially reduced the number of net license holders targeting Dusky Flathead (a decrease of 143 net licenses between 2008 and 2022). The commercial harvest of Dusky Flathead peaked in 1989–90 (approximately 85 t), subsequently declining to a historical low of approximately 23 t in 2020– 21. This decline can be partly attributed to the concurrent reduction in effort over this period. In 2021– 22, the commercial harvest of Dusky Flathead was approximately 27 t; less than half the long-term historical average (1988–89 to 2021–22: approximately 58 t). According to statewide surveys, the recreational harvest for Dusky Flathead has been variable among years, but with no clear changes over the last 20 years [QDAF 2021]. 

Since 2007, the size and age composition of Dusky Flathead in commercial and recreational catches have been relatively stable [unpublished, QDAF 2023]. All available size classes within the size slot limit (40–75 cm TL) are represented in the harvest, though fish between 40 and 60 cm TL are most common [unpublished, QDAF 2023]. The minimum size limit protects most male Dusky Flathead which grow slower and attain smaller maximum sizes than females [Gray and Barnes 2015, Gray, 2023]. It has been estimated that between 10 and 20 % of the yearly egg production in Queensland is likely to come from fish protected by the maximum size limit [Pollock 2015]. The above evidence indicates that the current level of fishing pressure is unlikely to cause this stock to become recruitment impaired. 

On the basis of the evidence provided above, Dusky Flathead in Queensland is classified as a sustainable stock.

Dusky Flathead biology [Gray and Barnes 2015, Hicks et al. 2015, Kailola et al. 1993]

Distribution of reported commercial catch of Dusky Flathead

Queensland – Indigenous (Management Methods). Please refer to https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Queensland – Commercial (Catch). QLD commercial and charter data have been sourced from the commercial fisheries logbook program. Further information is available from 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 are based at the whole of Queensland level and derived from statewide recreational fishing surveys. Where possible, estimates have been converted to weight (tonnes) using best known conversion multipliers. Conversion factors may display regional or temporal variability. In the absence of an adequate conversion factor, data are presented as number of fish.

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

New South Wales – Recreational (Catch). Henry and Lyle [2003]; West et al. [2015]; Murphy et al. [2020; 2022].

New South Wales – Indigenous (management methods). https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

Victoria – Indigenous (Management Methods). A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishing licence under the provisions of the Commonwealth’s Native Title Act 1993.

Victoria - Recreational fishing (Management Methods).  A recreational fishing licence is required, and  minimum  and maximum legal sizes  of 30 and 55 cm TL and a  bag limit of  5 apply for Dusky Flathead.  For further details see: https://vfa.vic.gov.au/recreational-fishing/recreational-fishing-guide

Commercial catch of Dusky Flathead - note confidential catch not shown

1. Bell, JD, Ingram, BA, Gorfine, HK and Conron SD 2023, Review of key Victorian fish stocks — 2022, Victorian Fisheries Authority Science Report Series No. 38, First Edition, June 2023. VFA: Queenscliff. 46pp.
2. Broadhurst, M and Stewart, J 2021, NSW Stock Status Summary 2020/21 — Dusky Flathead (Platycephalus fuscus), NSW Department of Primary Industries, NSW Fisheries, 9 pp.
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11. Hamer, P, Conron, S and Simpson, K 2019, Victorian Dusky Flathead symposium and recreational fishery online survey 2018, Recreational Fishing Grants Program Research Report.
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19. Queensland Department of Agriculture and Fisheries, 2023, Biological Monitoring Program – Dusky Flathead (Unpublished Data). For more information, visit: https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/monitoring-reporting/species-specific/dusky-flathead
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