*

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.

New South Wales

Dusky Flathead occur throughout estuaries and inshore areas of New South Wales, where they form a single stock, with at least some movements between estuaries; both during early life stages and as mature fish during their reproduction [Gray and Barnes 2015; Taylor et al. 2020; Broadhurst and Stewart 2021; Gray et al. 2022; Gray 2023]. The species is an important commercial and recreational target throughout its entire New South Wales distribution.

During the past decade, commercial catches of Dusky Flathead in New South Wales have fluctuated at between 110 and 172 tonnes (t) per year, and with more than 95% of the total caught using mesh nets (gillnets). During the past five years, catches have remained fairly stable at approximately 120 t, after reducing from 152 t in 2016. The latter reduction was associated with substantially reduced effort, but an increase in the nominal catch rate by mesh netters [Broadhurst and Stewart 2021]. Further, the sizes of Dusky Flathead measured from commercial catches in 2017 were similar to those from the preceding decade, suggesting broad temporal consistency in the size composition of the stock [Broadhurst and Stewart 2021]. 

The most recent recreational harvest estimate was approximately 182 000 or 115 t during 2019–20 [Murphy et al. 2022]. This estimate was based on a survey of recreational fishing licence (RFL) households, which comprised at least one person with a long-term (one or three year) fishing licence, but also included other fishers within the household. Similar surveys of RFL households were done in 2013–14 and 2017–18, during which considerably more (approximately 481 000 and 304 000) Dusky Flathead were recreationally harvested, but the numbers were commensurate with greater effort [Murphy et al. 2020; West et al. 2015]. In addition to these retained catches, large numbers (up to 68% of the total catches) of Dusky Flathead were released at each period (minimum legal size is 36 cm TL, and fishers are allowed only one individual greater than 70 cm TL within a total daily bag limit of 10 fish). The weight of evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired.

There are no modelled estimates of mortality for Dusky Flathead in New South Wales, with efforts limited to estuary-specific assessments of natural mortality based on maximum age [Gray 2023]. But it is well established that the species has very high short-term survival after being released by anglers [91%; Butcher et al. 2008]. While their survival after discarding by mesh netters is much less [23%; Broadhurst et al. 2009], in the last decade, mandated changes to mesh-net configurations, including increases in mesh size [Broadhurst et al. 2003, 2009; Gray et al. 2005] have improved selectivity, and therefore reduced discard mortality. Escape mortalities remain unknown, but these are presumed to be minimal [Uhlmann and Broadhurst 2015]. Consequently, the fishing mortality on undersized Dusky Flathead in New South Wales is likely to be quite low. The above evidence indicates 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, Dusky Flathead in New South Wales 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.
3. Broadhurst, MK, Gray, CA Young, DJ, and Johnson, DD 2003, Relative efficiency and size selectivity of bottom-set gill-nets for dusky flathead, Platycephalus fuscus and other species in New South Wales, Australia, Fishery and Marine Research, 50: 289–302.
4. Broadhurst, MK, Millar, RB and Brand, CP 2009, Mitigating discard mortality from dusky flathead Platycephalus fuscus gillnets, Diseases of Aquatic Organisms, 85: 157–166.
5. Butcher, PA, Broadhurst, MK and Cairns, SC 2008, Mortality and physical damage of angled and released dusky flathead Platycephalus fuscus, Diseases of Aquatic Organisms, 81: 127–134.
6. Conron, SD and Oliveiro, P 2016, State-wide Angler fishing Diary Program 2011–14 Recreational Fishing Grants Program Research Report June 2016, Department of Economic Development, Jobs, Transport and Resources, Queenscliff. 45 pp.
7. Gray, CA 2023, Historic, pre-stock enhancement, demographic conditions of exploited populations of dusky flathead, Platycephalus fuscus, in eastern Australia, Aquaculture and Fisheries, in press.
8. Gray, CA and Barnes, LM 2015. Spawning, maturity, growth and movement of Platycephalus fuscus (Cuvier, 1829) (Platycephalidae): fishery management considerations, Journal of Applied Ichthyology 31(3), 442–450.
9. Gray, CA, Broadhurst, MK, Johnson, DD and Young, DJ 2005, Influences of hanging ratio, fishing height, twine diameter and material of bottom-set gillnets on catches of dusky flathead Platycephalus fuscus and non-target species in New South Wales, Australia, Fisheries Science, 71: 1217–1228.
10. Gray, CA, Chapman, MG, Underwood, AJ and Rotherham D 2022, Spatial management of estuarine fisheries resources: do recreational-only fished estuaries provide conservation to harvested species? Reviews in Fish Biology and Fisheries 32, 1123–1140.
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.
12. Henry, GW and Lyle, JM 2003, The National Recreational and Indigenous Fishing Survey, Tasmanian Aquaculture and Fisheries Institute, Hobart. FRDC 99/158
13. Hicks T, Kopf, RK and Humphries, P 2015, Fecundity and egg quality of dusky flathead (Platycephalus fuscus) in East Gippsland, Victoria. Institute for Land Water and Society, Charles Sturt University, Report number 94. Prepared for the Recreational Fishing Grants Program, Fisheries Victoria, The State of Victoria Department of Economic Development, Jobs, Transport and Resources, Pp. 1–34. ISBN 978-1-86-467279-4.
14. Kailola, PJ, Williams, MJ, Stewart, PC, Reichelt, RE, McNee, A and Grieve, C 1993, Australian Fisheries Resources, Bureau of Rural Resources and the Fisheries Research and Development Corporation, Canberra, Australia.
15. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, Hughes, JM , and Taylor, MD 2022, Survey of recreational fishing in NSW, 2019/20 - Key results, Fisheries Final Report Series No. 161.
16. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, KE and Hughes, JM 2020, The NSW Recreational Fisheries Monitoring Program - survey of recreational fishing, 2017/18, NSW DPI - Fisheries Final Report Series No. 158.
17. Pollock, BR 2015, The annual spawning aggregation of dusky flathead Platycephalus fuscus at Jumpinpin, Queensland, Proceedings of the Royal Society of Queensland.
18. Queensland Department of Agriculture and Fisheries, 2021, Dashboard: Recreational Fishing Catch Estimates. Available at https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/monitoring-reporting/recreational-fishing/statewide-recreational-fishing-surveys/dashboard (Accessed: 29 September 2023)
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
20. Taylor, MD, Becker, A, Quinn, J, Lowry, MB, Fielder, S and Knibb, W 2020, Stock structure of dusky flathead (Platycephalus fuscus) to inform stocking management, Marine and Freshwater Research 71, 13782–1383.
21. Uhlmann, SS and Broadhurst, MK 2015, Mitigating unaccounted fishing mortality in gillnets and traps, Fish and Fisheries, 16: 183−229.
22. Uhlmann, SS and Broadhurst, MK 2015, Mitigating unaccounted fishing mortality in gillnets and traps, Fish and Fisheries, 16: 183−229.
23. van de Geer, C, Mills, M, Adams, VM, Pressey, RL and McPhee, D 2013, Impacts of Moreton Bay Marine Park on commercial fishermen, Marine Policy, 39: 248-256
24. West, LD, Stark, KE, Murphy, JJ, Lyle JM and Doyle, FA 2015, Survey of recreational fishing in New South Wales and the ACT, 2013/14. Fisheries Final Report Series.
25. Yang, WH, Martin, TSH and Moffitt, D 2022, Stock assessment of Queensland east coast dusky flathead (Platycephalus fuscus), Australia, with data to December 2020, Technical Report, State of Queensland, Brisbane