Dusky Flathead (2020)
Date Published: June 2021
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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.
Stock Status Overview
|New South Wales||New South Wales||Sustainable||
Commercial catch and CPUE, and length frequency
The biological stock structure of Dusky Flathead populations is unknown.
In the absence of information on biological stock boundaries, here 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 via mature fish during their reproduction [Gray and Barnes 2015; Taylor et al 2020]. 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 116 and 172 t per year, and with more than 95 per cent of the total caught using mesh nets. During the past five years, catches were initially consistent at 125 t, but peaked at 165 t in 2016, and declined to 118 t in each of 2018 and 2019. The latter reduction was associated with substantially reduced effort, and the nominal catch rate by mesh netters has increased during the past five years [Department of Primary Industries 2020]. Further, the sizes of Dusky Flathead measured from commercial catches in 2017 were similar to annual estimates during the preceding decade, suggesting broad temporal consistency in the size composition of the stock [Department of Primary Industries 2020].
The most recent recreational harvest estimate was ~304 000 fish or 190 t during 2017–18 [Murphy et al. 2020]. 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. A similar survey of RFL households was done in 2013–14 during which a comparable number (481 164) of individual Dusky Flathead were recreationally harvested. In addition to these retained catches, large numbers (up to 55 per cent of the total catches) of Dusky Flathead were released at each period (minimum legal size is 360 mm TL, and fishers are allowed only one individual >700 mm 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 current estimates of fishing or natural mortality for Dusky Flathead in New South Wales, but it is well established that the species has very high short-term survival after being released by anglers [91 per cent; Butcher et al. 2008]. While their survival after discarding by mesh netters is much less [23 per cent; 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, fishing mortality on undersized Dusky Flathead (360 mm TL) in New South Wales is likely to be quite low. The above evidence indicates that the currently 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]
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|Dusky Flathead||Females ≥ 16 years, 1 200 mm TL Males ≥ 11 years, 620 mm TL||Females 570 mm TL Males 320 mm TL|
Distribution of reported commercial catch of Dusky Flathead
|New South Wales|
|Hook and Line|
|Hook and Line|
|Hook and Line|
|Method||New South Wales|
|Fishing gear and method restrictions|
|In possession limits|
|Section 37 (1d)(3)(9), Aboriginal cultural fishing authority|
|Bag and possession limits|
|Fishing gear and method restrictions|
|New South Wales|
|Recreational||190 t (2017–18)|
Queensland – Indigenous (Management Methods) please refer to https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing
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.
Commercial catch of Dusky Flathead - note confidential catch not shown
- 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.
- Broadhurst, MK, Millar, RB, and Brand, CP 2009, Mitigating discard mortality from dusky flathead Platycephalus fuscus gillnets, Diseases of Aquatic Organisms, 85: 157–166.
- 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.
- Conron S., Giri K, Hamer P and Hall K 2016, Gippsland Lakes Fishery Assessment 2016. Fisheries Victoria Science Report Series No. 14
- 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.
- Conron, SD, Bell, JD, Ingram, BA and Gorfine, HK 2020, Review of key Victorian fish stocks — 2019, Victorian Fisheries Authority Science Report Series No. 15, First Edition, November 2020. VFA: Queenscliff. 176pp.
- Conron, SD, Grixti D and Morison AK 2010, Survival of snapper and black bream released by recreational hook-and-line fishers in sheltered coastal temperate ecosystems. Final report to Fisheries Research and Development Corporation Project No. 2003/074. Department of Primary Industries, Queenscliff, Victoria.
- Department of Primary Industries 2020, NSW DPI Commercial catch records, New South Wales Department of Primary Industries, Sydney.
- 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.
- 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.
- Hamer, P, Conron, S, and Simpson K 2019. Victorian Dusky Flathead symposium and recreational fishery online survey 2018. Recreational Fishing Grants Program Research Report.
- Henry, GW and Lyle JM, 2003, The National Recreational and Indigenous Fishing Survey. Tasmanian Aquaculture and Fisheries Institute, Hobart. FRDC 99/158
- Hicks T, Kopf RK, 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.
- Ingram, BA, Hall, K, and Conron, S 2016, Recreational fishery assessment 2016 – small eastern estuaries. Recreational Fishing Grants Program Research Report, Victorian Government, Department of Economic Development, Jobs, Transport and Resources.
- 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.
- Kemp, J, Bruce, T, Conron, S, Bridge, N, MacDonald, M and Brown, L 2013, Gippsland Lakes (non‐bream) fishery assessment 2011, Fisheries Victoria assessment report series no. 67, Fisheries Victoria, Victoria.
- Leigh, GM, Yang, WH, O'Neill, MF, McGilvray, JG and Wortmann, J 2019, Stock assessments of bream, whiting and flathead (Acanthopagrus australis, Sillago ciliata and Platycephalus fuscus) in South East Queensland, Technical Report, State of Queensland.
- McGilvray, J, Broadhurst, M, and Hamer, P, 2018, Dusky Flathead Platycephalus fuscus, in Carolyn Stewardson, James Andrews, Crispian Ashby, Malcolm Haddon, Klaas Hartmann, Patrick Hone, Peter Horvat, Stephen Mayfield, Anthony Roelofs, Keith Sainsbury, Thor Saunders, John Stewart, Simon Nicol and Brent Wise (eds) 2018, Status of Australian fish stocks reports 2018, Fisheries Research and Development Corporation, Canberra.
- Moreton Bay Seafood Industry Association 2012, Moreton Bay tunnel net fishery code of best practice.
- 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.
- Pollock, BR 2015, The annual spawning aggregation of Dusky Flathead Platycephalus fuscus at Jumpinpin, Queensland. Proceedings of the Royal Society of Queensland.
- QFish, Department of Agriculture and Fisheries, www.qfish.gov.au
- 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.
- Then, AY, Hoenig, NJ, Hall, NG, Hewitt, DA 2014, Evaluating the predictive performance of empirical estimators of natural mortality rate using information on over 200 fish species. ICES Journal of Marine Science.
- Uhlmann, SS and Broadhurst, MK 2015, Mitigating unaccounted fishing mortality in gillnets and traps. Fish and Fisheries, 16: 183−229.
- Webley, J, McInnes, K, Tiexiera, D, Lawson, A and Quinn R 2015, Statewide Recreational Fishing Survey 2013–14, Department of Agriculture and Fisheries, Queensland.
- 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.
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