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
Commercial catch and CPUE, angler diary catch rates 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.
Until its recent closure, the Gippsland Lakes Fishery was the only remaining Victorian fishery to commercially harvest Dusky Flathead. Recreational anglers continue to catch the species in the Gippsland Lakes, and in various eastern Victorian estuaries. Catch information is only available for the Gippsland Lakes, and, Mallacoota Inlet, and Lake Tyers. This assessment therefore focuses on those locations.
The impact of fishing pressure on stock biomass was evaluated using recreational CPUE and size composition data from fishers participating in an angler diary program [Conron and Oliveiro 2016]. The CPUE obtained from angler diarists showed a declining trend in Gippsland Lakes over almost two decades noting the low sample sizes and associated high uncertainty in the data [Conron et al. 2020]. Angler diarist CPUE declined in Mallacoota Inlet from 1999–2011, before stabilising at around one fish per angler hour through until 2018–19 [Hamer et al 2019, Conron et al. 2020]. The CPUE of angler diarists in Lake Tyers increased from 1999–2004 and was highly variable throughout the 2000s. From 2010, there was a consistent decline in CPUE from around 2.5 fish per hour to less than 1.0 fish per hour [Conron et al. 2020]. Elevated CPUE during 2004–2009 from angler diarists in Mallacoota Inlet was likely reflective of a strong recruitment event. Nevertheless, the time series is too brief to determine if this is part of the boom-bust cycle of recruitment that characterises this species [Hamer et al 2019; Hicks et al. 2015] or represents an ongoing depleted state in which recruitment has become impaired. A reduction in participation in the angler diary program has increased the uncertainty of angler diarist CPUE in recent years [Conron et al. 2020].
There is no direct measure of recreational fishing pressure for the Gippsland Lakes, Mallacoota Inlet and Lake Tyers estuarine systems. From 2003, slot limit regulations and reduced bag limits were introduced in Victoria specifically for Dusky Flathead to ameliorate the risks of overfishing. The regulations have been refined over time as more information became available, with the current regulations (minimum legal length 30 cm, maximum legal length 55cm, daily bag limit of 5) being established in 2012 [Hamer et al. 2019].
On balance, insufficient information exists to confidently determine stock status. Recreational catch rates (CPUE) have stabilised since 2014, however, future trends are uncertain as there is a lack of reliable information of recent recruitment.
On the basis of the evidence provided above, Dusky Flathead in Victoria is classified as an undefined 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
|Hook and Line|
|Hook and Line|
|Customary fishing permits|
|Indigenous||Unknown (No catch under permit)|
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.
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- 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.
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