I & I NSW
Wild Fisheries research Program
Dusky Flathead
(Platycephalus fuscus)
Exploitation Status
Fully Fished
Commercial landings and catch rates are steady, but the species is primarily harvested by
recreational fishers. Better catch information is required for the recreational fishery.
Scientific name
Standard name
comment
Platycephalus fuscus
dusky flathead
 
Platycephalus fuscus
Image © Bernard Yau
Background
The dusky flathead (Platycephalus fuscus) is
endemic to Australia occurring from Cairns
in Queensland to SA. In NSW waters, dusky
flathead are found primarily within estuaries,
but also occur in inshore ocean waters. They
are a bottom dwelling fish and are normally
found on soft substrates, including mud, sand
and seagrass. Dusky flathead eat small fish and
a variety of invertebrates including prawns,
crabs and squid. They are essentially ambush
predators that lie and wait (often partly buried)
for passing prey.
Spawning appears to occur both in the lower
reaches of estuaries and in the sea, typically
during summer. The larvae enter estuaries and
the small juveniles subsequently live in the
same habitats as the adults. Dusky flathead
grow quickly, reaching 40 cm total length (TL)
after 3 years in NSW. They mature at around
20 cm TL (males) and 55 cm (females). They are
reported to reach 120 cm in length, and about
10 kg in weight, but the majority of fish caught
are 40 to 50 cm in length and 0.5 to 1 kg. The
oldest fish in a recent NSW study was aged
16 years, but the majority of fish in catches are
aged 2 to 5 years.
The recreational catch of dusky flathead greatly
exceeds the commercial catch. The commercial
catch of dusky flathead is mostly taken by the
Estuary General Fishery. The highest levels of
commercial catches occur during the winter
months when overnight setting of mesh nets is
permitted.
s t a t u s o f f i s h e r i e s r e s o u r c e s i n n s w , 2 0 0 8 / 0 9 D u s k y F lat h ead | p 99
wild fisheries research program
Additional Notes
Landings by Commercial Fishery of Dusky Flathead
• Results of studies of growth and reproductive
biology have recently been published (Gray
and Barnes, 2008)
250
200
150
Landings (t)
0
50
• Assessments for this species need to
acknowledge the variability between
estuaries.
100
• The commercial catch declined after 2000
because of licence buy-outs during the
creation of Recreational Fishing Havens and
Marine Parks but landings have increased
again since 2004/05.
Estuary General (Primary Species)
• There is a minimum legal length of 36 cm
total length (TL) and a recreational bag limit
of 10 dusky flathead (with only one fish
greater than 70 cm TL).
97/98
99/00
01/02
03/04
05/06
07/08
Financial Year
Reported landings of dusky flathead by NSW commercial
fisheries from 1997/98. Fisheries which contribute less
than 2.5% of the landings are excluded for clarity and
privacy.
Catch
200
1.0
0.8
0.6
0.0
250
0.2
Historical Landings of Dusky Flathead
Catch Per Unit Effort Information of Dusky Flathead
Harvested by Mesh-Netting in NSW
0.4
The annual recreational harvest of Dusky
Flathead in NSW is likely to lie between 570
and 830 t. This estimate is based upon the
results of the offsite National Recreational and
Indigenous Fishing Survey (Henry and Lyle,
2003) and onsite surveys undertaken by
I & I NSW.
Relative Catch Rate
Recreational Catch of Dusky Flathead
00/01
02/03
04/05
06/07
08/09
150
Financial Year
100
Catch rates of dusky flathead harvested using meshnetting for NSW. Two indicators are provided: (1) median
catch rate (lower solid line); and (2) 90th percentile of
the catch rate (upper dashed line). Note that catch rates
are not a robust indicator of abundance in many cases.
Caution should be applied when interpreting these
results.
0
50
Landings (t)
98/99
58/59
68/69
78/79
88/89
98/99
08/09
Financial Year
Commercial landings (including available historical
records) of dusky flathead for NSW from 1952/53 to
2008/09 for all fishing methods. Note the decrease after
1999/00 with the introduction of Recreational Fishing
Havens.
p 100 | D u s k y F lat h ead
s tat u s o f f i s h e r i e s r e s o u r c e s i n n s w, 2 0 0 0 8 / 0 9
Growth Curve of Dusky Flathead - Males
Length Frequency of Dusky Flathead
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0.10
0.08
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0.00
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0
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1
2
30
3
4
5
6
50
60
70
90
100
Proportion
0.08
0.10
1995/96−1996/97
n = 25 284
0.02
Age-length data with fitted growth curve for male dusky
flathead (Gray and Barnes, 2008). Lengths are presented
as total length (TL).
0.00
Growth Curve of Dusky Flathead - Females
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80
7
Age (years)
100
40
0.06
20
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0.04
TL (cm)
30
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0.02
40
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1969/70−1989/90
n = 25 670
0.06
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Proportion
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0.04
50
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30
40
50
60
70
80
90
100
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0.10
Proportion
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0
2007/08−2008/09
n = 6588
0.08
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0.06
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0.04
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0.02
80
60
40
TL (cm)
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20
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5
10
15
Age (years)
Age-length data with fitted growth curve for female
dusky flathead (Gray and Barnes, 2008). Lengths are
presented as total length (TL).
30
40
50
60
70
80
90
100
TL (cm)
The length distribution of dusky flathead in NSW
commercial landings was relatively stable from the
1970s to the 1990s. There was an increase in the relative
proportion of larger fish (>40 cm total length (TL)) in
catches during the period 1995 to 1997. The minimum
legal length for dusky flathead was increased from 33 cm
to 36 cm TL in July 2001.
D u s k y F lat h ead | p 101
wild fisheries research program
Fur ther Reading
Anon. (1981). The ecology of fish in Botany Bay
- biology of commercially and recreationally
important species, State Pollution Control
Commission of New South Wales.
Broadhurst, M.K., C.A. Gray, D.D. Reid, M.E.L. Wooden,
D.J. Young, J.A. Haddy and C. Damiano (2005).
Mortality of key fish species released by recreational
anglers in an Australian estuary, Journal of
Experimental Marine Biology and Ecology 321: 171179.
Broadhurst, M.K., C.A. Gray, D.J. Young and D.D.
Johnson (2003). Relative efficiency and size
selectivity of bottom-set gillnets for dusky flathead
Platycephalus fuscus, and other species in New
South Wales, Australia, Archive of Fishery and Marine
Research 50 (3): 289-302.
Gray, C.A. (2002). Management implications of
discarding in an estuarine multi-species gill net
fishery, Fisheries Research 56: 177-192.
Gray, C.A., B.C. Pease, S.L. Stringfellow, L.P. Raines, B.K.
Rankin and T.R. Walford (2000). Sampling estuarine
fish species for stock assessment, FRDC Project
94/042. NSW Fisheries Final Report Series No. 18.
Cronulla, NSW Fisheries: 196 pp.
Gray, C.A., D.D. Johnson, D.J. Young and M.K.
Broadhurst (2003). Bycatch assessment of the
Estuarine Commercial Gill Net Fishery in NSW. Final
Report to Fisheries Research and Development
Corporation. Project 2000/172.
Gray, C.A., D.D. Johnson, D.J. Young and M.K.
Broadhurst (2004). Discards from the commercial
gillnet fishery for dusky flathead, Platycephalus
fuscus, in New South Wales, Australia: spatial
variability and initial effects of change in minimum
legal length of target species, Fisheries Management
and Ecology 11: 323-333.
Gray, C.A., D.D. Johnson, M.K. Broadhurst and D. Young
(2005). Seasonal, spatial and gear-related influences
on relationships between retained and discarded
catches in a multi-species gillnet fishery, Fisheries
Research 75: 56-72.
Gray, C., A., and L. M. Barnes (2008). Reproduction and
growth of dusky flathead (Platycephalus fuscus) in
NSW estuaries. Final Report Series No. 101. Cronulla,
NSW Department of Primary Industries: 26 pp
Gray, C.A., M.K. Broadhurst, D.D. Johnson and D.J.
Young (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.
p 102 | D u s k y F lat h ead
Gray, C.A., V.J. Gale, S.L. Stringfellow and L.P.
Raines (2002). Variations in sex, length and
age compositions of commercial catches of
Platycephalus fuscus (Pisces: Platycephalidae) in
New South Wales, Australia, Marine and Freshwater
Research 53: 1019-1100.
Henry, G.W. and J.M. Lyle (2003). The National
Recreational and Indigenous Fishing Survey. Final
Report to the Fisheries Research & Development
Corporation and the Fisheries Action Program
Project FRDC 1999/158. NSW Fisheries Final Report
Series No. 48. 188 pp. Cronulla, NSW Fisheries.
Potter, I.C. and G.A. Hyndes (1999). Characteristics
of the ichthyofaunas of southwestern Australian
estuaries, including comparisons with holarctic
estuaries and estuaries elsewhere in temperate
Australia: A review. Australian Journal of Ecology 24:
395-421.
Queensland Fisheries. (2010). Stock status of
Queensland’s fisheries resources 2009-10.
Queensland, Department of Employment, Economic
Development and Innovation: 65 pp.
Steffe, A.S. and D.J. Chapman (2003). A survey of
daytime recreational fishing during the annual
period, March 1999 to February 2000, in Lake
Macquarie, New South Wales. Final Report Series
No. 52. Sydney, NSW Fisheries. 124 pp.
Steffe, A.S., J.J. Murphy, D.J. Chapman and C.C. Gray
(2005). An assessment of changes in the daytime
recreational fishery of Lake Macquarie following
the establishment of a ‘Recreational Fishing Haven’.
Final Report Series No. 79. Cronulla, NSW Fisheries.
103 pp.
Steffe, A.S., J.J. Murphy, D.J. Chapman, G.P. Barret and
C.C. Gray (2005). An assessment of changes in the
daytime, boat-based, recreational fishery of the
Tuross Lake estuary following the establishment of a
‘Recreational Fishing Haven’. Final Report Series
No. 81 Cronulla, NSW Fisheries. 70 pp.
Steffe, S., J. Murphy, D. Chapman, B.E. Tarlington,
G.N.G. Gordon and A. Grinberg (1996). An
assessment of the impact of offshore recreational
fishing in New South Wales on the management of
commercial fisheries. Project no. 94/053. Sydney,
NSW Fisheries Research Institute: 139 pp.
West, R.J. (1993). Estuarine fisheries resources of two
south eastern Australian rivers. Sydney, University of
NSW. PhD Thesis.
Please visit the CSIRO website,
http://www.marine.csiro.au/caab/ and search for the
species code (CAAB) 37 296004, common name or
scientific name to find further information.
© State of New South Wales through Industry and Investment NSW 2010. You may copy, distribute and otherwise freely deal with this publication for any purpose, provided that you attribute Industry and Investment NSW as the owner.
Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (April 2010). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of Industry and Investment NSW or the user’s independent adviser.