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Stock Status Overview
|Victoria||Victoria||GLF||Sustainable||Commercial catch and CPUE|
- Gippsland Lakes Fishery (VIC)
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 Victoria1–6.
Most Dusky Flathead caught in Victoria are taken from the Gippsland Lakes using mesh net, although they are also caught incidentally using other methods. The most recent assessment for Dusky Flathead in the Gippsland Lakes (the system where most Dusky Flathead are caught in Victoria) was undertaken in 20165. Catches of Dusky Flathead reached a historical peak in 2006, when 53 t were harvested and then declined to 8 t in 20145,6. In 2015, catches increased to 12 t, which is still double the size of commercial catches from 2000.
Commercial catch rates were greatest during 2005–06 (3.5 kg per km per hour), although catch rates have since declined5, the 5-year average mesh net catch rate over 2014–15 of 1.12 kg per km per hour was above the long-term average of 0.83 kg per km per hour. The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished; however, declining catch rates will be closely monitored in the future.
Available recreational catch data (2005, 2006, 2009, and 2010) indicate that recreational fishers in the Gippsland Lakes rarely take Dusky Flathead larger than 500 mm total length (TL)6. In November 2013, Victoria introduced a slot limit for recreationally caught Dusky Flathead of 300–550 mm. The number of licensed commercial fishers in Victorian waters was reduced by two-thirds between 1986–87 and 2010–11. The majority of the licence removals occurred as a result of voluntary licence buyback schemes conducted in 1999–2000 and 2005–06.
A biological study of Dusky Flathead caught in Eastern Victoria estimated a potential annual fecundity of up to 4.8 million eggs (764 mm TL); and that the size of maturity for females was 328 mm (± 24 mm standard error) which is slightly larger than the minimum size slot length for recreational fishers13. Hicks (2015) suggested that the management of Dusky Flathead could be based on maintaining spawning biomass rather than implementing size restrictions on recreational fishers. The slot limits are likely to be effective in maintaining trophy size fish and while protecting recruits up to spawning size.
The above evidence indicates that the current level of fishing pressure is unlikely to cause the stock to become recruitment overfished.
On the basis of the evidence provided above, Dusky Flathead in Victoria is classified as a sustainable stock.
Dusky Flathead biology4,14
|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
|Hand Line, Hand Reel or Powered Reels|
|Fishing gear and method restrictions|
|Fishing gear and method restrictions|
|In possession limits|
|12 in GLF|
- Gippsland Lakes Fishery (VIC)
|Commercial||12.50t in GLF|
- Gippsland Lakes Fishery (VIC)
a Queensland - Indigenous In Queensland, under the Fisheries Act 1994 (Qld), Indigenous fishers are able to use prescribed traditional and non-commercial fishing apparatus in waters open to fishing. Size and bag limits and seasonal closures do not apply to Indigenous fishers. Further exemptions to fishery regulations can be obtained through permits.
b New South Wales - Indigenous Aboriginal Cultural Fishing Interim Access Arrangement - allows an Indigenous fisher in New South Wales to take in excess of a recreational bag limit in certain circumstances, for example, if they are doing so to provide fish to other community members who cannot harvest themselves.
c Victoria - Indigenous Aboriginal cultural fishing authority - the authority that Indigenous persons can apply to take catches outside the recreational limits under the Fisheries Management Act 1994 (NSW), Section 37(1)(c1), Aboriginal cultural fishing authority.
d Victoria - Indigenous In Victoria, regulations for managing recreational fishing are also applied to fishing activities by Indigenous people. Recognised Traditional Owners (groups that hold native title or have agreements under the Traditional Owner Settlement Act 2010 [Vic]) are exempt (subject to conditions) from the requirement to hold a recreational fishing licence, and can apply for permits under the Fisheries Act 1995 (Vic) that authorise customary fishing (for example, different catch and size limits or equipment). The Indigenous category in Table 3 refers to customary fishing undertaken by recognised Traditional Owners. In 2015, there were no applications for customary fishing permits to access Dusky Flathead.
e Victoria - Indigenous Subject to the defence that applies under Section 211 of the Native Title Act 1993 (Cth), and the exemption from a requirement to hold a Victorian recreational fishing licence, the non-commercial take by indigenous fishers is covered by the same arrangements as that for recreational fishing.
Commercial catch of Dusky Flathead - note confidential catch not shown
Effects of fishing on the marine environment
- In Queensland, coastal, river and estuary set gillnets have been shown to have minimal impact on the environment and are quite selective in their harvest15. Levels of bycatch are generally low when compared to the harvest of the target species15. Fishers using tunnel nets operate under an industry developed code of best practice guidelines16. Marine turtles are released with minimal difficulty, and a very high proportion of undersized or unwanted catch is returned to the water alive.
- In New South Wales estuaries, Dusky Flathead are targeted using mesh nets, which also catch other species, including undersized individuals targeted in other key fisheries17–21. These impacts can be minimised by using specifically designed Dusky Flathead mesh nets that target fish above the minimum legal size20.
- In a similar manner to the tunnel net fishery in Queensland, the New South Wales estuarine beach seine fishery operates in a manner that allows a proportion of non-target species to be released alive22.
- The Victorian Bays and Inlets commercial fishers have adopted responsible fishing practices23. It is likely that fishing activities have minimal impact on the environment.
- Seabirds and other marine life often become entangled in discarded recreational fishing tackle24. In south-east Queensland, a Fishing Line Recovery Bin program was instigated in 2012 in order to minimise the occurrence of discarded tackle at popular shore based fishing locations.
Environmental effects on Dusky Flathead
- Dusky Flathead are dependent on estuarine and inshore coastal habitats throughout their life cycle. Variable recruitment has been observed in all three states, and is thought to be environmentally driven5.
- Physical impacts on coastal marine vegetation, sub-surface topography and water quality are likely to influence the resilience and productivity of Dusky Flathead populations at local scales.
- 1 Hoyle, S, Brown, I, Dichmont, C, Sellin, M, Cosgrove, M, and McLennan, M 2000, Integrated Fish Stock Assessment and Monitoring Program, Fisheries Research and Development Corporation project 94/161, Queensland Department of Primary Industries, Brisbane.
- 2 O'Neill, MF 2000, Fishery assessment of the Burnett River, Maroochy River and Pumistone Passage, project report QO99012, Queensland Department of Primary Industries, Brisbane.
- 3 Gray, CA, Gale, VJ, Stringfellow, SL and Raines, LP 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: 1091–1100.
- 4 Gray, CA and Barnes, LM 2008, Reproduction and growth of dusky flathead in NSW estuaries, Fisheries final report series no. 101, NSW Department of Primary Industries, Cronulla.
- 5 Conron S., Giri K, Hamer P and Hall K 2016, Gippsland Lakes Fishery Assessment 2016. Fisheries Victoria Science Report Series No. 14
- 6 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.
- 7 Department of Agriculture and Fisheries 2016, Queensland Stock Status Assessment Workshop 2016, 13-14 June 2016, Brisbane, Queensland Department of Agriculture and Fisheries.
- 8 Webley, J, McInnes, K, Tiexiera, D, Lawson, A and Quinn R 2015, Statewide Recreational Fishing Survey 2013-14, Department of Agriculture and Fisheries, Queensland.
- 9 Pollock, BR 2015, The annual spawning aggregation of Dusky Flathead Platycephalus fuscus at Jumpinpin, Queensland. Proceedings of the Royal Society of Queensland.
- 10 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.
- 11 Hall, KC 2015, Dusky Flathead (Platycephalus fuscus), In: Stewart, J, Hegarty, A, Young, C, Fowler, AM and Craig, J (eds), Status of Fisheries Resources in NSW 2013–14, NSW Department of Primary Industries, Mosman, pp 87–91.
- 12 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.
- 13 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.
- 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 Halliday, IA, Ley, JA, Tobin, A, Garrett, R, Gribble, NA and Mayer, DG 2001, The effects of net fishing: addressing biodiversity and bycatch issues in Queensland inshore waters, Fisheries Research and Development Corporation project 97/206, Department of Primary Industries, Queensland.
- 16 Moreton Bay Seafood Industry Association 2012, Moreton Bay tunnel net fishery code of best practice.
- 17 Gray, CA, Broadhurst, MK, Johnson, DD and Young, DJ 2002, Management implications of discarding in an estuarine multi-species gill net fishery, Fisheries Research, 56: 177–192.
- 18 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.
- 19 Gray, CA, Johnson, DD, Young, J and Broadhurst, MK 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.
- 20 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.
- 21 Gray, CA, Johnson, DD, Broadhurst, MK and Young, DJ 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.
- 22 Gray, CA and Kennelly, SJ 2003, Catch characteristics of the commercial beach-seine fisheries in two Australian barrier estuaries, Fisheries Research, 63: 405–422.
- 23 Victorian Bays And Inlets Fisheries Association 2013, Environmental Management System Victorian Bays And Inlets Fisheries Association, Victoria.
- 24 Campbell, M 2013, Reducing the impact of discarded recreational fishing tackle on coastal seabirds, Fisheries Research and Development Corporation project 2011/057, Queensland Department of Agriculture Fisheries and Forestry, Brisbane.