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Deepwater Flathead

Platycephalus conatus

  • Andy Moore (Australian Bureau of Agricultural and Resource Economics and Sciences)
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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Commonwealth Great Australian Bight SESSF (CTS), SESSF (GABTS) Sustainable Spawning stock biomass, fishing mortality
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
SESSF (GABTS)
Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (CTH)
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Stock Structure

The biological stock structure of Deepwater Flathead is unknown; however, it is treated as a single biological stock in the Southern and Eastern Scalefish and Shark Fishery for management purposes. Stock assessments for Deepwater Flathead have only been completed for the Great Australian Bight part of the biological stock1.

Here, assessment of stock status is presented at the biological stock level—Great Australian Bight.

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Stock Status

Great Australian Bight

The most recent quantitative assessment1 estimated that the spawning biomass at the start of the 2014–15 fishing season was 45 per cent of the unfished (1978) level. This assessment was generally consistent with previous assessments and fishery-independent surveys2,3. A multi-year breakout analyses in 2015 suggested catch per unit effort (CPUE) has deviated from its expected model derived trajectory. Standardised CPUE was lower than the trajectory predicted by the quantitative assessment, but still within the 95 per cent confidence bounds produced by the assessment4. The most recent fishery-independent survey in 2015 suggested a dramatic decrease in Deepwater Flathead catch rates compared to previous surveys5. Relative biomass estimates derived from the fishery-independent survey decreased by 45–50 per cent from previous estimates. Industry also noted a decrease in catch rates during 2015. An updated stock assessment is scheduled for 2016 and should quantify the impact of these decreases in catch rates and abundance measures.

The 2013 assessment estimated that the spawning biomass was progressively fished-down in the mid-2000s, but the biological stock had recovered to above the maximum economic yield target by the start of 2010. The recovery was likely a result of lower fishing pressure in recent years, combined with at least one substantial recruitment event. The stock is not considered to be recruitment overfished6.

The biologically-derived1 total allowable catch (TAC) for the Great Australian Bight Trawl Sector (Commonwealth) for the 2015–16 fishing season was 1150 tonnes (t), which was adjusted to 1265 t to account for undercatch and overcatch. Landed catch of Deepwater Flathead from this fishery in the 2015–16 fishing season was 604 t6. The Commonwealth Trawl Sector also landed 30 t, leading to a combined catch that was below the TAC. The level of discards for this species is low7,8. This level of fishing pressure is unlikely to cause the stock to become recruitment overfished6.

On the basis of the evidence provided above, the Great Australian Bight (Commonwealth) biological stock is classified as a sustainable stock.

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Biology

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Deepwater Flathead Females: ~26 years; 820 mm TL  Males: ~19 years; 590 mm TL Females: 5–6 years; 430 mm TL Males: 4–5 years; 430 mm TL

Deepwater Flathead biology9,10,11

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Distributions

Distribution of reported commercial catch of Deepwater Flathead

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Tables

Fishing methods
Commonwealth
Commercial
Danish Seine
Otter Trawl
Management methods
Method Commonwealth
Commercial
Gear restrictions
Limited entry
Spatial closures
Total allowable catch
Active vessels
Commonwealth
11 in SESSF (CTS), 4 in SESSF (GABTS)
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
SESSF (GABTS)
Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (CTH)
Catch
Commonwealth
Commercial 30.62t in SESSF (CTS), 626.62t in SESSF (GABTS)
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
SESSF (GABTS)
Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (CTH)

Recreationala Indigenousb

a The Australian Government does not manage recreational fishing in Commonwealth waters. Recreational fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters, under its management regulations.

b The Australian Government does not manage non-commercial Indigenous fishing in Commonwealth waters, with the exception of the Torres Strait. In general, non-commercial Indigenous fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters.

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Catch Chart

Commercial catch of Deepwater Flathead

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Effects of fishing on the marine environment

  • The effects of trawl fishing on the marine environment are assessed through an environmental risk assessment and risk management framework and mitigated through spatial closures, and the implementation of bycatch and discard workplans14,15 in the Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (SESSF [CTS]) and Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (SESSF [GABTS]) fisheries.
  • There is bycatch in the both trawl sectors. In 2006, mandatory requirements for otter trawls to use 90 mm square-mesh codend panels were introduced in an effort to reduce the bycatch of small species and juvenile fish.
  • The Australian Fisheries Management Authority mandated individual vessel seabird management plans. The seabird action plans are used in the SESSF (CTS) and SESSF (GABTS) to mitigate the impacts of trawling on seabirds. From 1 May 2017, all vessels in the SESSF (CTS) and SESSF (GABTS) fisheries must use one of the following mitigation devices: sprayers, bird bafflers or pinkies with zero discharge of fish waste16.
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Environmental effects on Deepwater Flathead

  • Changes in ecosystem structure and function associated with changes in the climate may affect larval recruitment of Deepwater Flathead17.
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References

  1. 1 Klaer, N 2014, Deepwater Flathead (Neoplatycephalus conatus) stock assessment based on data up to 2012–13, in GN Tuck (ed) Stock assessment for the Southern and Eastern Scalefish and Shark Fishery  2013, Part 1, Australian Fisheries Management Authority and Commonwealth Scientific and Industrial Research Organisation Marine and Atmospheric Research, Hobart.
  2. 2 Knuckey, I, Koopman, M and Hudson, R 2009, Resource survey of the Great Australian Bight Trawl Fishery—2009, AFMA Project 2008/848, Report to the Australian Fisheries Management Authority, Canberra.
  3. 3 Knuckey, I, Koopman, M and Hudson, R 2011, Resource survey of the Great Australian Bight Trawl Fishery—2011, Report to the Australian Fisheries Management Authority, Canberra.
  4. 4 Haddon, M 2015 Multi-year breakout analyses for Deepwater Flathead and western Gemfish in the GAB (2014/15), CSIRO, Hobart.
  5. 5 Knuckey, I, Koopman, M and Hudson, R 2015, Resource Survey of the Great Australian Bight Trawl Sector—2015, Australian Fisheries Management Authority Project 2014/0809, Fishwell Consulting.
  6. 6 Moore, A, Georgeson, L and Savage, J 2016, Great Australian Bight Trawl Sector, in H Patterson, R Noriega, L Georgeson, I Stobutzki and R Curtotti (ed.s), Fishery status reports 2016, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, pp 238–256.
  7. 7 Knuckey, I and Brown, L 2002, Assessment of bycatch in the Great Australian Bight Trawl Fishery, Fisheries Research and Development Corporation Project 2000/169, Marine and Freshwater Resources Institute, Victorian Department of Natural Resources and Environment, Queenscliff.
  8. 8 Upston, J and Thomson, R 2015, Integrated scientific monitoring program for the Southern and Eastern Scalefish and Shark Fishery—discard estimation 2014, Australian Fisheries Management Authority and CSIRO Marine Resources and Industries, Hobart.
  9. 9 Kailola, PJ, Williams, MJ, Stewart, PC, Reichelt, RE, McNee, A and Grieve, C 1993, Australian Fisheries Resources, Bureau of Resource Sciences and Fisheries Research and Development Corporation, Canberra.
  10. 10 Stokie, T and Krusic-Golub, K 2005, Age estimation of Bight Redfish and Deepwater Flathead in the Great Australian Bight Trawl Fishery, 2004–05, Australian Fisheries Management Authority, Canberra.
  11. 11 Stokie, T and Talman, S 2003, Age estimation of Deepwater Flathead (Neoplatycephalus conatus), Report to the Australian Fisheries Management Authority, Canberra.
  12. 12 Australian Fisheries Management Authority 2009, Southern and Eastern Scalefish and Shark Fishery management plan 2009, AFMA, Canberra.
  13. 13 Australian Government Department of Agriculture, Fisheries and Forestry 2007, Commonwealth fisheries harvest strategy: policy and guidelines, DAFF, Canberra.
  14. 14 Australian Fisheries Management Authority 2014, Great Australian Bight Trawl Sector bycatch and discarding workplan, 2014–2016, AFMA, Canberra.
  15. 15 Australian Fisheries Management Authority 2014, Commonwealth Trawl Sector (Otter Board Trawl and Danish Seine) bycatch and discarding workplan 2014–2016, AFMA, Canberra.
  16. 16 Australian Fisheries Management Authority 2016, AFMA moves to strengthen seabird safety, AFMA media release 15 July 2016.
  17. 17 Hobday, AJ, Poloczanska, ES and Matear, R (ed.s) 2008, Implications of climate change for Australian fisheries and aquaculture: a preliminary assessment, CSIRO Marine and Atmospheric Research report to the Department of Climate Change, Canberra.

Archived reports

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