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Grey Mackerel (2020)

Scomberomorus semifasciatus

  • Anthony Roelofs (Department of Agriculture and Fisheries, Queensland)
  • Paul Lewis (Department of Primary Industries and Regional Development, Western Australia)
  • Michael Usher (Department of Industry, Tourism and Trade, Northern Territory Government)

Date Published: June 2021

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Summary

The five stocks of Grey Mackerel assessed across Australia’s northern waters are all sustainable.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Stock status Indicators
Western Australia Western Australia Sustainable

Catch, indicator species

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Stock Structure

Grey Mackerel (Scomberomorous semifasciatus) are found in southern Papua New Guinea and northern Australia from Shark Bay, Western Australia, to northern New South Wales. There are at least five Grey Mackerel biological stocks across northern Australia, with a possible additional stock in the north-east Gulf of Carpentaria [Welch et al. 2009, Charters et al. 2010, Newman et al. 2010, Broderick et al. 2011, Welch et al. 2015].

Here, assessment of stock status is presented at the biological stock level—Western Australia, North West Northern Territory, Gulf of Carpentaria, North East Queensland and South East Queensland.

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Stock Status

Western Australia

Grey Mackerel is exploited as a component of the Mackerel Managed Fishery (Western Australia) (MMF) [Charters et al. 2010]. The primary target species of the Mackerel Managed Fishery is Spanish Mackerel (Scomberomorus commerson). As such there has been no formal stock assessment of Grey Mackerel in Western Australia and the species is assessed on the basis of catch only and the status of the indicator species (Spanish Mackerel) that represents the pelagic suite of species. A stock assessment of Spanish Mackerel, examining catch and effort data, biological information, biomass and yield per recruit modelling indicated that this stock is sustainable [Gaughan and Santoro 2018]. Since significant management changes in 2006, the catch and effort in the MMF have remained stable. In addition, Grey Mackerel are fast growing and attain sexual maturity relatively early in life (less than two years old) [Cameron and Begg 2002, Welch et al. 2009, GBRMPA 2011]. The minimum legal size limit for Grey Mackerel in Western Australia exceeds length at first maturity, which helps with sustainability by potentially providing some resilience to fishing pressure pending information regarding post-release survival. 

Furthermore, annual Grey Mackerel catch levels by the MMF from 2000–19 have been low, ranging between 3.5 and 24 tonnes (t), with the vast majority of recent catches taken by only two vessels from a small area of their range [Gaughan and Santoro 2018]. This level of catch is well below the total allowable commercial catch (TACC ; 60 t for each of the three management areas) for Grey Mackerel and very low in comparison with other states. The low levels of catch are likely reflective of the low demand and limited targeting of the species in the fishery. In addition, there is low annual charter boat catch of < 1 t and recreational catch of the species is estimated at less than 3 t by the four boat-based surveys between 2011 and 2018 [Ryan et al. 2019] which is also likely due to low targeting. Thus, based on the catch history it is likely that the level of stock depletion is minimal and the level of risk is estimated to be low. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired. 

On the basis of the evidence provided above, the Western Australia biological stock is classified as a sustainable stock.

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Biology

Grey Mackerel biology [Cameron and Begg 2002, Department of Agriculture and Fisheries 2016]

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Grey Mackerel 14 years, 1 200 mm FL  Females 2 years, 650–700 mm FL Males 1–2 years, 550–600 mm FL
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Distributions

Distribution of reported commercial catch of Grey Mackerel
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Tables

Fishing methods
Western Australia
Commercial
Hand Line, Hand Reel or Powered Reels
Line
Trolling
Gillnet
Indigenous
Spearfishing
Hook and Line
Unspecified
Recreational
Spearfishing
Hook and Line
Charter
Rod and reel
Management methods
Method Western Australia
Charter
Bag limits
Limited entry
Passenger restrictions
Possession limit
Size limit
Spatial zoning
Commercial
Gear restrictions
Limited entry
Size limit
Spatial zoning
Total allowable catch
Vessel restrictions
Indigenous
Laws of general application
Recreational
Bag limits
Licence
Possession limit
Size limit
Catch
Western Australia
Commercial 12.13t
Charter < 0.5 t
Indigenous Unknown
Recreational Insufficient data

Western Australian – Recreational (catch) Western Australian boat-based recreational catch survey from 1 Sep 2017–30 Aug 2018 [Ryan et al 2019]. Shore based recreational catch (if any) largely unknown.

Western Australia – Recreational (Management methods) Western Australian boat-based recreational licence required.

Northern Territory – Charter (management methods) In the Northern Territory, charter operators are regulated through the same management methods as the recreational sector but are subject to additional limits on license and passenger numbers.

Northern Territory – Indigenous (management methods) The Fisheries Act 1988 (NT), specifies that “…without derogating from any other law in force in the Territory, nothing in a provision of this Act or an instrument of a judicial or administrative character made under it limits the right of Aboriginals who have traditionally used the resources of an area of land or water in a traditional manner from continuing to use those resources in that area in that manner”.

Queensland – Indigenous (management methods) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Indigenous The reporting period for the Commonwealth (Torres Strait) is the 2012–13 financial year.

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Catch Chart

Commercial catch of Grey Mackerel - note confidential catch not shown
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References

  1. Bessell-Browne P, Lovett R, Leigh G, O'Neill MF and Campbell A, 2019, Stock assessment of the Australian east coast grey mackerel (Scomberomorus semifasciatus) fishery. Technical Report. State of Queensland.
  2. Broderick, D, Ovenden, J, Buckworth, R, Newman, S, Lester, R and Welch, D 2011, Genetic population structure of grey mackerel Scomberomorus semifasciatus in northern Australia, Journal of Fish Biology, 79: 633–661.
  3. Cameron, D and Begg, G 2002, Fisheries biology and interaction in the northern Australian small mackerel fishery, final report to Fisheries Research and Development Corporation, projects 92/144 and 92/144.02, Department of Primary Industries, Queensland.
  4. Charters, R, Lester, R, Buckworth, R, Newman, S, Ovenden, J, Broderick, D, Kravchuk, O, Ballagh, A and Welch, D 2010, The stock structure of grey mackerel Scomberomorus semifasciatus in Australia as inferred from its parasite fauna, Fisheries Research, 101: 94–99.
  5. Department of Agriculture and Fisheries 2016. Grey Mackerel Update.
  6. Gaughan, DJ and Santoro, K (eds) 2018, Status Reports of the Fisheries and Aquatic Resources of Western Australia 2016/17: The State of the Fisheries. Department of Primary Industries and Regional Development, Western Australia.
  7. Great Barrier Reef Marine Park Authority, 2011, A vulnerability assessment for the Great Barrier Reef - Grey mackerel.
  8. Newman, S, Wright, I, Rome, B, Mackie, M, Lewis, P, Buckworth, R, Ballagh, A, Garrett, R, Stapley, J, Broderick, D, Ovenden, J and Welch, D 2010, Stock structure of grey mackerel, Scomberomorus semifasciatus (Pisces: Scombridae) across northern Australia, based on otolith isotope chemistry, Environmental Biology of Fishes, 89: 357–367.
  9. Northern Territory Government 2012, Fishery Status Reports 2011, Fishery Report 111, Northern Territory Government.
  10. Northern Territory Government 2017, Fishery Status Reports 2015, Fishery Report 118, Northern Territory Government Department of Resources, Darwin, Northern Territory.
  11. QFish, Department of Agriculture and Fisheries, www.qfish.gov.au
  12. Ryan, KL, Hall, NG, Lai, EK, Smallwood, CB, Tate, A, Taylor, SM and Wise BS 2019, State-wide survey of boat-based recreational fishing in Western Australia 2017/18, Fisheries Research Report 297, Department of Primary Industries and Regional Development, Western Australia.
  13. Welch, D, Buckworth, R, Ovenden, J, Newman, S, Broderick, D, Lester, R, Ballagh, A, Stapley, J, Charters, R and GribbleN 2009, Determination of management units for grey mackerel fisheries in northern Australia, Fisheries Research and Development Corporation project 2005/010, Fishing and Fisheries Research Centre Technical Report 4, Fishing and Fisheries Research Centre, James Cook University, Townsville, Australia.
  14. Welch, D, Newman, S, Buckworth, R, Ovenden, J, Broderick, D, Lester, R, Gribble, N, Ballagh, A, Charters, R, Stapley, J, Street, R, Garrett, R and Begg, G 2015, Integrating different approaches in the definition of biological stocks: A northern Australian multi-jurisdictional fisheries example using grey mackerel Scomberomorus semifasciatus, Marine Policy, 55:73-80.

Downloadable reports

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