*

King Threadfin

Polydactylus macrochir

  • Olivia Whybird (Department of Agriculture and Fisheries, Queensland)
  • Stephen Newman (Department of Fisheries, Western Australia)
  • Thor Saunders (Department of Primary Industry and Resources, Northern Territory)

You are currently viewing a report filtered by jurisdiction. View the full report.

Toggle content

Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Western Australia Western Australia KGBMF Sustainable Catch
KGBMF
Kimberley Gillnet and Barramundi ManagedFishery (WA)
Toggle content

Stock Structure

King Threadfin have numerous populations across northern Australia that are separated by 10–100s km or by large, coastal geographical features1,2. With the exception of the Gulf of Carpentaria, there is a lack of information on the degree to which this separation indicates separate biological stocks, and on boundaries between possible stocks.

Here, assessment of stock status is presented at the jurisdictional level—Western Australia and Northern Territory; at the biological stock level—Gulf of Carpentaria (Queensland)1,2; and the management unit level—East coast (Queensland).

Toggle content

Stock Status

Western Australia

King Threadfin is landed in the Kimberley Gillnet and Barramundi Fishery of Western Australia. Commercial catches in 2015 were 25 tonnes (t), similar to that reported in 2014. Recent catches are well below the average of 74.5 t for the 10-year period from 2004–13. This is due to low effort levels in the fishery3 following the removal of two fishing licenses from the Broome coast area. The Broome coast area has been closed to commercial fishing since late 2013. This commercial closure in the principal area for King Threadfin landings, in association with their productive life history characteristics, is likely to have substantially increased the spawning stock biomass of this species. In addition, the catch rates for King Threadfin are within the range exhibited by the fishery over the past 20 years. King Threadfin are landed by recreational and charter fishers, but only in small quantities (1 t). The above evidence indicates the biomass of this stock is unlikely to be recruitment overfished, and that the current fishing pressure is unlikely to cause the stock to become recruitment overfished.

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

Toggle content

Biology

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
King Threadfin 22 years; 1 600 mm TL  Males 2 years, 610 mm TL Females 6 years,1000 mm TL

King Threadfin biology2

Toggle content

Distributions

Distribution of reported commercial catch of King Threadfin

Toggle content

Tables

Fishing methods
Western Australia
Commercial
Various
Recreational
Hand Line, Hand Reel or Powered Reels
Management methods
Method Western Australia
Commercial
Gear restrictions
Limited entry
Spatial closures
Spatial zoning
Vessel restrictions
Recreational
Bag limits
Licence
Limited entry
Passenger restrictions
Spatial closures
Spatial zoning
Active vessels
Western Australia
4 in KGBMF
KGBMF
Kimberley Gillnet and Barramundi ManagedFishery (WA)
Catch
Western Australia
Commercial 25.49t in KGBMF
Indigenous Unknown
Recreational < 0.5 t, 0.8 t (2013–14)
KGBMF
Kimberley Gillnet and Barramundi ManagedFishery (WA)

a Western Australia – Recreational (catch) Boat-based recreational catch from 1 May 2013–30 April 2014

b Queensland – Recreational (catch) Survey of Queensland residents only from August 2013–October 201412

Toggle content

Catch Chart

Commercial catch of King Threadfin

Toggle content

Effects of fishing on the marine environment

  • The majority of King Threadfin are harvested by commercial gillnets. The catch from these nets is quite selective, with bycatch making up only a small proportion of the catch14, therefore the direct impact on the wider environment is limited.
  • The Northern Territory Fishery reported bycatch of less than one per cent of the total catch. This bycatch typically consists of Queenfish, unwanted shark species, catfish and Blue Threadfin15.
  • The most common interactions with threatened, endangered or protected species are with Saltwater Crocodiles and which are highly unlikely to impact populations of this species given that they are considered to have recovered from unregulated hunting. For example, the Northern Territory population of Saltwater Crocodiles is considered to be at carrying capacity in most catchments16.
  • Other species of conservation interest are interacted with in very low numbers (less than 10 per year). These species include sawfish, turtles and dugongs. The low bycatch and interaction levels in the fishery have been supported by fishery observer coverage on-board commercial vessels14,15.
Toggle content

Environmental effects on King Threadfin

  • The duration, magnitude and timing of the wet season has been shown to influence the catchability of King Threadfin17,18.
Toggle content

References

  1. 1 Moore, BR, Welch, DJ and Simpfendorfer, CA 2011, Spatial patterns in the demography of a large estuarine teleost: king threadfin, Polydactylus macrochir. Marine and Freshwater Research 62: 937−951.
  2. 2 Welch, DJ, Ballagh, A, Newman, SJ, Lester, RJ, Moore, B, van Herwerden, L, Horne, J, Allsop, Q, Saunders, T, Stapley, J and Gribble, NA 2010, Defining the stock structure of northern Australia’s threadfin salmon species. Draft Final Report to the Fisheries Research and Development Corporation, Project 2007/032. Fishing and Fisheries Research Centre, James Cook University, Townsville, Australia.
  3. 3 Brown, JI, Newman, SJ, Mitsopoulos, G, Skepper, C, Thomson, A and Wallis, D 2015, North Coast Nearshore and Estuarine Fishery Status Report, in Fletcher, WJ and Santoro, K (eds.), State of the fisheries and aquatic resources report 2010/11, Western Australian Department of Fisheries, Perth, 182–188.
  4. 4 Saunders,T 2015, King Threadfin Polydactylus macrochir, in Northern Territory Government 2015, Status of Key Northern Territory Fish Stocks Report 2013. Northern Territory Government. Department of Primary Industry and Fisheries. Fishery Report No. 114. 57–61.
  5. 5 Welch, D, Gribble, N and Garrett, R, 2002, Assessment of the Threadfin Salmon Fishery in Queensland – 2002. Department of Primary Industries, Brisbane.
  6. 6 Bayliss, P, Buckworth, R and Dichmont, C (Eds) 2014, Assessing the water needs of fisheries and ecological values in the Gulf of Carpentaria. Final Report prepared for the Queensland Department of Natural Resources and Mines (DNRM), CSIRO, Australia.
  7. 7 Halliday, IA, Robins, JB, Mayer, DG, Staunton-Smith, J and Sellin, MJ 2008, Effects of freshwater flow on the year-class strength of a non-diadromous estuarine finfish, king threadfin (Polydactylus macrochir), in a dry-tropical estuary. Marine and Freshwater Research 59: 157–164.
  8. 8 Department of Agriculture and Fisheries 2016, Queensland stock status assessment workshop 2016, 14–15 June 2016, Brisbane, DAF, Brisbane.
  9. 9 Moore, BR 2011, Movement, connectivity and population structure of a large, non-diadromous tropical estuarine teleost. PhD thesis, James Cook University.
  10. 10 Garrett, R 1992, Biological Investigation of King Salmon Polydactylus sheridani in the Gulf of Carpentaria: A Summary Report. In: Healy, T (ed) Gulf of Carpentaria Fishery Review Background Paper No. 1, QFMA, Brisbane.
  11. 11 Bibby, JM, RN Garrett, CP Keenan, GR McPherson and LE Williams 1997, Biology and Harvest of Tropical Fishes in the Queensland Gulf of Carpentaria Gillnet Fishery, Department of Primary Industries, Brisbane.
  12. 12 Webley, J, McInnes, K, Teixeira, D, Lawson, A and Quinn, R 2015, Statewide Recreational Fishing Survey 2013-14. Department of Agriculture and Fisheries, Brisbane.
  13. 13 Halliday, I, Staunton-Smith, J, Robins, J, Mayer, D and Sellin, M 2007, Using age-structure of commercial catch to investigate the importance of freshwater flows in maintaining barramundi and king threadfin populations, in I Halliday and J Robins (eds) Environmental flows for sub-tropical estuaries: understanding the freshwater needs for sustainable fisheries production and assessing the impacts of water regulation, Department of Primary Industries and Fisheries, Brisbane, 92–106.
  14. 14 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, Queensland Department of Primary Industries, Brisbane.
  15. 15 West, LD, Lyle, JM, Matthews, SR, Stark, KE and Steffe, AS 2012, Survey of Recreational Fishing in the Northern Territory, 200910, Fishery Report No. 109, Northern Territory Government, Darwin.
  16. 16 Fukuda, YP, Webb, G, Manolis, C, Delaney, R, Letnic, M, Lidner, G, and Whitehead, P 2011, Recovery of Saltwater Crocodiles following unregulated hunting in tidal rivers of the Northern Territory, Australia. The Journal of Wildlife Management, 75: 1253–1266.
  17. 17 Halliday, IA, Saunders, T, Sellin, M, Allsop, Q, Robins, JB, McLennan, M and Kurnoth, P 2012, Flow impacts on estuarine finfish fisheries of the Gulf of Carpentaria, Fisheries Research and Development Corporation project 2007/002, Queensland Department of Agriculture, Fisheries and Forestry, Brisbane.
  18. 18 Robins, JB, Halliday, IA, Staunton-Smith, J, Mayer, DG and Sellin, MJ 2005, Freshwater flow requirements of estuarine fisheries in tropical Australia: a review of the state of knowledge and application of a suggested approach, Marine and Freshwater Research, 56: 343–360.

Archived reports

Click the links below to view reports from other years for this fish.