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Blue Threadfin (2018)

Eleutheronema tetradactylum

  • Olivia Whybird (Department of Agriculture and Fisheries, Queensland)
  • Fabian Trinnie (Department of Primary Industries and Regional Development, Western Australia)
  • Shane Penny (Department of Primary Industry and Resources, Northern Territory)
  • Stephen Newman (Department of Primary Industries and Regional Development, Western Australia)

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

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Summary

Blue Threadfin is a short-lived, fast-growing species with low susceptibility to fishing pressure. It is classified as a sustainable stock in QLD and the NT, and as negligible in WA.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Northern Territory Northern Territory BF, CLF, ONLF, ACL, BNF, CNF Sustainable Catch, estimated harvest rate
ACL
Aboriginal Coastal License (NT)
BF
Barramundi Fishery (NT)
BNF
Bait Net Fishery (NT)
CLF
Coastal Line Fishery (NT)
CNF
Coastal Net Fishery (NT)
ONLF
Offshore Net and Line Fishery (NT)
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Stock Structure

Blue Threadfin is widely distributed in coastal waters throughout the Indo-West Pacific. Its range extends from the Persian Gulf eastward around the Indian Ocean rim to the Malay Peninsula, Gulf of Thailand, mouth of the Mekong River delta, China, Taiwan Province, Philippines, through Indonesia to southern New Guinea and northern Australia and in the north to southern Japan [Carpenter and Niem 2001]. In Australia, Blue Threadfin extend from the Exmouth Gulf region in Western Australia around the northern coastline to Sandy Cape in southern Queensland [Carpenter and Niem 2001].

A number of methods (genetics, otolith stable isotope chemistry, parasite abundances, life history and tag-recapture data) have been used to examine population structure in the Blue Threadfin [Ballagh et al. 2012, Horne et al. 2011, Horne et al. 2012, Horne et al. 2013, Moore et al. 2011, Newman et al. 2011, Welch et al. 2010, Zishke et al. 2009]. These studies have shown that adult Blue Threadfin do not move very far and tend to form localised populations around northern Australia. A tagging study on Blue Threadfin on the east coast of Australia found that ~70 per cent of tagged Blue Threadfin were recaptured within 10 km of their release location [Zischke et al. 2009]. Blue Threadfin comprise numerous populations across northern Australia that are separated by 10–100s km or by large, coastal geographical features, and which exhibit high levels of self-recruitment [Ballagh et al. 2012, Horne et al. 2011, Horne et al. 2012, Horne et al. 2013, Moore et al. 2011, Newman et al. 2011, Welch et al. 2010, Zishke et al. 2009]. There is a high likelihood of separate biological stocks occurring in each jurisdiction; however, the boundaries between possible stocks are not known. It is difficult to collect the biological and catch-and-effort information to determine the status of individual biological stocks.

Here, assessment of stock status is presented at the management unit level in Queensland—Gulf of Carpentaria and East Coast Queensland, and at the jurisdictional level—Western Australia and Northern Territory.

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Stock Status

Northern Territory

Blue Threadfin is incidentally caught in several inshore fisheries operating across the Northern Territory. The recreational harvest is significant, at around 40 per cent of the overall harvest of this species [NTG unpublished]. The majority of the recreational take of Blue Threadfin (85 per cent) is taken around the greater Darwin area, within a radius of approximately 150 km of this population center [West et al. 2012]. The spatial distribution of the commercial catch is similar, with some harvest from the northeast coast and the southern Gulf of Carpentaria. There are no estimates of the Indigenous harvest of Blue Threadfin in the Northern Territory. Due to the lack of a long-term time series of recreational and Indigenous catches, the assessment presented here is based on data from commercial logbooks.

The commercial catch of Blue Threadfin peaked at 100 t in 1996. Annual catches in the decade spanning 2008–17 averaged 23 t, with the catch in 2017 being 11.6 t. A preliminary assessment using catch data with a catch-MSY model, modified from Martell and Froese (2013), suggests that the predicted relative biomass (139 t) of Blue Threadfin at the conclusion of 2017 was slightly below the target biomass (i.e. 50 per cent of 1983 biomass). The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired.

The same assessment also indicated that the harvest rate in 2017 was below the target rate (0.18 per annum). The above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, Blue Threadfin in the Northern Territory is classified as a sustainable stock.

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Biology

Blue Threadfin biology [Bibby et al. 1997, McPherson 1997, Pember 2006, Stanger 1974, Welch et al. 2010]

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Blue Threadfin 7 years, 880 mm FL Variable on location and year Females: 2 to 4 years, 208–543 mm FL
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Distributions

Distribution of reported commercial catch of Blue Threadfin - note confidential catch not shown

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Tables

Fishing methods
Northern Territory
Commercial
Hook and Line
Gillnet
Pelagic Gillnet
Cast Net
Beach Seine
Indigenous
Spearfishing
Traps and Pots
Handline
Recreational
Handline
Management methods
Method Northern Territory
Charter
Bag and possession limits
Limited entry
Passenger restrictions
Spatial closures
Commercial
Gear restrictions
Limited entry
Spatial closures
Spatial zoning
Temporal closures
Vessel restrictions
Recreational
Bag and possession limits
Spatial closures
Temporal closures
Active vessels
Northern Territory
12 in ACL, 14 in BF, 13 in BNF, 14 in CLF, 3 in CNF, 7 in ONLF
ACL
Aboriginal Coastal License (NT)
BF
Barramundi Fishery (NT)
BNF
Bait Net Fishery (NT)
CLF
Coastal Line Fishery (NT)
CNF
Coastal Net Fishery (NT)
ONLF
Offshore Net and Line Fishery (NT)
Catch
Northern Territory
Commercial 795.50kg in ACL, 1.51t in BF, 4.59t in BNF, 654.67kg in CLF, 1.26t in CNF, 534.00kg in ONLF
Indigenous Unknown
Recreational 7.806 t
ACL
Aboriginal Coastal License (NT)
BF
Barramundi Fishery (NT)
BNF
Bait Net Fishery (NT)
CLF
Coastal Line Fishery (NT)
CNF
Coastal Net Fishery (NT)
ONLF
Offshore Net and Line Fishery (NT)

Northern Territory – Charter (management methods) Note Charter operators in the Northern Territory are under the same management methods as the recreational sector but have the additional restrictions of limited licences and passenger numbers.

Queensland – Indigenous (management methods) 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.

Queensland – Recreational (including some charter and Indigenous fishers) Survey of Queensland residents only from August 2013 to October 2014 [Webley et al. 2015]

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Catch Chart

Commercial catch of Blue Threadfin - note confidential catch not shown.

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References

  1. Ballagh, AC, Welch, DJ, Newman, SJ, Allsop, Q and Stapley, JM 2012, Stock structure of the blue threadfin (Eleutheronema tetradactylum) across northern Australia derived from life-history characteristics. Fisheries Research 121–122: 63–72.
  2. Bibby, JM, Garrett, RN, Keenan, CP, McPherson, GR and Williams, LE 1997, Biology and Harvest of Tropical Fishes in the Queensland Gulf of Carpentaria Gillnet Fishery. Brisbane: Department of Primary Industries.
  3. Carpenter, KE and Niem, VH (eds.) 2001, FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 5. Bony fishes part 3 (Menidae to Pomacentridae). Rome, FAO, pp. 2791–3380.
  4. Horne, JB, Momigliano, P, van Herwerden, L and Newman, SJ 2013, Murky waters: searching for structure in genetically depauperate blue threadfin populations of Western Australia. Fisheries Research 146: 1–6.
  5. Horne, JB, Momigliano, P, Welch, DJ, Newman, SJ and van Herwerden, L 2011, Limited ecological population connectivity suggests low demands on self-recruitment in a tropical inshore marine fish (Eleutheronema tetradactylum: Polynemidae). Molecular Ecology 20 (11): 2291–2306.
  6. Horne, JB, Momigliano, P, Welch, DJ, Newman, SJ and van Herwerden, L 2012, Searching for common threads in threadfins: phylogeography of Australian polynemids in space and time. Marine Ecology Progress Series 449: 263–276.
  7. Martell, S and R. Froese 2013, A simple method for estimating MSY from catch and resilience. Fish and Fisheries 14: 504–514
  8. McPherson, GR 1997, Reproductive biology of five target fish species in the gulf of Carpentaria inshore gillnet fishery. In: Garrett, R.N. 1997 Biology and Harvest of tropical fishes in the Queensland Gulf of Carpentaria gillnet fishery. pp 87–104.
  9. Moore, BR, Stapley, J, Allsop, Q, Newman, SJ, Ballagh, A, Welch, DJ and Lester, RJG 2011, Stock structure of blue threadfin Eleutheronema tetradactylum across northern Australia, as indicated by parasites. Journal of Fish Biology 78 (3): 923–936.
  10. Newman, SJ, Mitsopoulos, G, Skepper, C and Smith, E 2018, North Coast Nearshore and Estuarine Resource Status Report 2017. pp. 123–126. In: Gaughan, D.J. and Santoro, K. (eds.). 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, Perth, Australia. 237p.
  11. Newman, SJ, Pember, MB, Rome, BM, Mitsopoulos, GEA, Skepper, CL, Allsop, Q, Saunders, T, Ballagh, AC, van Herwerden, L, Garrett, RN, Gribble, NA, Stapley, JM, Meeuwig, JJ, Moore, BR and Welch, DJ 2011, Stock structure of blue threadfin Eleutheronema tetradactylum across northern Australia as inferred from stable isotopes in sagittal otolith carbonate. Fisheries Management and Ecology 18 (3): 246–257.
  12. Pember, MB 2006, Characteristics of fish communities in coastal waters of north-western Australia, including the biology of the threadfin species Eleutheronema tetradactylum and Polydactylus macrochir. 297. PhD Thesis, Murdoch University, Western Australia: Murdoch University.
  13. Queensland Department of Agriculture and Fisheries 2018, Queensland Stock Status Assessment Workshop Proceedings 2018. Species Summaries. 19–20 June 2018, Brisbane.
  14. Ryan, KL, Hall, NG, Lai, EK, Smallwood, CB, Taylor, SM and Wise, BS 2017, Statewide survey of boat-based recreational fishing in Western Australia 2015/16. Fisheries research Report No. 287. Department of Primary Industries and Regional Development, Government of Western Australia, Perth. 
  15. Stanger, JD 1974, A study of the growth, feeding, and reproduction of the threadfin, Eleutheronema tetradactylus (Shaw). 126. Hons Thesis, Department of Zoology. James Cook University, Queensland.
  16. Webley, J, McInnes, K, Teixeira, D, Lawson, A and Quinn, R 2015, Statewide Recreational Fishing Survey 2013–14. Department of Agriculture and Fisheries, Brisbane.
  17. Welch, DJ, Ballagh, AC, Newman, SJ, Lester, RJG, Moore, BR, van Herwerden, L, Horne, J, Allsop, Q, Saunders, T, Stapley, JM and Gribble, NA 2010, Defining the Stock Structure of Northern Australia's Threadfin Salmon Species. In Fish and Fisheries Research Centre Technical Report, 192. Townsville: James Cook University.
  18. Zischke, MT, Cribb, TH, Welch, DJ, Sawynok, W and Lester RJG 2009, Stock structure of blue threadfin on the Queensland east coast as determined by parasites and conventional tagging. Journal of Fish Biology 75: 156–171.