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Swordfish

Xiphias gladius

  • Scott Hansen (Australian Bureau of Agricultural and Resource Economics and Sciences)
  • Heather Patterson (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 Indian Ocean IOTC, WTBF Sustainable Spawning stock biomass, fishing mortality
Commonwealth South-West Pacific Ocean ETBF, WCPFC Undefined Spawning stock biomass, fishing mortality
ETBF
Eastern Tuna and Billfish Fishery (CTH)
IOTC
Indian Ocean Tuna Commission (CTH)
WCPFC
Western and Central Pacific Fisheries Commission (CTH)
WTBF
Western Tuna Billfish Fishery (CTH)
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Stock Structure

Swordfish in the Indian and Pacific Oceans are considered to be two distinct biological stocks and are managed as such under separate regional fisheries management organisations. In the Indian Ocean, genetic research has indicated the presence of a single biological stock with the markers used1. In the Pacific Ocean, genetic studies have suggested the presence of several biological stocks2, although the degree of genetic variation among these stocks is low3. Electronic tagging has indicated that there may be limited connectivity between eastern and western parts of the Tasman and Coral Seas4,5. Although considered to be a single biological stock, two sub-stocks are currently assessed in the Pacific Ocean: the South-west Pacific stock and the North Pacific stock. Only the South-west Pacific stock is relevant to Australia, and status is reported at the management unit level (that is, for the South-west Pacific Ocean). The Indian Ocean biological stock falls under the jurisdiction of the Indian Ocean Tuna Commission; and the Western and central Pacific Ocean stock falls under the jurisdiction of the Western and Central Pacific Fisheries Commission. These two commissions are intergovernmental organisations established to manage a number of highly migratory fish species.

Here, assessment of stock status is presented at the biological stock level—Indian Ocean; and at the management unit level—South-west Pacific Ocean.

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Stock Status

The temporal coverage of the data used to determine status differ, depending on the assessment, because of delays in reporting catch data to the Indian Ocean Tuna Commission, and the Western and Central Pacific Fisheries Commission. Data for the Indian Ocean assessments were from 1952–20134; data for the Pacific Ocean assessment were from 1952–20112.

Indian Ocean

The Indian Ocean biological stock is fished by Australian fishers endorsed to fish in the Western Tuna and Billfish Fishery (Commonwealth), and numerous other international jurisdictions. The assessments undertaken by the Indian Ocean Tuna Commission take into account information from all jurisdictions.

In the Indian Ocean, the most recent assessment6 estimates that biomass in 2013 was 74 per cent of the unfished level. The biological stock is not considered to be recruitment overfished7. This assessment also estimated that fishing mortality in 2013 was below the level associated with maximum sustainable yield (MSY) (34 per cent of fishing mortality at MSY; range 28–40 per cent). This level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished7.

Based on the evidence provided above, the Indian Ocean biological stock is classified as a sustainable stock.

South-West Pacific Ocean

The South-west Pacific Ocean management unit is fished by Australian fishers endorsed to fish in the Eastern Tuna and Billfish Fishery (Commonwealth), and numerous other international jurisdictions. The assessments undertaken for the Western and Central Pacific Fisheries Commission (WCPFC) take into account information from all jurisdictions.

At the time of the most recent assessment2, there was significant uncertainty around the growth and maturity schedules for South-west Pacific Ocean Swordfish and two alternate growth and maturity schedules (Hawaiian and Australian) were used to represent this uncertainty. The assessment models selected across both schedules estimated that current (2007–10) spawning biomass of the Swordfish management unit ranged from 27–55 per cent of initial unfished spawning biomass and was above the level that would produce MSY (115–254 per cent of the spawning biomass at MSY)8. The management unit is therefore not considered to be recruitment overfished9.

However, the assessment results for fishing mortality differed substantially depending on the alternate growth and mortality schedules. Under the Hawaiian schedule, fishing mortality was estimated to be below the level associated with MSY (40–70 per cent MSY), while under the Australian schedule fishing mortality was estimated to be above the level associated with MSY (106–177 per cent MSY). The WCPFC Scientific Committee was unable to determine which growth schedule was more reliable. The assessment of the current level of fishing pressure is therefore considered to be too uncertain to use for status determination9.

Based on the evidence provided above, the South-west Pacific Ocean management unit is classified as an undefined stock.

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Biology

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Swordfish 30+ years; 4 550 mm FL  Females ~4.4 years; ~1 815 mm FL Males: ~1 years; ~1 200 mm FL (Fork length is measured from the lower jaw for Swordfi SH)

Swordfish biology10,11

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Distributions

Distribution of reported commercial catch of Swordfish

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Tables

Fishing methods
Commonwealth
Commercial
Hand Line, Hand Reel or Powered Reels
Pelagic Longline
Pole and Line
Trolling
Gillnet
Purse Seine
Various
Recreational
Hand Line, Hand Reel or Powered Reels
Management methods
Method Commonwealth
Commercial
Area restrictions
Catch limits
Gear restrictions
Individual transferable quota
Limited entry
Recreational
Bag limits
Active vessels
Commonwealth
39 in ETBF, 2 in WTBF
ETBF
Eastern Tuna and Billfish Fishery (CTH)
WTBF
Western Tuna Billfish Fishery (CTH)
Catch
Commonwealth
Commercial 1.15Kt in ETBF, 41.74Kt in IOTC, 20.09Kt in WCPFC, 220.00t in WTBF
Indigenous Unknown
Recreational Unknown
ETBF
Eastern Tuna and Billfish Fishery (CTH)
IOTC
Indian Ocean Tuna Commission (CTH)
WCPFC
Western and Central Pacific Fisheries Commission (CTH)
WTBF
Western Tuna Billfish Fishery (CTH)

Recreationala,b Indigenousb,c Catchd,e

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 Recreational and Indigenous fishing sectors in the Indian Ocean are South Australia, Victoria and Western Australia. Recreational sectors in the Pacific Ocean are New South Wales, Queensland and Tasmania. A tick indicates that a measure exists in at least one of these jurisdictions.

c 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.

d Catches reported for the Indian Ocean Tuna Commission and Western and Central Pacific Fisheries Commission are for 2014, the most recent year available; data for ETBF and WTBF are for 2015.

e WCPFC catches are for the entire south Pacific Ocean (south of the equator).

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Catch Chart

Commercial catch of Swordfish

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Effects of fishing on the marine environment

  • Following completion of ecological risk assessments (levels 1–3) in the Western Tuna and Billfish Fishery (Commonwealth) (WTBF), no species were identified as high risk12. In the Eastern Tuna and Billfish Fishery (Commonwealth) (ETBF), a combined total of nine species were identified as being at high risk or precautionary high risk. This is the priority list of species for attention under the ETBF ecological risk management strategy; it includes two species of sunfish, four species of shark, two species of cetacean and one species of marine turtle13,14.
  • No target species, ecological communities or habitats were assessed to be at high risk from the effects of fishing in the ETBF or the WTBF12–14.
  • Australia implements regulations to minimise the environmental impact of fisheries for tuna and tuna-like species on pelagic ecosystems, specifically on seabirds, sea turtles and sharks15,16.
  • Australia has prohibited shark finning in longline fisheries managed by the Commonwealth and has also prohibited the use of wire leaders in these fisheries, to reduce fishery impacts on sharks15,16.
  • Both the Indian Ocean Tuna Commission17 and the Western and Central Pacific Fisheries Commission18 have passed conservation and management measures that are broadly consistent with each other and with Australia’s domestic requirements.
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Environmental effects on Swordfish

  • The distribution and abundance of tuna, and possibly billfish, can be affected by environmental factors19,20. For example, seasonal changes in the abundance of Bigeye Tuna and Yellowfin Tuna on the east coast of Australia are linked to the expansion and contraction of the East Australian Current21.
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References

  1. 1 Muths, D, LeCouls, S, Evano, H, Grewe, P and Bourjea, J 2013, Multi-genetic marker approach and spatio-temporal analysis suggest there is a single panmictic population of Swordfish Xiphias gladius in the Indian Ocean, PLoS One, 8: e63558, doi:10.1371/journal.pone.0063558.
  2. 2 Davies, N, Pilling, G, Harley, S and Hampton, J 2013, Stock assessment of Swordfish (Xiphias gladius) in the southwest Pacific Ocean, working paper WCPFC-SC9-2013/SA-WP-05, Western and Central Pacific Fisheries Commission Scientific Committee ninth regular session, Federated States of Micronesia, pp 6–14 August 2013.
  3. 3 Kasapidis, P, Magoulas, A, Gacía-Cortés, B and Mejuto, J 2008, Stock structure of Swordfish (Xiphias gladius) in the Pacific Ocean using microsatellite DNA markers, working paper WCPFC-SC4-2008/BI-WP-04, Western and Central Pacific Fisheries Commission Scientific Committee fourth regular session, Papua New Guinea, 11–22 August 2008.
    http://fish.gov.au/reports/Documents/2014_refs/Kasapidis et al. 2008.pdf
  4. 4 Sharma, R and Herrera, M 2014, An age-, sex- and spatially-structured stock assessment of the Indian Ocean swordfish fishery 1950–2012, using Stock Synthesis, working paper IOTC-2014-WPB12-26_Rev 2, Indian Ocean Tuna Commission Working Party on Billfish twelfth session, Tokyo, Japan, 21–25 October 2014.
  5. 5 Evans, K, Kolody, D, Abascal, F, Holdsworth, J, Maru, P and Sippel, T 2012, Spatial dynamics of swordfish in the South Pacific Ocean inferred from tagging data, information paper WCPFC-SC8-2012/SA-IP-05, Western Central Pacific Fisheries Commission Scientific Committee eighth regular session, Busan, Republic of Korea, 7–15 August 2012.
  6. 6 Indian Ocean Tuna Commission 2015, Report of the eighteenth session of the Scientific Committee, Bali, Indonesia, 23–27 November 2015.
  7. 7 Williams, A, Patterson, H and Bath, A 2016, Western Tuna and Billfish Fishery, 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 404–420.
  8. 8 Western and Central Pacific Fisheries Commission 2013, Summary report of the ninth regular session of the Scientific Committee for the Western and Central Pacific Fisheries Commission, Pohnpei, Federated States of Micronesia, 6–14 August 2013.
  9. 9 Larcombe, J, Williams, A and Stephan, M 2016, Eastern Tuna and Billfish Fishery, 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 359–381.
  10. 10 Froese, R and Pauly, DE 2009, FishBase, version 06/2016, FishBase Consortium.
    www.fishbase.org
  11. 11 Farley, J, Clear, N, Kolody, D, Krusic-Golub, K, Eveson, P and Young, J 2016, Determination of swordfish growth and maturity relevant to the southwest Pacific stock, working paper WCPFC-SC12-2016/SA-WP-11, Western Central Pacific Fisheries Commission Scientific Committee twelfth regular session, Bali, Indonesia, 3­11 August 2016.
  12. 12 Zhou, S, Fuller, M and Smith, T 2009, Rapid quantitative risk assessment for fish species in seven Commonwealth fisheries, report for the Australian Fisheries Management Authority, Canberra.
  13. 13 Zhou, S, Smith, T and Fuller, M 2007, Rapid quantitative risk assessment for fish species in selected Commonwealth fisheries, report for the Australian Fisheries Management Authority, Canberra.
  14. 14 Australian Fisheries Management Authority 2009, Residual risk assessment of the level 2 ecological risk assessment: species results, report for the Eastern Tuna and Billfish Fishery, AFMA, Canberra.
  15. 15 Australian Fisheries Management Authority 2016, Eastern Tuna and Billfish Fishery Management Arrangements Booklet: 2016 Fishing Season, AFMA, Canberra.
  16. 16 Australian Fisheries Management Authority 2016, Western Tuna and Billfish Fishery Managements Arrangements Booklet: 2016 Fishing Season, AFMA, Canberra.
  17. 17 Indian Ocean Tuna Commission 2016, Compendium of active conservation and management measures for the Indian Ocean Tuna Commission, 27 September 2016, IOTC Seychelles.
  18. 18 Western and Central Pacific Fisheries Commission 2016, Conservation and Management Measures (CMMs) and Resolutions of the Western and Central Pacific Fisheries Commission (WCPFC), WCPFC, Federated States of Micronesia.
  19. 19 Hobday, AJ and Young, J 2008, Pelagic fisheries, in AJ Hobday, ES Poloczanska and RJ Matear (ed.s), Implications of climate change for Australian fisheries and aquaculture: a preliminary assessment, report to the Department of Climate Change, Canberra.
  20. 20 Lehodey, P, Hampton, J, Brill, RW, Nicol, S, Senina, I, Calmettes, B, Portner, HO, Bopp, L, Ilyina, T, Bell, JD and Sibert, J 2011, Vulnerability of oceanic fisheries in the tropical Pacific to climate change, in JD Bell, AJ Johnson and AJ Hobday (ed.s), Vulnerability of tropical Pacific fisheries and aquaculture to climate change, Secretariat of the Pacific Community, Noumea, New Caledonia, pp 433–492.
  21. 21 Campbell, RA 1999, Long term trends in yellowfin tuna abundance in the south-west Pacific: with an emphasis on the eastern Australian Fishing Zone, final report to the Australian Fisheries Management Authority, Canberra.​

Archived reports

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