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Swordfish (2020)

Xiphias gladius

  • Heather Patterson (Australian Bureau of Agricultural and Resource Economics and Sciences)

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Summary

The migratory Swordfish is caught in in Commonwealth waters from two distinct biological stocks in the Indian Ocean and the Pacific Ocean. Both stocks are sustainable.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Stock status Indicators
Commonwealth South-West Pacific Ocean Sustainable Spawning stock biomass, fishing mortality
Commonwealth Indian Ocean Sustainable

Spawning stock biomass, fishing mortality

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Stock Structure

Swordfish in the Indian Ocean, and Western and Central Pacific Ocean are considered to be two distinct biological stocks, and are managed by separate regional fisheries management organisations. The Indian Ocean stock falls under the jurisdiction of the Indian Ocean Tuna Commission (IOTC) while the Western and Central Pacific Ocean stock falls under the jurisdiction of the Western and Central Pacific Fisheries Commission (WCPFC). These two commissions are international organisations established to manage a number of highly migratory fish species within their defined geographic ranges

In the Indian Ocean, genetic and otolith microchemistry analyses have not indicated more than a single biological stock [Muths et al. 2013, Davies et al. 2019]. In the Pacific Ocean, genetic studies have suggested the presence of several biological stocks [Takeuchi et al. 2017], although the degree of genetic variation among these stocks is low [Kasapidis et al. 2008]. Electronic tagging has indicated that there may be limited connectivity between eastern and western parts of the Tasman and Coral Seas [Evans et al. 2012, Sharma and Herrera 2014]. 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 fished by Australian fishers. 

Here, 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

Indian Ocean

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

In the Indian Ocean, the most recent assessment [IOTC 2019] estimates that biomass in 2015 was 31 per cent of the unfished level (range 26–43 per cent). The biological stock is not considered to be recruitment impaired [Williams et al. 2020]. This assessment estimated that fishing mortality in 2013 was below the level associated with maximum sustainable yield (MSY) (76 per cent of fishing mortality at MSY; range 41–104 per cent). This level of fishing mortality is unlikely to cause the biological stock to become recruitment impaired [Williams et al. 2020].

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 of Swordfish is fished by Australian fishers endorsed to operate in the Eastern Tuna and Billfish Fishery (Commonwealth), and members of the Western and Central Pacific Fisheries Commission. The assessments undertaken for the Western and Central Pacific Fisheries Commission (WCPFC) take into account information from all jurisdictions that take Swordfish in this region.

In the South-West Pacific Ocean, the most recent assessment [Takeuchi et al. 2017] estimates median spawning biomass as 35 per cent of unfished levels (range 29–43 per cent). There was a very low probability that the recent spawning biomass has breached the limit reference point [WCPFC 2019]. The stock is therefore not considered to be recruitment impaired [Larcombe et al. 2020, WCPFC 2019].

Recent fishing mortality was estimated as 86 per cent of the level of fishing associated with MSY [Takeuchi et al. 2017] (range 51–123 per cent). There was an approximately 32 per cent probability that the recent level of fishing mortality was above the level that results in MSY [WCPFC 2019]. The assessment of the current level of fishing pressure is therefore considered unlikely to cause the stock to become recruitment impaired [Larcombe et al. 2020].

Based on the evidence provided above, the South-West Pacific Ocean stock is classified as a sustainable stock.

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Biology

Swordfish biology [Farley et al. 2016, Froese and Pauly 2009]

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 Swordfish)
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Distributions

Distribution of reported commercial catch of Swordfish
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Tables

Fishing methods
Commonwealth
Commercial
Longline (Unspecified)
Recreational
Hook and Line
Management methods
Method Commonwealth
Commercial
Area restrictions
Catch limits
Gear restrictions
Individual transferable quota
Limited entry
Recreational
Bag limits
Catch
Commonwealth
Commercial 910.00t

Commonwealth Commercial (catch) Catches reported for the Indian Ocean Tuna Commission and Western and Central Pacific Fisheries Commission are for 2018, the most recent year available; data for Eastern Tuna and Billfish Fishery and Western Tuna Billfish Fishery are for 2018/2019. Western and Central Pacific Fisheries Commission catches are for the entire South Pacific Ocean (south of the equator).

Commonwealth – Recreational 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.

Commonwealth – Recreational and Indigenous 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. Measures listed here exist in at least one of these jurisdictions.

Commonwealth – Indigenous 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 Swordfish - note confidential catch not shown

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References

  1. Davies, C, Marsac, F, Murua, H, Fraile, I, Fahmi, Z, Farley, J, Grewe, P, Proctor, C, Clear, N, Lansdell, M, Aulich, J, Feutry, P, Cooper, S, Foster, S, Rodríguez-Ezpeleta, N, Artetxe, I, Nikolic, N, Krug, I, Mendibil, I, Agostino, L, Labonne, M, Darnaude, A, Arnaud-Haond, S, Wudiano, Ruchimat, T, Satria, F, Lestari, P, Taufik, M, Priatna, A, & Zamroni, A 2019, ‘Study of population structure of IOTC species and sharks of interest in the Indian Ocean using genetics and microchemistry: an update on progress and preliminary results’, paper submitted to the Scientific Committee Meeting, IOTC-2019-SC22-INFO-05, Karachi, Pakistan, 2 to 6 December 2019.
  2. 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.
  3. 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, 3–11 August 2016.
  4. Froese, R and Pauly, DE 2009, FishBase, version 06/2016, FishBase Consortium. www.fishbase.org
  5. Indian Ocean Tuna Commission, 2019, Report of the Twenty-second Meeting of the Scientific Committee, Karachi, Pakistan, 2 – 6 December 2019.
  6. 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.
  7. Larcombe, J, Patterson, H and Mobsby, D 2020, Eastern Tuna and Billfish Fishery, in H Patterson, J Larcombe, J Woodhams and R Curtotti (eds), Fishery status reports 2020, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, pp 377-399.
  8. 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.
  9. 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.
  10. Takeuchi, Y, Pilling, G and Hampton, J 2017, ‘Stock assessment of swordfish (Xiphias gladius) in the southwest Pacific Ocean’, working paper WCPFC-SC13-2017/SA-WP-013, WCPFC Scientific Committee thirteenth regular session, Rarotonga, Cook Islands, 9–17 August 2017.
  11. Western and Central Pacific Fisheries Commission 2019, Summary report of the fifteenth regular session of the Scientific Committee for the Western and Central Pacific Fisheries Commission, Busan, Pohnpei, Federated States of Micronesia 12–20 August 2019.
  12. Williams, A, Patterson, H and Mobsby, D 2020, Western Tuna and Billfish Fishery, in H Patterson, J Larcombe J Woodhams and R Curtotti (eds), Fishery status reports 2020, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, pp 421-438.

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