Capture method — Longline
Capture area — Indian Ocean: Western (FAO 51), Eastern ( FAO 57)
Stock area — Indian Ocean
Stock detail — All Areas
Updated: November 2019.
A new assessment was undertaken in 2017 and is a little more pessimistic than the 2014 assessment, but still indicates that the stock was neither overfished nor experiencing overfishing. Some countries in the IOTC do not report fishery data, which is important for stock assessment and management, and in 2018 the IOTC introduced a new measure aimed at improving reporting on direct and incidental catches, including prohibiting a country from retaining a species if they fail to report catches for that species. IOTC has set targets and thresholds for fishing effort and spawning stock biomass for the species it manages, but there is no harvest control rule in place for this stock. Provisional catch in 2018 (31,628t), is roughly equivalent to MSY (as is the 2014-2018 average, 31,343t). The Scientific Committee recommends maintaining catch levels at MSY. Given the uncertainty of most recent catches from Indonesian fresh tuna longline fisheries (which could have taken total catches to 39,777 t), more concrete advice needs to be developed after the next stock assessment, scheduled for 2020. The main management measure for the stock was a freeze on capacity and tonnage to 2003 levels, but this legislation is very generic and would be better replaced by spatial and temporal closures and quota allocation. There also appear to be concerns that the freeze has not been well enforced thus far. Additional measures may be needed in the southwest to prevent localised effort catches exceeding recommended levels and reversing stock recovery. Monitoring and mitigation of vulnerable bycatch species is fairly poor in the IOTC and observer coverage for large longliners is relatively low at 5%. There is concern for sharks, turtles and seabirds. It is likely that longline fleets are contributing to decline of these species.
Commercial buyers should establish what measures the flag state and fleet relating to their source is taking to reduce impacts to and improve reporting of interactions with vulnerable species. Large buyers should consider supporting such improvements. Some longline fleets operating in Indonesia and Sri Lanka are in Fishery Improvement Projects (FIP) which are making progress to improve some issues of environmental concern. More info is available at fisheryprogress.org.
Swordfish is the only member of the family Xiphiidae. It is a highly migratory species, moving towards temperate or cold waters in summer to feed and returning to warmer waters to spawn. They are apex predators that feed opportunistically. Squids and fishes are major prey items. In the Atlantic, spawning takes place in spring in the southern Sargasso Sea. In the Pacific, spawning occurs during spring and summer, and in the Mediterranean between June-August. Usually solitary, it forms large schools during spawning. A fast growing fish, swordfish begin to mature at two years of age, when they are about 150 to 170 cm in length, and by age four all are mature. They can attain a maximum size of 4.5m and a weight of 650kg. Swordfish tolerate temperatures of about 5 to 27C, but their optimum range is about 18 to 22C, and larvae have been found only at temperatures exceeding 24C.
Criterion score: 0 info
This stock is managed by the Indian Ocean Tuna Commission (IOTC). Between 1950 and 1980, catches of swordfish in the Indian Ocean slowly increased as the level of longline effort targeting tunas and sharks increased. Swordfish were not targeted by industrial longline fisheries before the early 1990s, but then the introduction of night fishing using longlines baited with squid and light sticks, increased catches. Piracy in the western Indian Ocean has significantly reduced longlining effort in the region since 2004, which has had a positive influence on the stock.
The most recent Indian Ocean swordfish assessment was undertaken in 2017, using data up to 2015. It was a little more pessimistic than the 2014 assessment, but still indicates that the stock was neither overfished (Spawning Biomass, SB, at 1.5 SBmsy) nor experiencing overfishing (Fishing mortality, F, at 0.76 Fmsy). Spawning stock biomass in 2015 was estimated to be around 31% of the unfished levels (as opposed to 60-90% in 2014), and Maximum Sustainable Yield was 31,590 t. Provisional catch in 2018 (31,628t), is roughly equivalent to MSY (as is the 2014-2018 average, 31,343t). The Scientific Committee recommends maintaining catch levels at MSY. There is a very low risk (less than 1%) of the stock undergoing overfishing or becoming overfished by 2025 if catches are maintained at recent levels. However, given the uncertainty of most recent catches from Indonesian fresh tuna longline fisheries (which could have taken total catches to 39,777 t), more concrete advice needs to be developed after the next stock assessment (scheduled for 2020).
The southwest component has previously been subject to intense fishing pressure and up until 2016 was treated separately to the rest of the IOTC swordfish stock.
Criterion score: 0.75 info
Swordfish stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. To tackle this, Intergovernmental Regional Fisheries Management Organisations (RFMOs) have been established; for this stock it is the Indian Ocean Tuna Commission (IOTC). There are five main tuna RFMOs worldwide and it is their responsibility to carry out data collection, scientific monitoring and management of these fisheries. Whilst the RFMOs are responsible for the development of management and conservation measures, the degree to which they are implemented, monitored and enforced still varies significantly between coastal states. For this reason, it is important to choose tuna that has been caught by vessels that are well regulated by their flag state.
There are persistent failures by some countries to report to the commission annually, including reporting catch data, and other issues with lack of data and poor quality data persist. In 2018 IOTC introduced a new measure aimed at improving reporting on direct and incidental catches, including prohibiting a country from retaining a species if they fail to report catches for that species.
IOTC has set targets and thresholds for fishing effort and spawning stock biomass for the species it manages, but there is no harvest control rule in place for the stock. Provisional catch in 2018 (31,628t), is roughly equivalent to MSY (as is the 2014-2018 average, 31,343t). The Scientific Committee recommends maintaining catch levels at MSY. There is a very low risk (less than 1%) of the stock undergoing overfishing or becoming overfished by 2025 if catches are maintained at recent levels. However, given the uncertainty of most recent catches from Indonesian fresh tuna longline fisheries (which could have taken total catches to 39,777 t), more concrete advice needs to be developed after the next stock assessment (scheduled for 2020). In 2017, the Commission noted that the development of a management strategy evaluation of swordfish is considered a high priority. This is scheduled for 2020.
The main management measure for the stock was a freeze on capacity and tonnage to 2007 levels for vessels over 24m, or vessels under this length operating in international waters. This measure expired in 2018, and IOTC reverted to previous legislation which froze capacity and tonnage to 2003 levels. This legislation is very generic, applying across all fleets, and would be better replaced by spatial and temporal closures and quota allocation. There also appear to be concerns that the freeze has not been well enforced thus far. Additional measures may be needed in the southwest to prevent localised effort catches exceeding recommended levels and reversing stock recovery.
Other IOTC conservation and management measures of note include:
A ban on the discarding of bigeye, yellowfin and skipjack tunas by purse seine vessels which from 2018 will extend to non target species such as other tunas and billfish.
A ban on the use of aircraft and unmanned aerial vehicles as fishing aids, which significantly contribute to fishing effort by helping to detect fish.
A ban on surface or submerged artificial lights for the purpose of aggregating tuna and tuna-like species beyond territorial waters.
In 2012 IOTC banned the use of driftnets on the high seas. In 2022 this will be extended to the entire IOTC area (i.e. within countries’ EEZs as well).
5% regional observer coverage is required for all vessels over 24m and for vessels under 24m fishing outside of their Exclusive Economic Zone (EEZ). In 2019 a proposal was put forward to increase this to at last 20%, as 5% was considered to be insufficient. However, consensus on minimum coverage could not be reached.
To help address IUU, the IOTC maintains an active vessel register and an IUU Vessel List and prohibits transhipments for large scale vessels at sea unless they are pre-approved, monitored by an observer and the vessel uses a Vessel Monitoring System (VMS).
In 2016 IOTC introduced a number of resolutions to improve the poor compliance with existing management measures, e.g. observer coverage, catch and effort reporting, support for countries to implement measures.
Criterion score: 0.75 info
Approximately 70% of the swordfish catch in the Indian Ocean is taken in pelagic longline fisheries. Longlining targets large mature fish compared with purse seining, yet is associated with significant incidental capture and mortality of vulnerable sharks, turtles and sea birds.
A number of threatened seabirds can interact with longline fisheries in the Indian Ocean, including the critically endangered Amsterdam albatross (which lives on Amsterdam Island in the southern Indian Ocean), shy, black-browed, and wandering albatrosses. As with most tuna RFMOs, the IOTC requires two seabird bycatch mitigation measures from a list of three options (weighted branch line, bird scaring lines, and night setting), but recommended best practice is for these three measures to be applied simultaneously. Monitoring and reporting is deficient, and there has not been enough information available to fully review the effectiveness of the applied mitigation measures.
There are currently too few data to carry out stock assessments for shark species, so the scientific committee recommends better monitoring and a precautionary approach to their management. Full utilisation of sharks is required (i.e. no fin removal), unwanted sharks must be released live wherever possible and shark catches must be reported annually. Transshipment of oceanic whitetips and thresher sharks is prohibited. Hooking mortality is apparently very high for bigeye and pelagic threshers, therefore the prohibition on retaining of any part of thresher sharks on-board and promoting live release of thresher shark may be largely ineffective for species conservation. In 2018 IOTC introduced a new measure on management of blue shark stocks, requiring better data collection on catches and discards and paving the way to consider additional management measures in 2021. Countries must develop conservation and management measures for vulnerable shark species. A number of countries are currently incorporating a ban on the retention of oceanic whitetip sharks into national legislation in accordance with IOTC resolutions, but it is too early to evaluate the impact of this. In 2019 the first resolution for any ray species in the IOTC area of competence was brought in. It protects mobulid rays, which are declining across the Indian Ocean. Targeted fishing, retention, transhipping, landing, selling, or storage of mobulid rays is prohibited, with exceptions made for accidental catch by artisanal fishing until 2022.
The status of all turtle species in the Indian Ocean is concerning. The scientific committee advises that maintaining or increasing fishing effort in the Indian Ocean without appropriate mitigation measures in place will likely result in further declines in biomass, and recommends that appropriate mechanisms are developed to ensure compliance with data collection and reporting requirements. Turtles must be released wherever possible and countries are requested to research other mitigation techniques. Longliners must carry cutters or de-hookers to aid with this but gear modification, such as circle hooks, is not required.
Interactions with all vulnerable non-target species should be recorded. Several countries have failed to implement national plans of action (NPOAs) for sharks, seabirds and turtles as required (although the shark plan is not binding in India as they have objected to the measure). In 2019, of the 34 members of IOTC, 16 countries had completed national plans of action (NPOAs) for sharks, 7 for seabirds and 11 for turtles. Click here to see which countries had and had not fully implemented NPOAs.
Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.Anchovy, anchovies
Herring or sild
Horse Mackerel, Scad
Salmon, Atlantic (Farmed)
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
ReferencesACAP, 2019. ACAP Review and Best Practice Advice for Reducing the Impact of Pelagic Longline Fisheries on Seabirds, Reviewed at the Eleventh Meeting of the Advisory Committee of the Agreement on the Conservation of Albatrosses and Petrels, 13 - 17 May 2019, Florianopolis, Brazil. Available at https://www.acap.aq/en/bycatch-mitigation/mitigation-advice/3498-acap-2019-review-and-best-practice-advice-for-reducing-the-impact-of-pelagic-longline-fisheries-on-seabirds/file [Accessed on 29.11.2019].
Dias, M. P., Martin. R., Pearmain, E., J., Burfield, I. J., Small, C., Phillips, R. A., Yates, O., Lascelles, B., Garcia Borboroglu, P. and Croxall, J. P., 2019. Threats to seabirds: A global assessment. Biol. Cons. 237, pp 525-537. https://doi.org/10.1016/j.biocon.2019.06.033 [Accessed on 29.11.2019].
Fishery Progress, 2018. Fishery Improvement Project Directory. Available at https://fisheryprogress.org/ [Accessed on 05.12.2018].
IOTC, 2017. Report of the 13th Working Party on Ecosystems and Bycatch, IOTC-2017-WPEB13-R, for the Indian Ocean Tuna Commission, 4-8 September 2017, San Sebastian, Spain. 124pp. Available at http://www.iotc.org/meetings/13th-working-party-ecosystems-and-bycatch-wpeb13 [Accessed 21.11.2017].
IOTC, 2018. Compendium of Active Conservation and Management Measures for the Indian Ocean Tuna Commission, 04 October 2018. Avaiable at http://www.iotc.org/cmms [Accessed on 6.12.2018].
IOTC, 2019. Resource Stock Status Summary - Swordfish: Status of the Indian Ocean swordfish (SWO: Xiphias gladius) resource, IOTC-2019-SC22-ES16 presented to the 22nd Indian Ocean Tuna Commission Scientific Committee, 2-6 December 2019, Karachi, Pakistan. 4pp. Available at https://iotc.org/documents/SC/22/ES16E [Accessed on 27.11.2019].
IOTC, 2018. Report of the 22nd Session of the Indian Ocean Tuna Commission, IOTC-2018-S22-R[E]. 21-25 May 2018, Bangkok, Thailand, 144pp. Available at https://iotc.org/documents/report-22nd-session-indian-ocean-tuna-commission [Accessed on 28.11.2019].
IOTC, 2019. Report for the 23rd session of the Indian Ocean Tuna Commission, IOTC-2019-S23-R_rev1[E], 17-21 June 2019, Hyderabad, India. Available at https://iotc.org/sites/default/files/documents/2019/10/IOTC-2019-S23-RE_Rev1_FINAL.pdf [Accessed on 26.11.2019].
IOTC, 2019. Status of development and implementation of national plans of action for seabirds and sharks, and implementation of the FAO guidelines to reduce marine turtle mortality in fishing operations. Paper IOTC-2019-SC22-06[E] presented to the 22nd Indian Ocean Tuna Commission Scientific Committee, 2-6 December 2019, Karachi, Pakistan. 11pp. Available at https://iotc.org/documents/SC/22/06E [Accessed on 27.11.2019].