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Swordfish

Xiphias gladius

Method of production - Caught at sea
Capture method - Longline
Capture area - South West Pacific (FAO 71,77,81)
Stock area - South West Pacific
Stock detail - All Areas
Accreditation -
Fish type - Oily fish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is not a good choice of sustainable fish to eat and should be only eaten very occasionally. Click on the rating icon above to read more and on the alternatives tab below to find more sustainable fish to eat.


Sustainability overview

Swordfish in this region are both targeted for and landed as byproduct in directed tuna fisheries. They are also taken in artisanal net fisheries. The last stock assessment for swordfish in the South West Pacific Ocean was carried out in 2013. Whilst the assessment indicated that the biomass was not in an overfished state, there were conflicting values for fishing mortality, which suggested that overfishing may or may not be occurring. Both these capture methods often encounter bycatch of vulnerable species such as sea birds, turtles and sharks. Buy swordfish from fisheries that are well regulated by their flag state to ensure that bycatch mitigation devices are being employed and monitored.

Biology

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, northern hemisphere 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. In the South-West Pacific Ocean however, age at maturity is much later at about 10years for females (1-2yr for males).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.

Stock information

Stock area
South West Pacific

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Stock information
Swordfish in the South West Pacific Ocean (SWPO) are assessed and managed by the Western and Central Pacific Fisheries Commission (WCPFC). The latest stock assessment was carried out in 2013 and indicated that there has been a relatively steep decline in biomass over the period between 1997 and 2011, corresponding with reductions in Catch Per Unit Effort (CPUE) and landed fish sizes. Estimates of stock size are highly uncertain as a result of high variation in assumed growth and maturity and mortality at age schedules between Australian and Hawaiian data sets. As a result, the ranges of current spawning biomass and fishing mortality with regards to Maximum Sustainable Yield (MSY) models differ, depending on whether the Australian or Hawaiian schedules are used. Assuming the Hawaiian schedule produces estimates between 0.40 to 0.70Fmsy (not being overfished)while, assuming the Australian schedule produces estimates that are between 1.06 to 1.77Fmsy (stock being overfished). However, both schedules indicated that the stock is not in an overfished state, with spawning biomass ranging from 1.15 to 2.54 Bmsy.

Management

As for tuna, individual swordfish stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. As a result, intergovernmental Regional Fisheries Management Organisations (RFMOs) have been established. There are five main tuna RFMOs worldwide and it is their responsibility to carry out data collection, scientific monitoring and management of these fisheries, including swordfish. 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. The Western and Central Pacific Fisheries Commission (WCPFC) manages this stock which is both targeted and taken in significant quantities as bycatch in tuna fisheries. The dominant countries reporting swordfish catches in the region are Japan, Australia, New Zealand, China and Spain.

There is no Total Allowable Catch (TAC) set for this stock yet most participating countries have set national TACs for their components. The WCPFC scientific committee have recommended that due to uncertainty in the assessment, there should be no increase in fishing mortality over current (2007 to 2010) levels. They also recommend developing management measures between the equator and 20S as this region now represent the largest component of the catch. Management measures that apply to directed tuna fisheries are expected to also benefit swordfish stocks.

Regarding bycatch: longliners are required to use at least 2 prescribed seabird mitigation measures (eg tori line, dyed bait, weighted branch line, night setting, underwater setting chute); vessels are to carry line cutters and de-hookers to promptly release turtles or to foster to recovery any sick or comatose turtles captured; and permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained. Monitoring of these measures is deficient.

To help address IUU, the WCPFC maintains an IUU Vessel List; and all transhipments at sea are to be documented and 100% observed as part of the regional observer programme.

There is 5% observer coverage for vessels over 20m.

Capture information

In the South-West Pacific Ocean, swordfish are mostly caught in mixed species longline fisheries off the coast of Australia and New Zealand and in the central South Pacific near the Cook Islands and French Polynesia. Longlining is a less fuel intensive method of fishing, yet is associated with high levels of bycatch. Bycaught species include shark, birds, other billfish and endangered marine turtles. There are a range of mitigation measures that can be employed such as tori lines, weighted baits, circle hooks, subsurface deployment and night deployment of gear, yet monitoring is generally deficient.

Read more about capture methods


References
WCPFC, 2013. Stock assessment of swordfish (Xiphias gladius) in the southwest pacific ocean. Scientific committee ninth regular session. 6 to14 August, 2013. Pohnpei, Federated States of Micronesia. vaiilable at http://www.wcpfc.int/system/files/SA-WP-05-SWO-Assessment.pdf [Last accessed Jan 2014].
WCPFC, 2012. Eighth regular session: spatial dynamics of swordfish in the South Pacific Ocean inferred from tagging data. 7-15 August 2012. Busan, Republic of Korea. Available at http://www.iotc.org/files/proceedings/2012/wpb/IOTC-2012-WPB10-INF05.pdf [Accessed Jan 2013].
IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . [Accessed December 2013].
www.fishbase.org [Accessed Nov 2012].

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