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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
Certification -
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 using pelagic longlines. 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. Further research is being undertaken by the Australian government that should provide further insight into these contradicting model outputs.

Pelagic longlining is associated with the incidental capture of vulnerable species including sharks, seabirds and turtles. Various measures are available and required to be used to reduce this bycatch yet monitoring is deficient is some fisheries and their effectiveness is yet to be evaluated. It is therefore important to buy swordfish from fisheries that are well regulated by their flag state.

Commercial buyers in particular should establish what measures the flag state or fleet is taking to improve these deficiencies and specify the need for ongoing and demonstrable improvements. Large buyers should consider supporting such improvements.

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 using data up to 2011 and indicated that there had been a relatively steep decline in biomass over the period between 1997 and 2011, corresponding with increased annual catches from approximately 2000t to 10,000t. 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 indicate that the stock is not in an overfished state, with spawning biomass ranging from 1.15 to 2.54Bmsy. Total recent catches have been relatively stable in recent years, but regional increases have been significant, especially in areas north off 20 degrees south.

In 2014, the Australian government agreed to undertake additional research on age, growth and age validation for swordfish and it is expected that project will also provide a description of any unresolved uncertainties and an indication of the stock status implications in the context of the 2013 stock assessment.

The next full stock assessment is not scheduled until 2017.

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. 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 main countries reporting swordfish catches in this region are (In order) Japan, Taiwan and the USA with smaller catches from many Pacific coastal states.

There is no Total Allowable Catch (TAC) set for this stock yet WCPFC participating coastal states are expected to have set national TACs which are not to exceed the maximum level reported in any one year between 2001 and 2006. Management measures that apply to directed tuna fisheries are expected to also benefit swordfish stocks.

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 pelagic longline fisheries off the coast of Australia and New Zealand and in the central South Pacific near the Cook Islands and French Polynesia, with smaller quantities taken in artisanal gill and fixed net fisheries. Pelagic longlining is associated with the bycatch of vulnerable species including sharks, seabirds, other billfish and endangered marine turtles.

There are various bycatch mitigation measures that are available and required including: the use of at least 2 prescribed seabird mitigation measures (e.g. tori line, dyed bait, weighted branch line, night setting, underwater setting chute) in certain areas; the use of circle hooks for shallow set gear to reduce turtle capture, along with the requirement to carry line cutters and de-hookers and to promptly release turtles or to foster to recovery any sick or comatose turtles captured; permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained; a prohibition to land silky and oceanic whitetip sharks; a prohibition on the use of wire leaders and lines running directly off the longline floats or drop lines - known as shark lines; catch limits for countries targeting sharks; and various monitoring and reporting requirements. However, monitoring is deficient in many fisheries and the effectiveness of these measures has not been evaluated.

Read more about capture methods


References
Froese, R. and Pauly, D. Editors, 2015. FishBase. Available at www.fishbase.org [Accessed Dec 2015].

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