Tuna, yellowfin

Thunnus albacares

Method of production — Caught at sea
Capture method — Pole & line; Handline
Capture area — Western & Central Pacific - WCPO (FAO 61,71,77)
Stock area — Philippines, Indo, PNG
Stock detail

Philippines, Indo, Vietnam, PNG EEZs


Picture of Tuna, yellowfin

Sustainability rating two info

Sustainability overview

A new stock assessment was carried out in 2017 and is similar to that from 2014 and indicating that overfishing is not occurring and the stock is not considered to be in an overfished state. The yellowfin catch for 2016 (650,491 t) was the highest recorded. The scientific committee continues to recommend measures to reduce fishing mortality on juveniles and maintain current spawning biomass levels. In 2018, the Western and Central Pacific Fisheries Commission (WCPFC) adopted a bridging measure to manage bigeye, yellowfin and skipjack (which are caught together) until harvest strategies are in place or February 2021. As part of this, spawning biomass depletion ratios for bigeye and yellowfin are to be maintained at or above recent average levels. Whiles there is no Total Allowable Catch (TAC) set for this stock, a range of measures have been implemented to try to limit catch and reduce effort. A small proportion of the catch is taken in pole & line fisheries. These are very selective but do rely on a substantial amount of small live fish for bait. The total catch of bait fish in pole & line fisheries is generally considered low compared to targeted fisheries for these species and is unlikely to overexploit these stocks, but could have implications for local availability.

There are a number of FIPs improving handline and pole & line fisheries in the tropical Western and Central Pacific. More info about the Vietnam FIP is available here;
Info about the Philippines FIP is available here; and
Info about the FIP in Indonesia is available here.

Biology

Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Yellowfin are found throughout the world’s tropical and subtropical seas, except the Mediterranean. They often form large, size specific schools, frequently associated with dolphins or floating objects. Yellowfin is a large fast growing species, reaching maximum sizes of 240cm in length, 200kg in weight and an age of 8 years. They mature when 2 to 5 years old and mainly spawn in summer. Smaller fish are mainly limited to surface waters, while larger fish are found in surface and deeper waters, but rarely below 250m. Yellowfin has medium resilience to fishing.

Stock information

Criterion score: 0 info

Stock Area

Philippines, Indo, PNG

Stock information

The yellowfin tuna fishery in the Western and Central Pacific Ocean (WCPO) is the second largest after skipjack, and is assessed and managed by the Western and Central Pacific Fisheries Commission (WCPFC).

A new stock assessment was carried out in 2017 and is similar to that from 2014, now including data up to the end of 2015. There is a 96% probability that overfishing is not occurring (F at 0.74Fmsy) and the stock is not considered to be in an overfished state (92% probability), with spawning biomass levels (SB) 33% of unfished levels and median spawning biomass levels, SB, at 1.39SBMSY. Maximum Sustainable Yield (MSY) has been revised upwards in the new assessment to 670,800 t (it was 586,400t in 2014).

Total yellowfin catch in the WCPO has slowly increased over time but jumped to a new level in 1998, with annual catches regularly exceeding 500,000t ever since. The stock has been continuously declining for about 50 years, since the late 1960’s. Levels of fishing mortality and depletion differ between regions, and fishery impact is highest in the tropical region, mainly due to the purse seine fisheries in the equatorial Pacific and the “other” fisheries within the Western Pacific. Both juvenile and adult fishing mortality show a steady increase since the 1970s, but while juvenile fishing mortality has stabilized since the late 1990s, adult fishing mortality has increased continuously. The scientific committee continues to recommend measures to reduce fishing mortality on juveniles and maintain current spawning biomass levels.

The yellowfin catch for 2016 (650,491 t) was the highest recorded (more than 40,000 t higher than the previous record catch of 2008 - 609,458 t); the increase in yellowfin tuna catch from 2015 levels was mainly due to increased catches in the purse seine fishery and the Indonesia and Philippines domestic fisheries.

Management

Criterion score: 0.5 info

Most tuna 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. The tuna fisheries in the Western and Central Pacific Ocean (WCPO) are managed by the Western and Central Pacific Fisheries Commission (WCPFC). 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 is a WWF coordinated Fisheries Improvement Project (FIP) for some local handline fleets in the Philippines - the Partnership Project Towards Sustainable Tuna (PPTST). The project aims to get the fishery to MSC application by 2017, and is working on numerous aspects including monitoring and reporting.

WCPFC has put in place a lower limit for the spawning biomass of bigeye, skipjack, and yellowfin tuna of 20 percent of unfished levels (SB/SBF=0, aka spawning biomass depletion ratio), below which the stock should not fall. For skipjack there is also an interim target of 50 percent of unfished levels, which was adopted in 2015 and has been reached. The scientific committee recommends reducing fishing mortality on juvenile bigeye and yellowfin in the tropics, through preventing increases in overall fishing mortality, until targets for these two stocks can be agreed. The commission is looking to establish harvest strategies for key fisheries and stocks but has not yet completed this work and so, as of January 2018, a bridging measure is in force to manage bigeye, yellowfin and skipjack - the measure lasts until harvest strategies are in place or until February 2021. As part of this, spawning biomass depletion ratios for bigeye and yellowfin are to be maintained at recent levels (the average from 2012-2015) and skipjack at 50 percent. The bridging measure includes a number of new measures and consolidates some pre-existing ones, and is outlined below.

In the tropical region, between 20 degrees North and 20 degrees South, the following applies:
The use and deployment of FADs is prohibited for 5 months of the year (3 months for Kiribati and the Philippines). VMS polling frequency increases to every 30 minutes during the FAD closure.
Effort limits (in vessel days) apply to purse seining on the high seas (excluding Small Island Developing States, SIDS): limits vary by country. In order not to undermine the effectiveness of this, countries cannot transfer effort into areas outside of this region.
To create an incentive to reduce the non-intentional capture of juvenile fish, to discourage waste and to encourage an efficient utilization of fishery resources, purse seiners must retain on board and then land or transship at port all bigeye, skipjack, and yellowfin tuna (also applies to national waters).
All purse seine vessels operating on the high seas or within national waters in this region must carry an observer. This also applies to purse seiners anywhere in the convention area fishing in waters under multiple countries’ jurisdiction or moving between the high seas and national waters.
The number and capacity of large (over 24m) purse seiners and longliners (with freezing capacity and ice-chilled) operating in this area is frozen to 2016 levels (excluding SIDs and Indonesia).

Other measures that apply to the wider convention area:
The number of drifting FADs with activated instrumented buoys deployed at any one time is limited to 350 per purse seine vessel.
Catch and/or effort limits apply for purse seining within national waters (both the type of limit and the amount vary by country).
There are country-specific limits on longline bigeye catch, and by 2020 hard limits for bigeye and a framework to allocate them amongst countries shall be developed.
Catches by other commercial tuna fisheries for bigeye, yellowfin or skipjack tuna (excluding those taking less than 2,000 tonnes) shall not exceed either the average level for the period 2001-2004 or the level of 2004.

More generally:
There is a requirement to submit FAD management plans, including information on strategies used to implement closures and other measures for reducing mortality of juvenile bigeye. A number of aspects in the bridging measure have been brought forward from previous management measures, and it isn’t clear how well they have been implemented, especially given the ongoing increases in total catch of skipjack. The scientific committee recommends more comprehensive data collection relating to FADs.
Observer coverage on purse seiners is poor in areas not specified in the bridging measure and only 5% coverage is required on longliners greater than 20m in length. 20% is considered to be the minimum to be effective.
To help address IUU, the WCPFC maintains an IUU Vessel List, prohibits transhipments at sea between purse seiners (some exemptions apply) and requires all other transhipments to be documented and 100% observed as part of the regional observer programme.
In 2017 a Compliance Monitoring Scheme was introduced to assess and improve compliance with obligations, and penalise non-compliance.

Capture Information

Criterion score: 0.25 info

Approximately 4% of the WCPO yellowfin catch was taken in domestic pole and line and handline fisheries in 2016. These methods are labour intensive yet very selective. Pole and line fisheries do rely on large amounts of bait fish to attract the tuna, and whilst bait fish species are generally small and resilient, some basic management measures are needed.

There is a WWF coordinated Fisheries Improvement Project (FIP) for some local handline fleets in the Philippines - the Partnership Project Towards Sustainable Tuna (PPTST). The project aims to get the fishery to MSC application by 2017, and is working on numerous aspects including monitoring and reporting.

References

Fishery Progress, 2017. Fishery Improvement Project Directory. Available at https://fisheryprogress.org/ [Accessed on 05.12.2017].

IPNLF, 2012. Ensuring sustainability of live bait fish, International Pole and Line Foundation, London, 57 pp.

WCPFC, 2017. Provisional outcomes document, WCPFC14-2017-outcomes, from the Western & Central Pacific Fisheries Commission Fourteenth Regular Session (As at 18 December 2017), 3-7 December 2017, Manila, Philippines. 15 pp. Available at https://www.wcpfc.int/meetings/wcpfc14 [Accessed on 18.12.2017]

WCPFC, 2017. Summary Report of the Thirteenth Regular Session of the Scientific Committee of the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, 9 - 17 August 2017, Rarotonga, Cook Islands. 281 pp. Available at https://www.wcpfc.int/meetings/sc13 [Accessed on 27.11.2017]