The 2013 stock assessment for yellowfin tuna in the Eastern Pacific Ocean indicated that the stock is overfished. Fishing mortality was about equal to the Maximum Sustainable Yield (MSY) suggesting that overfishing was unlikely to be occurring, though to rebuild the stock, effort in some parts of the fishery will need to be reduced. The stock is highly dependant on recruitment scenarios and it is suggested that the stock may now be moving from a regime of high productivity to an intermediate one. Relatively recent measures employed to monitor and reduce bycatch in most of these fisheries is quite good, yet there is a lack of definitive information demonstrating the commercial effectiveness of these measures in these fisheries. Non Fish Aggregation Device (FAD) associated purse seine caught yellowfin represent the best option in the East Pacific Ocean, as the bycatch of vulnerable species associated with longline and FAD associated purse seine fisheries in the area are still of concern.
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.
Yellowfin stocks in the Eastern Pacific Ocean (EPO) are managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). In 2012, catches were approximately 191,000t which is 13% lower than the previous five year average of 220,000t and less than half of the highest historical catch reported in 2001. The most recent stock assessment was carried out in 2013 and provided a more pessimistic view of the stock status, with spawning biomass, B, being below that which can support the Maximum Sustainable Yield (0.85Bmsy). This suggesting the stock is overfished. It is noted however, that the assessment is sensitive to recruitment levels for which remains some uncertainty for the future. The assessment suggests the fishery has undergone two to three productivity regimes and may now be going from a period of high productivity to an intermediate one. Fishing mortality is estimated to be approximately at its management objective (0.99Fmsy) suggesting the stock is not being subject to overfishing.
Current maximum sustainable yield (MSY) is 259,000t yet it is noted that this could increase by increasing the average weight of yellowfin tuna captured, such as those targeted by the longline and free schooling purse seine fisheries.
Most tuna stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. To try and achieve this, 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. Eastern Pacific Ocean bigeye tuna is managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). 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 Marine Stewardship Council (MSC) certified sustainable and well managed pole and line fishery for skipjack, yellowfin and bigeye based on the California Peninsula, Mexico.
The results of the latest assessment suggest that fishing mortality needs to be maintained at or below its current level to rebuild the stock above Bmsy. To achieve this will require strong management and adherence to measures already in place by the IATTC. The main stock conservation measures established include: a 62-day closure for purse seiners greater than 182 tons capacity; a seasonal closure of the purse seine fishery in an area known as “El Corralito”, west of the Galapagos Islands, where catch rates of small bigeye are high; and a full retention requirement for bigeye, skipjack and yellowfin tunas for all purse seine vessels yet the degree of enforcement regime may vary depending on the country or authority. There is no TAC in place for this fishery.
There is a requirement for longliners over 20m in length to use at least 2 prescribed seabird mitigation measures (eg tori line, dyed bait, weighted branch line, night setting, underwater setting chute); for vessels to carry line cutters and de-hookers 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. Monitoring of these measures is generally deficient although from January 2013, there has been 5% observer coverage on longliners greater than 20m.
To help address IUU, the IATTC maintains an IUU Vessel List; maintains a register of authorised fishing vessels; and prohibits transhipments at sea for most vessels (Some exemptions apply) and requires most other transhipments to be documented and observed as part of the regional observer programme.
Longline catches of yellowfin in the Eastern Pacific Ocean have been steadily decreasing and in 2011, represented only 3% of the total retained catch. Longlining in the EPO is associated with the incidental capture and mortality of sharks, turtles and sea birds. There are a range of measures that can be employed to reduce bycatch of these species including: circle and/or barbless hooks to prevent turtle and shark capture, and weighted branchlines, bird scaring lines, and night setting to reduce the capture of birds. The IATTC recommend at least two of these measures be employed at the same time. The broad-scale effectiveness of such devices is yet to be commercially quantified in many fisheries and requires further monitoring to assess this.
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.
IATTC, 2013. The fishery for tunas and billfish in the Eastern Pacific Ocean in2012. 4th meeting of scientific advisory committee. La Jolla, California (USA), 29 April -3 May 2013. Document SAC 04-03(Revised). Available at http://www.iattc.org/Meetings/Meetings2013/MaySAC/Pdfs/SAC-04-03-Fishery-in-the-EPO-2012REV.pdf [Accessed Nov 2013].
IATTC, 2013. Fishery status report number 11. Tunas and billfishes in the Eastern Pacific Ocean 2012. La Jolla, California (USA). 2013. Available at http://www.iattc.org/PDFFiles2/FisheryStatusReports/Fishery-Status-Report-11ENG.pdf [Last Accessed Jan 2014].
ISSF, 2013. ISSF Tuna Stock Status Update, 2013(2): Status of the world fisheries for tuna. ISSF Technical Report 2013-04A. International Seafood Sustainability Foundation, Washington, D.C., USA. Available at http://iss-foundation.org/resources/downloads/?did=487 [Accessed Nov 2013].
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