In the United States, Atlantic tunas - bluefin, bigeye, albacore, and yellowfin - are managed by both the Magnuson Stevens Act and the Atlantic Tunas Convention Act (ATCA). ATCA authorizes the Secretary of Commerce to implement binding recommendations made by the International Commission for Conservation of Atlantic Tunas (ICCAT) - one of several regional fishery management organizations (RFMOs) charged with managing highly migratory species (HMS) by the United Nations Law of the Sea. The management authority for US Atlantic tuna fisheries belongs to the National Marine Fisheries Service’s HMS Management Division. Management measures put in place by the HMS division include quotas, permit programs, and size limits.
On the West Coast of the United States, the Pacific FIshery Management Council developed a Fisheries Management Plan (FMP) for HMS species, including yellowfin tuna. General management measures in this FMP include gear restrictions, fishery observer programs, and quotas and harvest guidelines. For Pacific yellowfin tuna on the high seas, the US is a member of the Inter-American Tropical Tuna Commission (IATTC) RFMO and carries out the recommendations for management measures put forth by the organization.
For yellowfin tuna fisheries on the high seas, stocks are differentiated into four distinct groups that are assessed and managed by RFMOs: Atlantic Ocean, Eastern Pacific, Western Pacific and Indian Ocean. The RFMOs that manage yellowfin tuna stocks on the high seas are ICCAT, IATTC, the Indian Ocean Tuna Commission (IOTC), and the Western and Central Pacific Fisheries Commission (WCPFC).
ICCAT has made several management recommendations to its members with regard to yellowfin, bigeye and skipjack tuna. The Atlantic Ocean Tropical Tuna Tagging Programme (AOTTP) was established in order to gather more information on stock structure, natural mortality and growth for yellowfin tuna and other tropical tuna - all of which is important for stock assessments. Members must also implement a multi-annual management and conservation program for vessels harvesting yellowfin and bigeye tuna. As part of this multi-annual program, a total allowable catch of 110,000 t for yellowfin tuna has been set which is to remain in place until a change is made by the commision based on scientific advice. Additionally, area/time closures meant to protect juvenile tuna have been put into place through this program. FAD use has also been limited to 500 FADs per purse seine vessel. ICCAT members must also submit management plans for their vessels that use FADs and vessels must collect and report information on all FADs they deploy. The commission has established and maintained records of all tropical tuna vessels authorized by ICCAT members - members must keep their lists up to date and report any changes to the commission. If IUU activity is detected, the commission will alert members accordingly, who then must investigate the situation and stop fishing activity, if appropriate. Recommendations have also been made to increase scientific observers onboard vessels fishing for tuna species and information collected from observer programs are compiled by ICCAT and made available at annual meetings.
In recent years, IATTC has established several management measures for tuna in the eastern Pacific Ocean. A measure was implemented to collect vessel information for all vessels harvesting HMS in the eastern Pacific Ocean (area under IATTC’s Convention). The register is meant to assist the IATTC in monitoring and compliance efforts and in 2002, was made the authoritative source of identified purse seine vessels qualified to fish for tuna in IATTC’s Convention Area. A bycatch reduction program for purse seine vessels was also initiated in 2004. Under this program, vessels were required to retain and land all tuna brought on board and to release non-tuna species such as sea turtles that get caught purse seine nets. The program was meant to push for the development of gear or techniques that will reduce the amount of low-value tuna, such as small yellowfin, brought on board so that vessels would not be economically disadvantaged by the full retention program. Member countries also require purse seine vessel operators to maintain logbooks of catch and efforts and must make them available to fishery officials for inspection. In 2016, IATTC adopted a harvest control rule (HCR) to prevent fishing mortality of tropical tunas from exceeding MSY levels. If fishing mortality or spawning biomass approaches a set limit, the HCR also triggers an initiation of additional management measures meant to further reduce fishing mortality to help rebuild the stock. The measures established by the HCR include an annual fishing closure for purse seine vessels with a carrying capacity of 182 tons or more. In addition, this measure calls for a 1) seasonal closure of a purse seine fishery in an area west of the Galapagos Islands known as “El Corralito” where catch rates of tuna are high, 2) a full retention requirement for all purse seine vessels, and 3) a total annual catch limit of the average level observed during 2013-2015 for yellowfin and bigeye tuna (combined).
In the Indian Ocean, yellowfin tuna is addressed in several management measures adopted by the Indian Ocean Tuna Commission (IOTC). A recent resolution passed by the IOTC focuses on rebuilding the Indian Ocean yellowfin tuna stock through the various catch limit requirements for purse seine, gillnet, and longline fisheries. In addition, this resolution also requires that IOTC members monitor yellowfin tuna catches from their vessels. The Compliance Committee will use this monitoring information to evaluate compliance with required fishing reduction levels. There is also currently a ban on discards of yellowfin, skipjack, and bigeye tuna caught by purse seine vessels in the IOTC’s area of competence. This retention requirement states that all tuna caught must be retained on board and landed in order to reduce the amount of species discarded by purse seine vessels. To also reduce the amount of juvenile yellowfin tuna mortalities caused by FAD fishing efforts, the IOTC has moved forward with limiting the number of FADs that can be used by vessels. Members are also required to submit FAD Use Management Plans to the Commission which should include initiatives or surveys to investigate and minimize the capture of yellowfin and bigeye tuna. The IOTC’s Working Party on Tropical Tuna (WPTT) has also made recommendations that catches of yellowfin in the Indian Ocean should not surpass 300,000 t in order to bring the stock biomass levels that could sustain catch at the MSY level in the long term.
The objective of management measures established by the WCPFC for yellowfin tuna is to ensure that rate of fishing mortality does not affect the tuna stock’s ability to achieve maximum sustainable yield. Currently, members of the commission (China, Indonesia, Japan, Republic of Korea, Taipei, and the USA) are encouraged to reduce fishing mortality on juvenile yellowfin tuna in their territorial seas. Members also must establish effort/catch limits for purse seine fisheries in their EEZs that reflect the distribution of yellowfin tuna. For purse seine fisheries, members agree not to increase catches of their vessels harvesting yellowfin tuna. In 2014, members were required to have develop management plans for use of FADs by their high seas vessels which were to include strategies to limit the capture of both bigeye and yellowfin. Members are required to promote research to identify ways to avoid capture of juvenile tuna species during FAD sets and results must be presented annually to the Commission.