Atlantic Bluefin Tuna (Thunnus thynnus)

• Atlantic bluefin tuna population levels are low. International overfishing is occurring.
• Atlantic bluefin tuna is a highly migratory species that requires high levels of international cooperation for appropriate management and conservation. It is managed both domestically (by NOAA's National Marine Fisheries Service Highly Migratory Species Management Division) and internationally (by the International Commission for the Conservation of Atlantic Tunas and other organizations). NMFS recently called for a multi-year moratorium on bluefin tuna fishing in the Eastern Atlantic and Mediterranean.
• Bluefin is low in sodium and is a very good source of vitamins A, B6, and B12, selenium, niacin, and phosphorous. For more on nutrition, see Nutrition Facts. (USDA)
• Atlantic bluefin tuna is the highest valued Atlantic tuna species in the market.

Sustainability Status

Biomass: The 2008 ICCAT stock assessment of West Atlantic bluefin tuna created two scenarios (low recruitment and high recruitment) regarding the spawning biomass (the amount of sexually mature individuals in the population) of the stock. The low recruitment scenario resulted in a current population estimate that is 57% of the biomass needed to support maximum sustainable yield (B_MSY), while the high recruitment estimate was less optimistic at only 14% of B_MSY.
Overfishing: Yes
Overfished: Yes
Fishing and habitat: Atlantic bluefin tuna are caught with purse seines, handgear (rod and reel, handline, and harpoon), and longlines. Pelagic longline gear is not allowed to directly target bluefin tuna but is allowed to retain a limited amount of bluefin tuna caught incidentally while targeting other species (such as swordfish, yellowfin tuna, and bigeye tuna). Habitat damage by highly migratory species fishing gear, other than bottom longlines, is minor because the gear rarely comes in contact with the ocean floor.
Bycatch: The primary fishing gears used to target bluefin tuna (rod and reel and purse seine) target schools and are generally selective. They also allow for the live release of bycatch species to a great degree.
Aquaculture: There is currently no commercial aquaculture of bluefin tuna in the United States; however, there is aquaculture of bluefin tuna in the Mediterranean.

Science and Management

Atlantic bluefin tuna are highly migratory and are fished by many nations. The fishery is managed domestically by the NMFS Highly Migratory Species Management Division and internationally by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Two stocks are assumed: 1) Western Atlantic and 2) Eastern Atlantic and Mediterranean.

ICCAT has set and allocated Western bluefin tuna quotas by country since 1982 and Eastern bluefin quotas since 1994. In 1998, an international rebuilding program was adopted for countries fishing on the Western Atlantic stock, including the United States, Canada, and Japan. Stock assessments are conducted every 2 years. The latest stock assessment in 2008 confirmed that the Western and Eastern Atlantic stocks are overfished and overfishing is occurring.

The U.S. fishery for western Atlantic bluefin tuna is managed through the Consolidated Atlantic Highly Migratory Species Fishery Management Plan. The harvest of Western Atlantic bluefin tuna has been restricted since 1982. The U.S. bluefin fishery continues to be regulated by quotas, seasons, gear restrictions, limits on fish landed per trip, and size limits. Directed fishing for bluefin tuna is prohibited in the Gulf of Mexico in recognition of the area's value as an important spawning ground.

Mixing across management unit boundaries of fish of western and eastern origin is an important consideration for management of the resource in both areas. In particular, the condition of the Eastern Atlantic stock and fishery could adversely affect recovery in the West Atlantic. Therefore, it is important to continue efforts to manage the fisheries in both the East and West Atlantic according to ICCAT's objectives.

As part of its commitment to the ICCAT Bluefin Tuna Year Program, the U.S. supports research that concentrates on stock structure (including ageing and maturity), fish migration, spawning site fidelity, reproductive biology, and population modeling analyses.

Life History and Habitat

Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed. Bluefin tuna are late to mature, slow-growing, and long-lived, making them more vulnerable to fishing pressure than species that grow rapidly such as tropical tuna species.

• Geographic range: In the West Atlantic, bluefin are found from the Gulf of Mexico to Newfoundland; in the East Atlantic, they are found from roughly the Canary Islands to south of Iceland; bluefin live throughout the Mediterranean Sea.
• Habitat: Bluefin tuna are pelagic, living in the open ocean.
• Life span: Long - the oldest age considered reliable is 20 years, although it is believed that bluefin tuna may live longer.
• Food: Bluefin tuna are voracious carnivores that feed on fish, squid, and crustaceans.
• Growth rate: Slow. Western Atlantic bluefin tuna are believed to grow more slowly than bluefin tuna in the East Atlantic.
• Maximum size: Can grow to over 9.8 feet and reach more than 1,400 pounds. Western Atlantic bluefin tuna are believed to grow larger than bluefin tuna in the East Atlantic.
• Reaches reproductive maturity: Late – Western Atlantic bluefin tuna first spawn at age 8 and are believed to take longer to reach maturity than bluefin tuna in the East Atlantic. Recent studies indicate that the age at which 50% of bluefin are sexually mature is about 12 years.
• Reproduction: Females produce up to 10 million eggs a year.
• Spawning season: From mid-April to June in the West Atlantic.
• Spawning grounds: Principally in the Gulf of Mexico and in the Florida Straits.
• Migrations: Large bluefin tuna are adapted for migration to colder waters. Tagging of bluefin tuna has indicated that they move across the east/west boundary in the Atlantic. Bluefin tuna can migrate thousands of miles.
• Predators: Marine mammals, including killer whales and pilot whales, feed on bluefin tuna. Other predators include sharks and large predatory fishes. Juvenile bluefin tuna are also preyed upon by bluefish and seabirds.
• Commercial or recreational interest: Both
• Distinguishing characteristics: The bluefin tuna has a large, torpedo-shaped body that is nearly circular in cross-section. The fish is dark blue-black on the back and white on the lower sides and belly. On live bluefin, colorless lines alternate with rows of colorless spots on the lower sides. The second dorsal fin is reddish brown. The color of the dorsal fin, the number of gill rakers on the first arch, and the very short pectoral fins separate this species from other members of the tuna genus, Thunnus.

Role in the Ecosystem

Atlantic bluefin tuna are towards the top of the food chain and prey upon many aquatic species. They are also prey for top predators such as sharks.

Additional Information

Market name: Tuna, Bluefin Tuna, Toro, Maguro
Vernacular names: Giant Bluefin, Northern Bluefin Tuna, Tunny, Oriental Tuna

Biomass

Biomass refers to the amount of Atlantic bluefin tuna in the ocean. Scientists cannot collect and weigh every single fish to determine biomass, so they use mathematical models to estimate it instead. These biomass estimates can help determine if a stock is being fished too heavily or if it may be able to tolerate more fishing pressure. Managers can then make appropriate changes in the regulations of the fishery.

Until the 1950s, the U.S. commercial fishery for tunas employed mostly harpoons, handlines, and traps, and there was no commercial market for bluefin tuna. In the 1950s and 1960s, a large purse seine fishery targeted small bluefin tuna for the U.S. cannery industry. Bluefin stocks remained relatively stable until the 1970s when their value soared as sushi and fresh steaks in international markets, particularly in Japan, which led to a dramatic increase in fishing effort by the U.S. and Japanese longline fleet in the Gulf of Mexico. Spawning stock biomass (SSB) saw a steady decline from the early 1970s to 1992, but after that time it has fluctuated between 18 and 27% of the 1975 level.

Landings

Landings refer to the amount of catch that is brought to land. From 1961 to 1973, bluefin tuna represented 45 to 80% of the U.S. western Atlantic catch of large pelagic species. Since 1980, the percentage has dropped to less than 15%, reflecting the decline in the bluefin tuna population, catch restrictions, and the increasing harvests of alternative species. Landings for 2005, 2006, and 2007 were 718, 472, and 758 metric tons, respectively.

Biomass and Landings

Landings and biomass data can sometimes be used to detect trends in a fishery. U.S. bluefin tuna landings from the West Atlantic stock have been on a downward trend, but the spawning stock biomass of the population has remained at low levels. This may indicate that further reductions in fishing effort might be needed in order for biomass to increase, but other factors, such as changes in environmental conditions, may be limiting the growth of the population as well. Bluefin tuna is a highly migratory species that moves outside of U.S. waters, therefore fishing practices of foreign countries could affect U.S. West Atlantic bluefin tuna landings and the biomass of the population. Also, recreational fishing efforts may impact West Atlantic bluefin tuna populations.

Data sources:
Biomass from ICCAT 2008 Report of the Standing Committee on Research and Statistics (stock assessment update)

Landings from 2008 U.S. National Report to ICCAT

Important Dates

1960s – Large purse seine fishery on juvenile bluefin tuna for canneries emerges off mid-Atlantic coast
1966 – International Convention for the Conservation of Atlantic Tunas is signed creating the International Commission for the Conservation of Atlantic Tunas (ICCAT)
1960s-1970s – Large Japanese and U.S. pelagic longline fishery develops in the Gulf of Mexico for adult bluefin tuna
1970s – Value of bluefin soars as sushi and fresh steaks in international markets, particularly in Japan, and fishing pressure increases dramatically
1970-Late 1980s – Spawning stock biomass declines
1982 – U.S. harvest of bluefin is restricted
1988-1997 – Landings are close to landings limits, sometimes exceeding limits by 100 metric tons
1990 – Magnuson Act amended, giving authority to Secretary of Commerce to manage Atlantic tunas; secretarial authority iss delegated to NMFS
1992 – NMFS creates the HMS Management Division to manage Atlantic tunas, sharks, swordfish, and billfish
1998 – Rebuilding program adopted by ICCAT for western Atlantic bluefin, with intent to rebuild the stock by 2019
1999 – NMFS publishes the Final Fishery Management Plan (FMP) for Atlantic Tunas, Swordfish, and Sharks, the first FMP for Atlantic tunas; measures include prohibition of pelagic driftnets for tunas, implementation of the ICCAT Rebuilding Program for western bluefin tuna
2006 – Consolidated Atlantic Highly Migratory Species Fishery Management Plan is approved and implemented; combines the management of all Atlantic HMS into one comprehensive FMP; includes a variety of management measures for bluefin tuna such as creating a formalized winter bluefin tuna fishery, clarifying procedures for calculating quota, allowing seasonal and inseason management measures, and establishing individual quota category carry-over limits; allows the use of speargun gear in Atlantic tuna recreational fisheries and shifts the fishing year to a calendar year for all HMS
2007 – United States seeks temporary suspension of Eastern Atlantic and Mediterranean bluefin tuna fishing at ICCAT. Although ICCAT did not adopt the U.S recommendation, the United States was effective in raising public awareness of the need for action to recover the Eastern stock.
2008 – NMFS authorizes the use of green-stick gear to harvest Atlantic tunas

Notes and Links

General Information:
Atlantic Tunas Description

NMFS Sustainability Species Identification - Atlantic bluefin tuna

South Atlantic Fishery Management Council Fish ID for Atlantic Bluefin Tuna

Atlantic Tunas Fishery Information and Regulations

NMFS Atlantic Bluefin Tuna Permit Information

Fishery Management:
Consolidated Atlantic Highly Migratory Species Fishery Management Plan

International Commission for the Conservation of Atlantic Tunas (ICCAT)

Stock Assessments:
ICCAT 2008 Report of the Standing Committee on Research and Statistics (Stock assessment update)

2007 Stock Assessment and Fishery Evaluation Report for Atlantic Highly Migratory Species