Atlantic Bluefin Tuna (Thunnus thynnus)

• Atlantic bluefin tuna population levels are low. International overfishing is occurring.
• Bluefin tuna are a highly migratory species that requires high levels of international cooperation for appropriate management and conservation. NOAA's National Marine Fisheries Service 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 are caught by recreational fishermen in the Caribbean and the Atlantic Ocean.

Sustainability Status

Biomass: Spawning biomass (the amount of sexually mature individuals in the population) is 19% of the 1975 reference year level and 41% of the spawning biomass needed to support maximum sustainable yield.
Overfishing: Yes
Overfished: Yes
Fishing and habitat: Bluefin tuna are caught with purse seines, handgear (rod and reel, handline, and harpoon), and traps. Pelagic longline gear is not allowed to 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 in the open ocean environment.
Bycatch: The primary fishing gears used to target bluefin tuna (rod and reel and purse seine) 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 increasing interest in international 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 2006 confirmed that the Western and Eastern Atlantic stocks are overfished and overfishing is occurring. New stock assessments will be conducted in 2008.

The U.S. fishery for western Atlantic bluefin tuna is managed by 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 its 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 , research supported by the United States has concentrated 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.
• Maximum size: Can grow to over 9.8 feet and reach more than 1,400 pounds.
• Reaches reproductive maturity: Late - bluefin in the West Atlantic first spawn at age 8. 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.
• Migrations: Large bluefin are adapted for migration to colder waters. Tagging of bluefin tuna has indicated that bluefin move across the east/west boundary in the Atlantic. Bluefin can migrate thousands of miles.
• Predators: Marine mammals, including killer whales and pilot whales, feed on bluefin tuna. Other predators include sharks, other large predatory fishes, 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 fall into the fourth trophic level in the oceanic ecosystem. They are top predators that prey upon many marine species.

Additional Information

Market name: Tuna, Bluefin Tuna, Toro, Maguro
Vernacular names: Albacore, 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 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, and fishing pressure increased dramatically, particularly by the U.S. and Japanese longline fleet in the Gulf of Mexico. Spawning stock biomass (SSB) declined rapidly in the early 1970s followed by a more gradual decline in SSB through the early 1990s to about 21% of the 1975 level. From 1994 to 1998, SSB recovered somewhat to about 28% of the 1975 level in 1998. However, the 2006 stock assessment indicates gradual declines since then to about 19% of the 1975 level by the year 2004.

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 2004, 2005, and 2006 were 899, 718, and 472 metric tons, respectively.

Biomass and Landings

Are landings and biomass related? Landings are dependent on biomass, management measures in the fishery, and fishing effort.

Data sources:
Biomass from ICCAT Report of the 2006 Atlantic Bluefin Tuna Stock Assessment Session

Landings from 2007 U.S. National Report to ICCAT

Important Dates

1960s – Large purse seine fishery on juvenile bluefin tuna for canneries emerges off mid-Atlantic coast
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 was delegated to NMFS
1992 – NMFS created 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 2018
1999 – NMFS finalizes first FMP for Atlantic Tunas
2006 – Consolidated Atlantic Highly Migratory Species Fishery Management Plan is approved
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 is effective in raising public awareness of the need for action to recover the Eastern stock.

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

Fishery Management:
Consolidated Atlantic Highly Migratory Species Fishery Management Plan

International Commission for the Conservation of Atlantic Tunas (ICCAT)

Stock Assessments:
ICCAT 2007 Report of the Standing Committee on Research and Statistics (Stock assessment update)

ICCAT Report of the 2006 Atlantic Bluefin Tuna Stock Assessment Session

2005 Stock Assessment and Fishery Evaluation Report for Atlantic Highly Migratory Species