Western Atlantic Bluefin Tuna

Atlantic Bluefin Tuna

Thunnus thynnus

ALSO KNOWN AS:

    Tuna, Bluefin Tuna, Toro, Maguro, Giant Bluefin, Northern Bluefin Tuna

SOURCE:

    U.S. wild-caught from Maine to Louisiana
 

STATUS

  • POPULATION
  • FISHING RATE
  • HABITAT IMPACTS
  • BYCATCH
 

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OVERVIEW

School of bluefin tuna

School of bluefin tuna

LAUNCH GALLERY

Three species of bluefin tuna are found around the world – Northern (or Atlantic) bluefin tuna (Thunnus thynnus), Southern bluefin tuna (Thunnus maccoyii), and Pacific bluefin tuna (Thunnus orientalis). Atlantic bluefin tuna is divided into two stocks, the western (harvested off the coast of North America by Canada, Japan, and the United States) and the eastern (harvested off the coast of Europe and Africa and in the Mediterranean Sea).

Fisheries for bluefin tuna date back thousands of years in the Mediterranean but didn't emerge in the western Atlantic until the 1950s. Although today they're widely known as the most prized species of tuna, there was no commercial market for bluefin tuna in this area until the late 1950s. In fact, fishermen regarded giant bluefin tuna (greater than 310 pounds) as a nuisance because of the damage they caused to fishing gear. Ironically, a giant bluefin can fetch hundreds of thousands of dollars at fish markets today. As sushi and sashimi markets developed in the 1970s and 1980s, the demand and prices for bluefin tuna soared. Fisheries expanded, fishing pressure increased dramatically, and, in an all too familiar scenario, the western Atlantic bluefin tuna population plummeted.

Unfortunately, similar stories can be told for other bluefin tuna populations around the world, including in the eastern Atlantic and Mediterranean. Since bluefin tuna are late to mature, slow-growing, and long-lived, they're especially vulnerable to fishing pressure compared to faster growing, more productive species. On top of that, many nations harvest bluefin tuna and effective conservation and management of this resource and its fisheries are not possible without strong international cooperation.

In 1981, the International Commission for the Conservation of Atlantic Tunas (ICCAT) attempted to stop the decline in the western Atlantic population, prohibiting capture of bluefin tuna for the next fishing year and closing the Gulf of Mexico (the major spawning area for bluefin tuna) to directed bluefin fishing. In 1991, they determined that the stock was stable but not recovering as anticipated. They further reduced the amount of bluefin that could be harvested and increased the minimum size of bluefin that could be retained. After several more years of reduced harvests, the western Atlantic stock remained below sustainable levels (overfished), and in 1998 ICCAT adopted a rebuilding plan for the stock, with a goal of rebuilding the stock by 2019. This plan has been amended several times.

Today, fisheries for western Atlantic bluefin tuna are highly regulated. ICCAT sets catch limits based on scientific advice. The most recent catch levels set for 2011 and 2012 are expected to support continued growth and recovery of the stocks, as long as member nations comply with these limits. Strict measures are in place to ensure compliance – on the water, in port, and at the marketplace – through the implementation of the catch documentation scheme, which allows trade tracking for individual shipments of fish. The plight of bluefin tuna has received significant attention from the public, and this attention should encourage ICCAT and its member nations to continue their efforts to ensure the effective conservation and management of this important resource.

Finally, because the western and eastern stocks mix, western Atlantic bluefin are also affected by fishing pressure in the eastern Atlantic. There was rampant overfishing in the eastern Atlantic/Mediterranean during the 1990s and early 2000s. However, in recent years, catches in the eastern Atlantic have been reduced to levels consistent with scientific advice, and new monitoring and control measures have been adopted to address illegal, unreported and unregulated (IUU) fishing on that stock. Scientists advise that improved stock conservation in the eastern Atlantic would likely benefit the western stock as well.

Looking Ahead

NOAA Fisheries now requires U.S. commercial fishermen who fish for yellowfin tuna, swordfish, and other species with longlines in the Gulf of Mexico to use “weak hooks,” a new type of hook designed to reduce the incidental catch of Atlantic bluefin tuna. The Gulf of Mexico is the only known spawning area for the western stock of Atlantic bluefin tuna, and protecting these fish during spawning can help the long-term rebuilding of the depleted bluefin tuna population.

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LOCATION & HABITAT

Northern, or Atlantic, bluefin tuna are found throughout the entire North Atlantic and its adjacent seas, including the Mediterranean. In the western Atlantic, bluefin are found from Newfoundland to the Gulf of Mexico; in the eastern Atlantic, they’re found from south of Iceland to the Canary Islands, and throughout the Mediterranean Sea.

Bluefin tuna live near the surface in temperate waters but frequently dive to depths of 500 to 1,000 meters. Bluefin tuna are a highly migratory species – they can migrate thousands of miles across an entire ocean. Tagging studies have indicated that bluefin tuna move across the east/west boundary in the Atlantic. Although they’re highly migratory, they tend to spawn in the same areas in the Gulf of Mexico and Mediterranean.

 
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BIOLOGY

Bluefin tuna grow more slowly than other tunas and have a long life span, up to 20 years or more. In the western Atlantic, they mature late in life, around age 8. They spawn from mid-April to June, mainly in the Gulf of Mexico. Females can produce up to 10 million eggs a year. The eggs are fertilized in the water column and hatch in about 2 days.

Bluefin tuna are top predators. Juveniles eat fish, squid, and crustaceans, and adults feed mainly on baitfish such as herring, bluefish, and mackerel. Sharks, marine mammals (including killer whales and pilot whales), and large fishes feed on bluefin tuna. Bluefish and seabirds also prey upon juvenile bluefin tuna.

 
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PHYSICAL DESCRIPTION

The bluefin tuna has a large, torpedo-shaped body that is nearly circular in cross-section. They are the largest of the tuna species and can reach up to 13 feet and 2,000 pounds. Bluefin tuna are dark blue-black on the back and white on the lower sides and belly. Live bluefin have colorless lines alternating with rows of colorless spots on their lower sides. The second fin on their back (dorsal fin) is reddish brown, and they have short pectoral fins. These characteristics separate this species from other members of the tuna genus, Thunnus.

 
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OVERVIEW

There are two stocks of Atlantic bluefin tuna: 1) western Atlantic and 2) eastern Atlantic and Mediterranean. The International Commission for the Conservation of Atlantic Tunas’ (ICCAT) scientific committee typically assesses the abundance of both the western and eastern Atlantic stocks every 2 years. Managers use the results of these stock assessments to develop new conservation and management measures as needed.

 
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POPULATION STATUS

Scientists estimate the spawning stock biomass (a measure of the amount of bluefin that are able to reproduce) of the western stock declined steadily between 1970 and 1992. Since then, spawning stock biomass fluctuated between 25 and 36 percent of the 1970 level. In recent years, however, spawning stock biomass appears to have gradually increased from 27 percent of 1970 levels in 2003 to an estimated 36 percent in 2011. Since 1998, when the rebuilding plan was adopted, spawning stock biomass has increased by 19 percent.

In 2011, scientists estimated the biomass of the eastern stock to be between 37 and 89 percent of the target level, a substantial improvement from the 2009 levels of 19 to 35 percent.

Based on this information, ICCAT set catch limits for the 2011 and 2012 fishing seasons that would support continued growth for both stocks, as long as member nations comply with these limits. Scientists are expected to assess the stocks again in 2015.

 
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ADDITIONAL RESEARCH

The United States supports research that concentrates on stock structure, migration, aging, spawning behavior, reproductive biology, and population modeling analyses. NOAA Fisheries also collects data on fishing effort and catch from the United States for bluefin tuna to support ICCAT stock assessments and reports.

NOAA Fisheries scientists continue to study the possible effects of the 2010 Deepwater Horizon/BP oil spill on Atlantic bluefin tuna, as the Gulf of Mexico is one of the only known spawning grounds for the western stock of Atlantic bluefin tuna.

 
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Harvesting Bluefin Tuna

U.S. fishermen harvest bluefin tuna with purse seines and handgear (rod and reel, handline, and harpoon). They generally target schools of tuna, and these fishing gears are fairly selective and allow for the live release of any unintentionally caught species. Fishing gear used to catch bluefin tuna rarely contacts the ocean floor and therefore has minimal impact on habitat.

Although fishermen are not allowed to use pelagic longline gear to target bluefin tuna directly, strict regulations allow them to retain a limited number of bluefin tuna caught incidentally while fishing for other species such as swordfish and yellowfin tuna. NOAA Fisheries requires pelagic longliners fishing for swordfish and yellowfin tuna in the Gulf of Mexico to use “weak hooks” to reduce the number of bluefin tuna that are incidentally caught and help rebuild the depleted bluefin tuna population.

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Management

Who’s in charge? Management of highly migratory species such as bluefin tuna is complicated because these species migrate thousands of miles across oceans and international borders and are fished by many nations. Effective conservation and management of these resources require international cooperation as well as strong domestic management. With Atlantic bluefin tuna, NOAA Fisheries Atlantic Highly Migratory Species Management Division sets regulations for the U.S. fishery based on conservation and management recommendations from ICCAT, consistent with applicable U.S. laws.

Current management:
International: Taking into consideration the results of the most recent stock assessment, ICCAT member nations develop new conservation and management measures as needed. ICCAT sets and allocates western Atlantic bluefin tuna quotas by country. The total allowable catch is set for 1,750 metric tons for 2011 and 2012. There has been a history of strong compliance with these quotas and other conservation measures in the western Atlantic

ICCAT began to limit catches of eastern Atlantic and Mediterranean bluefin tuna in the mid-1990s. Unfortunately, limits were set in excess of scientific advice and compliance was poor for many years. However, adherence to individual quotas in the eastern Atlantic and Mediterranean has greatly improved in the past few years and catch limits are within the range of scientific advice and are expected to support continued growth, provided parties comply with the agreed limits. The United States does not fish in the eastern Atlantic; however, because the two stocks sometimes mix, management of the larger stock in the eastern Atlantic can have an impact on the western stock.

Domestic: Consolidated Atlantic Highly Migratory Species Fishery Management Plan

  • Annual quotas and limits on the amount of fish a vessel can keep per trip, seasons, gear restrictions, and minimum size limits, all designed to manage total U.S. harvests to conform to ICCAT recommendations.
  • Regulations prohibit directed fishing for bluefin tuna in the Gulf of Mexico due to the area’s value as an important spawning ground, but regulations allow for a limited number of incidentally caught bluefin tuna to be retained by the Gulf of Mexico pelagic longline fleet.
  • Pelagic longliners fishing for yellowfin tuna and swordfish in the Gulf of Mexico must now use “weak hooks” to reduce the number of bluefin tuna caught unintentionally. These regulations are designed to manage total U.S. catches consistent with ICCAT recommendations.
  • Vessels must have a permit to fish for, retain, possess, or sell Atlantic bluefin tuna and must report landings of all bluefin tuna. They can only sell to permitted dealers.
  • Management also regulates trade of Atlantic bluefin tuna – all fish dealers purchasing regulated Atlantic tunas from vessels holding an Atlantic tunas permit or an Atlantic Highly Migratory Species permit must obtain an Atlantic tunas dealer permit. An International Trade Permit is required for the international trade of all fresh or frozen bluefin tunas.
  • NOAA Fisheries monitors the bluefin tuna fishery and has the authority to take in-season actions (such as closing fisheries and adjusting retention limits) to ensure available quotas are not exceeded or to enhance scientific data collection from, and fishing opportunities in, all geographic areas.
  • Federal management for Atlantic tunas apply to state waters as well, except in Maine, Connecticut, and Mississippi; NOAA Fisheries periodically reviews these states’ regulations to make sure they’re consistent with federal regulations.
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Annual Harvest

Over half the global catch comes from the eastern and western Atlantic Ocean. ICCAT implemented harvest quotas for the western stock in 1982, and since then total western Atlantic catch has been relatively stable. U.S. commercial and recreational fishermen caught 884 metric tons of bluefin tuna (landings and dead discards) from the Atlantic and Gulf of Mexico in 2011. U.S. catch comprised 45 percent of total western Atlantic bluefin tuna catch and 7.5 percent of Atlantic-wide bluefin tuna catch (including the Mediterranean Sea).

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Economy

Ex-vessel prices (the price fishermen receive for their catch) for bluefin tuna have risen by over 50 percent since 2003. The ex-vessel price depends on a number of factors, including the quality of the fish (e.g., freshness, fat content, method of storage), the weight of the fish, the supply of fish, and consumer demand. Specifically, bluefin prices are influenced by many factors, including market supply and the Japanese yen / U.S. dollar exchange rate. In 2011, the annual ex-vessel revenue for the fishery was $10 million.

Over half of U.S. Atlantic bluefin catch is exported, mainly to the sushi markets in Japan. Exports of Atlantic bluefin tuna generally increase when commercial landings increase; domestic consumption of U.S. landings of Atlantic bluefin remain fairly constant from year to year.

In addition, recreational fishing for highly migratory species such as bluefin tuna also provides significant economic benefits to coastal communities through individual angler expenditures, recreational charters, tournaments, and the shoreside businesses that support those activities.

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Recreational

Recreationally caught Atlantic tunas may not be sold. Bluefin tuna must be larger than 27 inches to be retained. Depending on the recreational fishery, there is also a limit on the maximum size of bluefin that can be retained and a limit on the amount fishermen can keep per fishing trip. Regulations do not allow recreationally caught bluefin tuna to be retained in the Gulf of Mexico, an important spawning area for the species. All released bluefin tuna must be released in a manner that will maximize its survival, and without removing the fish from the water. For the latest information on current retention limits, see www.hmspermits.gov.

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OVERVIEW

Bluefin tuna flesh is the darkest and fattiest of any tuna. Because of its high fat content, bluefin tuna is especially prized for sushi and sashimi. A higher fat content in bluefin tuna is equated with a higher-quality product. Also, because of the high fat content, cooking is not advised as it produces a strong fish taste and odor when cooked. (Seafood Business, 2011)

 
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SEASONAL AVAILABILITY

Year-round

 
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NUTRITION

 

Servings 1
Serving Weight 100 g (raw)
Calories 144
Protein 23.33 g
Fat, total 4.9 g
Saturated fatty acids, total 1.257 g
Carbohydrate 0 g
Sugars, total 0 g
Fiber, total dietary 0 g
Cholesterol 38 mg
Selenium 36.5 mcg
Sodium 39 mg

Western Atlantic Bluefin Tuna Table of Nutrition

 
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RECIPES

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