Intrinsic rate of increase is unknown for Atlantic Bluefin Tuna. In the Western Atlantic, Atlantic Bluefin Tuna mature by age 8; in the Eastern Atlantic, they mature by age 4 to 5. Maximum age recorded for Atlantic Bluefin Tuna is 20 years, but they may live longer (ICCAT 2004).

Managers consider there to be two populations of Atlantic Bluefin Tuna (ICCAT 2003). West Atlantic Bluefin Tuna range from Canada to Brazil, including the Gulf of Mexico and the Caribbean Sea. East Atlantic Bluefin Tuna are distributed from Norway to the Canary Islands, including the Mediterranean and Black Seas (Fishbase 2004).

Western Atlantic Bluefin Tuna spawn in the Gulf of Mexico, and eastern Atlantic Bluefin Tuna spawn in the Mediterranean. The two populations converge in the North Atlantic to forage as young adults and adults, but do not move into each other's spawning grounds (Block et al. 2005).

Both the West Atlantic and East Atlantic populations of Atlantic Bluefin Tuna are overfished (ICCAT 2004).

Since trade data are poorly resolved, it is difficult to tell what fisheries supply Atlantic Bluefin Tuna to American markets. We can infer, however, that the U.S. imports most of its supply of Atlantic Bluefin Tuna from Canada and Spain (NMFS 2004a). Almost all domestic catches are exported (NMFS 2004a, 2005). Since Canadian fisheries are in the West Atlantic, and Spanish fisheries in the East Atlantic and Mediterranean (ICCAT 2003), we have to consider the abundances of both populations of Atlantic Bluefin Tuna here and throughout the ranking.

To monitor the West Atlantic population, managers use the abundance of spawning adults as a proxy measure for population abundance. Their goal is to rebuild the Spawning Stock Biomass (i.e. the breeding population) to the size that produces Maximum Sustainable Yield (SSBmsy; MSY is a benchmark commonly used in fisheries management). In 2001, the latest year for which we have data, the size of the spawning population was at most 31% of SSBmsy and may have been as low as 6% of SSBmsy (ICCAT 2004).

Managers do not monitor the East Atlantic population using SSBmsy as the benchmark measure of population abundance. Instead, they compare the current number of spawning adults to the abundance of spawners in 1970. The most recent assessment placed the breeding population in 2000 at 86% of the 1970 level, however there is considerable uncertainty associated with this estimate due to poor data reporting (ICCAT 2003).

We awarded 1.00 point here to account for the extremely low abundance of West Atlantic Bluefin Tuna and the low/medium abundance of East Atlantic Bluefin Tuna.

In the late 1980s, the number of spawning adults (SSB) in the West Atlantic Bluefin Tuna population was 20% of the SSB in 1975. In 2001, the abundance of spawners was estimated to be at 13% of the 1975 level (ICCAT 2003).

In 2000, the spawning population in the East Atlantic was 86% of the SSB in 1970. This represented an increase in the abundance of adults since 1997, when SSB was estimated to be 47% of the 1970 level (ICCAT 2003).

We chose not to subtract points here because, at the time of the last assessment in 2002, one Atlantic Bluefin Tuna population was declining while the East Atlantic population was increasing (ICCAT 2003).

In the West Atlantic Bluefin Tuna population, high fishing mortality has caused the proportion of older fish to decline. In the 1970s and 80s, the proportion of fish ages 10 and above was greater than 15%. Currently that age group only composes 7% of the population. A similar decline in the number of older fish in the East Atlantic population has also occurred: from the late 1990s to 2002, the mean weight of annual catches in Canada’s Atlantic Bluefin Tuna fishery declined (ICCAT 2003).

West Atlantic and East Atlantic Bluefin Tuna populations are overfished (ICCAT 2004). The West Atlantic population is listed as Critically Endangered and the East Atlantic population as Endangered by the IUCN's Red List (IUCN 2004).

The majority of Atlantic Bluefin Tuna that reaches U.S. markets is caught by Canadian vessels in the West Atlantic and Spanish vessels in the East Atlantic and Mediterranean (NMFS 2004a; ICCAT 2003).

Canadian fisheries land Atlantic Bluefin Tuna off the coast of Nova Scotia, in the southern Gulf of St. Lawrence, and on the Grand Banks, and they primarily use rod-and-reel and harpoon gears, with a limited contribution from trap fisheries. In the East Atlantic, the Spanish artisanal fleet catches Atlantic Bluefin Tuna with purse-seine nets set around baitboats (57% of the average annual catch, 1991 to 2001), traps (34%), and handlines (8%). In the Mediterranean, purse-seine and longline vessels dominate the Spanish fleet, accounting for 69% and 23%, respectively, of the total catch in 2000 and 2001 (ICCAT 2003).

Rod-and-reel, harpoon, purse-seine, handline, and pelagic longline gears fish at or near the surface and have little impact on habitat (Morgan and Chuenpagdee 2003). Trapnets, on the other hand, are anchored to the seafloor and likely cause some damage.

Fishers in St. Margaret’s Bay, Canada have a small-scale fattening operation, in which they trap Atlantic Bluefin Tuna. Before killing the tunas and exporting them to Japan, they feed them mackerel to increase their lipid content and market value (Brighton 2003). Young Atlantic Bluefin Tuna are also captured and raised in offshore pens in the Mediterranean (ICCAT 2003). Canadian and Mediterranean “fattening farms” likely supply a limited amount of Atlantic Bluefin Tuna, if any, to U.S. markets. However, the supply of fattened Atlantic Bluefin Tuna is likely increase in U.S. markets in the future, and, when this occurs, we will separately review fattening operations.

The western Atlantic Bluefin Tuna population spawns from mid-April to June in the Gulf of Mexico and the Florida Straits. In 2000, U.S. fishery managers prohibited longlining with live bait in the Gulf of Mexico, which has since reduced discards of Atlantic Bluefin Tuna in their spawning grounds. Other time/area closures for the pelagic longlining fleet include the June Mid-Atlantic Bight and Northeast Coastal time/area closures, which have resulted in considerable reductions in Atlantic Bluefin Tuna discards (NMFS 2005).

In the East Atlantic, Atlantic Bluefin Tuna spawn in the Mediterranean from late May to July. To protect juvenile Atlantic Bluefin Tuna, managers implemented a time/area closure in the Mediterranean Sea, including the Adriatic Sea. From 15 July to 15 August, purse-seine vessels are prohibited from participating in the Atlantic Bluefin Tuna fishery. Managers also banned the use of airplanes or helicopters in tuna fishing operations and longlining by vessels larger than 24 m during the month of June (ICCAT 2004).

However, French vessels target adults at spawning areas near the Balearic Islands in the Mediterranean Sea. Also, recent gear changes in the Albacore Tuna fishery (from driftnets to purse seines, longlines, and trawls) have resulted in high levels of juvenile Atlantic Bluefin Tuna bycatch, which may negatively impact the population (ICCAT 2003).

Despite efforts to protect spawning grounds of Atlantic Bluefin Tuna in the western and eastern Atlantic, fishing pressure continues to affect both populations. For example, a complete closure of the longline fishery on the northern slope of the Gulf of Mexico is needed to eliminate the fishery's bycatch of Atlantic Bluefin Tuna during a critical time in the species' lifecycle (Block et al. 2005).

Oceanic habitat is likely healthy enough to support Atlantic Bluefin Tuna populations.

Habitat effects of surface gears used to catch the majority of the Atlantic Bluefin Tuna supplied to U.S. markets are likely minimal.

Habitat effects of surface gears used to catch the majority of the Atlantic Bluefin Tuna supplied to U.S. markets are likely minimal.

The decline of large predatory fish in the oceans is well documented. In general, management agencies have succeeded only in stabilizing biomass of tuna populations at low levels compared to historic levels (Myers and Worm 2003).

The International Commission for the Conservation of Atlantic Tunas (ICCAT)’s management of Atlantic Bluefin Tuna is no exception. Since its creation in 1966, ICCAT’s mismanagement of Atlantic Bluefin Tuna fisheries has resulted in the listing of the West and East Atlantic populations as Critically Endangered and Endangered, respectively (IUCN 2004).

Atlantic Bluefin Tuna are managed as two populations, separated at 45° W above 10° N and at 25° W below the equator. In order to rebuild the West Atlantic Bluefin Tuna population by 2018 with a 50% probability, the Standing Committee on Research and Statistics within ICCAT recommended that the Total Allowable Catch (TAC) not exceed 2500 metric tons (mt). Despite this, in 2002, ICCAT increased the TAC to 2700 mt. In 2002, reported total catches alone (which includes discards but excludes, by definition, estimated unreported catches) were 3187 mt, the highest catch level since 1981. Fishing mortality of adults in 2001 was the highest on record (ICCAT 2004).

From 1988 to 1997 (excluding 1992), West Atlantic Bluefin Tuna catches (including discards) were generally 200-300 metric tons higher than the Total Allowable Catch limits set by ICCAT (ICCAT 2004). The West Atlantic Bluefin Tuna population is listed as Critically Endangered (IUCN 2004), and any overage of the TAC, much less a TAC set too high, impairs the ability of the population to rebuild.

In the East Atlantic and Mediterranean, managers know that current catch levels are not sustainable in the long term, yet they did not reduce the TAC in 2002. To some degree, however, ICCAT has addressed high fishing mortality on juveniles by increasing the minimum size regulation in the Mediterranean from 3.2 to 4.8 kg (ICCAT 2004).

Uncertainty in the level of mixing between the West and East Atlantic Bluefin Tuna populations could prevent managers from successfully rebuilding the West Atlantic population. Individuals from the depleted West Atlantic population migrate eastward, where they experience higher fishing mortality rates, and managers are not yet taking this behavior into account (Babcock, pers. comm., 2005). Increased levels of under-reporting catches and inadequate Catch Per Unit Effort (CPUE) and size data from important Mediterranean fisheries prevented ICCAT’s Standing Committee on Research and Statistics from having confidence in its 2002 assessment update of Atlantic Bluefin Tuna (ICCAT 2004).

Also, Atlantic Bluefin Tuna farming in the Mediterranean is largely unregulated. Managers do not account for the capture of the Atlantic Bluefin Tuna transported to the farms for fattening in fishing effort and catch data. Finally, little is known about changes in the Albacore Tuna fishery in the Mediterranean, which may now be targeting juvenile Atlantic Bluefin Tuna (ICCAT 2004).

In 2001, fishing mortality of spawning adults in the West Atlantic Bluefin Tuna population was the highest since 1970. Despite poor regulation of fishing mortality, ICCAT continues to insist that it is fulfilling the requirements needed to enable the population to recover in accordance with the 20-year Rebuilding Program established in 1998. In 2002, ICCAT raised the Total Allowable Catch (TAC) limit to 2700 metric tons (mt) from 2500 mt, against the recommendation of its Standing Committee on Research and Statistics (SCRS; ICCAT 2004).

East Atlantic Bluefin Tuna are overfished, and current catch levels are not sustainable in the long term. Catch limits are also poorly enforced; despite having reduced the TAC in 1999 to 29,500 mt, total catches exceeded the previous year’s TAC of 32,000 by more than 1500 mt. Fishing pressure on small fish has increased in recent years, subjecting the population to growth over-fishing. Catches of large fish have also increased, and making the catch sustainable would require major reductions in the number of both large and small fish killed (ICCAT 2004).

ICCAT recommends trade sanctions to encourage countries that do not comply with its regulations, including reporting requirements and catch limits, to change their practices. Currently, U.S. trade sanctions against the importation of Atlantic Bluefin Tuna from Georgian and Bolivian fisheries are in place. Sanctions against Panama, Honduras, Belize, and Equatorial Guinea have been lifted, when ICCAT deemed their Atlantic Bluefin Tuna fisheries to be in accordance with ICCAT’s rebuilding strategies (NMFS 2005).

A limited entry system and non-transferable individual vessel quotas prevent the U.S. purse-seine fishery for Atlantic Bluefin Tuna, which takes approximately 20% of the total annual U.S. landings, from becoming overcapitalized. That being said, this fishery exports almost all of its catch to Japan and does not contribute to the Atlantic Bluefin Tuna supply in U.S. markets (NMFS 2004a, 2005).

There is no evidence that ICCAT has reduced catch limits enough to provoke Canadian and Spanish fishery managers to cut capacity in tuna fleets that target Atlantic Bluefin Tuna.

Neither the International Commission for the Conservation of Atlantic Tunas (ICCAT) nor the countries that land Atlantic Bluefin Tuna have quantified or effectively addressed bycatch in fisheries that supply Atlantic Bluefin Tuna to U.S. markets.

The majority of Atlantic Bluefin Tuna in U.S. markets is likely captured by Canadian and Spanish vessels (NFMS 2004a), which use a diversity of gear types to catch Atlantic Bluefin Tuna (e.g., pole-and-line, harpoon, trap, purse-seine, and longline gears). These gears are associated with varying levels of bycatch (ICCAT 2004; Morgan and Chuenpagdee 2003).

Pole-and-line and harpoon fisheries are highly selective and associated with low levels of bycatch of non-targeted finfish and undersized Atlantic Bluefin Tuna, which fishers must discard due to minimum-size regulations (NMFS 2005; ICCAT 2004). Tuna trap fisheries have a relatively low diversity of bycatch associated with them, however data on bycatch rates in these fisheries are not available (ICCAT 2004).

Tuna purse-seine operations are notorious for having high levels of bycatch, especially in the Eastern Pacific (Safina 2001). In the Atlantic, bycatch rates are unknown, but data show that tuna purse-seine vessels affect 5 species of sea turtles and 15 species of marine mammals (ICCAT 2004). Purse seiners target several species of tuna, however, and sets that target Atlantic Bluefin Tuna are likely different from sets on schools of Bigeye, Yellowfin, and Skipjack Tunas. Therefore, these data may not accurately represent bycatch by purse-seine vessels or in specific sets that target Atlantic Bluefin Tuna.

Bycatch rates and composition are unknown for directed Spanish purse-seine operations for Atlantic Bluefin Tuna. However, for the small U.S. Atlantic Bluefin Tuna purse-seine fishery, observers have documented only low levels of non-targeted finfish, no bycatch of sea turtles, and few interactions with whales (NMFS 2004b, 2005).

Worldwide, longline fisheries for tunas deployed an estimated 1.2 billion hooks in 2000 (Lewison et al. 2004). ICCAT’s Subcommittee on Bycatch reports that longline gear affects the highest diversity of non-targeted species. Tuna and billfish longline fisheries affect 3 species of sea turtles and 6 species of marine mammals (ICCAT 2004). The IUCN currently lists all sea turtle species as either Vulnerable or Endangered (IUCN 2004).

Longline vessels took 23% of the Spanish Atlantic Bluefin Tuna catch in the Mediterranean between 2000 and 2001. In 2000, longlines in the Mediterranean caught and released or killed 60,000 to 80,000 Endangered Loggerhead Turtles and 250 to 10,000 Critically Endangered Leatherback (Lewison et al. 2004).

Populations of almost all sharks caught as bycatch in pelagic longlines in the Northwest Atlantic are declining and at risk of large-scale extirpation (e.g. Hammerhead, Tiger, Thresher, Mako, and Blue Sharks). This trend is likely applicable to sharks in the East Atlantic, as well as throughout the world’s oceans (Baum et al. 2003).

Tuna longline fisheries are implicated in the decline of a large diversity of species, including sharks, Endangered Loggerhead Turtles, and Critically Endangered Leatherback Turtles (IUCN 2004). Little quantitative information is available about bycatch in the other Spanish and Canadian fisheries that supply Atlantic Bluefin Tuna to the U.S. market, and, based on the data that are available, we chose to award the low score of 1.00 point here.

Longline fisheries in the Mediterranean Sea take Endangered Loggerhead and Critically Endangered Leatherback Turtles as bycatch (ICCAT 2004; IUCN 2004).

Bycatch of non-targeted species in rod-and-reel, harpoon, and trap fisheries for Atlantic Tuna is low and likely includes only minimal bycatch of non-targeted finfish and undersized Atlantic Bluefin Tuna (NMFS 2005; ICCAT 2004). Bycatch in the Mediterranean purse-seine fisheries that contribute Atlantic Bluefin Tuna to U.S. markets is unknown, and longline fisheries catch high levels of bycatch (Crowder and Myers 2001; Hoey 1995). We neither subtract nor add for this factor to account for the varied levels of bycatch associated with the many fisheries that land Atlantic Bluefin Tuna.

Bycatch of Atlantic Bluefin Tuna in longline fisheries for billfishes and other tunas is high and impeding its recovery. Bycatch of juvenile Atlantic Bluefin Tuna in Atlantic purse-seine fisheries for Yellowfin and Skipjack Tunas is also a problem (ICCAT 2004).

NOAA Fisheries banned directed longline fisheries for Atlantic Bluefin Tuna in 1981. Since, it has implemented incidental catch limits and established time/area closures, which have reduced Atlantic Bluefin Tuna discards by more than 30% in the U.S. EEZ. The prohibition on longlining with live bait in the Gulf of Mexico is especially important, because it reduces discards of the Critically Endangered West Atlantic population in its spawning area (NMFS 2005).

Since efforts to reduce bycatch of Atlantic Bluefin Tuna in other fisheries are largely restricted to U.S. waters, we chose to subtract here.

Populations of almost all sharks caught as bycatch in pelagic longlines in the Northwest Atlantic are declining and at risk of large-scale extirpation (e.g. Hammerhead, Tiger, Thresher, Mako, and Blue Sharks). This trend is likely applicable to sharks in the East Atlantic, as well as throughout the world’s oceans (Baum et al. 2003).