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 stock is harvested off the coast of North America by Canada, Japan, and the United States, and the eastern stock is 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 western Atlantic bluefin tuna 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 western Atlantic bluefin tuna) to directed bluefin fishing. In 1991, ICCAT 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, both U.S. and international fisheries for western Atlantic bluefin tuna are highly regulated. The most recent catch level set for 2014 is expected to support continued growth and recovery of the stocks. 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.