The bluefin tuna is one of the most remarkable fishes in the ocean, growing to more than 12 feet, weighing 1,500 pounds and living for up to 35 years. It can swim as fast as 25 miles per hour and cross the ocean in 21 days.
Bluefin tuna are the target of an incredibly lucrative fishery—a single giant Atlantic bluefin can sell for $100,000 or more in Japan. This has led to precipitous declines in tuna populations in recent decades. Of the three bluefin tuna species, Pacific bluefin are most in need of immediate conservation action. Strong international commitments are needed to support additional research and advance management measures that will reverse the population decline and ensure the species' recovery.
To conserve tuna, we need to know more about them—so fishermen can continue to fish, and tuna can thrive. Since 1994, staff at the Tuna Research and Conservation Center (TRCC)—a partnership between the Aquarium and Stanford University—has been tagging bluefin tuna in the wild and studying tuna at the TRCC facility next door to the Aquarium. It's the only place in the U.S. where live tuna are kept for research. Four tanks from 5,000 to 86,000 gallons, each with its own life-support system, hold fast-swimming tuna that can grow to hundreds of pounds.
Our unique mix of laboratory and field research is helping inform ecosystem-based management policies that will ensure that these animals thrive. The team studies molecular, biochemical and physiological characteristics, and has developed electronic tracking devices that provide detailed records of the migrations and behaviors of bluefin tuna.
Tuna is the second most popular seafood worldwide. But since the 1960s, the abundance of tuna and other top ocean predators has decreased dramatically around the world.
Experts warn that without concerted efforts to reduce overfishing and restore depleted stocks, tuna populations will continue to decline. Bluefin tuna in particular are prized by sushi chefs and the high demand for these fish has taken its toll in the Atlantic, Pacific and Southern Oceans. In the Pacific alone, the bluefin tuna population is at less than 5 percent of historic levels.
Bluefin tuna are slow to mature and many fisheries are catching young bluefin tuna that haven't had a chance to reproduce. Bluefin are also highly migratory, which means many nations, including the U.S., Mexico and Japan, need to cooperate on management plans to maintain global populations. In 2014, representatives from these countries, and other Pacific nations agreed to an initial set of catch restrictions for Pacific bluefin tuna, as well as an interim plan to rebuild the population. Additional action will be necessary in 2016 to ensure their recovery.
The Aquarium works with government agencies in the United States and with regional fisheries management organizations worldwide in support of policies to safeguard ocean health. These include: ecosystem-based fisheries management; elimination of illegal, unregulated and unreported (IUU) fishing; and support for multilateral policies to address global climate change and plastic pollution. Of the three bluefin tuna species, Pacific bluefin are most in need of immediate conservation action. Strong international commitments are needed to support additional research and advance management measures that will reverse the population decline and ensure the species' recovery.
Seafood Watch is increasingly consulted and engaged in a wide range of international sustainability and market discussions regarding tuna species, which are among the most economically important and widely traded seafood commodities. Seafood Watch offers a suite of global recommendations for tuna species. A number of tuna populations are performing well. However, all bluefin tunas carry an "Avoid" recommendation due to significant sustainability concerns.
The Monterey Bay Aquarium and the Tuna Research and Conservation Center (TRCC)—neighbors in Pacific Grove, California—are cooperating on a wide range of research initiatives to learn more about bluefin tuna and help inform conservation efforts for this iconic species. The TRCC is a collaboration between the Aquarium and Stanford University's Hopkins Marine Station.
Tuna are challenging to display and research because of their incredible size, strength and speed. We're pioneering techniques for collecting, handling, transporting, caring for and displaying tuna. At any given time dozens of tunas representing three species are swimming in the tanks at the Aquarium and TRCC. Captive tuna allow biologists and aquarists to improve husbandry and veterinary techniques, learn from these amazing animals and develop electronic tagging techniques prior to use in the field.
Tunas are remarkable athletes. They travel vast distances at amazing speeds, made possible by unique adaptations. In recent years researchers have studied the cardiac physiology of tunas to understand exactly how these extraordinary hearts deliver this performance over a range of temperatures, providing clues about why bluefin tuna routinely migrate and dive into much colder waters than yellowfin tuna.
Gene Expression Research
Recently, researchers have used gene markers to help assess the condition of captive tuna in response to tank size, feeding and longevity in captivity. This leads to better techniques for assessing the quality and condition of captive tuna. Gene markers can also provide information on the growth, health and vigor of cultivated tuna stocks, promising breakthroughs for health and reproduction.
International Tuna Tagging
Working with our Stanford colleagues at the TRCC and with international research teams, we've built the largest data-set in the world for Pacific bluefin tuna—more than 72,500 days of data. Already, we've placed more than 762 electronic tags on Pacific bluefin tuna. Remarkably, approximately half of these tagged fish have been caught and their electronic tags returned. Most were caught off California and Mexico; 15 were recovered near Japan from fish on their way to spawning grounds.
Our researchers work on both sides of the Pacific. We collaborate with the National Fisheries Research Institute of Japan's Far Seas Fisheries Lab and with other Japanese partners in tagging juvenile (1 year size class) bluefin in the western Pacific.
Our goal is use these data to contribute directly to policy changes that will assure the long-term sustainability of these commercially and ecologically important fishes.