Atlantic Bluefin Tuna Spawning Protection Areas: A Trans-Atlantic Insurance Policy to Ensure the Future Survival of the World's Biggest Tuna
The Atlantic bluefin tuna is not only one of the world's greatest game fish; it is also one of the most remarkable in nature. This great fish weighs up to 700kg (1,500 pounds), migrates across the Atlantic – a distance of more than 7,700km (4,800 miles) – and can dive to depths greater than 1,000 metres (3,000 feet). Like humans, bluefin are warm-blooded. As these tuna traverse the Atlantic, their ability to regulate their body temperature enables them to survive a wide range of conditions and depths.
Equally impressive is the bluefin's reproductive potential. They typically spawn at least a dozen times in a given spawning season, and a large female can produce upwards of 45 million eggs each time  – that's roughly 540 million eggs per spawning season.
Distressingly, though, relentless commercial fishing pressure on these once plentiful fish has pushed them to the brink of collapse. Overfishing, spurred on by the growing demand for sushi, severely depleted their numbers to the point where the international community considered banning international trade in the species in 2010. Now swift, decisive action is required to protect the bluefin's only known spawning grounds. This action will help rebuild populations and ensure the long-term sustainability of this valuable species.
Prohibiting the take of fish in specific areas, such as spawning grounds, is an effective fisheries management tool and is regularly used to protect biodiversity, rebuild depleted populations, and protect spawning fish – all crucial goals for both the Atlantic bluefin tuna and the fishermen who depend on these fish for recreation and income. The Atlantic bluefin has only two known spawning grounds – the Mediterranean Sea and the Gulf of Mexico – and the fish's well-documented annual return to these regions makes the protection of the spawning areas an urgent priority to conserve the species for future generations of fishermen.
Each year eastern Atlantic bluefin tuna gather in the warm waters of the Mediterranean to reproduce. And each year a fleet of commercial fishing vessels races to catch the tuna at this important and vulnerable stage in its lifecycle, encircling whole schools with nets known as ‘purse seines'. This technique captures entire schools of fish during their most crucial time of year, when they reproduce. Indeed, targeting this imperiled species on its only known eastern Atlantic spawning grounds during the peak of the breeding season unnecessarily threatens the future survival of this fish.
The western Atlantic population of bluefin also faces serious threats in its only known breeding ground – the Gulf of Mexico. These threats come from pollution and indiscriminate fishing methods such as surface longlining. The Deepwater Horizon oil disaster began on 20 April 2010, with more than 757 million litres (200 million U.S. gallons) of oil and 6.813 million litres (1.8 million U.S. gallons) of dispersants spilling into and polluting the bluefin spawning grounds of the Gulf of Mexico at the peak of its spawning season. The impacts of this catastrophe on bluefin are yet unknown, so as a precaution, commercial fishing mortality on these spawning fish in the Gulf must be eliminated.
Surface longliners fishing for yellowfin tuna and swordfish catch bluefin tuna as bycatch. Despite the almost three decade ban on directed fishing in the Gulf of Mexico for bluefin, commercial longline fishermen still set hundreds of hooks on lines averaging 30 miles in length, indiscriminately catching hundreds of non-target spawning bluefin tuna. While fishermen are allowed to keep and sell some of these fish, most are thrown overboard to die. Sadly, this waste is unnecessary as alternative commercial fishing methods that would reduce this bycatch already exist.
The Solution – A Trans-Atlantic Insurance Policy
The eastern and western populations of Atlantic bluefin tuna are not discrete: a significant amount of mixing in the Atlantic Ocean occurs between them. As the two populations are interconnected, it is crucial that their most important spawning habitats receive equitable protection on both sides of the Atlantic. Protecting these areas will help safeguard the future of the species; a species that recreational anglers have witnessed decline due to rampant commercial overfishing and international mismanagement.
The creation of no-take bluefin tuna spawning-ground protection areas in the Gulf of Mexico and the Mediterranean Sea would allow Atlantic bluefin tuna populations to rebuild more quickly, and would therefore be an insurance policy against potential future collapse, helping to ensure the very survival of the species. Enacting protections for bluefin tuna that span their only two known spawning grounds will give these great game fish an opportunity to recover, thrive and ensure future recreational angling opportunities throughout the range of these magnificent fish.
International Game Fish Association
Italian S778/portfishing Association
Big Game Clube de Portugal
Associação Açoriana de Pesca Desportiva de Mar, Portugal
SFC “Punta Rata” Jezera, Croatia
IGFA Representative, Croatia
Japan Game Fish Association
Asociacion Pesca Recreativa Responsable Europea
Big Game De Italia
Big Game Fishing Club France
Confederación Española de Pesca Recreativa Responsable
Nassim Joaquin Delbouis
Club De Pesca Con Mosca Peninsula A.C., Mexico
Mohamed Safyadin El-Sehrawy
IGFA Representative, Egypt
 Rooker, et al. 2007. Life History and Stock Structure of Atlantic Bluefin Tuna (Thunnus thynnus). Reviews in Fisheries Science, 15:265–310.