For too long international fisheries managers have ignored Pacific bluefin and now the population is severely depleted – at less than 4 percent of its historical high.
The story of Pacific bluefin tuna is a tale of extremes. They are pursued by fishermen at every turn but largely ignored by fisheries authorities. They migrate across the world’s largest ocean, but spawn in only three distinct areas. In parts of the world, they are caught one at a time by local artisanal fishermen; but in others, entire schools are scooped up by industrial purse seine nets. The Pacific bluefin is pursued at every stage of its life, from when it is a few kilogram (3 pound) juvenile to when it’s fully grown at more than 450 kilograms (1,000 pounds). A single fish commonly sells for tens of thousands of US dollars and the first fish auctioned in 2013 fetched more than 1.7 million dollars– but comparably little money goes toward research or conservation. Pacific bluefin have supported fishermen and coastal communities for thousands of years, but governments and managers have neglected this amazing fish. Now the population, at less than 4 percent of its historical size, is in grave danger.
While these fish weren’t even recognized as a distinct species until 1999, what little we do know about Pacific bluefin is awe-inspiring. Like their Atlantic cousins, Pacific bluefin play a very important role in their marine ecosystem as top predators, weighing up to 450 kg (1,000 pounds) and growing up to three meters (10 feet) in length. Compared to other fish species, bluefin mature slowly, which makes their populations especially vulnerable to overfishing. In the Pacific, scientists think that bluefin start reproducing between the ages of three and five years, though recent research suggests that some fish may reach maturity much later. Born in only three spawning grounds off the coast of Japan – in the East China Sea, the Sea of Japan and in the Pacific waters off Shikoku – many young Pacific bluefin begin a cross-oceanic migration when they are just one or two years old. While weighing only 2– 4.5 kg(five to 10 pounds), these juvenile fish make the 10,000 kilometer (6,000-mile) journey to the Baja California coast in search of food in the productive waters of the eastern Pacific. After two to four years foraging off the Mexican coast, they return home to the same western Pacific waters where they were born. Once they reach adulthood, they stay in the western Pacific for the rest of their lives, with some fish venturing further afield to southern waters off Australia and New Zealand.
Fishermen have targeted bluefin in the Pacific for thousands of years, chasing a fish prized for its high-quality, deep-red meat. Historical records indicate that coastal communities in both Japan and western Canada were landing bluefin as early as 3000 BC. In Japan, small-scale fishermen took bluefin primarily by harpoon and hook and line before the use of traps and driftnets began to spread throughout the region in the late nineteenth century. At the same time, recreational fishermen off the coast of California’s Catalina Island were targeting bluefin larger than 100 kg (220 pounds). In Mexico, the first commercial fisheries, mainly composed of purse seiners, started around 1914 and greatly expanded in the late-1950s, before declining in the 1980s and early-1990s. Also in the mid-20th century, the Japanese purse seine and longline fleets were expanding, catching bluefin on the spawning grounds and throughout the western Pacific.
To read the full story of Pacific bluefin, including the rise of ranching and the lack of management, download the document below.