Bluefin tuna populations have declined alarmingly over the past few decades - not just Atlantic bluefin tuna, but also Pacific bluefin tuna and southern bluefin tuna. In all cases, the decline has largely been driven by Japanese demand for sushi and sashimi
One of the world’s oldest fisheries, Atlantic bluefin tuna (Thunnus thynnus) have been an important part of Mediterranean culture for 12,000 years, and have been fished in the Mediterranean for at least 2,600 years. Homer described the fish in The Odyssey, written in 800BC, and Aristotle described their migration and spawning in 350 BC.
Traditionally giant adults were caught by traps in artisanal fisheries. This method can be very selective and sustainable. However, the advent of high-tech purse seines and long lines has now all but replaced the traps. A few still exist, but have seen their catches fall by as much as 80% in recent years.
Purse seine nets are currently responsible for 60-80% of the bluefin tuna catch in the Mediterranean. The fleets operate throughout the Mediterranean, but particularly in the Tyrrhenian Sea, Ligurian Sea, the Strait of Sicily, Aegean Sea, and the Sea of Marmara.
The vast majority of the bluefin tuna caught by purse seiners in the Mediterranean are destined for fattening in cages, to supply a new market in Japan for a cheaper version of the highly valued maguro for sushi and sashimi. The tuna are transferred directly from the purse seine net into the nets of a tug boat. The tug then tows the tuna to so-called tuna farms located in various places around the Mediterranean.
The caged tuna are fed once a day on herring, sardines, anchovies, and squid. They are fattened in this way for 6-7 months, and sometimes up to two years. This maximizes the price for each fish: the greater the fat content, the greater the price on the Tokyo fish market. However, this practice is not very efficient: 10-25kg of feed fish are needed to produce just 1kg of tuna. This has led to increased pressure on some feed fish stock, such as anchovies and sardinella.
Located not far offshore, the farms can also cause pollution of coastal habitats. Regulation has lagged behind this new industry, with many tuna farms operating illegally and flouting local laws. The number of tuna farms has increased exponentially since 1996, when the first appeared, to over 40 today. Farms are currently found offshore in Spain, Italy, Malta, Croatia, Turkey, Cyprus, Tunisia, and Libya. This explains why most bluefin tuna in the Mediterranean are now caught using purse seines - this is the only fishing method that allows capture of live tuna that can be moved. In 2004, around 22,500 tonnes of Atlantic bluefin tuna were transferred to Mediterranean tuna farms, representing nearly two-thirds of the entire annual quota for the Mediterranean and Eastern Atlantic.
The majority of tuna caught in the Mediterranean end up on giant tuna-reefer vessels - industrial cargo vessels that deep-freeze the tuna onboard for shipment primarily to Japan. Farmed tuna are slaughtered and frozen after the fattening season (October to March). Some tuna are frozen directly after catching during the fishing season (May to July), while others are also air freighted to Japan fresh.
In October last year, WWF called for an immediate three-year closure of the Mediterranean bluefin tuna fishery, following a season of unprecedented illegal and uncontrolled fishing. Official reports show that EU fishing fleets have exceeded EU catch quotas by some 4,000 tonnes. France, for example, almost doubled its national quota, fishing 10,165 tonnes by the end of August this year compared to its 5,593-tonne quota.
Other Mediterranean fishing nations, notably Italy and Turkey, are reported by the media to be involved in a web of fraud, such as laundering over-quota catches using false French catch documents. “What more evidence is needed of the dire lack of governance in this fishery?” stresses Miguel Jorge, Deputy Director of WWF’s Global Marine Programme. “An immediate moratorium is now the only sure way to avoid collapse.”
Despite being made aware of the crisis by WWF, Japanese traders — including the Mitsubishi Corporation, which accounts for some 40 per cent of Mediterranean bluefin imports to Japan — are benefiting from the stock’s mismanagement.
“Companies continuing to trade in Mediterranean bluefin are willing accomplices in the demise of this important species,” Jorge adds. The same applies to fish farming businesses like Ricardo Fuentes e Hijos, the biggest tuna farm company in the world, which dominates the Mediterranean farming industry.
According to WWF, it is impossible to determine how many illegal and unreported catches across the Mediterranean fishery remain unknown. It is also hard to know whether a bluefin tuna is illegal or not.
“Quite simply if it comes from the Mediterranean, it is suspect,” Jorge says. “What’s needed is an end to the Mediterranean bluefin fishery until further notice. It must not reopen before the stock can start to recover and sustainable management established.”
Following massive demand in recent years – especially from Japan – high-tech fishing fleets have hunted down, often illegally, ever-declining numbers of these migratory ocean giants. WWF exposed the drastically out-of-control nature of the Mediterranean bluefin tuna fishery in the 2007 season when illegal fishing was again rife – including the use of banned spotter planes, as well as widespread unreporting.
Scientists have already declared it “probable” that the magnificent bluefin tuna, the fish behind the finest sushi in the world, will soon collapse in the Mediterranean – unless action is taken now. At an international tuna management meeting last November (ICCAT – International Commission for the Conservation of Atlantic Tunas), WWF urged contracting countries to agree on a 3-year ban on bluefin tuna fishing. The conservation measure was rejected, instead putting short-term interests ahead of sustainability and long-term profitability.
