Tokyo, Japan - After several decades of reckless overfishing, mostly by Japanese fleets eager to satisfy their country's increasing demand for sushi and sashimi, stocks of bluefin tuna in the Pacific Ocean have declined alarmingly. Japan accounts for more than 70 percent of the Pacific bluefin tuna caught, according to the government's Fisheries Agency.
As a consequence, the most recent stock assessment of Pacific bluefin tuna made by the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC), noted that the population "level is near historically low levels and experiencing high exploitation rates".
The situation is so dire that Japan's Fisheries Agency felt compelled to announce in March it would cut the country's allowable haul of Pacific immature bluefin tuna by 50 percent in 2015. The agency followed this up by lobbying other countries fishing in the region to do likewise, and this month succeeded in obtaining their agreement.
During a conference of countries belonging to the Western and Central Pacific Fisheries Commission (WCPFC) that took place in Fukuoka, Japan, from September 1-4, the other major catchers of tuna - South Korea, Taiwan, Canada and the United States - promised to make the same deep cuts as Japan.
"People realised something had to be done about the level of catch," Glenn Hurry, executive director of the WCPFC, told Al Jazeera. "The biomass [of the bluefin tuna] that researchers are talking about is only three to four percent of the original spawning biomass, which is not a level you should commercially fish fisheries."
Now the challenge is to get everyone to act on their promise. The countries will meet again in December to ratify the agreement. "Once that's done, the commission will pass a regulation confirming the arrangements, and then the countries have to monitor and make sure [the agreement is] not breached," noted Hurry.
Some 98 percent of the catch is juvenile.
The 50 percent figure was advised by ISC and is based on a stock analysis of data supplied by WCPFC members, particularly data from Japan's Ministry of Agriculture, Forestry and Fisheries (MAFF) whose stock records date back to 1952. The recommendation came after a 15 percent catch reduction previously agreed on by WCPFC members proved inadequate to improve stocks.
Masanori Miyahara, an adviser to MAFF and head of research at the Fisheries Agency, told Al Jazeera: "Such a large cut is necessary so we can realise the recovery of adult stock. We've been catching the fish before they spawn. And this is detrimental to fishery sources."
As a first step, "this is a good move", Wakao Hanaoka, a marine eco-expert for Greenpeace Japan, told Al Jazeera. "Some 98 percent of the catch is juvenile."
The outcome for Japan is that in 2015 a 4,000 tonne catch limit will be imposed on young fish weighing less than 30kg and unable to breed, compared to the 8,000 tonne average catch of 2002-2004.
The 50 percent cut will remain in place for 10 years, until 2024, when it is estimated that stocks will be sufficiently recovered. The decision will inevitably impose a severe hardship on Japan's fishing industry. To spread the burden equitably, the Fisheries Agency has decided to split the yearly catch in half, so that ocean fleets relying on large net fishing and boats using fixed shore nets will be allocated roughly 2,000 tonnes each.
"It took two years to persuade the fishing industry [that such severe cuts were necessary]," said MAFF's Miyahara. "Some 20,000 fishing boats are involved, so it was no easy task. But we were successful in finally getting everyone to agree."
The agency has also divided Japan into six fishing regions and has set catch limits according to each region's past catches. "Having regions will make managing [catch limits] easier and more practical," explained Miyahara.
A second strategy the government and the fishing industry are pursuing is aquaculture: the breeding, raising and harvesting of marine life - or fish farming.
According to the National Oceanic and Atmospheric Administration (NOAA) in the US: "Approximately half the seafood eaten in the world - including the United States - is farm raised. Because harvest from many wild fisheries has peaked globally, aquaculture is widely recognised as the method by which we will meet the seafood demands of a growing population. As a result, aquaculture is the fastest growing form of food production in the world."
Bluefin farming in Japan got under way commercially more than a decade ago. One approach involves capturing and slowly towing young tuna in fish cages to coastal sea "ranches" around southeastern Japan where they are raised and fattened for harvesting.
According to MAFF data provided to Al Jazeera, aquaculture of Pacific bluefin tuna in Japan produced 9,639 tonnes in 2012. Valued at $265m, it accounted for about one-third of the 29,800 tonnes of all bluefin tuna - Pacific and Atlantic species - caught and imported into Japan that year.
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A single weighty tuna with the right fat and meat could sell for hundreds of thousands of dollars in Japan. In 2013, a record $1.8m was paid by a sushi restaurant owner for a single bluefin tuna weighing 222kg.
But critics of aquaculture point out that raising tuna is costly both in economic terms and in its impact on the ocean's ecosystem.
"The majority of aquacultured Pacific bluefin tuna sold in Japan still originally comes from the ocean," Greenpeace Japan's Hanaoka said. "Juveniles are caught in the sea and then raised in cages. So rather than being a solution, it is adding to the problem."
Moreover, raising a single tuna requires feeding it between "15 to 22 kilos of small fish to produce one kilo of tuna red meat," said Hanaoka. These bait fish, typically sardines and mackerel; have to be taken from the ocean, which causes its own problems. "So aquaculture is not a solution," he added.
But a second approach to farming the tuna is overcoming these hurdles. It involves raising the fish from eggs to adults, a procedure known as full-cycle aquaculture. A leader in this field is Kinki University, located near Osaka. In 2002 it became the first in the world to produce bluefin tuna using full-cycle aquaculture.
"Our breeding technologies have been so successful that we are now able to release juvenile tuna into the oceans," the university declares on its webpage.
Similar efforts, both government and commercial, are also under way. In May, the Fisheries Research Agency announced it had succeeded in spawning bluefin tuna in onshore tanks at a research facility in Nagasaki - a first of its kind.
"We accomplished this by controlling the water temperature, lighting, feeding and so on," said Miyahara. "In the future we will be able to supply tuna from aquaculture which will operate independently from catching wild fish."
And to reduce the need of feeding the spawned tuna entirely on smaller fish, Miyahara said researchers are working on developing feedstuffs from plant-based options such as soybeans.
Miyahara expects this type of aquaculture to significantly contribute to Pacific bluefin tuna numbers in the next five to ten years. And while it is not expected that it will replace the catching of wild tuna, he believes it will help reduce dependence on it.
Source: Al Jazeera