Tuna

Tuna is really two markets wearing one name. By volume it is a canning commodity: the global catch of the five main commercial tuna species runs about 5.8 million tonnes a year, and roughly three-quarters to four-fifths of it is canned. By value, the headline belongs to the tiny sashimi trade, above all bluefin, where the best fish command prices no canned tuna ever could. The two ends barely touch: a cannery buyer in Bangkok and a sushi buyer in Tokyo are competing for completely different fish.

Species are what separate the two. Skipjack, the smallest and fastest-breeding, is about 58 percent of the catch and is the workhorse of the can. Yellowfin is around 30 percent, split between cans and mid-grade steaks and sashimi. Bigeye, about 7 percent, is prized for sashimi because of its fat. Albacore, about 4 percent, is the pale "white meat" premium can. Bluefin, all three species together, is only about 1 percent of the catch but dominates the value conversation: it is the dense, fatty, cold-water fish behind top-grade sushi, and the toro belly cut is the most prized of all.

There is no tuna futures market. Like most fish, tuna trades by physical auction and by cash and contract. Sashimi-grade fish move through auction houses, the most famous being Toyosu in Tokyo (which replaced the old Tsukiji market in 2018) and the Honolulu fish auction, while canning-grade skipjack trades on reported reference prices such as the Bangkok and Manta (Ecuador) assessments published by trade services. Heterogeneity is again the reason no contract developed: a bluefin is graded individually on fat, freshness, and shape, while canning skipjack is a bulk frozen input, and neither fits a single standardized deliverable.

Geographically the catch is concentrated in the Western and Central Pacific, which alone produces a bit more than half the world total, most of it skipjack taken by purse seine. In trade, Thailand is the largest canned-tuna exporter, with Ecuador, China, and Spain behind it; the United States is the largest single importing country and the European Union the largest importing bloc, while Japan is the dominant importer of sashimi-grade fish. The industry is policed not by one body but by five regional fisheries management organizations, one per ocean: the WCPFC and IATTC in the Pacific, ICCAT in the Atlantic and Mediterranean, the IOTC in the Indian Ocean, and the CCSBT, which uniquely manages a single species, southern bluefin, across its whole range.

Bluefin is also the great conservation story of the fishery. Atlantic bluefin was fished close to collapse in the 1990s and 2000s, driven by Japanese sashimi demand and weak enforcement, before ICCAT imposed hard quotas and monitoring that turned it into one of the clearest rebuilding successes in fisheries: at its November 2025 meeting ICCAT actually raised bluefin quotas for 2026 onward as stocks recovered. Pacific and southern bluefin have followed similar, slower rebuilds under their own bodies. The catch limits are why a wild bluefin is scarce and valuable rather than simply caught at will.

Because wild bluefin is capped, much "farmed" bluefin is not truly farmed but ranched: boats catch wild juveniles and fatten them in sea pens for months before harvest, a practice long established in the Mediterranean and off South Australia. It still depends on the wild stock, so it eases price, not pressure. The harder prize is closing the life cycle in captivity, and Japan's Kindai University did it, completing the first full hatchery-to-harvest cycle of Pacific bluefin in 2002 and selling "Kindai tuna" since; volumes are still small relative to the wild catch but the technology is the long-run answer to feeding sashimi demand without mining the ocean.

It is worth being clear that tuna is not farmed the way salmon is, on any count. Salmon farming is true closed-cycle aquaculture from hatchery egg to harvest, takes two to three years in controlled cages, and runs on formulated pellets that are now mostly plant-based, with a feed-conversion ratio close to one to one. Tuna ranching skips the breeding entirely: it catches wild fish already years old and tens of kilos, then fattens them for only a few months, three to seven in the Mediterranean and off South Australia, so the "farm" stage is a short feedlot, not a life cycle. And the food is the opposite of salmon's. Tuna are voracious open-ocean predators that will not take pellets, so they are fed whole wild baitfish, sardine, herring, mackerel, and squid, at a brutal conversion ratio of roughly ten to fifteen kilos of forage fish for every kilo of tuna gained. That is the core knock on tuna ranching: it consumes far more wild fish than it produces. The reason the two diverge is biology. Tuna are warm-blooded, gigantic, and migratory, with fragile eggs and larvae and a need to swim constantly, which makes them extraordinarily hard to spawn and rear in captivity, whereas salmon spawn in freshwater and have been bred in hatcheries since the 1970s.

The price gap is the whole story. Canning-grade frozen skipjack trades at roughly 1,500 to 1,700 US dollars a tonne, about a dollar and a half a kilo, the price of a bulk protein. A top sashimi bluefin at the New Year Toyosu auction has reached the equivalent of thousands of dollars per kilogram, and even on an ordinary day prime bluefin is a luxury good. Same family of fish, a thousandfold spread in price, decided almost entirely by species, fat, and the buyer at the other end.