Tuna: Bluefin, Pacific

Atun de aleta azul, Horse mackerel

Kuromaguro, Honmaguro, Toro

There are three species of bluefin tuna: Southern, Atlantic, and Pacific. Atlantic and Pacific bluefin are found in the northern waters of their respective oceans, while southern bluefin tuna are found in the southern waters of the Atlantic and Pacific Oceans, as well as in the Indian Ocean. Bluefin tuna are highly migratory, crossing international borders along their migrations, and are targeted in various fisheries worldwide with a number of different gear types: purse seines, pelagic longlines, trolls, handlines, pole and line gear, and harpoons. Each of these gear types results in different levels of bycatch and habitat effects. Bycatch of threatened sea turtles, seabirds, sharks and billfish is of particular concern. Overall, bluefin tuna is ranked as moderately vulnerable to fishing pressure. Status of the stocks is also of serious concern for all species. The combination of high to critical bycatch concerns, poor management and poor stock conditions results in an overall recommendation of “Avoid” for all three species of bluefin tuna.

Compared to other major commercially-caught Pacific tunas, their range is small and their spawning grounds are unusually restricted. Their somewhat circumscribed distribution, fidelity to particular spawning grounds, and, in particular, their very slow sexual maturity, make Pacific northern bluefin tuna susceptible to fishing pressure.

IATTC (2001) reports that catches of Pacific northern bluefin have not declined recently, so the population is assumed to be holding steady. Heavy fishing on juveniles in the northwestern Pacific is considered to be restricting growth of the stocks and limiting the recruitment of mature fish into both western and eastern Pacific fisheries. The actual status of the stock remains unknown, as no fisheries-independent stock assessment has been prepared.

Because management is generally lacking for this species, the exact nature of the bycatch is not well understood. Pelagic longlining throughout the Pacific has been shown to catch high numbers of endangered turtles and seabirds.

Pelagic longlining has no direct habitat impact, however, the potential ecosystem effects of removing these large predators from the world’s oceans and the bycatch of vulnerable and threatened species have been identified as two environmental risks associated with the increased pressure by tuna fisheries.

IATTC collects data on this species, but does not manage the fisheries, as most of the range of this tuna falls in the far northwestern Pacific outside the boundaries of IATTC’s authority. Because the Pacific northern bluefin does not yet benefit from any regional management scheme, it is largely an unmanaged fishery.

What kind of tuna is this?

Bluefin tuna should be avoided

Elevated mercury and PCB levels + Men should limit intake to less than 1/2 a meal per month + Women and kids under 12 should not eat at all

No.