Bluefin Tuna

Bluefin are the heaviest of the tunas: a torpedo of dark metallic blue above and silver-white below, with short pectoral fins that do not reach past the second dorsal, a yellow-edged finlet row and a massive keeled tail. Atlantic bluefin (Thunnus thynnus) and Pacific bluefin (Thunnus orientalis) are separate species that look nearly identical; both are warm-blooded, can hold body temperature well above the surrounding water and cross entire ocean basins in a season.

On the US Atlantic coast, bluefin migrate from Gulf of Mexico and Mediterranean spawning grounds to feed from North Carolina to Nova Scotia, with giants over 500 pounds showing off Cape Cod, the Gulf of Maine and Prince Edward Island in summer and fall, and a winter fishery off Morehead City and the Outer Banks. In the Pacific, juvenile bluefin from Japanese spawning grounds spend several years off Baja and Southern California, and since 2014 the SoCal fleet has seen an unprecedented run of fish from 20 to over 300 pounds within day-trip range.

Bluefin are schooling predators that feed on sardines, anchovies, mackerel, herring, squid and, as giants, menhaden and bluefish. They push bait to the surface in explosive foamers, often with birds and marine mammals working overhead, and they also feed deep on the edges of banks and canyons. Water in the 55–68°F (13–20°C) range, current edges and bait concentrations dictate where they show up on any given day.

For anglers, bluefin are the ultimate test of tackle and stamina. A 200-pound fish on stand-up gear can take two hours; a giant on a harpoon-era Cape Cod boat is a day-long event. Both fisheries are tightly managed by NOAA with permits, size classes and daily retention limits that change in-season, so checking the current rules before each trip is part of the game.