Michael Stokesbury of Dalhousie University tagged the 1,250-pound, 10-foot-long fish in the Gulf of St. Lawrence off Nova Scotia Oct. 20.
Bluefin tuna are a threatened species.
Stokesbury was with a scientific team from the Tag-A-Giant campaign that includes Dalhousie and Stanford Universities, and the Monterey Bay Aquarium, working in collaboration with Canadian fishermen from Prince Edward Island and Nova Scotia.
The team, led by Stanford University Professor Barbara Block, has traveled from the Gulf of St. Lawrence to the Gulf of Mexico and from Ireland to Spain to tag Atlantic bluefin tuna.
The resulting data, researchers said, have been vital in identifying how populations of bluefin tuna use the North Atlantic, leading to new discoveries about their physiology, migratory patterns and population structure.
Bluefin tuna are among the largest fish on earth, weighing up to 1,500 pounds and capable of making transoceanic migrations in as few as 20 days.