Results of pop-up satellite tagging of spawning size class fish in the Gulf of Maine: do North Atlantic bluefin tuna spawn in the mid-Atlantic?

Twenty giant bluefin tuna were captured in September and October 1997 and tagged and released with pop-up satellite tags programmed to jettison from March through July, 1998. Seventeen tags successfully released from the fish (12 during the known May-July spawning period), all of which were located north of 33°N latitude, in a region of the mid-Atlantic bounded by Bermuda and the Azores. Our results argue for reconsideration of current assumptions about North Atlantic bluefin tuna migration patterns, mixing rates, spawning areas, and stock structure and highlight the need for additional studies.