Jay Rooker, Haritz Arrizabalaga, David Secor, Igaratza Fraile, Anna Traina, and Jessica Lee

Session 1, Talk 4, 18/1/16 @ 1030 hrs

The productivity and dynamics of bluefin tuna populations are influenced by patterns of movement during the life of an individual, and the degree of trans-Atlantic movement and connectivity between eastern and western populations remains unresolved. We investigated migratory patterns, stock mixing, and homing behaviors of bluefin tuna from several regions of the North Atlantic Ocean using natural, chemical markers—stable isotopes and trace elements—in otoliths (ear stones). Otoliths of young bluefin tuna were first used to develop natal signatures or “birth certificates” for members of eastern and western populations. Using our baseline sample, we then examined migratory behaviors of larger, older bluefin tuna, which indicated that trans-Atlantic and trans-boundary movements occur for individuals from both populations. In fact, adolescent bluefin tuna in the western fishery (U.S. waters) often originate from the eastern spawning area (Mediterranean Sea).  Despite the fact that both populations commonly cross the 45°W management boundary in the Central North Atlantic Ocean, we found that giant bluefin tuna collected from western (Gulf of Mexico) or eastern (Mediterranean Sea) spawning areas were nearly all (~100%) from the same area, demonstrating that bluefin tuna display natal homing.

Contact:  J. Rooker, Texas A&M University, USA, This email address is being protected from spambots. You need JavaScript enabled to view it.