ARCHIVAL TAGGING OF ATLANTIC BLUEFIN TUNA (THUNNUS-THYNNUS-THYNNUS)

The size, power, and speed of tunas and other pelagic fishes (e.g. swo rdfish, martins, sailfish) have made it a challenge to study their bio logy. These species are most often composed of large populations with broad geographic ranges and individuals are capable of traversing ocea n basins in weeks or months. Data on dispersal patterns are hard to ob tain because of the limited resolution of analytical tools available f or studying pelagic fish. What is currently needed are technologies th at can augment conventional tagging data sets to better define the geo graphic ranges and potential overlap of stocks. Archival, satellite an d molecular technologies offer the fisheries research community the ne w techniques required to resolve the movement patterns and stock struc ture of highly migratory species. We describe in this paper our use of archival tags on Atlantic bluefin tuna (Thunnus thynnus thynnus). Arc hival tags provide a record of thynnus ambient and internal body tempe rature, pressure, and light. From light intensity, augmented with data on sea surface temperature, it is possible to estimate latitude and l ongitude. In recent years, archival tags have dramatically increased t he understanding of the biology of several species of fish. Use of the tags has the potential to address major questions concerning stock st ructure hypotheses of Atlantic bluefin tunas. We have developed the ha ndling and surgical procedures necessary for internal placement of arc hival tags in medium and giant bluefin up to 234 kg. Additional studie s to examine the survivorship and healing rate of archival tagged fish are being conducted using captive tuna populations in Monterey, Calif ornia and acoustic and satellite technologies on wild fish.