| 英文摘要 |
This project is responsible for the training of scientific observers to collect otoliths of southern bluefin tuna (SBT, Thunnus maccoyii) on Taiwanese longline vessels. The age estimations were finished for about 80 SBT otoliths collected in 2005. The 4-year fishery data suggested that the SBT population in the central Indian Ocean is stable. The microchemical composition at otolith core area are very consistent for the SBT collected from the spawning ground and the central Indian Ocean. This result suggests that these SBT were from the same origin. Otolith oxygen stable isotope composition suggests that SBT experienced significant temperature change due to the shift of habitats in depth or latitude. In addition, otolith carbon stable isotope reflect the development, metabolism, environmental characters and feeding of the SBT. A lab was established to process and to analyze the otoliths that were collected by scientific observers from 3 oceans every years. |