Tuna and billfish are highly migratory species, with their habitat and migratory pathways often crossing the Exclusive Economic Zone of different countries. Taiwan is located in Northwestern Pacific Ocean,where tuna and billfish are of high economic value from both coastal and offshore fisheries. The extent of population structure, habitats and behavior of these fishes are emerging management and conservation issues requiring the attention of fisheries scientists. Meanwhile, the international cooperative tagging projects are getting increasing attention worldwide.Due to their pelagic lifestyles that encompass temporal and spatial scales, tuna and billfish have been fairly difficult to study. The advances in the deployment of electronic tags have provided researchers with new tools that can record detailed records of body or ambient water temperature, swimming depth and geographic information. When recovery of a tag is less certain, a subset of the data is available through the ARGOS system of satellites and can be easily accessed through the Internet. Fisheries scientists have affixed a variety of electronic tags on tuna and billfish that have revealed spatial and temporal movement patterns, often showing the impressive mobility and ecological adaptability of these species. These results can obtain information on local exploitation rates and productivity of species’ resources and will contribute to, and reduce uncertainty in fishery stock assessment.Eastern Marine Biology Research Center of Fisheries Research Center (FRI) is located at the eastern coast of Taiwan, where is the nice location for studying the population dynamic and stock structure of pelagic fishes.Also, it is very convenience to cooperative with Fishery Management Regional Fisheries Management Organizations (RFMOs) to conductive international cooperative projects. Furthermore, FRI have been collected a lot of fishery survey data on the marine environment around Taiwan and biological characteristics on pelagic fishes. These will be the important input parameters for the stock assessment and scientific references on setting management strategies. The objectives of this project are asking research to learning the international cooperative tagging study at University of Hawaii and PFRP working group, meanwhile inviting the expert to Taiwan who is major in the fishery stock assessment and population dynamic to improve technical guidance on fishery stock assessment at FRI.