Eel is catadromy species, whose migratory paths often cross the coastal waters of exclusive economic zones. Investigating the spawing migration and ecological traits are big challenge for fisheries science. Dischargeflow studies have provided a relatively new way for scientists to explore the population dynamics, distribution and the relationship between environmental factor and behavior. Our center already developed and tested four external attachment methods for PSATs to eel. However, The study of eel migratory paths is still in the initial stages.This main objective of this study is using the electronic tag to investigate migratory pathways of eel. Six eels were separately tagged with mark report PAT (mrPAT) or survivorship PAT (sPAT) tags or X-Tag or Highrate X-Tag and released during 2016 to 2017 at locations near the river of eastern of Taiwan. The tags were separately scheduled to detach after 30 days or 60 days or 8 months, after which data downloaded from satellites would provide pop-up position, and water temperature. Location and temperature data from the tags was compared to equivalent spatial and temporal data acquired from conductivity-temperature-depth casts (CTD). The longest tracking period (60 days) showed that the tagged eel experienced maximum temperatures during from 21.5°C to 26°C and minimum temperatures was from 16.5 to 24.5. Compared to the CTD data, the swimming depths of the tagged eels was estimated to be ~50 to 225 m.Overall, eels spent ~80% of their time in water less than 24.5°C. One eel tracked for three days showed evidence of diel vertical excursions suggesting they might be selecting a preferred minimum temperature rather than depth.