To understand the sea turtle and seabird bycatch of Taiwanese tuna longline fleets for conservation purposes, this research analyzed the data collected by onboard observers between 2008 and 2013. In total, data from 149 trips and 24.3 million hooks were analyzed, including 50 albacore large-scale tuna longline vessel (LTLVs) trips, 72 bigeye LTLVs trips, and 27 small-scale tuna longline vessel (STLVs) trips. Seabird bycatch was mostly from the albacore LTLVs.