Bycatch records of sea turtles obtained through Japanese Observer Program in the IOTC Convention Area

This document overviewed sea turtle bycatch occurred in the IOTC Convention Area obtained through Japanese Observer Program. The fishing areas covered in IOTC and CCSBT from 2010 to 2015 and 1992 and 2015, respectively. In total, 28 and 4 million hooks were observed by on-board observers for shallower-set and deeper-set longlines, respectively. Geographical distribution of bycatch changed not only among set types but also among species. Olive ridley occurred the most frequently in the bycatch data, followed by loggerhead and leatherback. There were no observations of green, hawksbill and flatback turtle in those data. Almost all the loggerheads were by-caught around the South African waters by shallower-sets. No olive ridley was caught in the south of 20o S. Leatherbacks were caught around South African and equatorial waters by both set types. Bycatch rate (per 1,000 hooks) of shallower-sets for leatherback, loggerhead, olive ridley, and unidentified turtle were 0.00009, 0.0003, 0, and 0.0001, respectively. Mean bycatch rate of deeper-sets were 0.001, 0.0003, 0.011, and 0.012 for leatherback, loggerhead, olive ridley, and unidentified turtle, respectively.