Transhipment observers – a tool for understanding seabird bycatch mitigation measures use on high seas tuna longline vessels

Augustyn PH, Wanless RM (2018) Transhipment observers – a tool for understanding seabird bycatch mitigation measures use on high seas tuna longline vessels. In: IOTC - 14th Working Party on Ecosystems and Bycatch. IOTC-2018-WPEB-44_Rev1, Cape Town, South Africa

Understanding the extent of use of the various combinations of seabird bycatch mitigation measures required in IOTC Resolution 12/06 is an important part of meeting the challenge to reduce seabird bycatch to negligible levels. Self-reporting of use of seabird bycatch mitigation measure by fleets is variable across countries, and carries no burden of evidence. Therefore, BirdLife International through its partner BirdLife South Africa, under the FAO’s Common Ocean tuna project, undertook an assessment of two readily-available sources of data to indicate use of bird scaring lines (BSL) and night setting by vessels that transhipped tuna in the IOTC area. Images from transhipment observers were evaluated for presence and likely suitability of ‘tori poles’ to indicate whether a Best Practice BSL, or a line that could meet the performance specifications for aerial extent in Res 12/06, could be deployed. We also evaluated likely use of night setting requirements based on logbook entries for setting times. Only vessels actively fishing in waters south of 25°S were evaluated. We estimate that of 119 high seas vessels assessed, ca a third had tori poles that could support an effective BSL. Of 117 vessels assessed for night setting, the data indicated that only 11% of vessels had consistent use of night setting. While these results point to very low levels of use of effective seabird bycatch mitigation measures, they should be interpreted with caution due to the challenges in analysing images that were not originally intended to be used for the purposes that we report here. However, despite the fact that it was not possible to determine use of line weighting in this study, our most optimistic evaluation is that at best one third of high seas vessels fishing south of 25°S consistently use two seabird bycatch mitigation measures. However, while we do not report on use of these measures by fishing entity, there are large differences, with vessels of certain fishing entities showing very high levels of both likely effective BSL use and night setting, and others showing very low levels. Despite some limitations, this pilot has identified there are clear opportunities for RFMOs to use transhipment observers, including through photographs, to check compliance with conservation measures for seabird bycatch mitigation. A draft report on this work will be presented to IOTC following discussion at WPEB 2018.