Information on bait casting position against tori-line

Tsuji S (2019) Information on bait casting position against tori-line. In: ACAP - Ninth Meeting of the Seabird Bycatch Working Group. ACAP SBWG9 Inf 34, Florianópolis, Brazil

Corresponding to the question raised at the previous ACAP bycatch WG meeting, this document examined the data collected by the Japanese observers on location of bait hitting the water surface in relation to the tori-line. The information was collected at the time of debriefing. The analysis here only covered the data collected by the observers onboard the vessels targeting on southern bluefin tuna for the period of 2012 to 2016, corresponding to 29 cruises. Majority of vessels placed baits underneath of tori-line, while one vessel placing baits slightly upwind side, just outside the tori line, one vessel indicating the tendency to place baits just inside the tori line, and one adjusting according to the wind situation. Three boats indicated that the bait-casting machine was not used for better control on bait location. The debriefing records also contained some additional details on tori line(s) utilized and the way of their deployment, though no clear relation was found with the resulted seabird bycatch rate.