Pacific Tuna Tagging Project, Phase 2 (Central Pacific) cruise CP-12, first leg: 9th September to 14th October 2016 Summary report.

Leroy B, Vanden Heuval B, Forget F (2016) Pacific Tuna Tagging Project, Phase 2 (Central Pacific) cruise CP-12, first leg: 9th September to 14th October 2016 Summary report.

The Central Pacific (CP) tagging cruises are part of the Pacific Tuna Tagging Programme (PTTP) that started in August 2006 with the objective of releasing tagged tropical tunas throughout the WCPO and concentrated in the latitudes where the tuna stocks are mostly harvested, approximately 10⁰ N to 10⁰ S. These CP cruises were designed to catch and tag tuna in areas where pole-and-line fishing gear is not efficient due to the absence of suitable bait grounds. Using specific trolling gears developed in Hawaii and initially targeting the NOAA TAO oceanographic buoys anchored east of the International Date Line, and more recently drifting Fishing Aggregating Devices (dFADs), the CP tagging cruises have improved the overall spatial coverage of PTTP tag releases and increased the number of tagged bigeye tuna that are not commonly caught by pole-and-line gear in the western part of the WCPO.
Eleven CP cruises have already been conducted, using Hawaii and Tonga-based fishing vessels; close to 38,000 tuna have been tagged and released, mostly bigeye (90%), on the TAO buoys anchored along the meridians 140⁰W, 155⁰W, 170⁰W and 180⁰W and between 5⁰N and 5⁰S.
This report summarizes activities during the 35 days of a twelfth CP cruise, named hereafter CP-12, on the Hawaii-based FV Gutsy Lady 4. This longline vessel was chartered for the second time but the same captain previously had the charter for Hawaii based CP cruises CP3, CP4 and CP7 on his old vessel, FV Ao Shibi Go.
Following the CP-11 experiment, CP-12 was designed to augment data collection for studies on tuna movements, exploitation rates and FAD association dynamics. In an attempt to cover the gap in bigeye tuna tagging data in the west part of the WCPO (west of the 180 meridian), the study area was selected to cover the 165E and 156E TAO mooring lines and the nearby waters.
This cruise was primarily funded by the European Union, SPC and International Seafood Sustainability Foundation (ISSF). Tri Marine International also supported the cruise by allowing for the participation of a scientist and by providing positions of drifting FADs in the neighbourhood of the cruise. South Pacific Tuna Corporation also agreed to providing positions of nearby FADs but it was not possible to visit these due to logistical constrains.

Note - see experiment as follows:
Pressure sensitive acoustic tags were implanted in tuna (SKJ, YFT, BET) and non-tuna species (silky shark: FAL, oceanic trigger fish: CNT and rainbow runners: RRU (see picture 4). The aim of this experiment was to:
1. Collect simultaneous vertical behavior of tuna and non-tuna species at dFADs in order to improve the interpretation of the echo sounder buoy data.
2. Collect data on the associative behavior of tuna and non-tuna species at dFADs to estimate residency at FADs and determine species specific vulnerability during the day at dFADs.