Summary of Research Activities and Results of the International Seafood Sustainability Foundation’s (ISSF) Second Bycatch Project Cruise WCPO-2 in the Western Central Pacific Ocean (WCPO)

Empirical and observational data were collected from 45 sets made from the Cape Finisterre, a U.S. flagged tuna purse seine vessel during the International Seafood Sustainability Foundation’s (ISSF) Western Central Pacific Ocean (WCPO)‐2 bycatch mitigation research cruise. Three researchers were hosted on a ride‐along style research trip and conducted experiments opportunistically on a 42 day voyage originating from Pago Pago, American Samoa. Sampling was completed on a total of 37 fishing days prior to the July 1st FAD closure and four days of free school fishing. Initially, it was desired that a selective release mechanism similar to the net panel design from the ISSF’s WCPO‐2012 bycatch cruise be tested, but due to a mechanical failure in the net yard, the net was not modified in time for the cruise. Nevertheless, observations of sharks and other bycatch in the net were made on most sets to determine if the spatial distribution of these animals was consistent. The objective was to determine the most appropriate placement of a release panel in the future. Visual observations using SCUBA and snorkel in the net were made to assess several areas of interest: 1) if sharks and other bycatch were consistently located in one area of the net, and if these animals could be selectively released, 2) natural behavior of bigeye, yellowfin, skipjack and bycatch species in the net to assess if behaviors occurred consistently and for what duration. Overall, there was a lower occurrence of silky sharks observed and caught (average of 2.3 sharks/set) as compared to the WCPO‐1 cruise (average of 9.5 sharks/set). Generally, catch rates of bony fish bycatch were also less than the WCPO‐1 cruise. Proportion of bigeye catch appeared to be higher than the WCPO‐1 cruise, which may be attributed to the location of the 1st 20 days of the cruise in and around the Line Islands, on the far eastern margin of the WCPO. BIA sampling was conducted on skipjack (n=1,057) to assess condition factor of dFAD vs unassociated skipjack, analysis of this work is still in progress. One whale shark was caught and released, but due to logistical challenges we were unable to deploy a pSAT tag in the animal. There were several ancillary projects including assessing skipper satisfaction and collecting comments about ISSF’s FADtrack software, net depth data collection, and documentation of unassociated schools once encircled in the net. Finally, we conducted genetic, isotope, and oral bacteria sampling on some or all of the following species: skipjack, yellowfin, bigeye, silky shark, oceanic triggerfish, rainbow runner.