2. Data2.1. Tag-recapture dataAs part of the RTTP-IO, large numbers of YFT, BET and SKJwere tagged in the western Indian Ocean, primarily off Tanzania(Fig. 1), between May 2005 and August 2007. Additional taggingalso occurred in the eastern Indian Ocean as part of small-scaletagging operations, including extensive tagging of SKJ and YFT offthe Maldives in 2004 and 2007–2009. In total, over 63 000 YFT,35 000 BET, and 100 000 SKJ were tagged as part of the RTTP-IO andsmall-scale tagging operations, collectively known as the IndianOcean Tuna Tagging Programme (IOTTP). Recaptures occurred sub-sequently in commercial fisheries operating in the Indian Ocean(Fig. 1). To date, the percent of tag returns has been approximately16% for each of the three species. More details of the tagging andrecovery operations can be found in Hallier (2008) and Hallier andFonteneau (this volume).