Fish aggregating devices (FADs) and other floating objects (OTHs) are used in tuna purse seine fishing because they are effective in attracting tunas. The objective of this study was to describe the fish species associated with FADs and OTHs in the Eastern Indian Ocean. A total of 25 FADs were deployed during fishing surveys in March-May 2012 and March-April 2013 operated by FRV Mahidol. Fifteen deployed FADs were tracked and observed, and three OTHs with fish schools were found and recorded during the fishing surveys. A total of 15 species of fish, including three species of cartilaginous fish and 12 species of teleost fish were recorded through visual census technique, trolling line and purse seine fishing around FADs and OTHs. For tuna species, skipjack and yellowfin tunas were found around FADs and OTHs at similar frequency of occurrence, while bigeye tuna was found only around FADs. Results revealed that there was no statistically significant difference in taxa richness or frequency of occurrence of 11 species of fish between FADs and OTHs. This study demonstrated that FADs and OTHs can be used to attract tunas and also other fish species in the Eastern Indian Ocean. Among the 15 species of fish, silky shark and devil ray were considered as non-target species, which are listed on Appendix II of CITES. The findings of this study could support the establishment of subsequent conservation and management measures of the Indian Ocean Tuna Commission in reducing the impact of bycatch through the efficient use of FADs in the tuna purse seine fishery in the Indian Ocean.
Keywords
Fish aggregating device, Other floating object, Tuna purse seine, Indian Ocean, Fish species