Analysis on stomach content of bigeye tuna (Thunnus obesus) in the eastern-central Pacific Ocean

Bigeye tuna (Thunnus obesus, BET) is one of the main target species by tuna longline. Analysis on stomach content of BET can improve understandingits feeding characteristics. Based on BET stomach samples collected from longline fishery in the eastern-central Pacific Ocean from September 2010 to January 2011, we analyzed the prey composition, diversity and feeding intensity (i.e., stomach fullness) of BET. The results show that fishes cephalopods, and crustacean were main preys of BET, with dominant prey species groups of Ommastrephidae, Sternoptychidae and Gempylidae. The feeding intensity compositions of BET were significantly different among various fork-length samples as indicated by One-Way ANOVA (P0.05). The proportion of empty stomachs in BET samples which was high, increasingalong with gonad maturity stages (empty stomach percentages were 32.7%, 38.4%, 47.5%, 50.7% and 50.7% for maturity stages Ⅰ~Ⅴ, respectively). There was no significant difference in feeding intensity composition between males and females (K-S test, P0.05). Moreover, the feeding intensity composition differed monthly (One-Way ANOVA, P0.05), with the highest stomach fullness in October and the lowest in January.