Abstract: For a better understanding the effects of environmental variables on catch rates of bigeye tuna (Thunnus obesus),the catch rates of bigeye tuna and environmental variables were collected in longlining surveys in waters near Cook Islands from Sept.8,2013 to Dec.31,2013.Data included:hook depth data,temperature and chlorophyll-a concentration,three-dimensional sea current vertical profile data,operating parameters and catch data.Stepwise regression was used to develop the hook depth calculation model.Statistics and clustering analysis were used to analyze the effects of environmental variables on bigeye tuna catch rate.Results showed that the depth,temperature,chlorophyll-a concentration,east-west current,south-north current,horizontal current and vertical current range with the high catch rate for bigeye tuna were 120.0～199.9 m,13.0～14.9 ℃,0.200～0.239 μg/L,0.1～0.2 m/s,-0.2～0 m/s,0.1～0.4 m/s,and 0.04～0.05 m/s,respectively.Results suggested that more hooks should be deployed in the environmental variables' range with the high bigeye tuna catch rate when fishing in the waters near Cook Islands and targeting bigeye tuna.