Four different dolphin species are well known to be associated to big yellowfin tuna's school along the Oriental Pacific Ocean such as the spotted dolphin, spinner dolphin, white belly spinner dolphin and common dolphin. From over 14000 hauls realized by the Mexican purse seine fleet this interaction was analyzed using different approaches: an univariate (factorial ANOVA), multivariate (Principal Component Analysis) and the conditional probabilities of the group; the environmental variation and the influence over the catches for 1998, 2001, 2002, 2005 and 2006.