Elasmobranchs typically occupy higher trophic levels in food webs and, consequently, have a propensity to accumulate high organochlorine contaminant (OC) concentrations. However, not all sharks accumulate the same types of contaminants or at the same rate, making use of OCs a potential ecological tool. Bioaccumulation with respect to ontogeny was examined among three species of pelagic sharks (Shortfin Mako Isurus oxyrhincus, Common Thresher Alopias vulpinus, and Blue Shark Prionace glauca) that have varying diets and life history characteristics. Using recently collected and archived tissue from sharks caught in southern California, an area known for high contaminant levels, organic contaminants (polychlorinated biphenyls and chlorinated pesticides) were measured in livers of both females and males from a range of size classes for all species. Significant differences were found in OC concentrations among species and by size. In addition, random forest analysis was able to distinguish species based on their contaminant signatures with a high degree of accuracy. The results of this study suggest that foraging ecology and species-specific life history characteristics impact the accumulation of organic contaminants.