As fisheries management is increasingly required to consider the full impacts of their operations, this work seeks to define the relationship between fishing effort and interactions with listed endangered species. The study employs logbook data containing over 64,000 sets, matched with observer data from 2008 to 2015 in an undisclosed purse seine tuna fishery. Specifically, we estimate a series of family specific, negative binomial models to account for over-dispersed outcomes, while controlling for factors such as the use of fish-aggregating devises, set location, proximate coastline, season, and water temperature. The study results show statistically significant relationships between observed interactions with endangered species and fishing effort, as well as with other independent variables. The results of the study suggest that the approach can be used to assess the probabilities of relatively rare interactions between fisheries and endangered species, or with other species of particular concern.