The baited hoop-net is one of the most heavily used sampling tools for monitoring freshwater turtle populations. In the past several years, we have published a series of studies that tested potential biases associated with this sampling method. For this paper, we used a new experiment to directly test the influence of trap-mouth opening size on both captures and escapes. We also summarized the results from previous studies to direct future research on this topic and provide a useful guide for managers and researchers using this sampling device. In our experiment during May 2013 in Texas, USA, we found that traps with larger mouth-openings were more efficient at capturing turtles, while escapes were minimal for both mouth sizes. Thus, at least within the boundaries we tested here, increasing mouth-opening size is an effective way to increase captures without introducing biases caused by differential escape probabilities. © 2014 The Wildlife Society.