It is difficult to estimate how many American lobsters (Homarus americanus) are living in the wild. Our recent studies suggest lots of lobsters escape from lobster traps, so estimates of the size of lobster populations may be incorrect. The goal of this study was to determine the relationship between the abundance of lobsters on the bottom, determined by SCUBA divers, and the number captured in traps. We videotaped the behavior of lobsters in, and around traps. We found that lobsters readily entered and exited traps and that lobsters inside traps often discouraged others from entering. Furthermore, this past summer, we conducted similar studies with ventless traps and found that they provide much more accurate information about the lobsters on the bottom. Therefore, these ventless traps are better for collecting data that is useful for managing this species.