Relatively little is known about how resource conservation practices and institutions emerge. We examine the historical emergence of territoriality and conservation rules in Maine’s lobstering industry, using a cultural evolutionary perspective. Cultural evolution suggests that cultural adaptations such as practices and institutions arise as a result of evolutionary selection pressure. The cultural multilevel selection framework of Waring et al. (Ecol Soc, 2015) further proposes that group cultural adaptations tend to emerge at a level of social organization corresponding to the underlying dilemma. Drawing on detailed history and ethnography, we conduct a retrospective assessment to determine which levels of social organization experienced selection pressures that might explain the emergence of lobstering territoriality and conservation practices we observe in history. The evidence strongly suggests that informal territoriality evolved by selection on harbor gang behavior, while some conservation practices spread via selection at other levels from individuals to regional lobstering zones. We identify two apparent historical shifts in the dominant level of selection for these practices over the history of the industry and discuss the implications of this trajectory for the evolution of lobster management in the Gulf of Maine.