Resource sustainability requires recognizing and developing pathways to integrate local and Indigenous knowledges alongside conservation and sustainability sciences within management practices and governance. However, knowledge never occurs in a vacuum and is always mediated by the beliefs, values, or stances towards its possession or use within particular contexts. Focusing on the unprecedented renewal of a traditional practice of natural resource management in French Polynesia called rāhui, this article investigates the local conceptions, perceptions, and expectations (CPE) which mediate between community knowledges, plans, and actions, and inputs from conservation and sustainability sciences. Drawing on a multi-year ethnographic study focused on the CPE of two coastal communities around Tahiti's Taiarapu coast, our results show that the CPE which shape relationships between conservation sciences' inputs toward decision and policy-making and community governance and management over nearshore marine resources can differ meaningfully. Moreover, we suggest that evidence of such differences despite socioeconomic, cultural, or demographic similarities indicates that the specificities of local communities' CPE around conservation and sustainability sciences should be carefully considered before and alongside any conservation or management action.