An ethnobiological survey of 174 local resource users was conducted in the Lower Sanaga Basin to assess the current conservation status of West African manatee (Trichechus senegalensis, Link 1795) within lakes, rivers, and coast (including mangroves, estuaries and lagoons). Using a multistage sampling design with semi-structured interviews, the study asked three main questions: (i) are manatees still present in Lower Sanaga Basin? (ii) If present, how are their numbers evolving with time? (iii) What are the main threats facing the manatee? Each of these questions led to the formulation and formal testing of a scientific hypothesis. The study outcome is as follows: (i)60% of respondents sighted manatees at least once a month, regardless of habitat type (rivers, lakes, or coast) and seasons (dry, rainy, or both); (ii) depending on habitat type, 69 to 100% of respondents perceived the trend in manatee numbers as either constant or increasing; the increasing trend was ascribed to low kill incidence (due either to increased awareness or lack of adequate equipment) and to high reproduction rate; and (iii) catches (directed or incidental) and habitat degradation (pollution) ranked in decreasing order as perceived threats to manatees. The catch incidence is threefold larger on lakes than in rivers and more adult manatees are caught than juveniles. Pollution occurs in several places by fishing enterprises, industrial plantations and individuals. The perceived incidence of boat collisions is presently negligible compared to catches and habitat degradation. A twelve-point strategy is set forth for improving manatee conservation in the study area.