This project aims develop a method to survey the endangered marine otter (Lontra felina) in central Chile, where knowledge of its distribution and threat management remains limited. Using passive eDNA samplers (PEDS), the project will conduct coastal surveys at selected sites within and beyond the known range to identify previously undocumented populations and potential habitat linkages between northern and southern regions. The project will develop and validate a species-specific qPCR assay for environmental DNA (eDNA) detection, enabling sensitive, non-invasive monitoring of this elusive species in marine environments. We will use a low-cost and previously tested sampling approach to facilitate future monitoring efforts of this elusive species, which are currently limited by the cost and time involved. Hydrodynamic particle backtracking will be applied to interpret positive detections and infer likely source areas. Complementary community interviews will gather local knowledge of sightings and threats, helping to integrate scientific and traditional information. In addition, simple ecological covariates such as dog presence, human activity, and habitat type will be recorded to explore factors influencing occupancy. The project will therefore combine molecular, environmental, and social data to generate updated distribution maps and practical recommendations for conservation