Abstract: Endangered aquatic species face greater survival challenges than their terrestrial counterparts under increasing pressures from global climate change and human activities in marine and freshwater ecosystems. Accurate data on population size, density, distribution, and dynamics are critical for effective conservation, yet traditional field surveys suffer from limitations such as high labor demands, subjective biases, and low efficiency due to the rarity and cryptic nature of these species. Moreover, conventional methods often disturb both target organisms and their habitats. Environmental DNA (eDNA) technology addresses these challenges by detecting species-specific DNA fragments in water samples, enabling non-invasive monitoring of presence, distribution, and abundance. This review examines eDNA applications for tracking endangered aquatic species, including population distribution, abundance, biomass, and life-history traits, while outlining the technical workflow, key steps, and current limitations. The discussion aims to advance both methodological and theoretical frameworks for conserving these vulnerable or endangered species.

Key words: Environmental DNA, Endangered aquatic animals, Population monitoring, Technical process, Influencing factors