Becoming a Protected Species Observer (PSO) is an exciting and important role for those passionate about marine conservation. As a PSO, your main responsibility is to monitor and mitigate the impact of human activities on marine protected species. This can involve working on various projects such as seismic operations, offshore wind farms, and marine construction projects. In this article, we will explore the requirements, responsibilities, and techniques used by PSOs, as well as the importance of population size estimation and photo-identification in marine research.