MPA Guardian is a crowdsourcing tool that allows citizens to submit reports of damaging, illegal, or otherwise concerning activities they observe in marine reserves through a website or smartphone apps. These reports can help document issues and ensure the protected areas stay healthy for future generations. The system integrates low-cost technology solutions to improve observation and data collection on illegal fishing from official and public sources, enabling action to stop this destructive activity through a central web-based hub that captures and analyzes vessel and area data.