Citizen Science Facilitates Reporting of Reef Fish Species’ Ecological Health Indicators in the Great Barrier Reef, Australia

A collaborative learning approach between citizen scientists, experts and managers transformed metrics of coral reef fish biodiversity into indicators for use in regional waterway health report cards. We tested a citizen science tool, iNaturalist, to identify species and monitor annual changes in fish biodiversity at a regional scale in the Great Barrier Reef, Australia. The participation of almost 1000 citizen scientists between 2013 and 2025 resulted in 13,131 research grade observations of 684 species of fish. Annual biodiversity data from three years (2023–2025) was compared to 10 years of baseline data (2013–2022) and calibrated for effort. Report cards scores for fish ecological health were generally ‘very good’ to ‘good’ and we conclude that a citizen science methodology is potentially suitable for fish ecological health at multiple spatial and temporal scales.