New study showcases how citizen science can bridge fish health data gaps on the Great Barrier Reef

A promising study led by Reef Ecologic in collaboration with the Healthy Waters Partnership has unveiled a new method to monitor fish diversity using citizen science data, strengthening reef health reporting for the Townsville Dry Tropics.

The Hook: why it matters

Fish are the backbone of marine ecosystems, supporting food security, tourism, and cultural values. Robust fish populations, important for fisheries, are a key goal of the Reef 2050 Plan.

While there is some data on commercially valuable species, the Great Barrier Reef is home to more than 1,600 species. Many of these play vital roles in reef health yet remain largely unmonitored.

Wheeler Reef (2017), showcasing a healthy reef with diverse fish species. Photo: Jo Hurford

“Reef managers rely on rigorous and robust ecosystem-wide data to make informed decisions,” explains co-author and Executive Officer for the Healthy Waters Partnership, Kara-Mae Coulter-Atkins. “Understanding marine fish diversity is essential.”

“This knowledge may shape protective regulations, sustainable fishing practices, habitat preservation, and community involvement,” said Kara-Mae.

In the Partnership’s annual Waterways Report Card, fish health data is only measured for freshwater zones at the basin level. That leaves estuarine and marine areas unknown.

“Citizen science gives us a way to fill this critical data gap and deepen our understanding of ecosystem health in the Townsville Dry Tropics,” continued Kara-Mae.

The Backbone: citizen science in action

To address the data gap, Reef Ecologic, who champion citizen science across the Great Barrier Reef, turned to iNaturalist. The global biodiversity platform allows everyday ocean enthusiasts to upload fish observations. Verified sightings become research-grade data, offering scientists a powerful tool to track species richness in different areas.

The number of species in a location can be used as a health check for a reef. The more species seen, the stronger and more resilient the ecosystem.

An underwater photographer can become a citizen scientist by uploading photos to iNaturalist. Photo: Matt Curnock

Catch of the Day: a new indicator

The team, which also includes the Partnership’s Environmental Data Analyst Adam Shand, adapted the method used for the freshwater fish indicator, the POISE (Proportion of Indigenous Species Expected) approach, and applied it to estuarine and marine zones in the Townsville Dry Tropics Waterways Report Card. This metric compares observed species in a given timeframe and area to a baseline dataset (2013–2022), providing a snapshot of fish diversity.

Key Findings:

• 472 fish species recorded during the baseline period.

• Grades based on POISE and sampling effort across Cleveland Bay, Halifax Bay and the offshore marine zone:

  • B (Good) for 2023 and 2024

  • A (Very Good) for 2025*

• Results align with the Great Barrier Reef Marine Park Authority’s Outlook Report rating of ‘good’ for bony fishes.

  
  

* Note: Each grade reflects data collected over a 12-month period ending in June of the previous year.

Reeling in the Future: what’s next?

The proposed methodology now awaits review by a technical working group and an independent science panel. Once approved, it could be rolled out across four other Report Card Partnerships, expanding its impact along the Great Barrier Reef.

“The study shows the incredible power of citizen science,” said Kara-Mae. “It bridges critical data gaps, strengthens collaboration between communities, scientists, and government, and builds a culture of stewardship for our marine ecosystems.”

Cast your net wider and get involved

• Read the paper, involving our Partner’s Reef Ecologic and TropWATER:

  • Smith, A.K.; Jefferies, J.; Gordon, I.J.; Coulter-Atkins, K.-M.; Shand, A.; Turton, S.M. Citizen Science Facilitates Reporting of Reef Fish Species’ Ecological Health Indicators in the Great Barrier Reef, Australia. Fishes 2025, 10, 547. https://doi.org/10.3390/fishes10110547

• Become a citizen scientist, upload your fish sightings to iNaturalist and contribute to reef health monitoring.

• Dive in and support other citizen science projects in the Townsville Dry Tropics that are helping to improve the health of our rivers, creeks, and coasts.