Survey reveals thriving turtle population at Agincourt Reef

23rd of March 2026

Pictured: Marine biologist Heather Platt with Charli the green sea turtle

A large population of juvenile green sea turtles is thriving at Quicksilver’s Agincourt Reef (AG3) platform, with ongoing research revealing the site is an important habitat for young turtles.

Marine biologist Heather Platt, Quicksilver’s Reef Biosearch Manager, said they have been conducting research into the resident turtle population for over 12 months using photo identification techniques. 

37 individual immature green turtles have now been identified with a total of 339 sightings recorded through a combination of targeted surveys and citizen science contributions.

The findings highlight the ecological importance of the AG3 area for feeding, residence and transit of juvenile turtles.

“All of our documented turtles are immature, which tells us Agincourt Reef provides an ideal environment for their juvenile years,” said Ms Platt.“ As the study continues, we’re hoping to better understand how long these turtles remain here before moving on to other parts of the reef.”

Among the growing catalogue of turtles, Little Foot has emerged as the most frequently sighted individual, followed by Jasper. Others, like T-Bone, appear to be more transient - disappearing from the survey area for months at a time before returning to the platform.

Long-term monitoring has also provided insights into a young turtle’s healing journey.

“The ‘OG’ of our turtle survey, Charli, (first identified in 2023) appears to be doing very well after being sighted with a significant carapace injury in July 2024. We’ve been able to document his/her healing journey throughout the months that followed. Sighted in recent weeks, you'd almost never know the injury had occurred.” 

Guests spending the day with Quicksilver are encouraged to submit their turtle photos to assist the Reef Biosearch team in monitoring the population.

Each turtle is identified by their unique pattern of facial scales, which remain consistent throughout their lifetime. During in-water snorkel surveys, both images and video are captured to accurately distinguish individuals, assigning each turtle an alphanumeric ID alongside any nicknames.

The data collected in the turtle survey is contributing to broader conservation efforts, with records shared with the Sea Turtle Observatory to support population tracking along the Queensland coast. This collaboration increases the likelihood of identifying these turtles again at future feeding or breeding sites across the Great Barrier Reef.

The research forms part of Quicksilver’s ongoing site stewardship which focuses on monitoring reef health and protecting the rich marine biodiversity of this globally significant ecosystem.

Green Sea Turtles

• Six of the world’s seven species of marine turtles are found on the Great Barrier Reef with the green turtle (Chelonia mydas) being the most abundant. Primarily feeding on seagrass and algae, they are a crucial part of the marine ecosystem.
• Generally, green sea turtles reach maturity between 30-50 years of age. An adult green turtle will have a straight carapace (shell) length of 65-90 cm. The green turtles identified at the Agincourt 3 platform site mostly range between 45-55 cm. 

Agincourt Reef 3 is located on the Great Barrier Reef, about 40km off Cape Tribulation along the outer edge of Australia’s continental shelf in a sheltered reef lagoon – a 90 minute fast catamaran journey from Port Douglas with Quicksilver.

Reef Biosearch is the Quicksilver Group’s pioneering environmental division. Founded in 1986, the team has over 20 university educated marine biologists who join our reef tours from Port Douglas and Cairns combining tourism, education, conservation and research.