In-Water Surveys

Since 2003, STCB has been conducting standardized in-water surveys and tagging programs to gather information on sea turtles in the waters surrounding Bonaire. These efforts provide valuable data over time to help us determine growth rates of sea turtles and estimate abundance, movement patterns and the health status of Bonaire’s resident turtles.

Tagging Program

When you see a turtle with a tag on its front flipper, it’s a sign that important information is being gathered. Research is a foundation of effective conservation, and each year STCB staff carefully capture, tag, weigh and measure approximately 250 turtles. Each turtle is checked for signs of injury and disease, then gently released where it was captured. It is arduous work, but over time the data gathered help us determine local trends in growth rates, the health status of our resident turtles, their movement around Bonaire and estimations of turtle abundance.

In 2003, we established standardized methods for the in-water survey and tagging program, and, as of November 2023, have tagged well over 4200 turtles.

What have we learned?


We have learned that green turtles at Lac (a large, shallow lagoon on Bonaire’s east coast) show much higher growth rates than those of turtles in the rest of the Caribbean. Lac green turtles are showing an annual average growth of 8 centimeters (3 inches), compared to an average of 3 centimeters (1.2 inches) per year in the wider Caribbean region.

This remarkable difference in growth rates underscores the exceptional ecological importance of Lac. A wide range of data will need to be collected and analyzed so that we may better understand what makes Lac such an outstanding habitat for growth while at the same time harboring a severe turtle disease (fibropapillomatosis). Only then will we be able to develop a management plan that can be used to promote optimum conditions. In the meantime, STCB is protecting habitat at Lac that is threatened by increasing human use.

  • Freediving Courses

    During our capture sessions, including the west coast, Lac Bay and outside Lac, we use freediving skills to capture sea turtles so we can collect the data. Our staff and trained volunteers are certified freedivers. They have completed the freediving course with Blue Classroom Bonaire. This course is to aim on how to best support STCB staff or trained volunteers when conducting capture research and how to ensure their safety above and below water.

    We would like to thank Blue Classroom Bonaire for teaching us all about freediving and safety!

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RSIN: 8240.89.297 | KvK: 7167