With more hatchlings to come, SCCF’s sea turtle team has documented a total hatchling to sea count of 29,627 hatchlings during the 2026 record-breaking nesting season. 

With nearly 1,200 nests on Sanibel and Captiva, a total of 29,116 loggerhead (Caretta caretta) and 511 green (Chelonia mydas) hatchlings account for nest productivity so far this season, which ends on Oct. 31.

“Nest productivity is one measure of a nesting season’s success. This can simply be thought of as the number of hatchlings that successfully make their way to the ocean,” says Sea Turtle Biologist Jack Brzoza.

This count indicates the number of eggs per nest that successfully hatched and produced hatchlings. Combining counts for each monitored nest gives an overall hatchling count and an indication of nest success and productivity for the entire surveyed beach.

RELATED STORY: Sea Turtle Hatchling Counts [in 2023] Lowest Since 2016

From Laid Egg to Emerging Hatchling

But going from an egg being laid to a fully formed sea turtle hatchling emerging takes a lot of time and a particular microclimate inside an egg within a nest.

Within hours after a sea turtle egg is laid, embryonic development that initially started inside the oviduct of a nesting female resumes. During the first several weeks, extraembryonic membranes develop around the embryo.

“These membranes anchor the developing turtle inside the egg, providing stability and the means for nutrient and gas exchange and waste storage,” says Brzoza. “The yolk sac supplies the energy and nutrients needed for growth throughout incubation.”

For approximately 45-60 days, the eggs exchange heat, water, and gases such as oxygen (O₂) and carbon dioxide (CO₂) with the surrounding beach. These exchanges vary as the embryo develops and its metabolic needs increase, and it produces or requires more gases and heat.

Incubation temperature also influences the rate of development and, as for many other reptiles, plays a critical role in determining the sex of a hatchling sea turtle.

Near the end of incubation, the hatchling has developed most of its major structures and absorbs the remaining yolk, which provides stored energy for the beginning of its life outside the egg. The hatchling then uses a temporary structure called a caruncle, or egg tooth, to break through the eggshell in a process known as pipping.

Emerging from the Nest

Pipped hatchlings may remain inside their eggs while others hatch around them. Their combined movements disturb and loosen the surrounding sand, allowing the group to gradually move upward through the nest chamber and eventually emerge, most often at night, to head toward the ocean.

“Several days after this emergence occurs, our monitors are permitted to inventory the nest, determining how many eggs were laid and how many produced a hatchling,” he says. “Hatchling production is one important piece of the puzzle in the road to population recovery.”

The ultimate goal for any nesting beach is a high number of highly productive nests, which can be thought of as a high number of emerged hatchlings.

Many environmental factors can disrupt embryonic development and reduce hatchling production, such as predation, tidal washovers and washouts, and rising temperatures.

“As a long-lived species with low survival rates — especially for hatchlings — nests producing a high number of hatchlings are important in ensuring that nesting populations are replacing themselves over time,” says Brzoza.

At the end of the nesting season, the sea turtle team will determine overall hatch success rates for loggerheads and greens on Sanibel and Captiva.

Check out our August Coastal Wildlife Tracker for the latest update on predation and washouts this season.